Research On Optimal Allocation Method Of Distributed Generation In Micro-grid Under Different Scenarios

With the traditional energy supply continues to stress and environmental pollution increasing, the distributed generation (DG) based on clean energy is developing. But the access of a large number of DG will have a negative impact on grid. In order to coordinate the contradiction between grid and DG, the micro-grid has been paid more attention as a new type of grid structure. Micro-grid is conducive to make full use of DG. It has great potential in improving energy utilization efficiency, operating flexibility and reliability.At present, the research on the related technologies of micro-grid has just begun. The optimal allocation of DG in micro-grid power is a primary problem to be considered in the planning stage of micro-grid. Reasonable power allocation scheme can effectively reduce operating costs, reduce environmental pollution and improve reliability. Therefore, researching on the optimal allocation of DG in micro-grid has important significance for the development of micro-grid in China.Firstly, learning from the planning evaluation method of grid, combined with the characteristics of micro-grid power planning, the paper establishes the evaluation index system of micro-grid power planning, including reliability, economic and environmental indicators.Secondly, according to the characteristics of resources and importance of load, the application of micro-grid is divided into two kinds of scenarios. One is the scenario of priority to renewable energy and the other one is the scenario of renewable energy used as the complementary power supply. Based on the optimization objectives, constraints and scheduling strategies, the optimization allocation principles of micro-grid under two scenarios are presented.Thirdly, combining with the characteristics of micro-grid power optimization allocation model, the basic genetic algorithm is improved. Validated by test function, with the selecting operation based on the roulette and the best individual preservation, dynamic crossover and dynamic mutation operator, the improved genetic algorithm is beneficial to improve the problem that traditional genetic algorithm is easy to fall into local convergence, as well as search speed and accuracy of the algorithm.Finally, the optimal allocation model of DG in micro-grid under the two scenarios is established. For the scenario of give priority to renewable energy, bi-level programming model considering economy and environmental protection is established. For the scenario of renewable energy as supplementary energy, the multi-objective programming model considering reliability and economy is established. The reliability index is calculated by Monte Carlo simulation. The model is solved by using the improved genetic algorithm. The sensitivity analysis of the optimal allocation results is carried out in the aspects of resource status, unit cost, pollutant discharge and so on.