基于无互联线控制的电子电力变压器并联技术

提出一种新的电子电力变压器(EPT)无互联线并联控制策略.所提出的控制策略基于功率下垂控制理论,由有功功率均分控制回路和无功功率均分控制回路2部分组成.为了抑制输出电压的相位偏差,在控制回路中增加了输出电压相位同步控制回路;为使系统在线性和非线性负载条件下都能获得好的功率均分性能,在控制回路中增加了谐波电流控制回路;为改善系统的动态响应特性,增加了微分控制环节;为分析系统的稳定性和动态性能,方便控制参数的设计,建立了系统的小信号模型.仿真结果表明,所提出的控制策略获得了好的功率均分性能和电压调制特性,具有良好的动态响应特性,且在非线性负载条件下也获得了较好的均流特性.

Parallel Operation of Electronic Power Transformers Without Control Interconnections

A novel parallel control strategy of electronic power transformers (EPT) without control interconnections is proposed. The proposed control strategy is based on the well-known power droop control method, which consists of an active power sharing control loop and a reactive power sharing control loop. The phase synchronization control loop is added to the corresponding control loop to reduce the phase differences of output voltages among paralleled EPTs. Linear and nonlinear loads can be properly shared due to the addition of a current harmonic control loop in the control loop. The derivative control link is also included in order to improve the dynamic response of the system. A small signal model is developed to analyze the stability and the transient response of the system and to facilitate the design of control parameters. Finally, on the basis of the parallel system with two EPTs, the solution of the average-power-sharing problem of AC side is discussed in detail using the proposed control strategy and correlative simulations are carried out. The simulation results show that the excellent power sharing and voltage regulation characteristic, a proper dynamic response and good current-sharing performance under the nonlinear load condition can be achieved.