Grounding fault analysis method of low-resistance grounding system with inverter distributed power supply

Abstract

The invention discloses a grounding fault analysis method of a low-resistance grounding system with an inverter distributed power supply. The method comprises the steps that firstly, a voltage amplitude value of a common junction point PCC when the low-resistance grounding system runs normally is calculated, then a loop current equations set when a grounding fault happens is built, a non-linear relation between the voltage of the common junction point PCC and the output current of the inverter distributed power supply is combined, the equations set is solved by using the gauss iteration method, and accordingly grounding fault analysis of the low-resistance grounding system with the inverter distributed power supply is achieved. Compared with the prior art, the low-resistance penetration capacity and inverter control strategy of the inverter distributed power supply are adopted, the accuracy of fault analysis is improved, and the method has extremely high practicability in engineering practice.

Description

technical field [0001] The invention relates to the field of power system fault analysis, in particular to a grounding fault analysis method for a small-resistance grounding system including an inverter-type distributed power supply. Background technique [0002] In order to cope with the fossil energy crisis and alleviate environmental pressure, distributed power generation technology represented by photovoltaic power generation and wind power generation has been vigorously developed in my country, especially the connection of inverter interface distribution generator (IIDG) in the power grid. access is becoming increasingly widespread. IIDG is connected to the grid through an inverter, and its output characteristics are mainly determined by the control strategy of the inverter, which has strong nonlinearity; and grid-connected regulations require that IIDG should have low-voltage ride-through capability, that is, after the grid fails, When the voltage of the fault phase dr...

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Problems solved by technology

However, due to the complex fault output characteristics of IIDG, the output current has a nonlinear relationship with the Point of Common Coupling (PCC) voltage, so the loop current equation cannot be directly solved by the linear transformation method

And when an asymmetric fault occurs in the power grid, if a common control strategy is adopted, the IIDG will output negative sequence current, which will not only affect the performance of the inverter, but also aggravate the asymmetry of the power grid, which is not conducive to the recovery of the fault

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