Two-Stage Robust Optimization Of Dynamic Reactive Power Optimizationin In Active Distribution Network

With the increasing of the distributed power supply penetration rate,the randomness and volatility of the distributed power supply bring great challenges to the reactive power optimization in the distribution network.The traditional distribution network is gradually shifting to the active distribution network.Active distribution network is actively managed in three aspects: “source”,“net” and“load”.“source”is a certain proportion of controllable active and reactive power supplies;"Net" is a flexible network structure of the distribution network."Load" is a flexible and controllable load,that is,demand side management.On the one hand,how to coordinate the development of the active management device control strategy is related to the optimal operation of the distribution network.On the other hand,due to the uncertainty of distributed power supply and load forecasting,the traditional deterministic optimization method will make the proposed control strategy not Accurate,for which the uncertainty of distributed power and load needs to be considered in the development of the control strategy.Based on the analysis of the reactive voltage characteristics of the active distribution network,the mathematical model of energy storage,static var compensator and on-load voltage tap changer are proposed in this paper.The grid-connected mode and equivalent model of distributed power supply are introduced.For the characteristics of the distribution network different from the transmission network,the pre-pushback method,the loop impedance method,the implicit Zbus method and the branch flow method are introduced.In order to promote the consumption of distributed energy,reduce network loss and voltage deviation,a multi-objective reactive power optimization model is proposed.Due to the non-convexity of the tidal equation,in order to increase the solution rate,the second-order cone programming theory is used to relax the tidal equation into the form of a second-order cone scheme.the Big-M method is used to linear thenonlinearity in the model.The analytic hierarchy process is used to weight themulti-objective function into a single objective function and the model became a mixed integer second-order cone programming model to solve.The simulation analysis on the improved IEEE33 node shows that with the continuous increase of distributed penetration rate,the network loss is significantly reduced,and the voltage is obviously improved.As the distributed power supply penetration rate increases,the network loss decreases first and then increases.ESS,OLTC,and CB can effectively reduce the network loss and reduce the voltage deviation.The validity and rationality of the model proposed in this paper.A two-stage robust optimization reactive power optimization model is proposed for the uncertain nature of load demands and intermittent renewable energy resources.It is proposed to put the number of switching groups of charge and discharge and group switching capacitors in the first stage,and the power level of the energy storage and discharge and the compensation amount of the static var compensator are placed in the second stage,so that the slow control The strategy allows fast-controlled devices to maintain a safe and stable operation of the distribution network in the worst-case scenarios.To reduce the conservativeness of robust optimization,an uncertain budget is introduced to reduce the conservativeness of robust optimization.The column constrained generation algorithm is used to solve the two-stage robust optimization.The simulation analysis is performed on the improved IEEE33 node.The results show that the proposed robust optimization control strategy is superior to the deterministic optimization strategy.