Wide area visibility can avoid cascading black outs in Asian interconnectionsBY EHTESHAM UDDIN
The trends of interconnections are gaining popularity in Asian power market. Beside the great advantages of these interconnections, a high risk is also associated with cascading effect of any local disturbance which may travelled through the interconnections and leads to a massive break down. Wide Area Monitoring System (WAMS) is now a necessity in Asian power market.
Complex configurations of interconnectors create a requirement of better visibility and disturbance analysis so that System operators have access to information about any potential threat in advance and with enough time to react and save the disaster. WAMS comes here to rescue.
WAMS can be used as standalone infrastructure that compliments the grid’s conventional SCADA system. Expressly designed WAMS can enhance the operator’s reach to monitor activities and happenings in neighborhoods of their control area and provide better visibility over the events taken place. Though the concept is too old, however with advancement in Information technology, telecommunication field and advanced operational structure make way for the better utilization of WAMS.
Basic ingredient to this concept is Phasors, a century old tool for ac circuit analysis, usually introduced as a means of representing steady state sinusoidal waveforms of fundamental power frequency. Even when a power system is not quite in a steady state, Phasor are often useful in describing the behavior of the power system.
Such as, when the power system is undergoing electromechanical oscillations during power swings, the waveforms of voltages and currents are not in steady state and neither is the frequency at its nominal value. Under these conditions, as the variations of the voltages and currents are relatively slow, Phasor may still be used to describe the performance of the network.
Recent developments in time synchronizing techniques, coupled with the computer-based measurement system, have provided a novel opportunity to measure the phasor, and phase angle differences in real time.
A high quality of Phasor Measurement Units (PMUs), similar to RTUs, installed at different locations of widely spread interconnected control areas, these devices use synchronization signal from Global Positioning System (GPS) and provide the Phasor of voltage and currents measured at different location with a single time stamp.
That’s why they are called “SynchroPhasors”, hence brought a new perspective to power system monitoring and analysis.
Currently available WAMS operates at 6-60 measurements per second, ideal to perform dynamic monitoring and analysis. Thus creates an early warning system for operators, also with the help of smart algorithms/software can be able to generate alarms in advance and suggest defense mechanism to protect or stop cascading impact of any disturbance over the interconnected network.
Multi fold improvement can be obtained in “Supervision” and “State Estimation (SE)” processes. Similarly improvement in “Protection” and “System Control” can be seen as well.
As dynamic supervision is now possible with smart use of PMU’s data and artistically build maps and overviews, provides an illusion of Real Time wide area visual perception.
Abu Dhabi being the hub of interconnections such as Gulf Interconnector that connects all Gulf States (Saudi Arab, Qatar, Bahrain. Kuwait) and on the other side with Emirates Grid that connect Dubai, Sharjah and Northern Emirates, it is advisable to look for such capability to enhanced operational excellence and to avoid any cascaded black out, such as recently occur in India and in past faced by North America.