考虑换相软开关三相不平衡调节的主动配电网多目标运行优化

Multi-objective Operation Optimization of Active Distribution Network Considering Three-phase Unbalance Regulation of Phase-switching Soft Open Points

由于三相负荷的日益不平衡,主动配电网中的功率损耗和三相电压相位不平衡问题日益严重。作为一种可取代传统联络开关的电力电子设备,智能软开关为减少网损与缓解不平衡问题提供了潜在方案。为此,引入三相四线制的背靠背电压源型变流器作为智能软开关的拓扑结构,同时针对该拓扑设计了相应的换相控制策略。在此基础上,提出了以减少网损和缓解电压不平衡度为优化目标的基于三相四线制换相软开关的主动配电网多目标优化运行模型;应用对称半定规划算法,通过凸松弛将原始非凸非线性模型转换为便于求解的半正定规划模型,该模型可对三相电网进行三相解耦与分析。最后,在改进的IEEE 123节点系统中进行案例研究,验证了所提模型及其求解算法的可行性和有效性。

Power loss and phase unbalance of three-phase voltage in active distribution networks(ADNs)become more and more serious due to the increasing unbalance of three-phase loads.As a kind of power electronic equipment which can replace the traditional tie switch,soft open point(SOP)provides a potential solution to reduce power loss and alleviate the unbalance problem.Therefore,a three-phase four-wire back-to-back voltage source converter is introduced as the topology of SOP,and the corresponding phase-switching control strategy is designed for the topology.On this basis,a multi-objective operation optimization model of ADNs based on three-phase four-wire phase-switching SOP is proposed to reduce the power loss and alleviate the voltage unbalance.The symmetric semi-definite programming algorithm is used to transform the original non-convex nonlinear model into a semi-definite programming model which is easy to solve by convex relaxation.This model can be used for three-phase decoupling and analysis of three-phase power grid.Finally,a case study is carried out in an improved IEEE 123-bus system to verify the feasibility and effectiveness of the proposed model and its solving algorithm.