基于双旋转移相变压器的新型无功补偿器及其双环控制策略

Novel Var Compensator Based on Dual-rotary Phase-shifting Transformers and Its Dual-loop Control Strategy

随着出力具有随机波动性特征的分布式电源渗透率的不断攀升以及城市电缆化率的进程加速,有源配电网线路中无功过剩和过电压的现象日益明显,对动态无功补偿装置的经济性、可靠性和精准调控能力提出更高要求。在电流源型静止同步补偿器的基础上,该文结合双旋转移相变压器的连续调节特性,提出一种新型旋转式无功补偿器(novel rotary var compensator,NRVC)拓扑电路。通过构建NRVC稳态数学模型,深入分析得到NRVC补偿调控机理及其补偿容量约束关系。针对NRVC结构特点,提出基于瞬时无功理论的无功补偿控制策略,其中功率外环可对功率因数进行精确控制,电流内环加入限幅环节有效限流,提高装置运行可靠性。通过仿真及动模实验验证所提拓扑及其控制策略的有效性,结果验证了NRVC具备双向、连续调节补偿无功的能力,具有调节精度高、谐波畸变率低的优点。

With the continuous increase in the penetration rate of distributed power sources with random fluctuation characteristics and the acceleration of the urban cableization rate,the phenomenon of excess reactive power and overvoltage in the active distribution is obvious,which puts forward higher requirements for the economy,reliability and precise control capabilities of dynamic reactive power compensators.This paper proposes a novel rotary var compensator(NRVC)topology circuit based on current source converter static synchronous compensator and combined with the continuous regulation characteristics of the dual rotary phase-shifting transformers.A steady-state mathematical model of NRVC is constructed.The compensation regulation mechanism and capacity constraint relationship of NRVC are analyzed in detail.A reactive power compensation control strategy based on instantaneous reactive power theory is proposed aiming at the structural characteristics of NRVC.The power outer loop can accurately control the power factor,and the current inner loop is added to the limiting link to effectively prevent overcurrent and improve reliability.The simulation and experimental results verify the effectiveness of the proposed topology and its control strategy,NRVC can adjust compensated reactive power bidirectionally and continuously,and it also has the advantages of high adjustment accuracy as well as low harmonic distortion rate.