Voltage drop generator used for low voltage ride through test and control method of voltage drop generator

Abstract

The invention provides a voltage drop generator used for a low voltage ride through test and a control method of the voltage drop generator. The voltage drop generator is connected with a grid-connected photovoltaic power generation unit through a boosting transformer. The voltage drop generator comprises a by-pass switch S1, a short circuit switch S2, a grounding combination switch S3, a grounding combination reactor Xp and a current-limiting combination reactor XS. A Y connection mode is applied to the high voltage side of the boosting transformer, the boosting transformer is connected with a grid through the current-limiting combination reactor XS, and the by-pass switch S1 is in parallel connection with the current-limiting combination reactor XS. The boosting transformer, the short circuit switch S2, the grounding combination reactor Xp and the grounding combination switch S3 are connection in series. The neutral point on the high voltage side of the boosting transformer is connected with the other end of the grounding combination switch S3 before being grounded. According to the voltage drop generator used for the low voltage ride through test and the control method of the voltage drop generator, a three-phase symmetrical drop, single-phase ground connection, two-phase ground connection, a two-phase short circuit and other network voltage fault types can be simulated, and network voltage simulated failure drops within a full range of 20 types of even drop depths with 5% of a grid rated voltage serving as a step length and the drop depth ranging from 0% of the grid rated voltage to 100% of the grid rated voltage are realized.

Description

technical field [0001] The invention relates to a detection device in the detection field of photovoltaic grid-connected inverters, in particular to a voltage drop generator for low voltage ride-through test and a control method thereof. Background technique [0002] With the rapid development of the photovoltaic industry, the proportion of photovoltaic power generation in the grid continues to increase. If the large-capacity photovoltaic grid-connected power generation unit cannot maintain the voltage and frequency of the grid when the grid fails and the voltage drops, it will have a major impact on the stability of the power system. Photovoltaic grid-connected inverters, as the core components of large and medium-sized photovoltaic power plants, must have low-voltage ride-through capabilities. Therefore, as a photovoltaic grid-connected inverter testing laboratory must have a testing device for testing whether the photovoltaic grid-connected inverter has low voltage ride-...

AI Technical Summary

Problems solved by technology

[0016] In addition, the current voltage drop generator used for the low voltage ride-through test of the photovoltaic grid-connected inverter generally needs to design the topology structure and the reactance of each three-phase reactor according to the specific three-phase grid voltage level U and the internal impedance a of the grid. Value calculation, such as designing a topology for a 10kV three-phase power grid, and correspondingly calculating the reactance value of the three-phase reactor; if designing a topology for a 35kV power grid, and correspondingly calculating the three-phase reactance In addition, even if the voltage level of the power grid is the same, if the internal impedance of the power grid differs greatly, the topology structure and the calculation of the reactance value of the three-phase reactor must be recalculated, and the control logic of each internal switch must be recalculated accordingly. Change

Images