Detecting device for low voltage ride-through of grid-connected photovoltaic inverter

Abstract

The invention relates to a detecting device for low voltage ride-through of a grid-connected photovoltaic inverter. The detecting device comprises a current-limiting reactor, a short-circuit reactor and a grounding combination switch, the current-limiting reactor, an intermediate reactor and circuit breaker unit, the short-circuit reactor and the grounding combination switch are sequentially connected in series, the current-limiting reactor is connected into a 10 / 35kV power grid, the intermediate reactor and circuit breaker unit and the grounding combination switch are respectively connected into a neutral point of a high-voltage side of a step-down transformer, and the step-down transformer is connected into the grid-connected photovoltaic inverter. The detecting device has the advantages that the proportion of the current-limiting reactor and the short-circuit reactor is changed by the aid of different on-off modes of a plurality of circuit breakers under the condition that short-circuit capacity is unchanged assuredly, accordingly, the requirement that low voltage ride-through with different dropping amplitudes is detected by the aid of fewer reactors is met, and the detecting device is used for detecting low voltage ride-through ability of the photovoltaic inverter.

Description

technical field [0001] The invention relates to a detection device, in particular to a low-voltage ride-through detection device for a grid-connected photovoltaic inverter. Background technique [0002] With the rapid development of my country's photovoltaic industry, the proportion of photovoltaic power generation in the grid continues to increase. If the power grid fails and the voltage drops, the photovoltaic power generation system will be disconnected and tripped, which will affect the stability of the power system and even cause a complete paralysis of the power grid. As the core component of the photovoltaic power station, the photovoltaic inverter can maintain grid connection when the grid fails, and even provide a certain amount of reactive power to the grid to support the recovery of the grid until the grid returns to normal, thereby "crossing" this low-voltage area. Therefore, as a photovoltaic inverter testing laboratory, it is necessary to have a testing device...

AI Technical Summary

Problems solved by technology

[0004] use figure 1 There are several characteristics in the form of passive reactors: first, high-power reactors must be selected, so the volume of the device is relatively large

Second, the number of drop points of the device is limited by the number of reactors, and it is impossible to satisfy many drop amplitudes at the same time

Third, it is cumbersome to replace the reactor configuration or change the main circuit structure during the test, which is not conducive to the rapid realization of voltage drops of various amplitudes and forms

[0012] Fourth: During low-voltage ride-through detection, the voltage amplitude error before, during and after the device falls shall not exceed ±5%, and the device's fall time and recovery time shall not exceed 20ms

This allows the device to match the Z 1 ,Z 2 When the reactance value is high, it is difficult to meet the requirements of the above four conditions at the same time

In addition, even if the configured reactor Z 1 ,Z 2 It can meet the requirements, but the device has cumbersome steps when replacing the reactor, which is not conducive to quickly realize the low voltage ride-through test of various drop amplitudes and multiple types of drop methods

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