| With the increasing energy problem,the utilization of renewable energy has become one of the key development strategies.Distributed generation(DG)as an effective means of renewable energy utilization makes the traditional distribution network transform to active distribution network.The coordinated development of DG and distribution network is an important trend of current energy development and utilization.This paper focuses on the investment decision and coordination control of DG and distribution network.Active distribution network operation characteristics are analysed from the three aspects of distribution network reliability,the equipment utilization and power quality,the evaluation system of reliability and the equipment utilization is constructed.And the comprehensive evaluation method and investment optimization strategy are presented.The characteristics of the electric spring and the complementarity between electric spring with DG are studied,and the optimal configuration model for power spring is presented.Specific research contents are as follows:(1)The paper analyzes the evaluation index system of the power reliability of the active distribution network,and comprehensively considers the problem of power reliability caused by changes in the user’s actual power consumption and power consumption behavior in the active distribution network,and proposes a comprehensive evaluation method based on AHP-entropy weight method.The evaluation index system can more fully reflect and evaluate the reliability level of the active distribution network and different users,and help to discover the reliability weak points of the distribution network.The method can effectively synthesize the subjective opinions of the experts and the objective contribution of the indicators.It can avoid the unbalanced weight of the indices obtained by the single method and lead to unreasonable evaluation results,making the assessment results more comprehensive and more in line with actual needs.(2)The influence of DG access to distribution network on equipment utilization efficiency is analysed from both qualitative and quantitative aspects.The proposed evaluation system is constructed from the three aspects of the load characteristic,equipment operation time and equipment parameters.Among which the impacts of the total DG output fluctuation rate,DG output ratio,DG average output rate and DG penetration ratio on the load characteristic,equipment operation time are considered.This evaluation system can fully reflect the impact of DG,equipment and users on the utilization of distribution network equipment.(3)In the active distribution network,there is a certain impact on power quality after DG access to distribution network.The influence mechanism of photovoltaic access to distribution network on voltage quality and harmonics is studied from the characteristics of the photovoltaic output power and its grid-connected.On this basis,Modeling analysis is used to study the impact of DG on voltage quality and harmonics.Modeling and simulation analysis show that the key factors of power quality obtained based on the mechanism analysis of selection can reasonably reflect the operation practice.The key factors of power quality can provide a theoretical basis and management reference.(4)Considering the improvement of DG integration and optimizing the coordination control of DG and distribution network,electric spring is proposed to govern voltage quality in active distribution network.Firstly,the working state and characteristics of electric spring at neutral,capacitive and perceptual are analysed.A new mode of operating at "intelligent load" and coordination and interaction with DG is studied based on the complementarity of electric spring with DG,and then The optimal configuration model of electric spring for active distribution network is presented.Finally,the simulation analysis shows that the proposed model has a remarkable effect on controlling the voltage fluctuation in active distribution network and ensuring the safe and stable operation of the key load,which also proves that it has the value of engineering practice.(5)The paper comprehensively considers the key operating characteristics of active distribution network,analyzes the interests and demands of multiple entities in the investment transformation process of active distribution network,and studies and analyzes the distribution network investment application scenarios,and proposes an optimization theory and method of active distribution network investment optimization based on object selection.The index system and investment optimization method take into account the power reliability and equipment utilization level of the distribution network.The research results can fully reflect and evaluate the reliability level of the active distribution network and different users and improve the economic benefits of distribution network investment.Based on the impact of DG access to distribution network,the investment decision method and operation strategy for DG and distribution network coordinated development is proposed around reliability of power utilization,equipment utilization efficiencyand power quality.It can enrich the theory and method of active distribution network operation and planning and has a wide application prospects in the fields of investment planning and optimization control of active distribution network.This work was supported by the National Natural Science Foundation of China(No.51777077)and the Science and Technology Project of CSPG(No.ZBKJXM00000020)... |
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