Research On Distribution Network's Adopt Capacity For Distributed Generation

With widely application of distributed generation technology and support from the government policy,large scale of distributed generations connecting to distribution network has become an irresistible tendency for the new power system.The accessing of distributed generation can alleviate the growing energy crisis and environmental pollution.In order to ensure the reliable and maintainable operation of power system and to maximize the utilization of clean energy,the research on the distribution network's adopt capacity for distributed generation has been gaining more and more attention.Firstly,on the basis of an open loop operation of distribution network,taking multiple influential factors of distributed generation into considerations,a power function model for grid-connected distributed generations under node volt and power factor constraints is established.And the features of distributed network with a comparatively high penetration is obtained through the analysis of better values for power function.Furthermore,the sensitivity index is put forward to analyze the interval monotonicity of power function,which reflects how the operating voltage of power source,the supply line impedance,and load power influence the accessing power of distributed generations.Subsequently,a partial increment analytical method is presented,which decomposes the Taylor expansion for total increment of power function into multiple factors.Through the analysis on the relation between the precision of expansion and the number of terms,the partial increment analytical model is established.In order to evaluate the influence degree of multiple factors on the adopt capacity,single factor increment and synergistic increment are presented as quantitative indexes.By setting the initial value and increment,and dividing the operating conditions of distribution network,partial increment calculation for different types of distribution network is conducted.According to the calculation result of increment indexes,the main influential factor can be found and the measures to improve the adopt capacity for distributed generations are given.On the foundation of the power function partial increment analytical model and method presented in this paper,distribution networks with a too-long power radius or a heavy-load or overload transformer are simulated and analyzed as study examples,illustrating that the presented method can be applied in quantitative evaluation on influential degree of different factors,which provides foundation for improving the adopt capacity for distributed generations.Online analysis and calculation of active distribution network can be conductive to taking immediate measurements to uncertain factors which introduced by grid-connected distributed distribution.Therefore,a modified back/forward sweep method for active distribution network based on electricity consumption data is proposed,which directly use real-time electricity consumption data acquired from the centralized meter reading system,and verify the calculated line losses through data collected from the energy metering of the distribution transformer.Finally,a typical transformer district is taken as a research example,and the results show that the presented calculation method has practical meaning to online calculation and analysis for active distribution network in distribution automation system.