Research On Multi-objective Optimal Configuration And Operation Of Distributed Energy Storage In Distribution Network With Renewable Energy

In recent years,with the rapid development of renewable energy,its proportion in energy structure has become larger and larger in China.Due to the uncertainty of the renewable energy output,the large-scale integration of renewable energy into the distribution network brings great challenges to its safety and stability.As an emerging flexible power source,distributed energy storage(DES)plays an increasingly important role in the operation of distribution networks due to its advantages such as smoothing power fluctuations,cutting peaks and filling valleys,and improving power quality.At the same time,mobile energy storage is receiving widespread attention due to its scheduling flexibility.On the basis of considering the random fluctuation of renewable energy output,how to build a DES multi-objective optimal configuration and operation model that takes into account various factors in the dispatching of distribution network,and how to effectively solve the multi-objective optimization problem,it is of great significance.This article first introduces the current research of optimization configuration and operation of DES,and multi-objective optimization calculation problems of power systems,and the algorithm for solving multi-objective optimization problems.Then,aiming at the voltage quality problem caused by the uncertain fluctuation of photovoltaic active power in the Low-Voltage Distribution Network(LVDN),a method for determining the total rated power and energy of DES required in a LVDN containing photovoltaic is proposed.Based on this,a multi-objective optimized configuration and operating model of DES is established.The model takes the minimum active power loss of the LVDN and the maximum load rate of the upper-level power grid as the target,considers the total number of DES installation nodes,and takes the LVDN and DES safe operation as constraints.The normalized normal constraint method is used to obtain the Pareto optimal solution.The compromise optimal solution is selected as the optimal configuration and operation scheme of DES by fuzzy membership and entropy weight method.A practical LVDN is taken as an example to verify the correctness and validity of the method.The simulation results show that the DES can effectively reduce the network loss and increase the load rate of the upper power grid.Furthermore,on the basis of DES,the impact of mobile energy storage with both mobile and energy storage characteristics on the optimal operation of the distribution network is studied.A multi-objective optimized operation model was established with the goal of minimizing the loss of the distribution network,the amount of abandoned wind and abandoned solar,and the operating costs of the distribution network,which comprehensively considers the distribution network operation constraints and mobile energy storage constraints.The mobile energy storage constraints include path uniqueness,flow balance constraints,maximum number of movements constraints,charge and discharge power and state-of-charge constraints,etc.A bi-level optimization model that directly solves the compromise optimal solution of the three-objective optimization problem based on the normalized normal constraint method is proposed.An improved composite algorithm that deals with equality constraints is used to solve the bi-level optimization model to obtain the compromised optimal solution of the three-objective optimization problem.Taking IEEE33 node system as an example,simulation results verify the correctness and effectiveness of the proposed model and method.