Method for calculating short-circuit current of power distribution network containing inverter type distributed power supply

Abstract

The invention discloses a method for calculating short-circuit current of a power distribution network containing an inverter distributed power supply. The method comprises the following steps of: 1, establishing an output characteristic equation of the distributed power supply, a node admittance matrix of the network and a fault point boundary condition; step 2, on the basis of the step 1, cyclic calculation is carried out by using a linear iteration method; step 3, on the basis of the steps 1 and 2, performing second-order convergence iterative calculation based on a Newton-Raphson principle and a positive sequence augmented network node voltage equation, and calculating to obtain each node voltage and branch current of the positive sequence network; and 4, calculating node voltage and branch current of the negative-sequence and zero-sequence network by combining the fault point boundary condition in the step 1 based on the calculation result in the step 3, synthesizing fault node phase voltage and branch fault current of the power distribution network by using a symmetric component method, and outputting a result. A reference basis is provided for power distribution network fault positioning, fault diagnosis and the like through an accurate short circuit calculation result.

Description

technical field [0001] The invention relates to the field of inverter-type distributed power grid-connected short-circuit calculations, in particular to a second-order convergence iteration method for inverter-type distributed power distribution network short-circuit calculations. Background technique [0002] With the proposal of the national dual-carbon target, the penetration rate of distributed power is getting higher and higher, and more and more inverter-type distributed power (Inverter Interfaced Distributed Generator, IIDG) is connected to the active distribution network, and the fault current of IIDG It is becoming more and more important in the calculation of short-circuit current in distribution network. In the calculation of the short-circuit current of the power grid, it can no longer be simply ignored or its output current can be replaced by 1.2 times the rated current. [0003] In the power grid, the inverter-type distributed power supply is integrated into t...

AI Technical Summary

Problems solved by technology

The change of the short-circuit current will affect the relay protection of the distribution network, which may lead to the malfunction of the relay protection. The setting value of the relay protection needs to be re-adjusted according to the calculation results of the short-circuit current of the distribution network containing distributed power.

[0005] For the above problems, some current methods use the linear iterative method based on the node impedance matrix to calculate the short-circuit current. With the expansion of the grid scale and the increase of the penetration rate of distributed power sources, this method: (1) Iterative The convergence is reduced, and the convergence speed is too slow; (2) The node impedance matrix is ​​difficult to form, and as a full matrix, the demand for system computing memory increases

Therefore, in the context of the increasing penetration rate of new energy in the future, the current linear iterative method based on the node impedance matrix is ​​not suitable for the short-circuit current calculation of large-scale power grids in the future.

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