Study On Reactive Power Optimization Of Distribution Network With Distributed Photovoltaic Power

As an important means of improving power quality,reducing network losses and improving the economy and stability of system operation,reactive power optimization in distribution networks has always been an important topic of research for power scholars.Nowadays,energy shortage and environmental pollution problems are of great concern.Distributed generation(DG)is becoming the main force of future energy use due to its high efficiency,economic and environmental protection,and renewable.However,after DG is integrated into the distribution network,while bringing convenience to the system,it also affects the tide distribution and has an impact on power quality and system operation.Therefore,it is of great theoretical value and practical significance to optimize the reactive power of distribution networks with DG.In this paper,we take photovoltaic(PV)power sources as an example and use distribution networks with distributed PV power sources as the object of study,aiming at a comprehensive study of the impact and reactive power optimization problems caused by the connection of distributed PV to distribution networks through theoretical and simulation analysis.Firstly,the impact of PV power connection on the distribution network is analyzed.Based on the grid-connected model of PV system,the impact of PV power supply on the voltage distribution and network losses of the distribution network under different access methods,capacity,location,and power factor conditions is analyzed using the backward/forward sweep method.The simulation is verified on the IEEE33 bus system.The simulation finds that a reasonable configuration of PV’s grid connection capacity and location can play a role in lifting the voltage and reducing the losses,laying the foundation for the reactive power optimization later on.Secondly,a reactive power optimization model for distribution networks with distributed PV power sources is established and proposed to be solved using Non-dominated sorting genetic algorithm(NSGA-Ⅲ).Based on the uncertainty of load and PV power output,the distributed PV and discrete reactive power device co-compensation method is adopted,and the fluctuation of controllable load(CL)and the equation constraints and inequality constraints are considered to establish a dynamic optimization model with the objectives of minimizing voltage deviation,reactive power compensation amount,system active network losses,CL active power reduction amount and PV active power reduction amount.Based on a detailed introduction of the principle and solution steps of the NSGA-Ⅲ algorithm,the zero-ductility transition(ZDT)and diode-transistor logic with zener diode(DTLZ)series of test functions are selected to verify the performance of the algorithm,and the results show the superiority of the algorithm in solving multi-objective optimization problems.The results demonstrate the superiority of the algorithm in solving multi-objective optimization problems.Finally,arithmetic tests are performed on the improved IEEE33 and IEEE123 bus systems.Two target cases are considered respectively,with minimizing voltage deviation and minimizing reactive power compensation as case 1,and minimizing system active network losses,controlled load active reduction,and PV active reduction as case 2,and the simulations are verified on the improved IEEE33 and IEEE123 bus systems respectively.The results show that the reactive power optimization of the balanced network system and the unbalanced network system using the algorithm proposed in this paper can obtain a relatively wide range of Pareto solution frontier distribution,and all the objectives set can achieve better performance,which proves the effectiveness and feasibility of the proposed strategy.There are 34 figures,13 Tables and 76 references in this paper.