Research On Reactive Power Optimization Of Active Distribution Network With High Proportion Of New Energy Grid-Connected

Under the background of global energy shortage,new energy units represented by wind and solar and new energy vehicles are rapidly rising and connected to the power grid on a large scale,which brings many challenges to the safe operation of the system due to their space-time dispersion and power randomness.Research shows that new energy units can provide both active power to the system and reactive power after adjustment.New energy vehicles with "source-load integration" are connected to the power grid through charging stakes,which can achieve bidirectional powe r flow and at the same time send out reactive power to the power grid through four-quadrant bidirectional charging stakes as reactive power devices.In this paper,the reactive power optimization of active distribution network with high proportion of new energy connected to the grid is studied under the premise of considering the reactive power response capacity of wind power unit and new energy vehicle.First,taking the wind turbine(WT),Photovoltaic(PV)unit and electric vehicle(EV)as the research object,the composition and operation mode of the wind turbine are explained,and the different types of electric vehicles and charging modes are compared and analyzed.Based on the power characteristics of the WT,PV and the charging behavior of the EV,the corresponding power model is established,and the influence of their access to the power grid on the operation of the distribution network is analyzed.Secondly,a static reactive power optimization model for distribution network considering the reactive power support capacity of WT and PV is set up.Based on quantifying the reactive power capacity of WT and PV,to improve the economy,security and stability of power network operation,the reactive power output of WT and PV,the position of the on-load voltage regulator and the number of shunt capacitor switching groups are optimized.An improved bat algorithm is presented to solve the problem.Sobol sequence and optimal particle neighborhood search mechanism are introduced to improve the speed and reliability of the algorithm.The results of simulation in the improved IEEE33 node system show that the reactive power optimization of distribution network considering the reactive power support capability of WT and PV can effectively reduce the active network loss and three-phase unbalance of the distribution network,increase the voltage level of each node,and verify that the improved bat algorithm has the adv antages of high search reliability and fast convergence speed in solving the reactive power optimization problem.Finally,a distribution network optimization model considering the reactive power response of the charging stake of the electric vehicle is bu ilt.In the pre-day optimization,with the goal of minimizing the total network loss throughout the day,the pre-day optimization scheme in each time period is obtained by dividing the day into 24 hours with the action number constraints of slow-motion devices.In the day optimization,a state factor matrix is proposed to calculate the real-time reactive power capacity of the charging station.The objective of the optimization is to minimize the system loss and node voltage offset during each 15-minute correction period,and the reactive power response capacity of the charging station is used to correct the previous plan.By improving the simulation in IEEE33 system,it is proved that using the reactive power response of the charging stake of the electric ve hicle to optimize the distribution network day before day to day can further reduce the line loss and voltage deviation of the power network,improve the security and economy of the system operation.