A practical method of state estimation in ship power system

Reactive power and voltage control is the important technical means to improve the voltage quality and reduce the active loss of power grid. It is hard to regulate the voltage and reactive power of Guizhou power grid by manual operation. In this paper, adopting to the successful experiences in automatic voltage control (AVC) system of several power companies in Europe and China, a new decomposition and coordination method is presented for multivariable coordinated control between generators, shunt capacitors, shunt reactors and adjustable reactive loads. Firstly, the method utilizes the primal-dual interior point algorithm to solve an large-scale discrete and mixing optimal reactive power flow (ROPF) calculation, which gives an optimal voltage profile of the whole power grid; Then the method utilizes the extended coordinated secondary voltage control to optimize the regional reactive power distribution with discrete and mixing variables coordination based on the local balance of reactive power, whilst satisfying the optimal voltage profile. The substation of district power network is equivalent to the adjustable reactive loads with coordination between provincial and district AVC systems. The paper also presents a new method of main and auxiliary dual instructions, which is used to control the plant voltage by master station. The newly developed AVC system has been put into practical operation in Guizhou power grid, and the results show that the AVC system is remarkably effective.