Research On Multi-Objective Optimal Sizing For Distributed Generation Of Wind-Solar-Diesel-Battery Isolated Microgrid

With the development of economy and society, the power demand is increasing, and the disadvantages of centralized power grid are becoming more and more obvious. Microgrid is composed of distributed power, energy storage device, load, monitoring and protection device and power electronic energy conversion device. As an effective supplement to the large power grid, micro grid plays an important role in integrating the advantages of distributed power, improving the reliability of power supplement and the performance of the power grid. To optimize the configuration of distributed generation’s type and size reasonably, reduce pollution emissions and improve energy utilization efficiency, which has important significance to economical, environmentally friendly and reliable operation of microgrid. In this paper, the optimal sizing for distributed generation of wind-solar-diesel-battery isolated microgrid is studied. The main research content is divided into the following aspects:Firstly, the system architecture and the operation mode of the typical wind-solar-diesel-battery hybrid microgrid are studied. Considering the randomness and volatility of wind speed and light, the output power timing model of wind generator, PV, diesel and energy storage device are studied.Secondly, aiming at the independent hybrid microgrid, the HOMER software is used for simulation and optimization. With respect to the optimization results under the conditions of different air pollution punishment, diesel price, annual average light intensity, annual average wind speed, equipment investment costs and battery technology, the sensitivity analysis is conducted with a view to pollution emission, economy and power supply reliability of the system. And some practical suggestions for optimization of independent microgrid are given.Thirdly, taking the output of distributed generation, capacity of energy storage device, reliability of power supply as the constraints, a multi-objective optimal model of microgrid is constructed, which takes economy, environmental protection and energy efficiency into consideration. Besides, the entropy theory is introduced to determine the weight coefficient of each index of the multiple function. An improved cycle charge (ICC) control strategy is developed, which adds charge and discharge management for energy storage device. Moreover, improved population movement, self-adaptive iterative steps, self-adaptive mutation strategy and reduction of search space are adopted to improve the convergence of the electromagnetism-like mechanism (ELM) algorithm. Based on improved cycle charge (ICC) control strategy, the improved ELM is used to solve the optimal model. The correctness and effectiveness of the optimization model and solving algorithm are verified by simulation experiments.Finally, the common optimization process need to iterate through all the annual data for time series analysis, which will result in extensive computations and low operation efficiency. In order to solve this problem, an optimization method of ELM based on Markov is proposed:the fuzzy c-means clustering (FCM) algorithm is used to extract typical operational scenarios from the annual 8760h wind speed, light and load data, the corresponding Markov models are established using stochastic process method. Then, the above Markov models are embedded in the improved ELM for optimization solution. Taking Guangxi Weizhou Island as a case study, the effectiveness of models and algorithms is verified.