一种可有效提高临界增益的改进型电力系统稳定器

An Improved Power System Stabilizer for Higher Critical Gain

目前,实际电力系统中广泛使用电力系统稳定器（power system stabilizer,PSS）进行低频振荡阻尼控制。但是,PSS在低频振荡控制中有一定的局限性,可能使其增益整定值难以同时满足系统阻尼水平以及《电力系统稳定器整定试验导则》规定的增益必须小于临界增益1/3的投运要求。该文通过分析,发现自并励条件下,PSS临界增益主要受励磁模式限制,而励磁模式是由励磁–PSS回路在3~8 Hz频段的固有特性形成。在上述分析的基础上,提出在励磁–PSS回路外环引入一个功率增量软反馈,形成一种带有并联环节的改进型PSS模型,改善了回路相位特性,提高了PSS临界增益,解决了上述问题。最后,以锡盟火电集中外送仿真系统为例,验证了所提方案的有效性。

Recently, power system stabilizer（PSS） is widely used in the power system in China. However, PSS may have some shortcomings. That is, the gain of PSS may not satisfy both the damping ratio and the principle that it must be lower than 1/3 gain margin as the ＂Guide for setting test of power system stabilizer＂ required. After careful analysis, it was found that the gain margin is limited by exciter mode when using the self-excited excitation system. Exciter mode was formed by the natural characteristic of exciter-PSS loop. Therefore, a novel PSS with a parallel sector by introducing a soft feedback on the outer loop of exciter system was proposed. By improving the phase characteristics of the loop, the gain margin of PSS was increased effectively and the problem above was solved. Finally, case studies were undertaken based on the Ximeng thermal power centralized delivery simulation system. Simulation results validate the effectiveness of the proposed PSS.