统一电能质量调节器最优输出跟踪控制策略

Optimal Output Tracking Control Strategy of Unified Power Quality Conditioner

统一电能质量调节器（UPQC）由串联型有源滤波器和并联型有源滤波器组合而成,能同时对电压和电流质量进行综合补偿,但必须考虑其串并联单元的相互影响。为此,首先对外输入干扰电网电压和负载电流进行状态估计,以获取其各频次分量;进而提出了基于UPQC统一数学模型的最优输出跟踪控制策略,使得系统输出跟踪参考值,从而将负载电压和电网电流补偿到正常状态。由于该最优控制策略中的性能指标同时反映了负载电压和电源电流的输出跟踪性质,因此能够从全局最优的角度消除UPQC串、并联变流器补偿单元之间的相互影响,从而提供统一协调的电能质量调节功能,且具有良好的暂态响应特性。同时该策略在三相abc坐标系下实现,无需进行锁相环节与dq转换,其控制参数矩阵可以根据黎卡提方程事先求得,而与系统状态无关,易于工程实现。通过在PSCAD/EMTDC中搭建仿真模型,验证了该策略可以有效解决电压跌落/骤升以及谐波负载引起的电能质量问题,并具有优越的暂态响应特性。

The unified power quality conditioner（UPQC） is composed of a series active power filter and a shunt active power filter, which can comprehensively compensate the voltage quality and current quality simultaneously. However, the interaction effect of its series and shunt units must be taken into consideration. First, we established a united mathematical model of UPQC.Based on the model, the input disturbance of grid voltage and load current was estimated for each frequency component. Then, we proposed an optimal output tracking control strategy, which can make system output to track the reference values and to compensate the grid voltage and load current to normal state. Since the performance index reflects the tracking properties of the load voltage and the supply current simultaneously, the strategy can effectively eliminate the mutual influence between the series and shunt units of UPQC, and can provide a unified, coordinating power quality regulation function with good transient response characteristics. In the meantime, the strategy is realized in the three-phase abc coordinate system without need of phase-locked loop and dq transformation. The control parameter matrix is available in advance according to the Riccati equation and has no relationship with system state, which is easy for project implementation. Simulations in PSCAD/EMTDC verify that the proposed control can effectively solve the power quality issue caused by voltage sag/rise and harmonic load with superior transient response.