UPFC新型非线性控制策略

统一潮流控制器(UPFC)可以有效控制线路的有功和无功功率。基于UPFC控制线路功率的非线性数学模型,提出了一种新型的非线性控制方法:根据系统能量守恒的特点构造出一个满足Lyapunov大范围渐近稳定的函数,再结合精确线性化方法,将控制系统转化为一个简单的线性系统,最后通过线性反馈确定系统的输入量。基于软件EMTP/EMTPWorks对UPFC的控制装置进行建模,并在典型的长距离输电线路的测试系统中运行,仿真结果验证了所提新型非线性控制策略的正确性,较之于传统的PI控制方法,提出的非线性控制方法具有更高的有效性和动态性能;同时也表明了小容量的UPFC装置能够很大程度地补偿线路的有功功率,当发生单相接地故障时,UPFC能提高系统的稳定性。

Novel nonlinear control scheme of UPFC

UPFC(Unified Power Flow Controller) is always used to control the active and reactive power of transmission lines.Based on the nonlinear mathematic equations of power system with UPFC,a nonlinear control method for UPFC is proposed.A function is constructed based on energy conservation to meet the Lyapunov globally asymptotical stability.Combined with exact linearization,the nonlinear control system is then degraded to a simple linear system and input variables are deduced by linear feedback control.Devices of UPFC are modeled on EMTP/EMTPWorks and tested in a typical system with long transmission lines.Simulation results demonstrate the correctness of the proposed controller and its better stability and dynamic performance than PI controller.It also indicates that the UPFC device with small capacity can offer larger series compensation to system and enhance system stability,especially when a single-phase grounding fault happens.