See It Fast to Keep Calm: Real-Time Voltage Control Under Stressed Conditions

Abstract

A AS THE ELECTRICAL UTILITY INDUSTRY ADDRESSES ENERGY AND environmental needs through greater use of renewable energy, storage, and other technologies, power systems are becoming more complex and stressed. Increased dynamic changes that require improvements in real-time monitoring, protection, and control increase the complexity of managing modern grids. In an effort to ensure the secure operation of power systems, more attention is being given to voltage management. Voltage management includes addressing voltage stability and fault-induced delayed voltage recovery (FIDVR) phenomena. Deployment of phasor measurement unit (PMU) technology, in combination with recently developed methodologies for tracking voltage behavior, has resulted in improved real-time voltage monitoring, protection, and control. This article describes simple and accurate methodologies based on real-time measurement-and independent of the system model-designed for tracking both slowdeveloping and transient voltage stability conditions under various and changing system confi gurations. Tests with real-time supervisory control and data acquisition (SCADA) and PMU data, as well as data from comprehensive simulation studies, from the Bonneville Power Administration (BPA) and Southern California Edison (SCE) systems show very accurate detection as the system is approaching voltage instability. The calculated reactive power margin and other indices are easily visualized for operator awareness. For quickly developing disturbances, they allow the initiation of fast control and protection actions. This methodology also discriminates well between FIDVR and short-term

Wide Area Information-Based Transmission System Centralized Out-of-Step Protection Scheme

“…One of the defining protection functionalities of the WAMPAC system is a MFLP. It has two main modules [27][28][29][30] To be able to respond to system wide transmission network disturbances (voltage, frequency and angle instability) in a proper way, the system protection function must be parametrized carefully in the setting phase. Phasor data streams from different parts of the transmission network must be collected in the control center.…”

“…One of the defining protection functionalities of the WAMPAC system is a MFLP. It has main modules [27][28][29][30]: system protection function module and line back-up protection func module (Figures 4 and 5). Conditions at each transmission line ends are covered with P measurement data and data gathered from the SC and the BC.…”

Practical challenges of integrating synchrophasor applications into an EMS

“…To be compatible with real-time monitoring requirements computations involved in power margins determination should be simple. Measurement based modelfree approaches [4,5] offer simple algorithmic solution at the expense of decreased accuracy. Some of such algorithms are based on the Thevenin equivalent calculation of impedances [3].…”

“…Approximate nature of these algorithms is partly compensated by re-computation of all parameters and variables with new samples of measurements preferably collected at high rates using synchronized phasor measurements. Several variants of algorithmic solution based on Thevenin equivalent are now available [5] and able to provide approximate computation of power margins at the level of single station, transmission corridor, and load center.…”

Multi-Phase Under Voltage Load Shedding Scheme for Preventing Delayed Voltage Recovery by Induction Motor Power Consumption Characteristics

“…Systems with a large portion of inductive (IM) loads might face delayed voltage recovery (DVR) after the fault. The DVR phenomenon, observed and reported in various parts of the world, has been recognized as a voltage stability issue [1][2][3][4]. The phenomenon is basically caused by stalling of IM loads, and it could in turn potentially result in the cascading effect on other IMs in the same feeder or in their vicinity.…”