Electrical power outages are major concerns to power utilities throughout the world. Unfortunately, power outages will continue to happen and they cannot be totally prevented. Outages could be due to lightning strikes, tree encroachments or equipment failures. However, the impact can be reduced if power system operators are equipped with appropriate tools to analyze the root causes of the outages. To ensure system operators have the system fault conditions immediately after a tripping has occurred, this paper discuses practical solutions to be applied in the control center. This paper presents a tool for analyzing protection system performance with special emphasis on the fault signatures using Digital Fault Recorders (DFRs).
Nowadays, consumers throughout the world place greater demand on power utilities to provide higher quality and reliability of power supply. Electricity is no longer a luxury item. It is now an essential commodity which has great economic and security implications. Power outages and blackouts have become unacceptable disruptions to our daily lives and routine activities in this challenging 21st century.
In the year 2003, the world experienced at least five major electrical power supply disturbances affecting a few countries resulting either partial or total national blackouts. The famous wide-scale power outages are as follows:
(i)
14th August 2003 at 1610 h, north-eastern United States of America (USA) and central Canada [18], [46] and [13].
(ii)
28th August 2003 at 1826 h, central United Kingdom [18], [46] and [13].
(iii)
1st September 2003 at 0958 h, northern Malaysia [34].
(iv)
23rd September 2003 at 1235 h, eastern Denmark and southern Sweden [18], [46] and [13].
(v)
28th September 2003 at 0328 h, whole of Italy and southern Switzerland [31].
All those blackouts have caused great financial losses that were estimated to be more than a billion US Dollars [18]. Blackouts can be initiated by many causes, such as severe demand and generation imbalance, protection system failures, incorrect or slow actions of system operator. Generally, blackouts are due to a combination of circumstances which stresses the network beyond its limits. The difficulty is in seeking solutions that would prevent cascaded tripping that eventually lead to partial or even total blackouts.
An important fact is that, electrical power outages will continue to happen and they cannot be completely prevented. Outages could be due to lightning strikes, storms, broken conductors, random equipment damages, fire, tree encroachments or human errors. Unfortunately, system operators are not equipped with sufficient tools to identify the nature of the faults and the accuracy of the protection system operations before any decision can be made to restore the supply. This is one of the factors that often delay the restoration process.
In actual fact, system operators have to depend mainly on information from relay indications, flags, facias and Supervisory Control and Data Acquisition (SCADA) system. The information provided may sometimes leads to inaccuracies in fault analysis due to uncertainty of correct relay operations and unsynchronized information. Unfortunately, with complex disturbance events in a power system, system operators have to make critical decision in order to minimize the duration of outages and economic impact although the exact nature of the faults are not known.
Protection system analysis is a complicated task and time consuming for inexperienced engineers. Currently, most power utilities manage their protection problems by using simulation tools to identify the desired operation. Day-ahead operation planning only considers scheduled outages and normal N − 1 contingencies. However, during forced outages or trippings, most power utilities have to rely mainly on information from SCADA to handle the protection issues. All the protection analysis relied predominantly on the relay indications, flags and facias, which sometimes lead to inaccuracy in the fault analysis due to the uncertainty of the correct relay operations and time synchronization. More often than not, they use the relays operation to make judgments on the cause of tripping. Under such situations, wrong judgment could lead to cascaded trippings.
The significant contributions are the fault signature analysis which is capable of identifying the causes of the trippings and diagnosis of the protection system operations. The contributions and innovations from this research have helped TNB to improve their performance by reducing transmission system minutes from 14 min on FY2005 to 7.3 min on FY2006 (a reduction of 47.9%). It is also supports TNB’s Electricity Technology Roadmap [36] which is related to the implementation of self-diagnostics of power and protection systems in the year 2010. It also aligns with the 9th Malaysia Plan 2006–2010 which emphasizes on security and reliability of electricity supply [17].
