Optimal Reactive Power Planning Of Radial Distribution System With Consideration Of Voltage Stability

The purpose of optimal reactive power planning is to determine the optimal sizing and location of VAR sources, so that the security and the economic operation of power system at different load levels and operation conditions can be maintained. Considering right,normal,heavy load operation conditions and fault conditions, the mathematical model has been established in which the sum of yearly active power loss fee and minimized investment in new addition of VAR equipment divided into each year is used as the objective function. A kind of optimal method for reactive power compensation planning in radial distribution system considering fault condition giving attention to both security and stability constraints is presented in this paper. We coordinate the first three models by using heavy load loss time. Therefore, various operating conditions are considered so that the result is precise and the algorithm is simple and can be easily realized. The calculation of reactive power compensation and regulating transformer rate are done with the backward and forward sweep adapting to the radial distribution system. The result of example systems approves that the method is feasible in technique and has obvious economic benefits.Taking two bus systems for examples, the validity and rationality of the methods are proved.