Research On Distributionally Robust Coordinated Optimization Of Active And Reactive Power In Active Distribution Network

With the access of high-penetration distributed power sources,energy storage systems,flexible loads and other equipment,the traditional distribution network is gradually changing to an active distribution network with a variety of controllable equipment.How to coordinate and control the active distribution network numerous controllable devices are of great significance to the economic and stable operation of the distribution network.The line impedance in the distribution network is relatively large,and the active power and reactive power are strongly coupled.If the traditional decoupling theory is used to optimize the active or reactive power of the distribution network,it is not conducive to comprehensively improving the economy and safety of the distribution network operation.In addition,the randomness of distributed power output and the volatility of load increase the uncertainty in the distribution network,which makes the optimization strategy obtained by the deterministic optimization method deviate from the actual demand for system operation,which is not conducive to the safe operation of the distribution networkIn response to the above problems,this article firstly starts from the perspective of active and reactive power coordination and optimization,and establishes coordinated optimization of active and reactive power in active distribution network with photovoltaic units,micro gas turbines,on load tap changers,energy storage systems and reactive power compensation equipment as control methods.In order to reduce the difficulty of solving the model,linearization and second-order cone relaxation are performed on the objective function and constraint conditions in the coordination optimization model,and the original optimization model is transformed into a mixed-integer second-order cone programming model.In addition,this paper uses the scenario analysis method to deal with the uncertainty of the output of the photovoltaic unit and load,uses the l-2 norm to construct the uncertainty set of the scenario probability distribution,and establishes distributionally robust coordinated optimization of active and reactive power model based on scenario analysis method in active distribution network,and use the column and constraint generation algorithm to solve the model.On the modified IEEE33 node calculation example,the ability of the coordinated optimization strategy to reduce the network loss and the effectiveness of the distributionally robust optimization strategy are verified.In order to enable the optimization strategy to follow the real-time changes of the system and make corresponding adjustments,this paper applies the model predictive control theory to the coordinated optimization of the distribution network,and at the same time considers the prediction error and the action characteristics of different control equipment,and proposes a coordinated optimization of active and reactive power based on distributionally robust model predictive control in active distribution network.In the day-a-day optimization link,a deterministic optimization method is used to determine the control strategy of slow-motion speed equipment such as on load tap changer;the intra-day optimization link uses a time-series rolling optimization method to coordinate and optimize the distribution network by using distributionally robust optimization,and use the measured value of the photovoltaic unit and load to correct the prediction model,to reduce the impact of power fluctuations and prediction errors on the operation of the distribution network.The revised IEEE33 node calculation example verifies that the proposed optimization strategy can effectively respond to the impact of prediction errors on the operation of the distribution network while making corresponding adjustments to the real-time changes of the system,and reduce the occurrence of node voltage violations.