A low-voltage ride-through control method for high-power photovoltaic grid-connected inverters

Abstract

The invention relates to a low voltage ride through control method for a high-power photovoltaic grid-connected inverter. The method includes steps: recognition of two states of voltage drop and voltage normal; determining a control strategy of the inverter according to a recognition result: a normal control mode or a low voltage ride through control mode; the low voltage ride through control mode: calculating the voltage amplitude Em of a grid-connected point in real time, and solving the drop depth k according to Em and the rated value VN of the grid-connected voltage amplitude; and setting a reactive power current instruction value and an active power current instruction value according to the drop depth k, the reactive power current requirement during voltage drop, and the capacity of the inverter. According to the control method, the problems of lock phase in the state of zero voltage and off-grid due to easy occurrence of impulse current during voltage drop and recovery are simply and stably overcome, the inverter can stably realize low (zero) voltage ride through in the condition of high-power operation, enough reactive power current support can be provided for the power grid according to the requirement, and the stability of the inverter and the operation of the power grid is improved.

Description

technical field [0001] The invention relates to a low-voltage ride-through control method, in particular to a low-voltage ride-through control method for a high-power photovoltaic grid-connected inverter. In particular, it refers to a low-voltage ride-through control method for high-power photovoltaic grid-connected inverters when the voltage drops to 0V instantaneously. Background technique [0002] Patent 201310380141.6 discloses a photovoltaic grid-connected inverter compatible with low voltage ride-through positive and negative sequence decoupling control method, the technical solution is as follows: [0003] ①. Use the positive and negative sequence decoupling method to decompose the detected grid voltage into positive sequence components and negative sequence components, and divide the inverter output current into positive sequence components and negative sequence components, and control them separately; [0004] ② Make the positive sequence component of the inverter ...

AI Technical Summary

Problems solved by technology

[0008] Aiming at the defects existing in the prior art, the purpose of the present invention is to provide a low-voltage ride-through control method for high-power photovoltaic grid-connected inverters, which simply and stably overcomes the phase-locking problem in the zero-voltage state, as well as voltage drop and It is easy to recover the problem of inrush current and off-grid at the moment of recovery, so as to ensure that the inverter can smoothly realize low (zero) voltage ride-through under high-power operating conditions, and provide sufficient reactive current support to the grid as required to improve the efficiency of the inverter. The stability of the device and grid operation

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