Ac Dc System State Estimation Study

With the development of high voltage direct current (HVDC) transmission technology, there is a great demand to do some research in the influences of HVDC systems on modern Energy Management System (EMS). As a important part of EMS, state estimation algorithm of AC/DC systems is studied in this paper. And to program a AC/DC system state estimator based on CC-2000 systems of China Electric Power Research Institute (CEPRI). The operation and control character of DC link is discussed. The static model of DC link is set up for state estimation, which is considered about control character of DC link. The different AC/DC system state estimation algorithms is discussed in this paper, including a simultaneous approach, a sequential approach, a improved sequential method. They are compared in convergence behavior, solution accuracy and amount of programming. The important part of this paper is developing a AC/DC system state estimator. The algorithms used in program is a sequential approach because the older AC state estimator can be made use of easily. So the developing work of the AC/DC system state estimator can be minimized. The developed program had been tested on IEEE 30-bus system with a DC link and a real 630-bus system with three DC links. The program had been installed on CC-2000 systems in National Power Dispatching and Communication Centre. The program came into use in Jan,2004. It has operated for a half year very well. It is concluded that program can do well with realtime data.