Chapter 21. Harmonic Analysis

Transcription

1 Chapter 21 Harmonic Analysis Because of the wide and ever increasing applications of power electronic devices, such as variable speed drives, uninterruptible power supplies (UPS), static power converters, etc., power system voltage and current quality has been severely affected in some areas. In these areas components other than that of fundamental frequency can be found to exist in the distorted voltage and current waveforms. These components usually are the integer multipliers of the fundamental frequency, called harmonics. In addition to electronic devices, some other non-linear loads, or devices including saturated transformers, arc furnaces, fluorescent lights, and cycloconverters are also responsible for the deterioration in power system quality. Operation Technology, Inc ETAP PowerStation 4.0

2 Introduction The presence of harmonics in a power system can give rise to a variety of problems including equipment overheating, reduced power factors, deteriorating performance of electrical equipment, the incorrect operation of protective relays, interference with communication devices, and in some cases, circuit resonance to cause electric apparatus dielectric failure and other types of severe damage. Even worse, harmonic currents generated in one area can penetrate into the power grid and propagate into other areas, resulting in voltage and current distortions for the entire system. This phenomenon has become a major concern for power quality due to the ever-increasing usage of electronic devices and equipment in power systems. Using computer simulation, the phenomena of power system harmonics can be modeled and analyzed. The PowerStation Harmonic Analysis program provides you with the best tool to accurately model various power system components and devices to include their frequency dependency, non-linearity, and other characteristics under the presence of harmonic sources. This program has two analytical methods, Harmonic Load Flow and Harmonic Frequency Scan, which are the most popular and powerful approaches for power system harmonic analysis. By using those two methods in combination, different harmonic indices are computed and compared with the industrial standard limitations, existing and potential power quality problems, along with security problems associated with harmonics, can be easily revealed. Causes to those problems can be identified and different mitigation and corrective schemes can be tested and finally verified. Some of the main features of the PowerStation Harmonic Load Flow Study are summarized below: Common & Integrated Database Fully Inherited 3-D Data Structure, Including Infinite Presentations, Unlimited Configurations, & Multiple Data Revisions Looped, Radial, or Combined Systems Systems with Multiple Swing Buses Systems with Isolated Sub-Systems Systems with Zero Impedance Branches (Tie Circuit Breakers) Systems with De-Energized Buses & Branches Automatic Adjustment of Cable/Line Resistance According to Operating Temperatures Automatic Adjustment of Transformer Impedance According to Tolerance Automatic Adjustment of Current Limiting Reactor Impedance According to Tolerance Multiple Loading Categories Load Diversity Factors Complete Fundamental Load Flow Calculation Automatic LTC Settings for Fundamental Load Flow Modeling of Frequency Dependency of Rotary Machine Impedance Modeling of Non-linearity & Frequency Dependency of Cable/Line & Transformer Impedance Modeling of Frequency Dependency of Other Power System Components & Loads Effect of Transformer Phase Shifting to Harmonic Flow Effect of Machine & Transformer Winding Connections & Grounding Types to Harmonic Flow Harmonic Current Injection Method Positive, Negative, & Zero Sequence Harmonics Harmonic Order up to 73 rd Harmonic Voltage Source Harmonic Current Source User-Expandable Harmonic Source Library User-Selected Harmonic Source Inclusion by Device Categories Operation Technology, Inc ETAP PowerStation 4.0

3 Introduction Calculation of Various Harmonic Indices Based on IEEE Standards Total RMS Value (RMS) for Both Bus Voltages & Branch Currents Total Arithmetic Summation Value (ASUM) for Both Bus Voltages & Branch Currents Total Harmonic Distortions (THD) for Both Bus Voltages & Branch Currents Telephone Influence Factors (TIF) for Both Bus Voltages & Branch Currents I*T Product for Branch Currents Built-in Harmonic Filters in Different Types Automatic Filter Sizing Based on Different Criteria Check and Flag Filter Overloading Verifying Performance of Harmonic Filters Graphic One-Line Display of Study Results Slider Bar to Display Fundamental Load Flow, Total & Individual Harmonic Distortion Graphic Plots of Voltage & Current Waveform for Viewing & Printing Graphic Plots of Voltage & Current Spectrums for Viewing & Printing Text Report for Input Data, Fundamental Load Flow Results, Voltage & Current Harmonic Indices, Tabulated Voltage & Current Harmonic Crystal Reports for Preformatted Reports Flag Violations of Bus Total & Individual Harmonic Distortion Limits Some of the main features of the PowerStation Harmonic Frequency Scan Study are summarized below: Same System & Component Modeling Capabilities for Harmonic Load Flow & Fundamental Load Flow Modeling of Frequency Dependency of Rotary Machine Impedance Modeling of Non-linearity & Frequency Dependency of Cable/Line & Transformer Impedance Modeling of Frequency Dependency of Other Power System Components & Loads Transformer Phase Shifting Machine & Transformer Winding Connections & Grounding Types Built-in Harmonic Filters in Different Types Automatic Filter Sizing Based on Different Criteria User-Definable Frequency Scan Range & Step Graphic One-Line Display of Study Results Slider Bar to Display Bus Driving Point Impedance Magnitude & Phase Angle at Selected Frequencies Graphic Plots of Bus Driving Point Impedance in Ohms for Viewing & Printing Graphic Plots of Bus Driving Point Impedance Phase Angle for Viewing & Printing Text Report for Input Data, Fundamental Load Flow Results, Tabulated Bus Driving Point Impedance Magnitudes & Phase Angles Operation Technology, Inc ETAP PowerStation 4.0

4 Study Toolbar 21.1 Study Toolbar The Harmonic Analysis Study Toolbar will appear on the screen when you are in the Harmonic Analysis Study mode. This toolbar has eight function keys as shown below. Run Harmonic Load Flow Run Frequency Scan Display Options Report Manager Harmonic Analysis Plots Halt Current Calculation Get On-Line Data Get Archived Data Run Harmonic Load Flow Select a study case from the Study Case Toolbar when you are in Harmonic Analysis Study mode. Click on the Run Harmonic Load Flow button to perform a harmonic load flow study. A dialog box will appear for you to specify the output report name if the output file name is set to Prompt in the Output Report list box. The harmonic load flow study results will appear on the one-line diagram and can be viewed in output report text and plot formats after the calculation completes. Run Frequency Scan After selecting a study case from the Study Case Toolbar, click on the Run - Frequency Scan button to perform a harmonic frequency scan study. A dialog box will pop up asking you the output file name if Prompt is set in the Output Report list box. As in the harmonic load flow study, study results are displayed on the one-line diagram and can be viewed in output report text and plot formats after the calculation completes. Display Options Click on the Display Options button to customize the one-line diagram annotation display options under the Harmonic Analysis Study mode. See Display Options for more information. Report Manager Click on the Report Manager button to select a format and view harmonic analysis output report. Harmonic analysis reports are provided in two formats: ASCII text files and Crystal Reports. Operation Technology, Inc ETAP PowerStation 4.0

5 Study Toolbar The Report Manager provides four pages (Complete, Input, Result, and Summary) for viewing the different parts of the output report for both text and Crystal Reports. Available formats for Crystal Reports are displayed on each page of the Report Manager. Choosing any format other than TextRept in the Report Manager activates the Crystal Reports. You can open the complete harmonic analysis report or just a part of it, depending on the format you choose. The preformatted Crystal Reports names are: Branch Bus Cable Complete Cover Filter Overloading Filter HA Source Harmonic Library Harmonic Source Impedance Line Load Flow Report Machine Reactor Results Summary Transformer UPS VIHD Report VTHD Report You can also select output files from the Output Report list box. Operation Technology, Inc ETAP PowerStation 4.0

6 Study Toolbar This list contains all the output files in the current project folder with the same file extension specified. To change output file extensions, you can click on the List Output Reports button next to the Output Report list box, which will allow you to select a different output file extension. The output reports for harmonic load flow studies have an extension of.har. PowerStation text output reports can be viewed by any word processor such as Notepad, WordPad, and Microsoft Word. Currently, by default, the output reports are viewed by Notepad. You can change the default viewer in the ETAPS.INI file to the viewer of your choice. Refer to Chapter 1 for detailed information on changing the INI file. The text output reports are 132 characters wide with 66 lines per page. For the correct formatting and pagination of output reports, you MUST modify the default settings of your word processor application. For Notepad, WordPad, and Microsoft Word applications we have recommend settings that are explained in the Printing & Plotting chapter. Operation Technology, Inc ETAP PowerStation 4.0

7 Study Toolbar Harmonic Analysis Plots Click on the Harmonic Analysis Plots button to select and plot the curves from the selected output plot file. The plot file name is the same as the output text file displayed in the Output Report list box. Plot files for harmonic load flow have.hfp as an extension. Halt Current Calculation The Stop Sign button is normally disabled. When a harmonic load flow or a harmonic frequency scan has been initiated, this button becomes enabled and shows a red stop sign. Clicking on this button will terminate the current calculation. One-line diagram displays and plots will not be available if you terminate the calculation before it completes, and the output report will be incomplete. Get On-Line Data If the ETAP key installed on your computer has the on-line feature, you can copy the on-line data from the on-line presentation to the current presentation. Get Archived Data If the ETAP key installed on your computer has the on-line feature, you can copy the archived data to the current presentation. Operation Technology, Inc ETAP PowerStation 4.0

8 Study Case Editor 21.2 Study Case Editor The Harmonic Analysis Study Case Editor contains solution control variables, system loading conditions, report options, harmonic source modeling options, and component plot selection. PowerStation allows you to create and save an unlimited number of study cases for each type of study. Like all other study types, you can easily switch between different harmonic analysis study cases. This feature is designed to organize your study efforts and save you time. A study case can be used for any combination of any configuration status, one-line diagram presentation, and Base/Revision Data. To create a new harmonic analysis study case, go to the Project Editor, right-click on the Harmonic Analysis sub-folder inside the Study Cases folder, and select Create New. The program will then create a new study case, which is a copy of the default study case, and adds it to the Harmonic Analysis subfolder. When you are in the Harmonic Analysis mode, you can access the Harmonic Analysis Study Case Editor by clicking on the Study Case button on the Study Case Toolbar. You can also access this editor from the Project View by clicking on the Harmonic Analysis sub-folder under the Study Cases folder. The Harmonic Analysis Study Case Editor consists of three pages: Info page, Model page, and the Plot page. Operation Technology, Inc ETAP PowerStation 4.0

9 Study Case Editor Info Page This page is provided for you to specify some general solution parameters, loading conditions, report options, and study case information. Study Case ID The study case ID is shown in this entry field. You can rename a study case by simply deleting the old ID and entering a new ID. Study case ID can be up to 12 alphanumeric characters. Use the Navigator button at the bottom of the editor to go from one study case to another. Fundamental Load Flow These settings are used for the fundamental load flow calculation solution control, and apply to both harmonic load flow and harmonic frequency scan studies. Max. Iteration Enter the maximum number for iterations. If the solution has not converged before the specified number of iterations, the program will stop and inform the user. The recommended and default value for maximum iteration is Operation Technology, Inc ETAP PowerStation 4.0

10 Study Case Editor Precision Enter the value for the solution precision, which is used to check for the fundamental load flow convergence. This value determines how precise you want the final solution to be. The default and recommended value for precision is Accel. Factor Enter the convergence acceleration factor for the fundamental load flow calculation. Typical values are between 1.2 and 1.7. The default value is Frequency Scan These values are used for only harmonic, frequency scan calculations. From Specify the starting frequency in Hz for frequency scan. The default is the system fundamental frequency. To Specify the finishing frequency in Hz for frequency scan. This value should be greater than the From frequency and is an integer multiplier of the system fundamental frequency. Step (df) Specify the frequency step in Hz. This value is the interval between two adjacent frequency points during a harmonic frequency scan study, and is a positive integer number. Plot Step This value determines the resolution of the frequency scan plot. The smaller it is, the smoother the plot will look, but requires more data to be recorded. The default value for it is 1, which means every point calculated from the harmonic frequency scan study will be plotted. Fundamental Loading In this section, you can specify the system loading conditions for the fundamental load flow calculation. The fundamental loading conditions will also affect the harmonic load flow and the harmonic frequency scan calculations. Loading Category Select one of the ten loading categories for this study case. With the selection of any category, PowerStation uses the percent loading of individual motors and other loads as specified for the selected category. Note that you can assign loading to each one of the ten categories in the Nameplate page, Loading page, or Rating page for most load components. Harmonic Filter loading is calculated from its parameters. Operating Load Check this option to operate P and Q as specified in the relevant component editors. Operation Technology, Inc ETAP PowerStation 4.0

11 Study Case Editor Charger Loading Load Category Select this option to use the P and Q specified in the Loading Category section of the Charger Editor for chargers. Operating Load Select this option to use the P and Q as specified in the Operating Load section of the Charger Editor. Note that if this option is selected, it is required that a DC load flow calculation is run first in order to estimate the charger load. Load Diversity Factor Apply appropriate load diversity factor(s) for the fundamental load flow as well as harmonic load flow and frequency scan analysis. The choices are: None Select None to use the percent loading of each load as entered for the selected loading category, i.e., no diversity factor is considered. Bus Maximum When the Bus Maximum option is selected, the loading of all motors and other loads will be multiplied by the maximum diversity factor of the bus, which they are directly connected to. Using this option, you can define the initial loading for harmonic analysis studies with each bus having a different maximum diversity factor. This study option is helpful when the future loading of the electrical system has to be considered. Bus Minimum When the Bus Minimum option is selected, the loading of all motors and other loads will be multiplied by the bus minimum diversity factor of the bus that they are directly connected to. Using this option, you can define the initial loading for harmonic analysis studies with each bus having a different minimum diversity factor. This study option may be useful in some cases where the effect of light loading condition needs to be investigated. Global When this option is selected, PowerStation will ask you to enter global diversity factors for constant kva and constant Z loads, respectively. When you select this option, PowerStation will globally multiply all constant kva and constant Z loads of the selected loading category with the entered values. Using this option you can define the initial loading for harmonic analysis studies with fixed diversity factors for all loads. Note that a constant kva load diversity factor of 125% implies that the constant kva loads of all buses are increased by 25 percent above their values as specified by the selected loading category. This value can be smaller or greater than 100 percent. Operation Technology, Inc ETAP PowerStation 4.0

12 Study Case Editor Report This section allows you to specify report options for Crystal Reports. VTHD If this box is checked, a summary of buses whose VTHD (Voltage Total Harmonic Distortion) exceeds the limit will be reported. VHD If this box is checked, a summary of buses whose individual VHD (Voltage Harmonic Distortion) for any harmonic exceeds the limit will be reported. Filter Overloading If this box is checked, a summary of overloaded filters will be reported. Remarks 2 nd Line You can enter up to 120 alphanumeric characters in this remark box. Information entered here will be printed on the second line of every output report page header. These remarks can provide specific information regarding each study case. Note that the first line of the header information is global for all study cases and entered in the Project Information Editor Model Page This page is provided for you to choose the modeling methods for different types of components. Operation Technology, Inc ETAP PowerStation 4.0

13 Study Case Editor Skip Harmonic Source In this section, you can specify globally what types of components you do NOT want to model as harmonic sources. The results will affect both the harmonic load flow and the harmonic frequency scan studies. For example, if a type of component is selected to not be modeled as a harmonic source, then all components of this type will be modeled as impedances with the appropriate values in both the harmonic load flow and the harmonic frequency scan studies. Utility If this box is checked, then all the power grid (utility) components will not contribute harmonics to the system. This corresponds to the situation where the grid has no or negligible harmonic contamination. Generator Saturation If this box is checked, then all synchronous generator components will not be considered as harmonic sources. This corresponds to the situation that generators are not significantly saturated; thus, they generate near-ideal sinusoidal voltages. Transformer Saturation If this box is checked, then all transformer components, both 2-winding and 3-winding, will not be considered as harmonic sources. This is true for transformers, which are close to their rated loading conditions. Charger/Converter If this box is checked, then all charger and converter components will not be considered as harmonic sources. Inverter If this box is checked, then all inverter components will not be considered as harmonic sources. UPS If this box is checked, then all UPS components will not be considered as harmonic sources. VFD If this box is checked, then all VFD components will not be considered as harmonic sources. Static Load If this box is checked, then all static load components will not be considered as harmonic sources. Operation Technology, Inc ETAP PowerStation 4.0

14 Study Case Editor Plot Page Select the components you want to display on the one-line diagram and in plot format. The selections are applied to both the harmonic load flow and the harmonic frequency scan studies. Device Type Select the type of components or devices from the list. Only the components associated with the listed types can be selected for plotting. Plot Options Device ID This table provides a list of the devices or components for the given Device Type. Plot/Tabulate Column You can select a device or component and click next to it under the Plot/Tabulate column. An X will be placed next to this device or component to include it in the plot list. Plot/Tabulate You also can include a device or component in the plot list by first selecting that device or component, and then checking this box. An X will be placed next to this device or component in the Plot/Tabulate column. Operation Technology, Inc ETAP PowerStation 4.0

15 Display Options 21.3 Display Options The Harmonic Analysis Display Options consist of a Results page and three pages for AC, AC-DC, and DC info annotations. Note that the colors and displayed annotations selected for each study are specific to that study Results Page Select the result information to be displayed on the one-line diagram. Color Select the color for the harmonic analysis result annotations to be displayed on the one-line diagram. Bus Select kv or % to display bus voltages in kv or percent of the bus nominal voltage. Operation Technology, Inc ETAP PowerStation 4.0

16 Display Options Show Units Click on this check box to include or suppress bus display units. Flows Branch Current Click on this check box to include or suppress one-line displays for branch current and other information for branches from the harmonic load flow and the harmonic frequency scan calculations. Show Units Click on this check box to include or suppress branch display units. Total Harmonic Info In this section, you can select specific information to display for buses and branches. The information is related to the total harmonic distortion, etc. Bus Voltage RMS or ASUM Choose to display the bus total voltage in RMS or ASUM (Arithmetic Summation) including contributions from the fundamental component and all harmonic components. THD or TIF Choose to display the bus voltage THD (Total Harmonic Distortion) or TIF (Telephone Influence Factor). Branch Current RMS or ASUM Choose to display the branch total current in RMS or ASUM, including contributions from the fundamental component and all harmonic components. THD or TIF Choose to display the branch current THD or TIF. Frequency Scan This section sets the option for one-line display of the harmonic frequency scan results. Z Magnitude Click on this check box to display the bus driving point impedance magnitude. Z Angle Click on this check box to display the bus driving point impedance phase angle. Show Unit Click on this check box to show units for the bus display from the harmonic frequency scan study. Operation Technology, Inc ETAP PowerStation 4.0

17 Display Options AC Page This page includes options for displaying info annotations for AC elements. Color Select the color for information annotations to be displayed on the one-line diagram. ID Select the check boxes under this heading to display the ID of the selected AC elements on the one-line diagram. Rating Select the check boxes under this heading to display the ratings of the selected AC elements on the oneline diagram. Device Type Gen. (Generator) Power Grid (Utility) Motor Load Panel Transformer Branch, Impedance Branch, Reactor Cable / Line Bus Node CB Fuse Relay PT & CT Rating kw / MW MVAsc HP / kw kva / MVA Connection Type (# of Phases - # of Wires) kva / MVA Base MVA Continuous Amps # of Cables - # of Conductor / Cable - Size ka Bracing Bus Bracing (ka) Rated Interrupting (ka) Interrupting (ka) 50/51 for Overcurrent Relays Transformer Rated Turn Ratio kv Select the check boxes under this heading to display the rated or nominal voltages of the selected elements on the one-line diagram. For cables/lines, the kv check box is replaced by the cable/line conductor type on the one-line diagram. button. Click on this button to display the A Select the check boxes under this heading to display the ampere ratings (continuous or full-load ampere) of the selected elements on the one-line diagram. For cables/lines, the Amp check box is replaced by the cable/line length on the one-line diagram. button. Click on this button to display the Operation Technology, Inc ETAP PowerStation 4.0

18 Display Options Z Select the check boxes under this heading to display the impedance values of the selected elements on the one-line diagram. Device Type Impedance Generator Subtransient reactance Xd Power Grid (Utility) Positive Sequence Impedance in % of 100 MVA (R + j X) Motor % LRC Transformer Positive Sequence Impedance (R + j X per unit length) Branch, Impedance Impedance in ohms or % Branch, Reactor Impedance in ohms Cable / Line Positive Sequence Impedance (R + j X in ohms or per unit length) D-Y Select the check boxes under this heading to display the connection types of the selected elements on the one-line diagram. For transformers, the operating tap setting for primary, secondary, and tertiary windings are also displayed. The operating tap setting consists of the fixed taps plus the tap position of the LTC. Composite Motor Click on this check box to display the AC composite motor IDs on the one-line diagram, then select the color in which the IDs will be displayed. Use Default Options Click on this check box to use PowerStation s default display options AC-DC Page This page includes options for displaying info annotations for AC-DC elements and composite networks. Color Select the color for information annotations to be displayed on the one-line diagram. ID Select the check boxes under this heading to display the IDs of the selected AC-DC elements on the oneline diagram. Rating Select the check boxes under this heading to display the ratings of the selected AC-DC elements on the one-line diagram. Device Type Charger Inverter UPS VFD Rating AC kva & DC kw (or MVA / MW) DC kw & AC kva (or MW / MVA) kva HP / kw Operation Technology, Inc ETAP PowerStation 4.0

19 Display Options kv Click on the check boxes under this heading to display the rated or nominal voltages of the selected elements on the one-line diagram. A Click on the check boxes under this heading to display the ampere ratings of the selected elements on the one-line diagram. Device Type Charger Inverter UPS Amp AC FLA & DC FLA DC FLA & AC FLA Input, output, & DC FLA Composite Network Click on this check box to display the composite network IDs on the one-line diagram, then select the color in which the IDs will be displayed. Use Default Options Click on this check box to use PowerStation s default display options DC Page This page includes options for displaying info annotations for DC elements. Color Select the color for information annotations to be displayed on the one-line diagram. ID Select the check boxes under this heading to display the IDs of the selected DC elements on the one-line diagram. Rating Select the check boxes under this heading to display the ratings of the selected DC elements on the oneline diagram. Device Type Battery Motor Load Elementary Diagram Converter Cable Rating Ampere Hour HP / kw kw / MW kw / MW kw / MW # of Cables - # of Conductor / Cable - Size kv Select the check boxes under this heading to display the rated or nominal voltages of the selected elements on the one-line diagram. For cables, the kv check box is replaced by the type on the one-line diagram. button. Click on this button to display the conductor Operation Technology, Inc ETAP PowerStation 4.0

20 Display Options A Select the check boxes under this heading to display the ampere ratings of the selected elements on the one-line diagram. For cables, the Amp check box is replaced by the length (one way) on the one-line diagram. button. Click on this button to display the cable Z Select the check boxes under this heading to display the impedance values of the cables and impedance branches on the one-line diagram. Composite Motor Click on this check box to display the DC composite motor IDs on the one-line diagram, then select the color in which the IDs will be displayed. Use Default Options Click on this check box to use PowerStation s default display options. Operation Technology, Inc ETAP PowerStation 4.0

21 Calculation Methods 21.4 Calculation Methods Power system harmonic analysis involves modeling the frequency characteristics of different components of power systems, computing harmonic indices at given buses and branches, identifying problems associated with the existing harmonics, and providing an environment to simulate and test any migration methods. This section briefly discusses these topics and prepares you to use the PowerStation Harmonic Analysis program to carry on your projects or analyze your systems in the most effective way Standard Compliance PowerStation Harmonic Analysis program fully complies with the latest version of the following standards: 1. IEEE Standards 519, IEEE Recommended Practices and Requirements for Harmonic Control in Electrical Power Systems 2. IEEE Standards 141, IEEE Recommended Practice for Electric Power Distribution for Power Plants 3. ANSI/IEEE Standard 399, IEEE Recommended Practice for Power System Analysis Component Modeling For harmonic analysis, frequency characteristics and the non-linearity of power system components must be recognized and modeled appropriately. Depending on their nature and behavior, these components are modeled in very different ways. Non-linear loads in power systems are essentially either injecting harmonic currents into the system or applying harmonic voltages at the given points. Therefore, they are conventionally modeled as current sources and voltage sources with harmonic frequencies. Normal power sources such as power grids or generators, if they contain harmonic components in their fixed voltages, are modeled as voltage sources with harmonic frequencies. Harmonic Current Source Non-linear loads that can be modeled as a harmonic current source in PowerStation are: Static Load UPS Charger/Converter VFD Transformer Static loads, chargers/converters and VFDs, if they are modeled as a harmonic current source, will inject harmonic current into the connected buses. When a saturated transformer contributes significant harmonic current into the system (most likely when the transformer is lightly loaded), it can also be modeled as a harmonic current source. Harmonic current source generated by a transformer is normally placed at the primary side; however, if there is a triple n th harmonic current specified for a transformer and the transformer winding and ground connections do not allow the triple n th harmonic current to flow in the primary winding, the secondary side and then the tertiary side will be considered as the location for the harmonic current source. Operation Technology, Inc ETAP PowerStation 4.0

22 Calculation Methods When a UPS is modeled as a load, it injects harmonic current into the connected bus. On the other hand, if a UPS is modeled as a branch, then it will inject harmonic current into both the AC input bus and the AC output bus. As a result, the path from the AC input bus to the AC output bus inside the UPS will be opened in harmonic load flow calculations. To model a component as a harmonic current source, go to the Harmonic page of that component and select an appropriate harmonic current library via the Library button and Harmonic Library Quick Pick Editor. Magnitudes of harmonic current from a harmonic current source are in percentage of the component rated fundamental current. Harmonic Voltage Source The following components can be modeled as a harmonic voltage source in PowerStation: Power Grid Synchronous Generator Inverter Charger/Converter Static Load Polluted power grids (utilities) or saturated synchronous generators can be modeled as harmonic voltage sources if they contain significant voltage distortion. Inverters, chargers/converters, and static loads can also be modeled as harmonic voltage sources if they primarily cause voltage distortion instead of current distortion. To model a component as a harmonic voltage source, go to the Harmonic page of that component and select an appropriate harmonic voltage library via the Library button and Harmonic Library Quick Pick Editor. Magnitudes of harmonic voltage from a harmonic voltage source are in percentage of the nominal voltage at the connected bus. Harmonic Impedance for Rotating Machines If a rotating machine is not modeled as a harmonic source, its equivalent harmonic impedance is its negative impedance. Harmonic Impedance for Load Components For a load or a shunt component, when it is not modeled as a harmonic source, its equivalent harmonic impedance is calculated from its fundamental loading using an equivalent parallel R and X circuit. The reactance part of the harmonic impedance for rotating machines and load components are adjusted linearly based on the order of harmonic. Harmonic Impedance for Branch Component Harmonic impedance of a branch component is computed from the impedance at the fundamental frequency by considering adjustments due to harmonic frequency. For an impedance branch, the adjustment is linear and only applies to the reactive part. For cable, transmission line, transformer, and reactor components, the adjustment applies to both the resistive and reactive parts. This is because of the skip effect and non-linear change in their reactance under high frequency. Operation Technology, Inc ETAP PowerStation 4.0

23 Calculation Methods Zero Sequence Impedance If the triple n th harmonics (3 rd, 9 th, etc.) exist in the system, then zero sequence impedance of a component is used for the calculation. For rotating machines and some of the branch components, if their zero sequence impedances are specified in their editors, these impedances will be used with the adjustment to the harmonic frequency. For other components, their equivalent zero sequence impedances are assumed to be the same as their positive counterpart. It is very important to point out that for rotating machines (including the utility grid), transformers and harmonic filters, Delta or Wye connections, grounding methods, and grounding impedances will all affect the triple n th harmonic flow in the system. Harmonic Indices The effect of harmonics is usually measured in terms of several indices that are defined below. Note that the definitions are applied to both voltage and current. Total Harmonic Distortion (THD) Total Harmonic Distortion (THD), also known as Harmonic Distortion Factor (HDF), is the most popular index to measure the level of harmonic distortion to voltage and current. It is a measure that shows the ratio of the mean-square-root of all harmonics to the fundamental component. For an ideal system, THD is equal to zero. THD is determined by: THD = 2 F 1 F 2 i where F i is the amplitude of the i th harmonic, and F 1 is that for the fundamental component. Individual Harmonic Distortion (IHD) Individual Harmonic Distortion (IHD) simply calculates the ratio of a given harmonic component to the fundamental component. This value is sometimes used to track the effect of each individual harmonic and examine its magnitude. IHD is determined by: IHD = F i F 1 Root Mean Square (RMS) - Total This is the square root of the sum of the squares of the magnitudes of the fundamental plus all harmonics in the system. For a system with no harmonics at all, the total RMS should be equal to the fundamental component RMS. The total RMS is determined by: RMS = 1 2 F i Operation Technology, Inc ETAP PowerStation 4.0

24 Calculation Methods Arithmetic Summation (ASUM) This is the arithmetic summation of the magnitudes of the fundamental and all harmonics. It adds the magnitudes of all components directly to have a conservative estimation of the crest value of voltage and current, and is useful for the evaluation of the maximum withstanding ratings of a device. ASUM is determined by: ASUM Telephone Influence Factor (TIF) Telephone Influence Factor (TIF) is a variation of the THD with a different weight given to each of the harmonics based on its amount of interference to an audio signal in the same frequency range. Normally, the current TIF has a more significant impact on adjacent communication systems. The TIF is determined by: = 1 F i TIF = 1 ( W F ) 1 i F i i 2 2 where W i is the TIF weighting factor. The values for the weighting factors for different harmonic frequencies are given in the IEEE Standard 519. ASUM = 1 F i I*T Product (I*T) I*T Index is a product current components (fundamental and harmonics) and weighting factors, as shown in the formula below: I T = H h= 1 ( I h T h ) 2 where I h = current component T h = weighting factor h = harmonic order (h=1 for fundamental) H = maximum harmonic order to account Operation Technology, Inc ETAP PowerStation 4.0

25 Calculation Methods Harmonic Load Flow Study The Harmonic Load Flow Study first carries out a load flow calculation at the fundamental frequency. The results of the fundamental load flow sets the base for the fundamental bus voltage and branch currents which are used later to calculate different harmonic indices. Then, for each harmonic frequency at which any harmonic source exists in the system, a direct load flow solution is found by using the current injection method. The harmonic frequencies considered are all the low order frequencies from the 2 nd to the 15 th, plus the characteristic harmonics from the 17 th up to the 73 rd. Impedance of components is adjusted based on the harmonic frequencies and the types of components. For a triplen harmonic frequency, a zero sequence impedance is adjusted to the actual frequency and the zero sequence network is used. From the harmonic load flow calculation, the harmonic components for bus voltages and branch currents are found, and then all harmonic indices are computed accordingly. The computed bus THD and IHDs are compared with their limits as specified by the user in the Bus Editor and, if any violations are detected, flags are placed in the text report next to the associated bus in the Harmonic Information section. The harmonic load flow study generates text output reports showing the system input data, fundamental load flow results, system harmonic information, and tabulation of bus voltages and branch currents with all harmonic contents. These results can also be viewed directly from the one-line diagram using the Harmonic Load Flow Slider and the Harmonic Display Options Editor. Along with the text report and one-line display, bus voltage and branch current plots are also available to show both voltage and current waveforms in time domain and the harmonic spectrums in a bar chart Harmonic Frequency Scan Study One particular concern with harmonics is the resonance condition in the power system. Because of the existence of both inductive components and capacitive components in the system, at certain frequencies, resonance conditions might occur at some buses. If the resonance occurs at a bus where a harmonic current is injected into the system, an overvoltage and overcurrent condition will be observed. The PowerStation Frequency Scan program is the best tool to investigate the system resonance problem. It calculates and plots the magnitudes and phase angles of bus driving point impedance over a frequency range specified by the user; thus, any parallel resonance condition and its triggering frequency can be clearly identified. The harmonic frequency scan study also allows users to tune their harmonic filter parameters and test the final results. The frequency range for scanning is defined by the user, which starts from the fundamental frequency and can go as high as the user needs. The results from the frequency scan study are reported in a text report which includes the system input data, the fundamental load flow results, and a tabulation listing bus driving point impedances. The same tabulated information is also given on the one-line diagram, as well as in a plot format. Operation Technology, Inc ETAP PowerStation 4.0

26 Calculation Methods Harmonic Filter Harmonic filters are extensively used to mitigate harmonic problems. A properly designed harmonic filter can prevent the harmonic current from injecting into the system, or it can provide a low impedance path at the tuned frequency to remove a parallel resonance. The PowerStation Harmonic Filter Editor provides all the practical and popular filter structures for you to choose from. A Filter Sizing program is also available in this editor for the Single Tuned filter type, with which users can optimize the filter parameters based on different installation or operation criteria. Harmonic filter loading is usually a concern in practical application. Two loading conditions are to be checked: capacitor Max. kv and inductor Max. I, both of those values are specified in the Harmonic Filter Editor, Parameter page. The capacitor Max. kv is a peak value, calculated by considering voltage drop across the capacitor, and the inductor Max. I is an rms value, calculated by considering current flow through the inductor. Note that in calculating these values, all voltage and current components including fundamental and harmonics are included. If Filter Overloading, check box in the Harmonic Analysis Study Case Editor. If Info page is checked, comparisons will be made between the calculated values and the specified values by Harmonic Load Flow study. Percentage of overloading will then be computed and reported in the Filter Overloading report Transformer Phase Shift Properly configuring transformer phase-shift can be helpful for cancellation of certain harmonics, thus improving system power quality. ETAP PowerStation Harmonic Analysis program uses transformer phase-shift to adjust network impedance phase angle in the Harmonic Load Flow study. Transformer phase-shift is specified in the Transformer Editor Tap page based on transformer connection convention, namely Standard Positive Sequence connection and Standard Negative Sequence connection. In addition, a user also can specify Special phase-shift for a transformer. Operation Technology, Inc ETAP PowerStation 4.0

27 Required Data 21.5 Required Data To run a harmonic analysis study, you need to provide all the data required for load flow and short-circuit calculations. In addition to that, you need to provide some harmonic related data, such as harmonic sources, modeling methods, and filters. A summary of these data for different types of components is given in this section. Note that except for the harmonic library information, which is required only for the harmonic load flow study, all other data are mandatory for both the harmonic load flow and the harmonic frequency scan studies. Bus Data Bus ID Nominal kv Load Diversity Factor (when Loading is set to Maximum or Minimum Diversity Factor) Harmonic Limit Category VTHD (Voltage Total Harmonic Distortion) Limit VIHD (Voltage Individual Harmonic Distortion) Limit Branch Data 2-Winding & 3-Winding Transformers Transformer ID Bus Connections Rated kv & MVA Positive & Zero Sequence Impedance & X/R Ratios Impedance Tolerance Tap & LTC Settings Winding Connections for all Windings Phase Shift as in Standard Positive or Negative Sequence connections, or Special configurations Grounding Type & Parameters for all Windings Harmonic Library Information, if any Cable/Transmission Line Cable or Transmission Line ID Bus Connections Conductor Type, Size, Rated kv, # of Conductors per Phase, & Length Use Library Data or Enter Cable Resistance, Reactance, & Susceptance Values, Both Positive & Zero Sequence Values Required Impedance Impedance ID Bus Connections Resistance, Reactance, & Susceptance Values, Both Positive & Zero Sequence Values Required Current-Limiting Reactor Current-Limiting Reactor ID Bus Connections X/R ratio & Impedance, Both Positive & Zero Sequences Values Required Impedance Tolerance Operation Technology, Inc ETAP PowerStation 4.0

28 Required Data Machine Data Power Grid (Utility) Data Power Grid (Utility) ID Bus Connection Operating Mode (Swing, Voltage Control, or Mvar Control) Nominal kv %V & Vangle for Swing Mode %V, MW Loading, & Mvar Limits (Qmax & Qmin) for Voltage Control Mode MW & Mvar Loading for Mvar Control Mode 3-Phase MVAsc & X/R Values or Positive Sequence %R & %X 1-Phase MVAsc & X/R Values or Zero Sequence %R & %X Grounding Connection Grounding Type Harmonic Library Information, if any Synchronous Generator Data Synchronous Generator ID Bus Connection Operating Mode (Swing, Voltage Control, or Mvar Control) Rated kv %V & Vangle for Swing Mode of Operation %V, MW loading, & Mvar Limits (Qmax & Qmin) for Voltage Control Mode of Operation MW & Mvar Loading for Mvar Control Mode of Operation Rated MVA Harmonic Z (X2) Zero Sequence Impedance X/R Ratio Winding Connection Grounding Type & Parameters Harmonic Library Information, if any Synchronous Motor Data Synchronous Motor ID Bus Connection Quantity Status & Associated Demand Factor Rated kw/hp & kv Power Factors & Efficiencies at 100%, 75%, & 50% Loadings Loading Category ID & % Loading Equipment Cable Data Harmonic Z (X2) Zero Sequence Impedance X/R Ratio Winding Connection Grounding Type & Parameters Operation Technology, Inc ETAP PowerStation 4.0

29 Required Data Induction Machine Data Induction Machine (Motor or Generator) ID Bus Connection Quantity Status & Associated Demand Factor Rated kw/hp & kv Power Factors & Efficiencies at 100%, 75%, & 50% Loadings Loading Category ID & % Loading Equipment Cable Data Negative Impedance X2 Zero Sequence Impedance X/R Ratio Winding Connection Grounding Type & Parameters MOV Data MOV ID Bus Connection Quantity Initial Status & Associated Demand Factor Rated kw/hp & kv Power Factor & Efficiency Loading Category ID & % Loading Equipment Cable Data Load Data Static Load Data Static Load ID Bus Connection Quantity Status & Associated Demand Factor Rated kva/mva & kv Power Factor Loading Category ID & % Loading Equipment Cable Data Grounding Connection/Type Harmonic Library Information, if any Lumped Load Data Lumped Load ID Bus Connection Status & Associated Demand Factor Rated kva/mva & kv Power Factor % Motor Load & % Static Load Loading Category ID & % Loading Grounding Connection/Type Operation Technology, Inc ETAP PowerStation 4.0

30 Required Data Capacitor Data Capacitor ID Bus Connection Status & Associated Demand Factor Rated kv Mvar/Band & # of Banks Loading Category ID & % Loading Equipment Cable Data Grounding Connection/Type Harmonic Filter Data Harmonic Filter ID Filter Type Rated kv & 3-Phase kvar for Capacitors Xl & Q for Reactors R, if applicable Grounding Connection/Type UPS Data UPS ID Bus Connection AC Connections Rated kw/mw & kv AC Input & Output Rated kv Power Factor and Efficiency Loading Category ID & % Loading Harmonic Library Information, if any VFD Data VFD ID Bus & Motor Connection Harmonic Library Information, if any Charger Data Charger ID Bus Connections Status & Associated Demand Factor AC Ratings Loading Category ID & % Loading Harmonic Library Information, if any Operation Technology, Inc ETAP PowerStation 4.0

31 Required Data Inverter Data Device ID Bus Connection AC Rating AC Output Voltage in % Harmonic Library Information, if any Study Case Parameters Study Case ID Max. Number of Iterations Precision Acceleration Factor From Frequency (for Harmonic Frequency Scan) To Frequency (for Harmonic Frequency Scan) Step (for Harmonic Frequency Scan) Plot Step (for Harmonic Frequency Scan) Fundamental Loading Category Fundamental Loading Condition (Loading Category, Operating Load) Load Diversity Factor (None, Bus Maximum, Bus Mininum, or Global) Charger Loading Option (Loading Category, Operating Load) Report Option (for Crystal Reports) All Options in Model Page Buses & Branches to be Plotted Operation Technology, Inc ETAP PowerStation 4.0

32 Output Reports 21.6 Output Reports Output reports for harmonic analysis studies are available in different levels and are arranged into three formats: text output reports, one-line diagram displays, and plots View from Study Case Toolbar This is a shortcut for the Report Manager. When you click on the View Output Report button, PowerStation automatically opens the output report listed in the Study Case Toolbar with the selected format. In the picture shown below, the output report name is Harm-LF and the selected output report format is TextRept Harmonic Analysis Report Manager Click on the View Output File button on the Harmonic Analysis Toolbar to open the Harmonic Analysis Report Manager. The Harmonic Analysis Report Manager consists of four pages. Operation Technology, Inc ETAP PowerStation 4.0

33 Output Reports Complete Page From this page you can select the report format that gives you the complete output report. Both TextRept in ASCII format and Complete in Crystal Reports are available. Input Page This page provides the formats for different input data. The following formats are available: Branch Bus Cable Complete Cover Filter HA Source Harmonic Library Harmonic Source Impedance Line Machine Reactor Results Transformer UPS Operation Technology, Inc ETAP PowerStation 4.0

34 Output Reports Result Page This page provides the formats for different calculation results. The following two formats are available: Load Flow Report Results Operation Technology, Inc ETAP PowerStation 4.0

35 Output Reports Summary Page This page provides the formats for different summaries from both input data and calculation results. The following four formats are available: Filter Overloading Summary VIHD Report VTHD Report Operation Technology, Inc ETAP PowerStation 4.0

36 Output Reports Harmonic Load Flow Text Report If the last study you have run is the harmonic load flow, or you have selected the output file extension.har, then by clicking on the View Output Report button on the Study Case Toolbar or by selecting the TextRept format from the Harmonic Analysis Report Manager, you will be able to open and view the text output report for the harmonic load flow study. The harmonic load flow study text report contains the following major sections: Cover Page This is the first page of the harmonic load flow study text report. It includes the information from a number of different types of buses, branches, system frequency, unit system, project file name, and the output file name and its location. HARMONIC ANALYSIS ================= Harmonic Load Flow SWING GEN. LOAD TOTAL ===== ===== ===== ===== Number of Buses: XFRM 3XFRM REACT. CALBE LINE IMP. C.B. UPS TOTAL ===== ===== ====== ===== ==== ===== ==== === ===== Number of Branches: System Frequency: 60.0 Hz Unit System: English Data File Name: Example Output File Name: E:\TEMP\EXAMPLE\HarmLF.har Operation Technology, Inc ETAP PowerStation 4.0

37 Output Reports Bus Input Data This section reports the input data related to system buses, including their ID, type, nominal kv, description, initial voltage, generation and/or loading, and voltage harmonic distortion limit for both total and individual harmonics. Bus Information & Nominal kv Ini Voltage Generation Motor Load Static Load Mvar Limits % VHD Limits ============================================= ============ ============= ============= ============= ============ ============ ID Type kv Description % Mag. Ang. MW Mvar MW Mvar MW Mvar Max. Min. Total Single Bus1 Load Bus2 Load Bus3 Load LVBus Load Main Bus SWNG MCC1 Load Sub2A Load Sub2B Gen Sub 3 Load Sub3 Swgr Load Buses Total Machine Data This section reports the input data related to system machines, which include power grid (utility), synchronous generator, synchronous motor, and induction machine. The input data reported are machine connected bus ID, machine ID and type, machine rating in MVA, kv and RPM, machine negative and zero sequence impedance, and machine winding connection and grounding. Conned Bus Machine Info. Rating (Base) Negative Seq. Imp. Grounding Zero Seq. Imp. ============ ================= ==================== ==================== ================== ===================== Bus ID Machine ID Type MVA kv RPM X/R % R % X2 Conn. Type Amp X/R % Ro % Xo Main Bus Utility Uty Wye Solid Sub 2B Gen1 Gen Wye Solid Bus3 Syn4 SynM Wye Open LVBus Syn2 SynM Wye Open Sub 2B Syn1 SynM Wye Open Bus3 Mtr2 IndM Wye Open MCC1 Mtr6 IndM Wye Open MCC1 Mtr4 IndM Wye Open MCC1 Mtr3 IndM Wye Open MCC1 Mtr5 IndM Wye Open Sub3 Swgr Pump 1 IndM Wye Open Branch Input Data This section reports the input data related to system branches, which include cables, transmission lines, impedances, reactors, 2-winding and 3-winding transformers. The input data reported are branch ID, library information (if any), positive and zero sequence impedances and shunt susceptances in both ohms and 100 MVA base. CKT / Branch Ohms/1000 ft per Conductor (Cable) or per Phase (Line) Impedance ============ ===================================================================== ================================= ID Library Size L(ft) #/ø T C R1 X1 Y1 Ro Xo MVAb % R1 % X1 % Y Cable2 5MCUS3 4/ Cable11 15MCUS Cable14 1MCUN Operation Technology, Inc ETAP PowerStation 4.0

38 Output Reports If the branch is a transformer, then its tap setting, LTC information (if any), winding connection, and grounding type are also reported. CKT / Branch Transformer %Tap Setting XFRM Grounding Imped. ============ ======================================= ============= ==================== ====== ID MVA kv kv % Z X/R From To Conn. Type Amp % Tol T D-Y Solid 0.00 T D-Y Restr T D-Y Solid 0.00 XFMR D-Y Restr Branch Connection This section reports branch connection information for all branches in the system. It shows the branch ID, from which bus and to which bus it is connected, and positive sequence impedance converted to the system base. CKT / Branch Connected Bus ID %Impedance (100 MVA Base) ======================== ========================== ========================= ID Type From To R X Z Cable2 Cable Sub 3 Sub3 Swgr Cable11 Cable Sub 2A Bus Cable14 Cable Bus1 Bus T2 2W Xfmr Main Bus Sub 2A T3 2W Xfmr Sub3 Swgr LVBus T4 2W Xfmr Sub 3 Bus XFMR 3 2W Xfmr Sub3 Swgr MCC T1 3W XFMR Main Bus Sub 2B Main Bus Sub Sub 2B Sub Harmonic Library Data This section lists harmonic library data, including all harmonic libraries used in the current study with their model ID and manufacturer ID, harmonic spectrum up to 73 rd harmonic in % of the device rated current. Note that each harmonic library can be used by multiple devices; however, each library will be reported only once. Device % Harmonic Source Current ========================= ===================================================================================================== Manufacturer Model Harmonic 12 Pulse Harmonic 6 Pulse Harmonic Source Data This section lists harmonic sources existing in the system, including bus ID, where the source is connected to, source type, and reference to the harmonic library. Connected Bus Harmonic Library Info ============= ===================================== ID Type Manufacturer Model Bus2 Current Harmonic 12 Pulse1 Bus2 Current Harmonic 6 Pulse1 Operation Technology, Inc ETAP PowerStation 4.0

39 Output Reports Fundamental Load Flow Report This section reports the fundamental load flow. The fundamental load flow establishes a base for all bus voltages and branch currents, which are later used for calculating harmonic voltage, current percentages, and other harmonic indices. The format of the fundamental harmonic load flow report is identical to that of the regular load flow report. Bus Information & Nom kv Voltage Generation Motor Load Static Load Load Flow XFRM ======================== =========== ============ ============ ============ ====================================== ===== ID Type kv % Mag. Ang. MW Mvar MW Mvar MW Mvar To Bus ID MW Mvar Amp %PF % Tap Bus1 Load Bus Sub Bus2 Load Bus Bus3 Load Sub2A LVBus Load Sub3 Swgr *Main Bus Swng Sub2A Sub2B & Sub 3 MCC1 Load Sub3 Swgr Sub2A Load Bus Main Bus *Sub2B Gen Sub & Main Bus Sub 3 Load Sub3 Swgr Bus Main Bus & Sub2B Sub3 Swgr Load Sub LVBus MCC Harmonic Information Report Following the fundamental load flow section, system harmonic information is reported. This section has three parts. In the Bus Info. & Rated kv part, the bus ID and its nominal voltage are reported. In the Voltage Distortion part, the fundamental bus voltage value, RMS value, ASUM value, THD value, and TIF value are reported. The fundamental voltage value, RMS value, and ASUM value are all on the base of nominal voltage of bus. The Current Distortion part shows the connected bus ID, fundamental current value, RMS value, ASUM value, THD value, TIF value, and I*T value. The fundamental current value, RMS value, and ASUM value are all in amperes. Also, in this section of the report, a * sign will be placed next to the bus if its total harmonic voltage distortion exceeds the limit, and a # sign will be placed next to the bus whose individual harmonic voltage distortion exceeds the limit. Bus Info. & Rated kv Voltage Distortion Current Distortion ==================== ===================================== ================================================================ ID kv Fund(%) RMS(%) ASUM(%) THD(%) TIF To Bus ID Fund.(A) RMS(A) ASUM(A) THD(%) TIF IT * # Bus Bus E+06 Sub E+06 * # Bus Bus E+06 Bus Sub2A E+02 LVBus Sub3 Swgr E+05 Main Bus Sub2A E+02 Sub2B E+02 Operation Technology, Inc ETAP PowerStation 4.0

40 Output Reports Sub 3 MCC Sub3 Swgr E+05 Sub2A Bus E+02 Main Bus E+02 Sub2B Main Bus E+03 Sub 3 Sub Sub3 Swgr E+04 Bus E+05 Main Bus E+03 Sub2B Sub3 Swgr Sub E+04 LVBus E+04 MCC E+04 * - THD ( Total Harmonic Distortion exceeds the limit) # - IHD (Individual Harmonic Distortion exceeds the limit) Bus Tabulation In the Bus Tabulation section, the bus ID, fundamental kv, and voltage harmonics up to the 73 rd harmonic in percent of fundamental voltage are reported. Note that only the buses that are selected for plotting in the Harmonic Analysis Study Case Editor are tabulated. Bus Harmonic Voltages (% of fundamental voltage) ===================== ===================================================================================================== ID Fund. kv Bus Bus LVBus MCC Sub For your convenience, the bus voltage harmonics converted to the bus nominal voltage are also tabulated. Bus Harmonic Voltages (% of nominal voltage) ===================== ===================================================================================================== ID Nom. kv Bus Bus LVBus MCC Sub Operation Technology, Inc ETAP PowerStation 4.0

41 Output Reports Branch Tabulation In this section, branch currents are tabulated on 1 MVA base for harmonics up to the 73 rd harmonic. Note that only the branches that are selected for plotting in the Harmonic Analysis Study Case Editor are tabulated. Branch % Harmonic Current Contents in 1 MVA Base ============ ===================================================================================================== ID Cable Cable Cable T T T XFMR For your convenience, the branch currents are also tabulated on the base of fundamental current. Branch % Harmonic Currents (% of fundamental current) ==================== ===================================================================================================== ID Fund(A) Cable Cable Cable T T T XFMR Harmonic Frequency Scan Report If the last study you have run is the harmonic frequency scan, or you have selected the output file extension.fsr, then by clicking on the View Output Report button on the Study Case Toolbar or selecting the TextRept format from the Harmonic Analysis Report Manager, you will be able to open and view the text output report for the harmonic frequency scan study. The harmonic frequency scan text report shares the same sections for Summary Page, Bus Input Data, Machine Data, Branch Input Data, Branch Connection, and Fundamental Load Flow Report with the harmonic load flow text report. It does not have Harmonic Library Data and Harmonic Source Data, since the harmonic frequency scan does not actually use any harmonic source information. Operation Technology, Inc ETAP PowerStation 4.0

42 Output Reports Frequency Scan This section reports the driving point impedance, and its magnitude and phase angle, at each frequency specified in the Harmonic Analysis Study Case Editor. Note that only the buses that are selected for plotting are tabulated. Bus1 Bus2 LVBus MCC1 Sub Freq Mag. Angle Mag. Angle Mag. Angle Mag. Angle Mag. Angle (Hz) (ohm) (rad) (ohm) (rad) (ohm) (rad) (ohm) (rad) (ohm) (rad) Operation Technology, Inc ETAP PowerStation 4.0

43 One-Line Diagram Displayed Results 21.7 One-Line Diagram Displayed Results The one-line diagram displays the study results after the current calculation is complete. Based on the study type and selected options from the Display Options, different results are displayed Harmonic Load Flow Display By using the Harmonic Load Flow Slider and the Harmonic Analysis Display Options Editor, you can choose different results to be displayed on the one-line diagram for the harmonic load flow analysis study. Harmonic Load Flow Slider The Harmonic Load Flow Slider is located on the top of the PowerStation window. To make it visible, you need to select the Harmonic Load Flow Slider option. This slider has three sections. They are Total, 1 (fundamental frequency), and h (a harmonic order from 2 to 73). To set the slider to different positions, put your mouse pointer on top of the indicator, hold the left mouse button down, then drag it to the desired location on the slider. Total At this position, harmonic information of buses and branches is displayed. The information displayed is: Bus Voltage RMS or ASUM Bus Voltage THD or TIF Branch Current RMS or ASUM Branch Current THD or TIF 1 (Fundamental Frequency) At this position, the fundamental load flow results are displayed. The information displayed is: Bus Voltage Magnitude in kv or in Percent Bus Voltage Phase Angle in Degree Branch Current in Amperes Branch Current in Percent of Fundamental Current Base Operation Technology, Inc ETAP PowerStation 4.0

44 One-Line Diagram Displayed Results Harmonic Order n (n from 2 to 73) At this position, the bus voltages and branch currents for the given harmonic order are displayed. The information displayed is: Bus Voltage Magnitude in kv or in Percent Bus Voltage in Percent of the Fundamental Voltage Branch Current in Amperes Branch Current in Percent of the Fundamental Current Base The following screen capture shows a one-line diagram display with the slide position at Total. Operation Technology, Inc ETAP PowerStation 4.0

45 One-Line Diagram Displayed Results Harmonic Frequency Display By using the Harmonic Frequency Scan Slider and the Harmonic Analysis Display Options Editor, you can choose different results to display on the one-line diagram for the harmonic frequency scan analysis study. Harmonic Frequency Scan Slider The Harmonic Frequency Scan Slider is located on the top of the PowerStation window. To make it visible, you need to check the Harmonic Frequency Scan Slider option. This slider goes from the From frequency to the To frequency with the Plot Step specified by the user. The values of From frequency, To frequency, and Plot Step are all specified in the Harmonic Analysis Study Case Editor. You can use the same technique as described for the Harmonic Load Flow Slider to move the pointer to any frequency and see the one-line diagram display changes. The Harmonic Frequency Scan Slider displays the magnitude and phase angle of the bus driving point impedance for the selected frequency. Only those buses, which are selected in the Harmonic Study Case Editor for plotting, are available to display. The following is a screen capture of a Harmonic Frequency Scan one-line display. Operation Technology, Inc ETAP PowerStation 4.0

46 Plots 21.8 Plots Plots are available for both the harmonic load flow study and the harmonic frequency scan study Harmonic Analysis Plot Selection The plot files share the same name as the text output files, so the procedure for selecting plot files is the same as that described in Section To select a plot, click on the Harmonic Analysis Plots button located on the Harmonic Analysis Toolbar. Harmonic Load Flow Check this radio button for plots of the harmonic load flow study. Frequency Scan Check this radio button for plots of the harmonic frequency scan study. Device Type Select a device type. Device ID Select the devices that you want to plot. This box lists all the devices, which are selected in the Harmonic Study Case Editor, Plot page, for the selected device type. Multiple devices can be selected. Operation Technology, Inc ETAP PowerStation 4.0

47 Plots Plot Type For Harmonic Load Flow plot, following curves are available. Waveform Plot voltage or current waveforms for the selected devices. Curves are plotted in the time domain for one cycle duration. The scale for voltage waveform is in percent of the nominal bus voltage. The scale for current waveform is in percent of the fundamental branch current. Spectrum Plot voltage or current harmonic spectrum. Both voltage and current harmonics in spectrum charts are in percent of their fundamental values. For harmonic frequency scan plots, the following curves are available. Z Magnitude Plot the driving point impedance magnitudes for buses in Ohms. Z Angle Plot the driving point impedance angles for buses in radians Harmonic Load Flow Plots A set of sample plots for a harmonic load flow study is shown below. Operation Technology, Inc ETAP PowerStation 4.0

48 Plots Harmonic Frequency Scan Plots A set of sample plots for a harmonic frequency scan study is shown below. Operation Technology, Inc ETAP PowerStation 4.0