Lin Weifang

A frequency-domain parallel eigenvalue search algorithm of power systems based on multi-processing

With the rapid development of large-scale interconnected power systems, inter-area low frequency oscillation phenomena occasionally occur; thus, the small signal stability problem has become a serious issue affecting power system stability. When analyzing the small signal stability of a large-scale power grid (in particular, on-line dynamic security early warning systems), given the high rank of the differential algebra equations (DAEs), the serial eigenvalue algorithm cannot meet the requirements of computation speed. In recent years, the development of multi-core CPU technology has been very rapid. By fully using the hardware resources of multi-core CPU computers, the small signal stability calculation speed problem can be effectively solved in parallel computing technology. In this paper, a frequency-domain parallel eigenvalue search algorithm of power systems based on multi-processing is described, with the algorithm realized in the PSD-SSAP system, which is widely used in China. The calculation is accurate, the realization of the algorithm is simple, and the parallel computing efficiency is very high. Numerical simulation results of actual large-scale power systems show that the proposed algorithm is correct and efficient.

Voltage stability analysis of multi-infeed AC/DC power system based on multi-infeed short circuit ratio

The definitions of multi-infeed short circuit ratio (MSCR) were analyzed in the paper, which were proved to be equal. The relation between MSCR and traditional short circuit ratio (SCR) was discussed, and it came to a conclusion that the traditional SCR is the particular case of MSCR. Then, the decoupled model of MSCR system was presented in the paper, and based on it, the index of multi-infeed critical short circuit ratio (MCSCR) was given, which could be used as a criteria for weighing the strength of the system. Simulation results show that it is effective to use MSCR for denoting the level of voltage stability.

Study on the mechanism of dynamic reactive power reserves in respect of voltage stability

At present, few studies focusing on dynamic reactive power reserves in respect of voltage stability have been reported. In the paper, the definitions of dynamic reactive power sources such as synchronous generators, SVC and STATCOM are proposed firstly. Then the mechanisms of dynamic reactive power reserves of synchronous generators, SVC and STATCOM in respect of voltage stability are studied, respectively. It demonstrated that in steady-state operation, with more generator reactive power output, the static voltage stability and transient voltage stability of power system are better; with less reactive power output of SVC and STATCOM, thats more reactive power reserves, the static voltage stability and transient voltage stability of power system are better.

A dynamic reactive power reserve optimization method to enhance transient voltage stability

Dynamic reactive power reserve of power system is vital to improve transient voltage security. A novel definition of reactive power reserve considering transient voltage security in transient procession is proposed. Participation factor to evaluate reactive power reserves contribution to transient voltage stability is computed through trajectory sensitivity method. Then an optimization model to enhance transient voltage stability is built and a solving algorithm is proposed. Based on an analysis of the transient voltage stability characteristics of East China Power Grid, the effectiveness of the proposed dynamical reactive power reserve optimization approach for improving transient voltage stability of large-scale AC-DC hybrid power systems is verified.