Wide-area measurement system-based supervision of protection schemes with minimum number of phasor measurement units

Abstract

Cascade tripping of power lines triggered by maloperation of zone-3 relays during stressed system conditions, such as load encroachment, power swing and voltage instability, has led to many catastrophic power failures worldwide, including Indian blackouts in 2012. With the introduction of wide-area measurement systems (WAMS) into the grids, real-time monitoring of transmission network condition is possible. A phasor measurement unit (PMU) sends time-synchronized data to a phasor data concentrator, which can provide a control signal to substation devices. The latency associated with the communication system makes WAMS suitable for a slower form of protection. In this work, a method to identify the faulted line using synchronized data from strategic PMU locations is proposed. Subsequently, a supervisory signal is generated for specific relays in the system for any disturbance or stressed condition. For a given system, an approach to decide the strategic locations for PMU placement is developed, which can be used for determining the minimum number of PMUs required for application of the method. The accuracy of the scheme is tested for faults during normal and stressed conditions in a New England 39-bus system simulated using EMTDC/PSCAD software. With such a strategy, maloperation of relays can be averted in many situations and thereby blackouts/large-scale disturbances can be prevented.This article is part of the themed issue 'Energy management: flexibility, risk and optimization'.

Wide-Area Backup Protection Using Sparse Synchronized/Unsynchronized PMU Measurements

“…Without loss of generality, let us assume that FLC2 is determined in this step. Then, FLC3 and FLC4 are located so that (12) holds true. This procedure should be done for all buses.…”

“…According to (12), all procedures for locating FLCs and calculating their coefficient vectors are conducted offline, thereby incurring no during-fault computational burden. Hence, the 𝑀𝐷 indices for every FLC using ( 8) can be quickly computed in near real-time.…”

Smart energy systems for sustainable smart cities: Current developments, trends and future directions

“…As system connectivity and complexity increases, ensuring system resilience can become more challenging. Cascade failures [236] and communication faults must now be mitigated, with suitable failure modes designed. As previously discussed, the control architecture is founded on a layer of standard controllers, which in the event of a loss of communication, can operate the various assets in an isolated manner.…”

Energy management: flexibility, risk and optimization

“…In particular, there are two 'framework' contributions that cover important general applications of stochastic and probabilistic modelling, namely smart grid and low-carbon power system planning [1], and system stability analysis [13]. Then, a number of papers deal with more specific and technical topics such as optimal location of advanced measurement devices in transmission networks [14], distribution network voltage control through multi-agent systems [15] and identification of analytical conditions for synchronous generators' stability [16].…”

“…Gajare et al [14] discuss a specific smart grid technology that can improve power system operation and stability (also see [13]) by decreasing the number of protection maloperations under stressed system conditions that may often lead to blackouts/large-scale disturbances. This technology is a wide area measurement system that allows real-time monitoring of the transmission system through the so-called phase measurement units.…”