用于不平衡负荷的D-STATCOM数学建模与系统仿真

不平衡负荷无功补偿及分相控制的配电系统用静止同步补偿器(D-STATCOM)动态性能好、谐波含量小、功率密度大,可实现无功功率的实时、就地以及不平衡负荷平衡化补偿。为研究其特性和在系统中的应用,首先定义了二值逻辑开关函数,分别建立D-STATCOM在abc三相坐标系下的微分方程与传递函数动态数学模型;然后根据瞬时无功功率理论建立了不平衡负荷指令电流检测系统与D-STATCOM的直接电流控制方式;最后分别基于数学模型及装置器件模型,应用不平衡负荷指令电流检测方法与直接电流控制建立D-STATCOM双闭环系统,在三相四线制配电系统中对D-STATCOM系统的静态、动态性能进行了仿真分析。仿真结果验证了所建数学模型的正确性以及指令电流检测系统和直接电流控制方式的有效性,表明用于不平衡负荷动态无功补偿的D-STATCOM具有良好的动态性能与静态补偿效果。

Modeling and Simulation of D-STATCOM for Unbalance Three-phase Distribution Power System

D-STATCOM,which is applied to compensate unbalance load in distribution electrical power system,has many advantages such as perfect dynamic characteristic,low total harmonics distortion and high power density,it can compensate balance and unbalance load real-timely on the spot.Consequently,based on the power circuit of the D-STATCOM with segregated phase compensation,after logical on-off function was defined as 1 or-1 firstly,the dynamic mathematic model with fourth-order of D-STATC OM was established in time domain,then was transformed to transfer function in frequency domain.Subsequently,based on the instantaneous power theory,command current detection method of unbalance load and direct current control mode were presented.The double closed-loop control system,which includes three phase current and the voltage of capacitor,was realized.Furthermore,the whole system of D-STATCOM was simulated using the mathematic model proposed in this paper and devices respectively in 380 V three-phase four-wire distribution power system.Simulation results show that the dynamic process was 0.01 s when the load changed from 100 kVA inductive load to-100 kVA capacitive load,and after compensation,the active power became smooth and the reactive power was around zero.In addition,the voltage of the capacitor was around 400 V but fluctuant due to the absorbability and release of power which was to keep the voltage of capacitor and to complete the compensation.It is concluded that the proposed mathematic model of D-STATCOM is correct,command current detection method of unbalance load and direct current control mode are valid,and D-STATCOM has good dynamic and static compensation performance in balance and unbalance distribution power system.