Research On Operational Risk Assessment Of Distributed Energy Connected To Distribution Network

In recent years,distributed clean energy has developed rapidly in highly developed countries and has been widely used.Many countries attach great importance to it.As a result,the utilization of distributed power sources has also received more and more attention.Due to the instability of clean distributed energy generation such as PV and WT connected to the distribution network,it will cause complex and diverse adverse effects.Therefore,a comprehensive risk assessment method is proposed to improve the accountability of the operation of the distribution network containing distributed power.Proposing a reliability evaluation method is an important means to solve such problems.First,it introduces the research background of the risk assessment of distributed energy access to the distribution network,and elaborates the risk indicators of the distribution network assessment.Analyze the research status at home and abroad on the early warning technology for the acceptance of distributed power sources in the distribution network and the current risk assessment of distributed energy access to the distribution network.Secondly,based on the consideration of weather factors and working age factors,the outage model of lines,equipment and distributed power sources in the distribution network was established.Obtain the state transition relationship of the components of the distributed power source and the output characteristics of the distributed power source.Use the risk assessment function to propose the line overload risk index and the bus voltage over-limit risk index in the island area and the load point blackout risk index of the faulty line.The quantitative and qualitative indicators are scientifically processed,and the comprehensive risk indicators of the distribution network are obtained through the weighting method.Then use Monte Carlo to sample the operating status of distributed power sources and distribution networks.Use the planned island algorithm to traverse multiple weather conditions,multiple operation scenarios,and multiple island states according to the fault status.Calculate the risk of line overload and bus voltage over-limit risk.Simulate examples of69-node radial distribution network and 54-node ring distribution network.From the perspective of different penetration rates,different types,and different power capacity allocation combinations,the risk assessment of distributed energy access to the distribution network is carried out.A 10 KV distribution network in a certain area of northwestern Liaoning Province is used for example verification.The experiment shows that the risk impact of the distribution network with different structures and different nodes is different.Finally,an early warning technology for the ability of the distribution network to accept distributed power sources is proposed.According to the selection principle of early warning indicators,analyze the voltage amplitude and voltage distortion rate of the grid connection point to study the dangerous boundary.Through fuzzy set theory,the membership function and risk classification early warning model are determined with harmonic level and line capacity as constraints.