Commissioning and Testing of AVR and PSS

Transcription

1 Commissioning and Testing of AVR and PSS Excitation System Upgrade and commissioning challenges Vetti Bala Principal C&I Engineer G E N E S I S E N E R G Y L I M I T E D

2 Contents Asset Testing - AVR AVR routine testing requirements Life Cycle Management Excitation System Replacement Related opportunities PSS Function Advantage of tuning PSS correctly Challenges AVR testing challenges D E C E M B E R C o m m i s s i o n i n g a n d t e s t i n g o f A V R a n d PSS

3 Asset Testing - AVR What prompts for the testing Analogue AVRs 5 yearly cycle Digital AVRs 10 yearly cycle Replacement of AVR (asset life cycle management) Life cycle management Improve reliability Archive compliance Protect asset with better limiter controls D E C E M B E R

4 Excitation System Replacement D E C E M B E R

5 Excitation System Replacement Challenges with life cycle management Takes over two years to achieve it; justification, status of asset condition, budget allocation, resources availability, etc.. Key milestones replacement project Project approvals Technical spec ready / Tendering Contract award Design phase Build phase (inc FAT) Outage work Commissioning system AVR Testing 2 year prior 6-12 months 9 months prior 6 months 5 months 4 weeks 5 days 1 day D E C E M B E R

6 Excitation System Replacement First activity: prepare for Model building Key information required for proposed model build; (in addition to technical spec) Generator parameters Gen Transformer parameters Grid info at the connection point Possible sources for Model input data; PTI Reports ACS Previous commissioning data New equipment specification Injection point Grid data (from SO) D E C E M B E R

7 Excitation System Replacement Design and design approvals Design Phase New system supplier system design Customer interface design (DCS or SCADA interface) control, etc.. Grid requirements (dialogue with SO) Design approval Owner s requirements approval SO approvals for the proposed AVR settings (3 months) D E C E M B E R

8 Excitation System Replacement - Asset Life Cycle Management DC Exciter AVR Cabinet Original DC exciter from 40 s coupled to the main shaft Analogue AVR installed over 25 years ago Electronics drifting with ageing D E C E M B E R

9 Excitation System Replacement - Replacement digital excitation system Digital AVR Cabinets Excitation Transformer D E C E M B E R

10 Excitation System Replacement - Decommission old equipment Removal of exciter Removal of old AVR cabinets and cables D E C E M B E R

11 Excitation System Replacement Related activities A replacement project brings other opportunities or requirements Unit ultimate over-speed protection replacement Carbone dust extraction system (if required) Removal of previously decommissioned equipment D E C E M B E R

12 Morden Unit Over-speed Protection - Unit Safety and Reliability issues Original Mechanical Over-speed device from 40 s Single centrifugal switch to shut down the Unit Moving parts, shown wear and tear issues Unreliable and hidden failure D E C E M B E R

13 Morden Unit Over-speed Protection - Replacement tooth wheel and pickup sensors Built in redundancy, 2 out of 3 electronic system Fail safe and monitored of any failures High level of reliability Ease of routine testing D E C E M B E R

14 Excitation System Replacement Related activities The consequence of exciter removal Re-check Unit Balance Re-check Unit Vibration New speed probes and tooth wheel commissioning Unit Start / Stop sequence - recommission Unit creep detection and shutdown - recommission Complete functional trip test of ultimate over-speed protection by running the turbine to over-speed set point thresholds D E C E M B E R

15 Commissioning and AVR Testing D E C E M B E R

16 AVR Testing Commissioning new system Site acceptance test (owner s requirements) Verify Local / Remote controls Functional trip test Demonstrate reactive power (MVAr) controls D E C E M B E R

17 AVR Testing From Asset testing companion guide Purpose of Test: As stipulated in the ancillary services contract, testing is required to determine if the service meets the performance standards. The system operator needs to ensure the integrity of the voltage-support ancillary-service provision by issuing requirements to service providers for assessing the voltage support capability of their assets. To ensure the asset complies with the performance standards outlined in ancillary services contract Outcome: The required outcome of AVR testing is to provide the system operator with a verified mathematical model that describes the steady state and dynamic behaviour of the equipment. An accurate representation allows the system operator to model interactions with the system and other generating stations, when subjected to disturbances on the system, and thereby control the voltage stability of the system. To validate the mathematical model D E C E M B E R

18 AVR Testing AVR Compliance testing Intense AVR testing Model validation Test EIPC requirements Demonstrate reactive power support D E C E M B E R

19 AVR Testing Generator Capability Diagram with limiters D E C E M B E R

20 AVR Testing Demonstrate Exporting Reactive Power Capability: Minimum of +50% reactive power at the Grid injection point of the maximum continuous MW capability in the voltage range of -10% to +10% +50% MVAr 220kV: 198kV to 242kV 110kV: 99kV to 121kV Importing Reactive Power Capability: Minimum of 33% reactive power at the Grid injection point of the maximum continuous MW capability in the voltage range of -5% to +10% -33%MVAr 220kV: 209kV to 242kV 110kV: 104.5kV to 121kV D E C E M B E R

21 AVR Testing EIPC Testing requirements Offline from -10% to +10% of nominal voltage Offline step responses Online step responses at unity power factor Online step responses from under excited regions Online step responses from over excited regions Under excited limiter tests Over excited limiter tests Field voltage rise time Tests PSS Performance tests Unsychronised Unsychronised UPF UER OER UEL OEL D E C E M B E R

22 PSS Power System Stabilizer D E C E M B E R

23 PSS Advantage of modern system with PSS and tuning it correctly The PSS function improves the stability of the generator and the transmission system as a whole by using the excitation to damp power oscillations PSS is not very effective in low power range PSS is intended for the improvement of the damping of the electromechanical oscillations by appropriate influencing the AVR control loop Increase the working range of the generators MW smoothing from hydraulic instability or spikes Reduce maintenance issues Integrated PSS should be available with modern excitation system D E C E M B E R

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31 PSS

32 PSS Advantage of PSS function MW oscillation due to hydraulic instability PSS On smooths out MW oscillation Rangipo D E C E M B E R

33 AVR Testing In summary Testing is typically takes a full day and is a very intense activity External customers satisfied (Transpower) A dialogue is essential during the testing with SO to ensure the attained data is acceptable by SO Ensure the dispatch is met by the new excitation system Internal customers satisfied (Genesis Ops) Ensure the PSS tuning and resultant unit behaviour is acceptable by the operations Ensure the MVAr support is acceptable by the operations (the operational regions generator capability) D E C E M B E R

34 AVR Testing Challenges D E C E M B E R

35 AVR Testing Challenges Challenges during testing Peak hours Grid emergency Parallel activities (other major outages) Ops shift change Weak Grid Plant / hydrology limitations D E C E M B E R

36 Thank you G E N E S I S E N E R G Y L I M I T E D