Optimal Placement Of PMUs In Power System And Assessment Of Feasible Schemes

With the development of power system and the increasingly stricter requirement on security and stability, traditional monitoring systems based on steady state, such as SCADA/EMS, can not meet the needs of dynamic monitoring. Wide area measurement system (WAMS) based on phasor measurement unit (PMU) can effectively handle the problem of wide area synchronous mearsurement in power system, and offer a new approach for stable monitoring and control of power network. A lot of researches indicate that it can guarantee full network observability to place PMUs in certain buses in power grid.To place PMUs optimally is a discontinuous, high dimensinal, nonlinear, optimization grouping problem. Firstly, main steps for network observability analysis are proposed by studying the mathematical model of PMU optimal placement; secondly, the optimization is processed in two stage: preliminary placement and assessment for feasible scheme.In preliminary stage, the binary particle swarm optimization (BPSO) is applied to the issue of optimal PMUs placement. Considering the deficiency of convergence rate in conventional BPSO, a probability shifting factor is introduced to adjust the probability of value on 0 or 1 according to bus-outlet number so that the ability of convergence rate of solutions is improved based on analyzing. The limitation of general optimization algorithm on multiple solutions is analyzed, and then improving measures are presented. The effectiveness of proposed algorithm is verified by the numerical calculation results of New England 39-bus system ,IEEE 30-bus system and Hunan Chang-Zhu-Tan 42-bus system respectively.In the assessment stage, the weak voltage buses are identified after network analysis with continuation power flow firstly, and then a coefficient is introduced to compare the sum of voltage drops of every scheme, finally the scheme with larger coefficients are recommended. The test program is designed in Matlab and the recommended schemes of IEEE 30-bus system are proposed...