III Improvement of Reliability

2. Establishment of Systematic Interruption Statistic Management System

2-1 Use International Standard Reliability Index

As there has been reliability index managed by PLN in a systematic manner, PLN is expected to be able to improve the reliability significantly only by managing reliability indices without additional investment.

It is a global trend that customer-centered indices are used for reliability management. About 80% of the utilities surveyed by EEI use SAIFI, SAIDI and CAIDI as their reliability index.

Therefore, such reliability indices can be regarded as international standard. Reliability level of PLN can be compared with those of the utilities elsewhere if international standard reliability indices are adopted, indicating where the reliability of PLN stands in the world and what reliability level should be targeted.

Reliability target is also one of the critical elements for any utility interested in assessing its operational efficiency and developing long term vision and strategy. Therefore, it takes no genius to see that international standard reliability indices should be employed in determination of reliability target as PLN develops a strategy to become one of the globally-renowned energy supplier.

2-2 Analyze Cause of Interruption

The most fundamental driver of reliability index management by utilities is to identify and analyze current status and causes of their interruptions and develop effective counter measures accordingly. Therefore, After interruption data collection and input, the data should be analyzed periodically to account for causes of interruptions, develop enforceable measures to an extent as allowed by applicable budget, analyse effect of such measures after a certain lapse of time to provide an input for development of long-term strategy. That is why accuracy in entry of raw system data and interruption records is required. Otherwise, lots of trials and errors will be suffered and budget wasted. It has been found that causes of interruptions are not accurately analyzed in PLN at the moment. To analyze cause of interruption accurately, accurate cause of interruption should be recorded first. It is not easy to account for cause of interruption in many cases. But, it is essential to improve reliability. Interruption data should be analyzed monthly, quarterly, semi-annually and annually and all the employees trained on interruption to identify and enforce solutions against issues associated with interruptions. Interruption data can be analyzed by area, feeder, voltage, cause or facility to provide an input to identify causes of recent interruptions, set up short-term objectives and centralize preventative maintenance.

2-3 Recommendation on Interruption Classification

Interruption mitigation strategy should be based on accurate analysis of cause of interruption more than anything else. Developing the right interruption mitigation strategy is a key to effective use of limited budget. Therefore, number of interruptions, causes thereof and interrupted facilities should be recorded. In addition, breakdown of interruptions at macro and micro level is required to ensure input to interruption analysis to be utilized effectively.

As PLN does not have an integrated interruption classification structure yet, we have recommended an integrated standard interruption classification structures based on the one used by KEPCO and the other one used by the instruction of fault investigation in Indonesia.

PT PLN has defined and utilized its own interruption classification system. However, the classification system has not been updated for considerably long and not defined with simplicity and clarity, making it difficult for engineers to use it actually on site. Fortunately, PT PLN now plans to revise the interruption classification system recently and, as the revision is completed, faults are expected to be analyzed more accurately and significant contribution is expected to be made to improving supply reliability if fault prevention activities are performed in reference to fault analysis results. An integrated standard interruption classification system based on KEPCO’s fault classification system will be proposed to extend support for the revision of interruption classification system by PT PLN.

2-4 Input Data & Implement Reliability Management System

Determination and accuracy of input data is essential for proper management of reliability indices. In case that a section in a line is interrupted, accurate statistics data can be obtained only when the number of connected customers or interruption duration of the section is accurate. Interruptions can be classified into source side interruption, scheduled interruption and unscheduled interruption. And also, they are classified into primary side interruption and secondary side interruption.

Customer management by bank is essential to use customer-centered reliability index. It is related with effective transformer management. None the less, if the scope is limited to reliability indices, it means a system that manages number of customers by bank. Since PLN is supposed to control faults only in primary distribution lines, it is possible to identify the number of customers per section. However, it is still necessary to manage customers by transformer to control faults in low voltage lines. In addition, to improve fault data accuracy, data needs to be managed per transformer and section in separate logs respectively and updated on a monthly basis. Such data can be managed by IT system or transformer management card. In general, transformer management card is preferred if there are not many facilities to be managed and IT system if it is the other way around. However, IT system is believed to be more efficient in any case.

2-5 Utilization of Interruption Statistics Management Program

Reliability index calculation with a computer program promises many advantages such as more convenience in data calculation, management, update and statistical analysis. However, it requires additional costs required in development or procurement of SW applications, implementation of technical infrastructure and recruitment of IT system administrators, etc.

Deploying simple standalone application packages to branch offices will ensure sufficient benefits for PLN. If communication infrastructure is enhanced and integrated IT systems are deployed so that branch offices may share data and manage customers in an integrated manner, PLN will be able to perform reliability index management system integrated at an enterprise level, analyze reliability indices more in detail by period, facility, cause of interruption or area, identify outstanding issues and develop counter measures far more effectively.

2-6 Introduction of Root Cause Analysis System

Rather than relying on visual analysis of fault cause as is the current practice, revision of fault cause classification system that enables more systematic and scientific determination of fault cause based on phenomenon is being called for. To address such a shortcoming, KEPCO plans to develop a root cause analysis system and incorporate it with the as-is New Distribution Information System (NDIS). The business flow of root cause analysis system under implementation by KEPCO. However, it is still premature for PLN to introduce a similar system as PLN does not operate an integrated system comparable to the New Distribution Information System (NDIS) and enough of underlying data for interruption analysis classification structure.

It will be more effective to introduce a root cause analysis system after the business practice relating to the fault cause analysis system propsoed in the above has taken roots. Therefore, the root cause analysis system introduced below is expected to provide references for PLN to consider in relation to fault analysis and prevention.

To implement a root cause analysis system, fault type must be classified per each equipment/material as per fault phenomenon in the first place. Fault phenomenon is further divided into 3 stages to ensure more accuracy in cause analysis. And, as some faults may be combinations of different faults, several fault type are allowed to be applied to a single fault.

Verdict of fault cause is configured to allow for identification of fault cause from high-level items likely to be seen frequently to more specific items per stage with focus on ease of use so that everyone from technician to engineer can utilize it. Fault causes are to be determined in 4 stages and the system is configured to interface with historical distribution interruption statistics and comprehensive power system interruption statistics for interoperability across systems.

2-7 Important Customer Interruption Detection & Automatic Notification System

When distribution lines of electrical utilities are interrupted, interruption is recovered by DCC, DOC and DAS, etc. However, even after interruption recovery, some electrical facilities on the premise of high voltage customers remain interrupted because of power-receiving facility UVR(Under Voltage Relay) activation in some high voltage Important customers, which is attributable to the absence of or mistake by maintenance engineer responsible for the power-receiving facilities in such high voltage Important customers and leads to prolonged outage or even social scandal in some cases. Furthermore, most of the general public recognize such interruption not as the interruption of on-premise facilities of high voltage customers but as the interruption of electrical utilities’ facilities. Mass media also ascribes such interruption to faults in power distribution line of electrical utilities, inflicting significant damage to the corporate image of electrical utilities. Therefore, KEPCO has implemented automatic interruption detection and notification system on the premise of high voltage Important customers to prevent propagation of interruption by customers.

Therefore, KEPCO needed a more advanced system and implemented a system that would notify outage information promptly when interruption occurred on the premise of high voltage Important customers which were premium customers from KEPCO’s perspectively. The apartment complex interruption detection and automatic notification system notifies details of on-premise interruptions to KEPCO engineers, apartment complex administration staffs and relevant electrical engineers automatically.

It is a system that compares power sources of meter and power-receiving facility upon detection of interruption signal on the premise of Important customers and notifies interruption details to predefined phone numbers in real time if interruption is determined to have happened.

KEPCO and apartment complex facility administration staffs confirm notification details and detect/recover interruptions more promptly and accurately thanks to the system.