A calculation method for optimal capacity of dg access distribution network

Abstract

The invention relates to the relay protection field of a power distribution network circuit, and particularly relates to a DG connection distribution network optimum capacity calculation method, wherein for researching the DG optimal grid-connection capacity, the short circuit conditions in the distribution network are divided into three conditions, namely, short circuit on the downstream of DG, short circuit on the upstream of the DG and short circuit in adjacent feeder lines; and next, influence of DG connection to the original protection of the distribution network, and constraint of the original protection of the distribution network on DG capacity are analyzed separately, and critical values of the DG capacity in the three conditions are worked out separately, wherein the minimum value is the DG optimum connection capacity. The invention aims to solve the problem of circuit protection error operation when a fault is caused in DG connection to the distribution network; and startingfrom the aspect of not changing the original current protection set value of the distribution network, and by considering the injection condition of the DG capacity on each fault point short circuitcurrent in a fault, the optimum connection capacity without influencing the protection action is determined, thereby improving operational stability and safety of the distribution network.

Description

technical field [0001] The invention relates to the field of relay protection of distribution network lines, in particular to a calculation method for the optimal capacity of DG access distribution network. Background technique [0002] Due to the use of a large amount of fossil energy, the environmental pollution is serious, and the global energy crisis is becoming increasingly prominent. A new type of power generation mode that is directly arranged in the distribution network or distributed near the load, with a power of thousands of watts or tens of megawatts of small modules, and is compatible with the environment - distributed power has been highly valued by all parties. After the distributed power generation is connected to the power grid, the characteristics of the original distribution network of "centralized power generation, long-distance power transmission and large power grid interconnection" have been changed. , Improving the reliability of power supply plays a...

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Problems solved by technology

[0004] The purpose of the present invention is to solve the problem of line protection misoperation when DG is connected to the distribution network and cause a fault. From the perspective of not changing the original current protection setting value of the distribution network, consider the injection of DG capacity to the short-circuit current of each fault point when a fault occurs , to determine an optimal access capacity that does not affect the protection action, thereby improving the stability and security of the distribution network operation

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