Evaluation Of Power Supply Capability For Distribution Network With Distributed Generation

The problem of energy and environment is becoming serious increasingly,which accelerates the development of new energy.Based on the utilization of new energy,distributed generation(DG)can improve power supply capability of distribution network and relieve power supply pressure.However,when DG is connected to distribution network,not only the new node type is introduced into power flow calculation,but also new requirement for the power flow algorithm is put forward.And the intermittency and volatility of DG output also affect distribution network.Power supply capability is a technical index that can reflect the safety,economy and reliability of distribution network,and it is a reference for power sector to guide the planning and construction of distribution network.With increasing proportion of DG,the impact for distribution network is more complex.Therefore,the evaluation of power supply capability,scientifically and synthetically,is particularly important to understand the operation of the power grid.In the paper,two operation ways of Micro-grid are considered.According to their respective characteristics,different evaluation indexes are set up to quantify the influence of DG on power supply capability from multiple angles.As a whole,the reliability,economy and volatility of main distribution network are considered,and two new indexes are added: "qualification rate of power supply capacity " and "drop rate between peak and valley of power supply".The former is used to reflect the security of power supply,and the last is used to reflect the influence of DG on load characteristics.For isolated operation Micro-grid,two aspects,the sustainability and adaptability between the source and the load,are quantified.The evaluation index system of power supply capability for distribution network with DG,clear structure and prominent features,is established.On the basis of analyzing relative importance of each evaluation index,the triangle fuzzy analytic hierarchy process is used to determine the index weight reasonably.Considering timing characteristics of DG and load,the paper calculated power flow and analyzed power supply capability in real time with the Matlab platform.The modified calculation example of PG&E69 is set into multi-scene modes,and the power supply capacity calculation and comprehensive evaluation of various schemes are carried out.The comparison analysis shows that the evaluation index system is effective and feasible,and can provide a new idea for the study of power supply capability evaluation of smart distribution network.The new added indexes,"qualification rate of power supply capacity " is conducive to the guidance of planning and construction for distribution network and "drop rate between peak and valley of power supply" can directly quantify the impact of distributed power supply on power supply capability from the angle of load characteristics.