Voltage security assessment and optimal load shedding of power system using the case-based reasoning approach

Abstract

This paper presents the case-based reasoning (CBR) technique, a novel approach for voltage security assessment and optimal load shedding plan in a real time environment. CBR extracts the information of voltage security from large sets of possible operating conditions of the power system, which are screened off-line by randomly varying the real and reactive loads at PQ buses. In a real time environment, a database may be created by keeping the record of operating states by state estimation. The severity of the contingency is assessed by the number of insecure operating states caused by that contingency, which is predicted by CBR. Security classes are defined by the threshold value of the maximum loadability margins (MLM), calculated using the continuation power flow (CPF) method. For insecure states, the presented technique also gives an optimal load shedding plan to bring the system into secure mode.