The Study Of Power Modulation For Ac/dc Parallel Systems

One notable advantage of DC transmission systems is that can be controlled well, which is helpful for improving the stability of systems. In order to exert this advantage more effectively, it is necessary to expand the controllability of DC link by appending control methods. Power modulation is one of valid supplementary control methods for AC/DC parallel systems. Following up the change of some parameters in AC systems, it can regulate the active power transmitted by DC link and damp power oscillation in systems. This paper discusses the theory of power modulation in detail.The system of TSQ-GBJ is the first AC/DC parallel system in China. For improving stability of the system by power modulation, this paper presents a new method to damp two power oscillation modes. One is inter-area oscillation mode in low frequency and the other is intra-area oscillation mode in high frequency. According to economic and technical argumentation, the frequency difference of two terminals is used as input signals for the controlABSTRACTsystem.Evaluations of the stabilization efficiency of the proposed power modulation control are obtained by simulation methods, in which simulation software EMTDC is used. The simulation results show that this power modulation method is effective for damping two power oscillation modes.