Reliability Indices Measurement Reliability Indices Measurement for three 11 kv and 66 kv substations in Brunei Darussalam (PWR 01)

Transcription

1 BNERI Reliability Indices Measurement Reliability Indices Measurement for three 11 kv and 66 kv substations in Brunei Darussalam (PWR 01) NUR SABIQAH HAJI ROSLI

2 ACKNOWLEDGEMENT I would like to express my deepest appreciation to all those who provided me the possibility to complete this report. I would also like to acknowledge with much appreciation the crucial role of Robinson Goh, Hajah Zuriyati and Haziqah Nordin, the staff of Department of Electrical Services in the Distribution Department, who provided their power outages and Single Line Network data to complete this Reliability Indices Measurement project. A special gratitude I give to our supervisor, Chief Researcher of Power Department, Dr. Arvind K S Chaudhary, whose contribution in stimulating suggestions and words of encouragement helped me to coordinate this project especially in writing this report. Draft dated 27 th May 2015 i

3 EXECUTIVE SUMMARY One of the Key Performance Indicators (KPI) under the Energy White Paper 2014 is to reduce the number of power outages by 2035, which is in line with Wawasan Therefore, quantitative reliability indices measurement such as System Average Interruption Duration Index (SAIDI) and System Average Interruption Frequency Index (SAIFI) has been calculated for three 11 kv and 66 kv substations in Brunei Darussalam. In this study, IEEE Guide for Electric Power Distribution Reliability Indices (IEEE Std ) is used as the methodology and only unplanned and sustained interruptions are taken into account to provide consistency in all four districts, to review and improve current reliability and performance of distribution system in Brunei Darussalam. To further improve the performance of distribution system, design and implementation of Smart Grid technologies can be utilized in Brunei Darussalam Draft dated 27 th May 2015 ii

4 Table of Contents ACKNOWLEDGEMENT... i EXECUTIVE SUMMARY... ii 1. INTRODUCTION Scope of Work ACRONYMS GLOSSARY POWER SYSTEM RELIABILITY Background SYSTEM AVERAGE INTERRUPTION DURATION INDEX (SAIDI) Distribution System METHODOLOGY IEEE GUIDE Factors that cause variation in reported indices Outages that should not be taken into account when calculating indices Example of using MED definition to identify Major Event Sample System to calculate SAIDI and SAIFI with no MED Catastrophic Days List of data requested from DES for both 11 kv and 66 kv substations SYSTEM RELIABILITY CALCULATION FOR BRUNEI DARUSSALAM Step Restoration Analysis of three 11 kv substations in Brunei Darussalam SAIDI calculation for 11 kv substations SAIFI calculation for 11 kv substations Analysis of three 66 kv substations in Brunei Darussalam SAIDI calculation for 66 kv substations SAIFI POWER OUTAGE Causes of power outages Weather related power outages Faulty Equipment Overcurrent Flashover transformer Animal Contacts People induced including: pole and overhead contacts and underground digging Draft dated 27 th May 2015 iii

5 7.1.7 Short Circuit Electrical Trees Examples of power outages (historical blackouts) CONCLUSION FUTURE WORK References Appendix... A Appendix 1: Power Outages for 2014 and A Appendix 2: List of required data for accurate calculation of SAIDI and SAIFI... W Draft dated 27 th May 2015 iv

6 1. INTRODUCTION More than half of Brunei Darussalam s revenue comes from the energy sector. The Energy White paper has outlined three strategic goals to realize Brunei Darussalam s energy vision. One of the Key Performance Indicator (KPI) is to reduce the number of power outages by 2035, in line with the goals of Wawasan 2035 [1]. The main aim of this project is to provide electric power distribution reliability indices, namely System Average Interruption Duration Index (SAIDI) and System Average Interruption Frequency Index (SAIFI), to benchmark DES (Department of Electrical Services) and chart improvements used in all utilities worldwide. As well as to identify root causes of power outages in Brunei Darussalam. The reliability indices of electric power distribution will follow a set of methodology outlined in IEEE Guide for Electric Power Distribution Reliability Indices [2] to ensure the indices obtained are consistent with best practices in the Power Industry. 1.1 Scope of Work Understand existing distribution equipment and protection philosophy. This includes the understanding of IEEE Std methodology (and other standards Department of Electrical Services (DES) used) and consultation from DES personnel. Gather information from DES. Conduct survey at a few substations and their feeders. Create and understand scenarios given by DES. Obtain and analyze the data given to calculate SAIDI (in minutes) and SAIFI. Compare the results obtained for SAIDI and SAIFI with DES. Write report on SAIDI and SAIFI results and peer review. Execution plan (Gantt chart) is attached at the back of this report. Draft dated 27 th May of 34

7 2. ACRONYMS SAIDI SAIFI DES MIS System Average Interruption Duration Index System Average Interruption Frequency Index Department of Electrical Services Main Intake Station Draft dated 27 th May of 34

8 3. GLOSSARY Customer Interruption Interruption Duration Major Event Major Event Day (MED) Momentary Interruption Outage Planned Interruption Reporting period Sustained Interruption Total number of served A metered electrical service point for which an active bill account is established at a specific location. The total loss of electric power on one or more normally energy conductors to one or more connected to the distribution portion of the system. The time period from the initiation of an interruption until service has been to the affected. An event that exceeds the reasonable design and or operational limits of the electric power system. A day where the daily SAIDI index exceeds a Major Event Day (MED) threshold value. Interruptions which occur on MED should be separately analyzed. The brief loss of power delivery to one or more caused by opening and closing operation of an interrupting device. Usually less than 5 minutes. The loss of ability of a component to deliver power. The loss of electric power to one or more that results from a planned outage. The time period from which interruption data is to be included in the reliability index calculations. Any interruption not classified as a part of a momentary event. Interruption which lasts more than 5 minutes. The average number of served during the reporting period. If a different customer total is used, it must be clearly defined in the report. Draft dated 27 th May of 34

9 4. POWER SYSTEM RELIABILITY 4.1 Background Electric power system is one of the most important and complex systems created by human. It comprises countless facilities and structures, systems and subsystems, components and equipments and interactions between all [3]. It was also reported that more than 50% of reliability depends on the performance of distribution system [3] Electric power has become an essential part of humans lives up to an extent that it is impossible to live without electrical power. This stresses the importance of power system reliability. Reliability of power system is mainly concerned with customer interruptions, thus, it is a subset of power quality [4]. In this report, two main power system reliability indices are looked into, particularly SAIDI (System Average Interruption Duration Index) and SAIFI (System Average Interruption Frequency Index). Additional index such as CAIDI (Customer Average Interruption Duration Index) can also be derived from the initial indices. There are mainly two main types of interruptions, sustained and momentary. Where sustained interruption is closely related to reliability issue (more than five minutes), and momentary interruptions as power quality issue (usually less than five minutes) [2,4]. Figure 1: shows Power Quality Subset [4] Draft dated 27 th May of 34

10 4.2 SYSTEM AVERAGE INTERRUPTION DURATION INDEX (SAIDI) The System Average Interruption Duration Index (SAIDI) indicates the sum duration of interruption for the average customer during a predefined set of time [2]. The unit used to measure SAIDI is in minutes or hours of interruption. The equation used to measure SAIDI is given in Eq. (1)[2]. CustomerMinutesof Interruption SAIDI (1) Total Number of Served To calculate the index, Eq (2) can be used, where r i is restoration time for each interruption event, N i stands for number of for each sustained interruption event during a reporting period, N T is total number of served for the area and CMI stands for customer minutes of interruption [2]. ri Ni CMI SAIDI (2) N N T T Figure 2 shows Unplanned SAIDI for various countries, including exceptional event [5]. Draft dated 27 th May of 34

11 Figure 3 shows Unplanned SAIDI for various countries, excluding exceptional events [5] From Figures 2 and 3, it can be observed that due to the elimination of exceptional events, the SAIDI decreases. Draft dated 27 th May of 34

12 4.3 SYSTEM AVERAGE INTERRUPTION FREQUENCY INDEX (SAIFI) The System Average Interruption Frequency Index (SAIFI) shows how frequently the average customer experiences a sustained interruption over a predefined period of time. The equation used to calculate SAIFI is (Eq 3) [2]. Total Number of Interrupted SAIFI (3) Total Number of Served To calculate the index, Eq (4) can be used. Where CI is [2], Ni CI SAIFI (4) N N T T Figure 4 shows Unplanned SAIFI for various countries, including exceptional event [5]. Draft dated 27 th May of 34

13 Figure 5 shows Unplanned SAIFI for various countries, including exceptional event [5]. 4.4 Distribution System The distribution system is the final stage in delivering electrical power to consumers. An ordinary distribution system consists of step down transformer with various lengths (a few hundred meters to several kilometers), so the voltage can be stepped down to distributed levels for industrial, commercial and residential users [9]. Draft dated 27 th May of 34

14 5. METHODOLOGY IEEE GUIDE In order to accurately develop indices of a power system reliability measurement, IEEE Std was used as a methodology, so as to obtain consistent results amongst utilities in the region. A Major Event Day (MED) is an identified day in which the daily system SAIDI exceeds a threshold value called T MED. Thus, the SAIDI index obtained will be consistent regardless of size of utility and any anomaly (MED value) which may lead to a higher SAIDI value is analyzed separately and removed from indices calculation. A T MED value is typically obtained at the end of each reporting period (one year) for use during the next reporting period as follows [2]: Obtain daily SAIDI values for five years, which ends on the final day of the last entire reporting period. Only include days which have SAIDI/day value which can contribute in calculation of T MED, i.e exclude days where interruptions did not occur. Take the natural log of each daily SAIDI value in the data set Find alpha, the average of the log of the data set Find Beta, the standard deviation of the log of the data set. Compute the MED threshold, using Eq. (5) [2] ( 2.5 ) T MED e (5) Any day with daily SAIDI greater than the threshold value T med that occurs during the subsequent reporting period is classified as MED. 5.1 Factors that cause variation in reported indices There are various factors that can cause difference in the indices reported by different utilities. Some examples are in [2]; Level of automated data collection Geography System design Data classification Draft dated 27 th May of 34

15 It is highly essential to classify performance for each day in the data set to be analyzed as either day-today or MED; false decision may occur when this important step is not performed, as MED may disguise overall daily performance. 5.2 Outages that should not be taken into account when calculating indices There are several types of outages that should not be included when calculating the indices, such as [2]: Interruptions that occur as a result of outage on customer owned facilities Loss of supply from another utility Planned interruptions Momentary interruptions These interruptions are not included in calculation of SAIDI and SAIFI as to provide uniform and consistent policy in all four districts. Furthermore, the calculation is done to review and improve current performance of unplanned events. 5.3 Example of using MED definition to identify Major Event. The following example shows the calculation of Daily SAIDI MED threshold, T MED Identification of MEDs and calculation of adjusted indices. Table 1 shows selected data for all interruptions which occur on a certain day for a utility which serves 2000 DATE TIME DURATION (MIN) NUMBER OF CUSTOMERS INTERRUPTION TYPE July 15, :34: Sustained July 15, :38: Momentary July 15, :42: Sustained Table 1 shows Interruption data for July 15, Draft dated 27 th May of 34

16 For July 15, 1995, daily SAIDI (assumption: a 2000 customer utility) is given in Eq (6): (20 200) ( ) SAIDI min 5.4 Sample System to calculate SAIDI and SAIFI with no MED Table 2 below shows an extract from one utility s customer information system (CIS) database for feeder 7055 [2], which serve 2000 with a total load of 4MW. In this sample system, Circuit 7055 is a representation for the system where the indices are to be calculated. Furthermore, the system consists of all the circuits together in a region for a whole company. Date Time off Time on Circuit Number of Duration Interruption Load kva (min) type Jan :20: S Feb 15 18:23:56 18:24: M Mar 13 00:23:10 01:34: S Apr 24 23:17:00 23:47: S May 27 09:30:10 09:31: M June 22 15:45:39 20:12: S July 19 08:20:00 10:20: S Aug 31 17:10:00 17:20: S Sep 3 10:15:00 10:55: S Table 2: An example of interruption data for a utility Note: S Sustained Interruption, M Momentary Interruption Equations (2) and (3) should be used to calculate the annual indices, using the data shown in Table 2, assuming there were no MEDs in the data. ( ) ( ) ( ) ( ) ( ) (101500) (40100) SAIDI 86.11min SAIFI Draft dated 27 th May of 34

17 5.5 Catastrophic Days It is assumed that, when calculating the daily SAIDI and the 2.5β method, the distribution of the natural log values will look like a Gaussian distribution (a bell-shaped curve) [2]. Events such as hurricanes or ice storms typically result in abnormally higher daily SAIDI values, and these events are called catastrophic events, and have a slim probability of happening [2]. It is typical for catastrophic event, which leads to higher SAIDI values to exist in data sets and this will cause relatively small outward shift in the resulting reliability metric trends [2]. Thus, measures have been taken to identify and process catastrophic, in order to remove the effect it has on reliability metric trends [2]. Furthermore, when catastrophic events are not taken into account, this may cause a huge increase in the events identified as MEDs. It was also proposed that catastrophic events should be processed and determined on an individual company basis by regulators and utilities itself, as no universal solution has been devised to achieve acceptable results [2]. Draft dated 27 th May of 34

18 5.6 List of data requested from DES for both 11 kv and 66 kv substations Data Requested Mentiri Substation Beribi Substation Kuala Belait Substation Mentiri Substation Beribi Substation Kuala Belait Substation Date of power outage Duration of power outage Number of Number of served Step restoration information Stages required to restore power Duration to restore power at each stage Number of at each stage Causes of outage Draft dated 27 th May of 34

19 6. SYSTEM RELIABILITY CALCULATION FOR BRUNEI DARUSSALAM. 6.1 Step Restoration When power outages occur, power is not always fully in one stage, but, it takes a series of stages to restore power to all, this process is called step restoration. A sample calculation is shown below to illustrate how SAIDI is calculated when step restoration takes place. It is also important to know the duration of outages during restoration and number of at a particular restoration time to accurately calculate SAIDI. Figure 6: Single line network representation Draft dated 27 th May of 34

20 Figure 6 shows a representation of single line network. A sample case of step restoration can be broken down into a few steps as follow: When a fault occurs at X, Breaker number 1 opens and isolates the fault. Operation on Breaker number 1 also opens the load break switch (LBS) of substations A, B, C and D. At this point, outage of power occurs at A, B, C and D Operator is sent to site to locate the Fault Circuit Indicator (FCI) which identifies the fault location path. 1. LBS at A 1 is closed to restore partial power. Since load at substation A is, then A 2 is closed. 2. Operator arrives at substation B, checks the FCI and closes LBS B 1 to restore partial power. Since the load at substation B 1 is, then B 2 is closed. 3. Operator arrives at substation C, checks the FCI and closes LBS C 1 to restore partial power. Since the load at substation C 1 is, then C 2 is closed. 4. Operator arrives at substation D, checks the FCI and closes LBS D 1 to restore partial power. Since the load at substation D 1 is, and then D 2 is closed but due to the presence of fault, power is not back to the affected, and fault is detected. This fault is then isolated and reported by operator. Permanent repairs are completed, and power to all is. The outage event is concluded. One example of step restoration took place in Kuala Belait on the 28 th of March 2014; the number of at each restoration was not known in detail. Thus, percentages of are used to illustrate how the amount of initially affects the SAIDI value. Three sample cases are tabulated to calculate SAIDI where the percentages of are varied. The three sample cases are: In Table 4: Equal number of is in four separate restoration times (25%). In Table 5: More are in the first 20 minutes (75%) In Table 6: Remaining 75% of after 80 minutes. Scenario orders numbered 1-4, in Tables 4, 5 and 6 represent the steps (stages) taken to close each LBS (A B, C and D refer to Figure 6), locate the fault and restore power back to Draft dated 27 th May of 34

21 Scenario Order % of remaining Time off Time on Interruption duration (min) (CI) Customer minutes of interruption(cmi) - 0% % :00 12: % :00 12: % :00 1: % :00 1: % SAIDI in mins 50 Table 4: Sample step restoration with equal number of at each stage Scenario Order % of remaining Time off Time on Interruption duration (min) (CI) Customer minutes of interruption(cmi) - 0% % :00 12: % :00 12: % :00 1: % :00 1: % SAIDI in mins 29 Table 5: Sample step restoration where 75% of are in the first 20 minutes Draft dated 27 th May of 34

22 Scenario Order % of remaining Time off Time on Interruption duration (min) (CI) Customer minutes of interruption(cmi) - 0% % :00 12: % :00 12: % :00 1: % :00 1: % SAIDI in mins 71 Table 6: Sample step restoration where 75% of are in the last 20 minutes From the SAIDI values obtained from Table (4), Table (5) and Table (6) above, it can be observed that SAIDI value is smaller when the first batch of are higher (29 mins from Table 5). Meanwhile, when the remaining 75% of are after 80 minutes, the SAIDI value increases to 71 minutes and when equal number of takes place at each restoration time, the value of SAIDI lies in between 71 and 29 minutes, that is 50 minutes. In conclusion, when the distribution of and the number of at each restoration time are not known, it can be seen that, the SAIDI value lies more towards the time when the largest number of are at. 6.2 Analysis of three 11 kv substations in Brunei Darussalam To carry out the calculation to estimate the SAIDI and SAIFI for Brunei Darussalam, three 11 kv substations have been analyzed, which are: Kuala Belait Substation Mentiri Substation Beribi Substation Draft dated 27 th May of 34

23 6.2.1 SAIDI calculation for 11 kv substations To develop the estimates of SAIDI for the three 11 kv substations, a few parameters were looked into in the power outages data provided by DES (Appendix 2), as mentioned in previous chapter (Chapter 5). The parameters are: If restoration of power occur in full or in steps (step restoration) If Major Event Day (MED) is involved (outage which will increase the SAIDI value typically due to natural disasters where outages can last for days) A few step restoration scenarios were identified in Kuala Belait outages in year 2014 and 2013 (no step restoration identified in Beribi and Mentiri). The identified step restoration outages are highlighted in Appendix 2. Further breakdown on calculation of SAIDI for step restoration is laid out below (Tables 7-11). The calculation of SAIDI which involves step restoration cannot be done accurately as the number of at a particular restoration time is not known in detail. Moreover, due to unavailability of five historical years of data, calculation of MED threshold, as per reference from IEEE Std [2] cannot be performed. Thus, in this calculation, it is assumed that equal number of are at each restoration time. KB outage on 22/06/2013 Scenario order % of remaining Time off Time on Interruption duration (min) (CI) Customer minutes of interruption (CMI) - 0% % :00 AM 9:40 AM % :00 AM 10:45 AM TOTAL 100% Table 7: Step restoration calculation for power outage in KB on 22/06/2013 Draft dated 27 th May of 34

24 KB outage 03/08/2013 Scenario order % of remaining Time off Time on Interruption duration (min) (CI) Customer minutes of interruption (CMI) - 0% % :30 AM 4:00 PM % :30 AM 10:00 PM TOTAL 100% Table 8: Step restoration calculation for power outage in KB on 03/08/2013 Scenario order KB Outage 20/01/2014 % of customer s remaining interrupte d Time off Time on Interruption duration (min) (CI) Customer minutes of interruption (CMI) - 0% % :20 PM 7:03 PM % :20 PM 8:55 PM % :20 PM 10:40 PM TOTAL 100% Table 9: Step restoration calculation for power outage in KB on 20/01/2014 Scenario order KB Outage 11/05/2014 % of remaining Time off Time on Interruption duration (min) (CI) Customer minutes of interruption (CMI) - 0% % :15 PM 5:00 PM % :15 PM 5:25 PM TOTAL 100% Table 10: Step restoration calculation for power outage in KB on 11/05/2014 Draft dated 27 th May of 34

25 Scenario order KB Outage 28/05/14 % of remaining Time off Time on Interruption duration (min) (CI) Customer minutes of interruption (CMI) - 0% % :37 AM 1:15 PM % :37 AM 5:15 PM % :37 AM 6:00 PM TOTAL 100% Table 11: Step restoration calculation for power outage in KB on 28/05/2014 To calculate the SAIDI values for Kuala Belait, Mentiri and Beribi; the number of served at each is defined in Table 10, this information is obtained from DES. Venue Number of served Description Kuala Belait Mentiri *84167 Beribi *84167 Table 12: Number of served Total number of accounts in KB Total number of accounts in Brunei Muara Total number of accounts in Brunei Muara *NOTE: No detailed information on the number of served in Mentiri and Beribi, thus total number of accounts in Brunei Muara is used. Upon calculation of customer minutes of interruptions (CMI) for respective 11 kv substations for year 2013 and 2014 (Appendix 2), SAIDI values were calculated and have been tabulated in Figures 7a and 7b as shown below. Draft dated 27 th May of 34

26 Figure 7a: SAIDI chart for 11 kv substations Figure 7b: SAIDI chart for 11 kv substations - with step restoration analysis Draft dated 27 th May of 34

27 6.2.2 SAIFI calculation for 11 kv substations Estimate of SAIFI is carried out for the three substations mentioned earlier. It is observed that the value of SAIFI for Kuala Belait and Mentiri increases from 2013 to 2014, this is possibly due to deteriorating of the equipment for example excess lightning, storm and animal contact. Figure 8: SAIFI chart for 11 kv substations Draft dated 27 th May of 34

28 6.3 Analysis of three 66 kv substations in Brunei Darussalam. Three representative 66 kv substations have also been analyzed to obtain the SAIDI and SAIFI values, which are: Kuala Belait Substation Mentiri Substation Beribi Substation SAIDI calculation for 66 kv substations To develop the estimates of SAIDI for the three 66 kv substations, a few parameters were looked into in the power outages data provided by DES (Appendix 2), as mentioned in previous chapter (Chapter 5). The parameters are: If restoration of power occur in full or in steps (step restoration) If Major Event Day is involved (outage which will increase the SAIDI value typically due to natural disasters where outages can last for days) Scenario order A few step restoration scenarios were identified in Kuala Belait outages in the year 2014 and From the data given by DES, there were no recorded outages in 66 kv substations Mentiri for year 2014 and Beribi for the year 2014 and Further breakdown on calculation of SAIDI for step restoration is laid out below (Tables 13-21). The calculation of SAIDI which involves step restoration cannot be done accurately as the number of at a particular restoration time is not known in detail. Thus, in this calculation, it is assumed that equal number of are at each restoration time. KB Outage on 04/06/2014 % of remaining Time off Time on Interruption duration (min) (CI) Customer minutes of interruption (CMI) - 0% % :30 PM 1:55 PM % :30 PM 2:35 PM TOTAL 100% Table 13: Step restoration calculation for power outage in KB on 04/06/2014 Draft dated 27 th May of 34

29 KB Outage on 21/07/2014 Scenario order % of remaining Time off Time on Interruption duration (min) (CI) Customer minutes of interruption (CMI) - 0% % :15 AM 12:45 PM % :15 AM 1:23 PM % :15 AM 1:47 PM TOTAL 100% Table 14: Step restoration calculation for power outage in KB on 21/07/2014 KB Outage on 07/08/2014 Scenario order % of remaining Time off Time on Interruption duration (min) (CI) Customer minutes of interruption (CMI) - 0% % :19 PM 10:50 PM % :19 PM 11:23 PM TOTAL 100% Table 15: Step restoration calculation for power outage in KB on 07/08//2014 Scenario order KB Outage on 20/03/13 % of remaining Time off Time on Interruption duration (min) (CI) Customer minutes of interruption (CMI) - 0% % :37 AM 8:57 AM % :37 AM 9:45 AM % :37 AM 10:55 AM % :37 AM 12:56 PM TOTAL 100% Table 16: Step restoration calculation for power outage in KB on 20/03/2013 Draft dated 27 th May of 34

30 Scenario order KB Outage on 20/06/13 % of remaining Time off Time on Interruption duration (min) (CI) Customer minutes of interruption (CMI) - 0% % :50 AM 12:45 PM % :50 AM 2:10 PM % :50 AM 6:09 PM TOTAL 100% Table 17: Step restoration calculation for power outage in KB on 20/06//2013 KB Outage on 02/07/13 Scenario order % of remaining Time off Time on Interruption duration (min) (CI) Customer minutes of interruption (CMI) - 0% % :15 PM 2:05 PM % :15 PM 2:57 PM TOTAL 100% Table 18: Step restoration calculation for power outage in KB on 02/07/13 Scenario order KB Outage 18/07/13 % of remaining Time off Time on Interruption duration (min) (CI) Customer minutes of interruption (CMI) - 0% % :37 PM 9:00 PM % :37 PM 9:38 PM TOTAL 100% Table 19: Step restoration calculation for power outage in KB on 18/07//2013 Draft dated 27 th May of 34

31 Scenario order KB outage 02/08/2013 % of remaining Time off Time on Interruption duration (min) (CI) Customer minutes of interruption (CMI) - 0% % :48 PM 12:21 AM % :48 PM 12:52 AM % :48 PM 1:26 AM TOTAL 100% Table 20: Step restoration calculation for power outage in KB on 02/08//2013 Scenario order KB Outage 07/11/2013 % of remaining Time off Time on Interruption duration (min) (CI) Customer minutes of interruption (CMI) - 0% % :00 AM 11:14 AM % :00 AM 11:45 AM TOTAL 100% Table 21: Step restoration calculation for power outage in KB on 07/11/2013 Upon calculation of customer minutes of interruptions (CMI) for respective 66 kv substations for year 2013 and 2014 (Appendix 2), SAIDI values were calculated and have been tabulated in Figures 9a and 9b as shown below. Draft dated 27 th May of 34

32 Figure 9a: SAIDI chart for 66 kv substations Figure 9b: SAIDI chart for 66 kv substations with step restoration calculation Draft dated 27 th May of 34

33 6.3.2 SAIFI SAIFI calculations have been carried out for the three substations mentioned earlier. It can be observed that the SAIFI values for Kuala Belait and Mentiri decrease from 2013 to Since, there were no recorded outages in Beribi for the two consecutive years, the SAIFI value remains zero. Figure 10: SAIFI chart for 66 kv substations Draft dated 27 th May of 34

34 7. POWER OUTAGE Power system outage means a failure of part of the power supply system for example transformer out of service, an open breaker when it should be closed, and a line down [6], a power outage consequentially will lead to a number of consumers being in an absence of electrical energy for a duration of time [3]. Power outage can last a few hours up to several days, and this may greatly impact businesses, manufacturers (in downtime and lost production) [8], and hospitals. 7.1 Causes of power outages. There are several reasons that may contribute to power outages, such as weather related outages (i.e lightning, rain) and other outages caused by man and animals. While it is possible to identify the causes of power outages, absolute future power outage prevention is highly unlikely to take place, but it can be minimized up to a certain degree. Weather related power outages Faulty equipment faulty underground cable Overcurrent trip Flashover transformer Animal contacts People induced including pole and overhead contacts underground digging [9] Weather related power outages. A large number of power failures and outages are caused by natural weather such as thunderstorm, high winds, snow, ice and even dust [7]. In Brunei Darussalam, the occurrence of lightning and thunderstorm is highly frequent, thus, this can be categorized as one of the main causes of power outages in this country. Power outages are mainly caused by damage from trees falling on electrical lines and poles, especially on longer transmission lines which carry bulk power [8], thus circuit breakers or other protective equipment shut off power flow [13] Draft dated 27 th May of 34

35 7.1.2 Faulty Equipment Faulty underground cable has also been identified as one of the reasons for power outages in Brunei Darussalam Overcurrent Overcurrent occurs when excessive electric current flows through a conductor, which may dangerously lead to excessive generation of heat and cause failure in equipment. Thus, circuit breakers trip to shut off power flow Flashover transformer This happens when power lines touch each other or the ground, and consequently lead to short circuit and an arc or a flashover Animal Contacts Animals such as monkeys and squirrels may climb on certain pieces of equipment (transformers and fuses), which consequently causes the equipment to shut down [13] People induced including: pole and overhead contacts and underground digging Pole and overhead contacts during maintenance and excavation work by contractors may accidentally hit underground cables, thus, directly affecting power supply [9] Short Circuit Short circuit happens when an electric current travels a different path from the planned one in an electrical circuit [7]. Due to the excessive electric current, this may lead to circuit damage and consequentially fire and explosion Electrical Trees Electrical treeing is a scenario which affects high power installations such as high power cables and transformers [7]. Partial electric discharges may form in the equipment due to impurities or mechanical defect used in high voltage installations [7]. If the fault goes undetected, this can lead to constant degradation of the equipment and finally result in a major breakdown power loss [7] Draft dated 27 th May of 34

36 7.2 Examples of power outages (historical blackouts). Power outages are common in this modern world, but its adverse effects have played a major role in trying to improve the electrical power system. Some power outages have affected thousands of people, and lasted for a couple of days, in which, this has led to further economic losses. Brazil and Paraguay (10 November 2009) This outage occurred due to natural event; where continuous heavy rain and strong winds had caused a number of transformers to short circuit and consequentially shutting all 20 turbines in the hydroelectric power plant due to sudden fall of power demand. This incident has put a halt to subways operations, and most of Brazil s phone network collapsed. This outage has affected about 87 million people, and lasted from 25 minutes to 7 hours [10]. India (2 January 2001)[cite] A technical failure, more specifically, failure of substation in Uttar Pradesh has caused a widespread of power outages which affected major hospitals, treatment plants, and pumping stations. As a result from this failure, millions of people were affected as the water supply broke down. The outage has also caused chaos in train and land operations. This disruption has affected 226 million people, and lasted for 12 hours and economic losses were estimated to be USD 110million [10]. USA (North East) + Canada (Central) 14 August A large area of Midwest and Northeast United States and Ontario, Canada suffered from power outages due to human error, lack of maintenance and total equipment break down. The power outage lasted for four consecutive days and 50 million people were affected. A total economic loss of USD 6 Billion was also recorded. [10] From the list of examples of outages, it can be observed that reliability of electrical power system plays a major role in everyday life. A power outage may last from a few hours to a few days, and the economic loss a country has to endure during this period can reach billions of dollars. Thus, it is important to put emphasis on reliability of power system, to benchmark and simultaneously improve the electrical power system supplied to consumers. Draft dated 27 th May of 34

37 8. CONCLUSION Reliability indices measurement for SAIDI and SAIFI has been carried out for three 11 kv and 66 kv substations in Brunei Darussalam which are Kuala Belait, Mentiri and Beribi substation. Different types of interruptions were looked into, and to provide consistent policy to all four districts, only sustained and unplanned interruptions are included to review and improve current reliability performance. In the event of widespread of power outages, restoration of power needs to be done in stages (steps). Thus, step restoration sample calculation has been outlined to calculate SAIDI more effectively, by varying the number of per stage since the number of at each stage is not known in detail. A few causes of power outages have also been identified in Brunei Darussalam such as weather related causes (lightning and thunderstorms), faulty equipment, and animal contacts. Furthermore, collection of more data (five years of data) would enable the study of the reliability trend of SAIDI and SAIFI numbers. Specific power outages could also be identified such as problematic circuits or failing of specific equipment, thus, further corrective action can be taken to benchmark DES to other utilities worldwide. This power failure may affect a large number of people and may greatly impact businesses, manufacturers, hospitals and cause economic losses; thus, improving power reliability is of utmost importance. Draft dated 27 th May of 34

38 9. FUTURE WORK From the SAIDI and SAIFI calculations developed for Brunei Darussalam, a few measures can be taken to improve the accuracy of the calculations, such as having a more detailed record of power outages. DES is currently doing a remarkable job at recording power outages across Brunei Darussalam; further addition on the number of at each restoration stage would greatly increase the accuracy of SAIDI and SAIFI calculation. One of the causes of prolonged power outages in Brunei Darussalam is due to the delay in mobilization of personnel to affected areas. Further design improvement of distribution systems using Smart Grid technologies [13] would identify fault location, and enable personnel to reach the affected area faster, thus, a decrease in time to normalize the power outage [11] and a reduced SAIDI number. Furthermore, implementation of advanced intelligent real time communications-based load shedding schemes can be employed to minimize the number of by matching actual loads to required loads to be shed [14]. Typically, pre determined feeders regardless of actual load (based on peak loading conditions) are selected to shed the required loads. Assume priority order for load shedding is Feeder 1, Feeder 2, Feeder 3 and finally, Feeder 4. Assume that the required load shed in stage 1 under frequency is 8 MW. Assuming peak loading for Feeder 1, Feeder 2, Feeder 3 and Feeder 4 is 2, 3, 5 and 8 MW, respectively. During the requirement for under frequency load shedding, the actual loading is 1, 2, 3 and 6 MW respectively. This conventional scheme will result in a total of 12 MW; 4 MW greater than what is necessary. Thus, the utilization of intelligent load shedding [14] would only select Feeder 2 and Feeder 4 to total 8 MW and unnecessary load shedding can be avoided and a better SAIDI and SAIFI number achieved. Draft dated 27 th May of 34

39 References [1] Energy Department, Prime Minister s Office, Energy White Paper, Bandar Seri Begawan: Energy Department, Prime Minister s Office, [2] IEEE Guide for Electric Power Distribution Reliability Indices, IEEE Std , [3] Marko Cepin, Assessment of Power System Reliability: Methods and Applications, London: Springer. [Online]. [4] Richard E. Brown, Electric Power Distribution Reliability, 2 nd edition, USA: CRC Press, 2008 [Online] [5] Council of European Energy Regulators, CEER Benchmarking Report 5.1 on the Continuity of Electricity Supply, CEER, Brussels, Belgium, REF: C13-EQS-57-03, 2014 [Online]. [6] H. Lee Willis, Power Distribution Planning Reference book, 2 nd edition, USA: New York: Marcel Dekker AG, [7] The Many Causes of Power Failures Internet: [Apr. 31, 2015] [8] Richard J. Campbell Weather Related Power Outages and Electric System Resiliency, Congressional Research Service, [9] Distribution Feeder Principles Internet: [Date accessed] [10] Power Blackout Risks. Internet: kout_risks.pdf [11] How the Smart Grid Makes Restoration Faster and Easier for Utilities Internet: [12] Causes of Power Outages Internet: [13] Smart Grid Investments Improve Grid Reliability, Resilience, and Storm Responses [14] Farrokh Shokooh, et. Al. An Intelligent Load Shedding (ILS) System Application in a Large Industrial Facility, in Proc. Industry Applications Conference, 2005, pp , vol. 1. Draft dated 27 th May of 34

40 Appendix Appendix 1: Power Outages for 2014 and 2013 Kuala Belait Outages for 2014 (for 11 kv substation) Date Description Action Taken Time off Time on Duration of Interruptio n in mins Affected area No. of custo mers affecte d Customer minutes of interruption Transformer tripped at substation Telekom Fault was due to bushing HT terminal yellow phase which leaked. Temporary power supplied through gengset. Transformer was replaced by SEC Mashibah at 8.00 am and power supply is normalized. 7.45pm 9.30pm Faulty underground cable from substation Jalan A until X22 Found out that MIS Setia Di-Raja TAMCO (panel 10) and MIS Hospital (Panel 3 Panglima 1) tripped. 6.20pm 10:40pm 260 PekanBelait Kg Pandan RPN Kg Pandan Sg Tujoh and Mumong received power at 7:03 PM. Pandan 3&4 Pandan 6 Jln Panglima and Jalan Maulana received power at 8:55PM. Kg Mumong Utara Kg Mumong Selatan JlnPandan received power at 10:40 PM Mumong (postpaid) JalanSetiaDiraja Incoming panel number 2 from SetiaDiraja tripped on o/c at MIS BatuTiga Overcurrent trip triggered, open bus section to distribute loading. 7:00pm 7:28pm 28 Pandan 6 Kg Pandan Draft dated 27 th May 2015 A

41 RPN Kg Pandan JalanMaulana JalanMaulana, SgPandan Faulty underground cable from in between substation Pandan 5 and Substation Wisma Yakin Power supply given from S/S Kerma Negara to S/S Wisma Yakin at 5:00PM. Power supplied from S/S Batu 2 to S/S Pandan 5 at 5:25 PM 12:15pm 5:25pm 310 Kg Pandan RPN Kg Pandan JalanMaulana JalanMaulana, SgPandan RMU flashover at substation H3 Spg 15 Pandan 5 Trip at TAMCO MIS SetiaDiraja Panel 5 and found RMU flashover at S/S H3. 11:37 PM 6:00 PM 98 JalanMaulana JalanMaulana, Sg. Pandan Normalised affected area at 1:15 PM. Temporary power given to Spg 15 at 5:15 PM. Kg Pandan RPN Kg. Pandan Pandan 3&4 Spg 29 and Spg received power supply at 6:30 PM. Repairs of RMU started at 6:00 PM and ended at 12:50 AM KVA transformer flashover at substation H21 Spg Temporary power supply given through gengset from 8:00 PM until 2:50 AM. Power normalized back at 3:00 AM. 5:00 pm 8:00 pm 180 JalanMaulana JalanMaulana, SgPandan Pandan Kg. Pandan RPN Kg. Pandan Draft dated 27 May 2015 B

42 Panel 5 Panaga Fuji to circuit Kuala Balai trip on overcurrent Switch on again. Intermittent fault. 9:30 am 11:15 am 105 Kg Kuala Balai Panel number 5 to circuit Kuala Belait trip on overcurrent at MIS Panaga Switch on again. Intermittent fault. 7:00 pm 7:15pm 15 Kg Kuala Balai Panel number 5 Fuji to circuit Kuala Balai trip on overcurrent at MIS Panaga Switch on again. Intermittent fault. 5:45pm 7:30 pm 105 Kg Kuala Balai Fault 800KVA transformer at substation Buruh housing Temporary power supplied through 500 kva started at 4:20 PM. 2:45pm 4:20pm 95 Kg Mumong Utara Kg Mumong Selatan Mumong (postpaid) ERM feeder (Substation SekolahPersediaan Arab to Substation Mumong A) trip due to BSP contractor (seismic project) hit underground cable (blue phase) between substation Jati 6 and Jati 7. Affected areas normalized at 3:20 pm. 2:07 pm 3:20 pm 73 Kg Mumong Utara Kuala Belait Outages for 2013 (11 kv substation) Date Description Action Taken Time off Time on Duration of Interruptio n in mins Affected area No. of custo mers affecte d Customer minutes of interruption Received complaint from 144 informing low voltage Low voltage found at S/S w7 and S/S Batu 4 due to 66 kv transformer at MIS Panaga low tapping and changed tapping from 6 to 9. 10:00 PM 12:00 AM 120 JalanMaulana JalanMaulana (postpaid) Draft dated 27 May 2015 C

43 Flashover of transformer at substation Jati 1 Spg Changed to a new transformer. Temporary power supplied using two gengset. 5:00 PM 12:00 AM 420 STKRJA area, SPG , SPG and JalanDipa Negara Faulty underground cable from human work? Isolated faulty cable between MIS Batu 3 until S.S Eng Hong. Supplied power through ring. 9:30AM 12:05 PM 155 JalanMaulana JalanMaulana (postpaid) JalanPandan 1 JalanPandan 2 JalanPandan 3 Pandan 7 Pandan Faulty underground cable from MIS BT.3 to substation Eng Hong Power supplied via alternative circuit. 8:50 AM 9:31 AM 41 JalanSingaMenteri Pandan Faulty underground cable between MIS Panaga to Substation Kuala Balai Power supplied from 4 gengset at S/S Kuala Balai. 9:40 AM 6:30 PM 530 JalanSingaMenteri Kuala Balai Power cut off Power cut off due to animal contact on jumper HT cable and aerial cable, which caused breaker at Panel Bandaran to get tripped. Switched off supply to S/S SgDuhon and switched breaker back on at MIS SetiaDiraja Power cut off Found RMU 2R2T (ABB) flashover at s/s Kuala Balai A. Temporary power supplied using 4 gengset Power cut off Found out transformer 1000Kva tripped at S/S 4:25 PM 4:45 PM 20 Jalan Sungai Duhun :00 AM 10:45 AM 225 Jalan Kuala Balai :18 AM 9:45 AM Draft dated 27 May 2015 D

44 Kuala Balai E HjTalip. Switched back on, and normalized affected area No power Found faults at station transformer. Temporary power supplied using mobile generator. 7:50 PM 10:45 PM Faulty underground cable due to human work?? Found out underground cable from Jati 7 to S/S penapisan najis 1 (JKR) faulty and a trip at MIS Panaga. Isolated faulty underground cable and found out more faults at cable from S/S Mumong to package unit (RMU) at S/S. Power supply normalized at 4:00 PM except Spg 284 Mumong, power supplied through generator at S/S Saluran najis at 10: 00 PM 11:30 AM 10:00 PM 630 JalanSingaMenteri Pandan 8 Mumong B Kg Mumongutara Mumong (postpaid) Power cut off Checked and found out transformer No. 3 tripped due to overcurrent at MIS Setia DiRaja Siemen. Transformer switched back on and normalized affected areas Power cut off 1000 kva transformer tripped at S/S Jalan Patai. Transformer switched back on. 1:45 PM 3:30 PM 105 Pekan KB Kg Pandan RPN Kg Pandan JlnMaulana, SgPandan (postpaid) Pandan 3&4 Pandan 6 4:00 PM 4:30 PM 30 JlnPetai LubokNipah Power cut off Electricity tripped at TAMCO Panel 5 at MIS 10:50 AM 12:26 PM 96 JalanSetiaPahlawan Draft dated 27 May 2015 E

45 Setia Di Raja. Found out there was a flashover at termination in RMU in S/S Pejabat Elecktrik. Normalised affected areas. JalanSgSatu Pandan 5 Pandan 6 Beribi Outages for 11kV substation 2014 Date Description Action Taken Time off Time on Duration of Interruptio n in mins Affected area No. of custome rs Affected Customer minutes of interruption Substation Jalan Jasmin Beribi The RMU oil type (Long &Crowfort). 2:00 PM 3:30 PM 90 Jalan Jasmin Kg Beribi Feeder T tripped. Change to RMU (Brush Hacker Siddley) Overcurrent due to load transfer Transferred load and energized one by one by considering the load. 9:00 AM 11:32 AM 152 Baiduri Bank Kg Kiarong Kg Beribi Kg Kiulap MIS Telanai P#13 tripped and indicated earthfault and overcurrent. HV underground yellow phase faulty. 12:30 AM 1:50 AM 80 Spg 493, Spg 2, Flat E, SgSunda Housing New Housing Kg Beribi MIS Beribi Industry Phase 1 P#4 tripped to ERM Beribi Industry 3 and indicated earthfault. 3:00 AM 4:30 PM 90 Light Beribi Industrial area Draft dated 27 May 2015 F