Voltage longitudinal protective method of power distribution network with inversion type distributed power supplies

Abstract

The invention relates to a voltage longitudinal protective method of a power distribution network with inversion type distributed power supplies. The method comprises the steps that a protective relaying device is electrified; line parameters are initialized; a practical rated capacity of each distributed power supply is initialized; a voltage setting value is calculated; latest active power reference values, collected before start of the protection, of the distributed power supplies collected before start of the protection are obtained; positive-sequence voltage phasor U<M_pcc0> and current phasor I<M> of a bus M as well as positive-sequence voltage phasor U<N_pccn+1> and current phasor I<N> of a bus N are obtained; positive-sequence voltage calculated values U<M_pcck> and U<N_pcck> of each common joint point PCC are calculated; the positive-sequence voltage difference between the positive-sequence voltage calculated values U<M_pcck> and U<N_pcck> is calculated; a maximal positive-sequence voltage difference of n+2 nodes is selected as an action value of protection; whether the action value of protection is greater than a voltage setting value is determined; and if YES, a fault in the area is determined, and protection action is implemented. Thus, the distributed power supplies can be connected to the power distribution network in a flexible and scattered way needless of extra longitudinal channels, and the method has the advantages of high applicability, reliability and practicality in engineering practice.

Description

technical field [0001] The invention relates to the technical field of relay protection methods for power systems, in particular to a voltage longitudinal protection method for a distributed power distribution network with an inverter type. Background technique [0002] In recent years, with the increasing energy crisis and the increasing awareness of environmental protection, distributed power based on renewable clean energy has played an increasingly important role in modern power grids. However, after the widespread access of distributed power, the distribution network has evolved from a single-source radiation network to a multi-source network, and the short-circuit current level and distribution path have changed significantly during faults. At the same time, the fault characteristics of inverter-type distributed power sources mainly based on photovoltaic and wind power generation are different from traditional power sources, and the protection established based on trad...

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Problems solved by technology

In this case, even if the conventional double-terminal current differential protection is adopted, it is difficult to set the value, which has become a difficult point of protection.

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