An optimization method of UFLS/UVLS considering the interaction of system state information

Abstract

Because of the differences of grid network architecture, generator parameters, and load characteristics, frequency and voltage at grid nodes show certain spatial distribution characteristics when faults happen. Therefore, the same stability control measures may result in different control effects if applied at different nodes. Meanwhile, in order to improve the control effect and reduce stable control cost, the impacts of the interactions between strongly coupled factors, such as frequency, voltage, active power, reactive power and other quantities, on the effects of stability control measures need to be considered. A new optimization control strategy of under‐frequency load shedding/under‐voltage load shedding is proposed in this paper based on the load control sensitivity index. The method takes into consideration the spatial distribution characteristics of frequency and voltage, as well as the real‐time interaction characteristics of the coupled electrical quantities. Compared with the traditional load‐shedding scheme, the proposed scheme can achieve better control results. The effectiveness of the proposed method is verified through a time‐domain simulation of two actual provincial power grids. © 2018 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Multiobjective optimal setting for UFLS relays considering voltage deviation

“…Finally, neglecting small terms, the linearized AC power flow equations for the flow on line ij are obtained as follows: …”

“…Finally, neglecting small terms, the linearized AC power flow equations for the flow on line ij are obtained as follows 26,27 :…”

“…The integrated information of voltage and frequency and defining the LS distribution factors for active and reactive power have been used to adjust LS allocation . A new UFLS and UVLS optimal control scheme has been proposed by analyzing the spatial distribution characteristics of power grid frequency and voltage and real‐time dynamic interaction characteristics of various coupling electric quantities . Three adaptive combinational LS methods have been proposed using locally measured frequency and voltage signals.…”

“…25 A new UFLS and UVLS optimal control scheme has been proposed by analyzing the spatial distribution characteristics of power grid frequency and voltage and real-time dynamic interaction characteristics of various coupling electric quantities. 26 Three adaptive combinational LS methods have been proposed using locally measured frequency and voltage signals. In the proposed algorithms, LS is started from the locations which have higher voltage decay for longer period of time.…”