同步发电机-电力电子变压器组的最优协调控制

电力电子变压器(PET)是一种通过电力电子变换实现电力系统电压变换和能量传递的新型变压器.文章研究了电力系统中发电机-PET组的协调控制问题,首先建立了由发电机-PET组构成的电力系统数学模型,然后应用最优控制理论,提出了一种发电机-PET组的最优协调控制器.该控制器中的控制量分别为发电机励磁电压、PET一次侧和二次侧的电压源变换器中的脉宽调制的调制度和相角,反馈量则为发电机的功角、角速度、机端电压以及PET的直流环节电压.仿真结果表明,与由常规发变组构成的系统相比,该最优协调控制器有效地提高了扰动条件下的系统阻尼,同时改善了系统的电压特性.

OPTIMAL COORDINATED CONTROL OF SYNCHRONOUS GENERATOR-POWER ELECTRONIC TRANSFORMER UNIT

Power Electronic Transformer (PET) is a new type of transformer, which realizes voltage transformation and power delivery in the power system through power electronic conversion. The authors research the coordinated control of Generator-PET unit in power system. Firstly a mathematical model of power system constituted by generator-PET units is built, on this basis a new optimal coordinated control strategy for generator-PET unit is proposed by use of optimal control theory, where the control variables are defined as the generator excitation voltage, the modulation index and phase angle of pulse width modulation of the voltage source converter (VSC) in primary and secondary sides of PET while the feedback variables are power angle, angle velocity, voltage at generator terminals and DC bus voltage of PET. Simulation results show that compared with the power system constituted by traditional generator-transformer units equipped with auto voltage regulator (AVR) and power system stabilizer (PSS) controller, the proposed coordinated controller can effectively improve the system damping and voltage characteristics under disturbances.