Reliability improvement of power system observability with minimum phasor measurement units

The size and complexity of power network and the cost of monitoring equipments, make it unfeasible to monitor the whole system variables. Conventional system analysers use voltages and currents of the network for monitoring purposes, which affects the system analysis, control and protection. A strategic placement of phasor measurement units (PMUs) is crucial to monitor the whole system with minimum number of devices. This study improves a topological circuit observation method to find essential PMUs. Besides the observability of the normal network, observability of abnormal network is considered. Consequently, a high level of system reliability is achieved. The reliability is maintained by observability under bad current data (CT errors) and all possible single single-line outage. These limitations are taken into the account in a hybrid genetic particle swarm optimisation strategy to minimise monitoring cost and avoiding unobservability under abnormal conditions. Proposed algorithm is tested on 14, 30, 39 and 118-bus IEEE standard test systems and a 24-bus network of Mazandaran Regional Electric Company located in north of Iran.