Economic Evaluation Of Distribution Network Projects With Electricity Price And Supply Energy Allocation Being Involved

Under the background of new electricity reform,refined planning has become the key to improve the efficiency of power grid enterprises.For the feasibility analysis of a certain distribution network engineering project(or project group),it is necessary to evaluate whether the project is economically reasonable with the corresponding technical superiority,reliability and applicability being ensured.At present,too much attention is paid to technology for the evaluation of domestic distribution network planning projects,and the related economical efficiency is usually ignored,resulting in unreasonable investment and poor input-output effect.Therefore,the research on the economic evaluation methods of distribution network planning projects has important practical significance,which can promote the scientific decision-making of power construction and improve the economic benefits of projects.In order to reasonably evaluate the economic benefits of distribution network planning projects,a set of ideas,models and methods for reasonably calculating the benefits was proposed.First of all,it is made clear that there is no allocation of power supply energy and electricity price for computing the income from the line loss improvement and the improvement of power supply reliability.Secondly,in order to reasonably calculate the incremental supply energy’s income,a distribution network is classified based on the specific location of the project.Then,the formula of electricity price allocation is proposed to calculate the incremental supply energy’s income with line loss and outage loss being taken into account,and the formulas of supply energy allocation is presented based on the power network’s power supply capacities before and after the project is put into operation.Finally,a simplified economic evaluation method is given.Because the supply energy allocation model involves the calculation of power supply capacities of a multi-voltage distribution network,a practical method is proposed for calculating the power supply capacity based on power supply area dividing and voltage classification.Based on relatively independent power supply subareas,the power supply capacity is obtained for the distribution network with the same voltage by the direct accumulation of its subareas’ power supply capacities.Based on the mutual restriction of power supply capacities among the related sub-networks with different voltages,the overall power supply capacity of a multi-voltage distribution network is obtained by taking the minimum value among the power supply capacities of related sub-networks.An approximate estimation formula is deduced,which can convert line allowable voltage losses into corresponding capacity constraints with the influence of voltage quality on power supply capacity being concisely considered.The approximate formulas are deduced to estimate the power supply capacities of HV and MV subareas(or typical wiring modes)for manual calculation or intervention.For the HV and MV power supply subareas connected with MV lines,their power supply capacities are respectively predicted according to existing feeder loads and their changing trends,so that the results are more realistic.Starting from the application purpose of real distribution network planning,the transformation is achieved from large distribution network scales to small ones and from complex planning methods to simple ones.A reasonable income model,electricity price allocation method and energy allocation method are proposed for the distribution network planning,which effectively solve the problem of large errors for the project income calculation.The proposed models and methods are intuitive,simple,stable and effective,and are suitable for the practical application.