Positive and negative sequence component separation method of low-voltage ride-through control of photovoltaic grid-connected inverter

Abstract

The invention discloses a positive and negative sequence component separation method of low-voltage ride-through control of a photovoltaic grid-connected inverter. The positive and negative sequence component separation method of the low-voltage ride-through control of the photovoltaic grid-connected inverter is characterized by comprising the following steps of obtaining three-phase voltage instantaneous values and three-phase current instantaneous values through detection of voltage and current of a power gird, obtaining output signals which are a voltage synchronous phase angle sine value and a voltage synchronous phase angle cosine value of the power grid, and output signals which are a current synchronous phase angle sine value and a current synchronous phase angle cosine value of the power grid through processing of a synchronous phase locking unit, obtaining three-phase reference voltages of the photovoltaic grid-connected inverter according to four obtained voltage positive and negative sequence components, four obtained current positive and negative sequence components and four current positive and negative sequence component set values which are set according to output power of a photovoltaic cell panel through a current control unit, and obtaining a PWM switching signal corresponding to the three-phase inverter according to the three-phase reference voltages and bipolar triangle carrier signals through a PWM wave generating unit to achieve the low-voltage ride-through control of the photovoltaic grid-connected inverter. The positive and negative sequence component separation method of the low-voltage ride-through control of the photovoltaic grid-connected inverter is simple and reliable in method and good in practicability.

Description

technical field [0001] The invention belongs to the technical field of smart grid voltage control, and relates to a positive and negative sequence component separation method for low voltage ride-through control of photovoltaic grid-connected inverters. Background technique [0002] As the installed capacity of photovoltaic grid-connected power generation systems increases year by year, when the grid voltage is unbalanced or the AC system has an asymmetric fault, a large number of negative sequence components and non-characteristic harmonics will be generated on both sides of the converter station. If the weight is light, it will cause a system fault protection action, and if it is heavy, it will seriously threaten the safety of the converter device and endanger the stability and reliability of the three-phase power grid. Therefore, when a short-circuit fault occurs in the power grid and the voltage drops, it is necessary to solve the problem of how to adopt corresponding co...

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Problems solved by technology

However, the implementation process of the above method is relatively co

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