High-power low-voltage ride-through testing device based on alternating-current simulation source experiment platform

Abstract

The utility model belongs to a testing device of grid-connected equipment applied to the field of power electronics, and particularly discloses a high-power low-voltage ride-through testing device based on an alternating-current simulation source experimental platform, which comprises a low-power grid simulation source, a low-power direct-current source, an isolation transformer, a high-power feedback PCS, a load and a connection relation thereof. According to the utility model, the isolation transformer and the high-power feedback PCS are added on the basis of an original small-capacity AC simulation source experiment platform as feedback, so that energy forms a loop in the isolation transformer, the high-power feedback PCS and the equipment to be tested, and capacity expansion is achieved.

Description

TECHNICAL FIELD

[0001] The utility model relates to the test device of grid connected equipment applied to power electronics field, especially a kind of high-power low voltage ride through test device based on alternating current simulation source experimental platform. BACKGROUND

[0002] The low voltage ride through test of traditional wind energy grid connected inverter needs that the grid capacity configuration of test table, the power of alternating current simulation source is greater than or equal to the power of measured inverter.

[0003] The shortcoming of traditional test scheme is when needing to develop high-power wind energy grid connected inverter, corresponding need to transform the grid capacity of company, simultaneously need to purchase large alternating current simulation source etc., need to invest a lot of funds to carry out work. UTILITY MODEL CONTENT

[0004] The utility model discloses a kind of high-power low voltage ride through test devices based on alternating current simulation source experimental platform, and the technical problem of the background art is solved.

[0005] To achieve the above-mentioned purpose, the technical scheme adopted by the utility model is as follows:

[0006] The high-power low voltage ride through test device based on alternating current simulation source experimental platform includes small-power grid simulation source, small-power direct current source, isolation transformer and high-power feedback PCS;

[0007] The input end of the small-power direct current source is connected to a small-capacity grid, and the output end of the small-power direct current source is electrically connected to the input end of the measured device. The output end of the measured device is electrically connected to the input end of the isolation transformer, and the output end of the isolation transformer is electrically connected to the input end of the high-power feedback PCS. The output end of the high-power feedback PCS is electrically connected to the input end of the measured device.

[0008] The input end of the small-power grid simulation source is connected to a small-capacity grid, and the output end of the small-power grid simulation source is electrically connected to the input end of the isolation transformer.

[0009] The measured device is a grid-connected inverter in DC side constant voltage mode, and the DC constant voltage point of the grid-connected inverter is V4. V4 is the input side voltage of the grid-connected inverter. The voltage limiting point of the small-power direct current source is V3, and V3 is the output side voltage of the small-power direct current source. The DC constant voltage point of the high-power feedback PCS is V6, and V6 is the output side voltage of the high-power feedback PCS, wherein V6>V3>V4.

[0010] The following is the further defined technical scheme of the utility model, small capacity power grid and small power DC source's AC input electric connection, small power DC source's DC output and the measured equipment's DC input electric connection, the measured equipment's AC output and the input of isolation transformer electric connection, the output of isolation transformer and the AC input of high power feedback PCS electric connection, the DC output of high power feedback PCS and the DC input of measured equipment electric connection.

[0011] The following is the further defined technical scheme of the utility model, small capacity power grid and small power grid simulation source's AC input electric connection, small power grid simulation source's AC output and the input of isolation transformer electric connection, the output of isolation transformer and the AC input of high power feedback PCS electric connection, the DC output of high power feedback PCS and the DC input of measured equipment electric connection.

[0012] The following is the further defined technical scheme of the utility model, still including load, small power grid simulation source's AC output and load electric connection, the measured equipment's AC output and load electric connection.

[0013] Compared with the prior art, the utility model has the following technical effects:

[0014] The utility model adds an isolation transformer and a high power feedback PCS as feedback on the basis of original small capacity AC simulation source experiment platform, so that energy forms a loop in isolation transformer, high power feedback PCS and measured equipment, and capacity expansion is achieved.

[0015] The utility model is further described below in connection with the drawings and examples. DRAWINGS

[0016] In order to more clearly illustrate the technical scheme in the embodiment of the utility model or prior art, the following will briefly introduce the drawings needed to be used in the embodiment or prior art, and obviously, the drawings in the following description are only some embodiments of the utility model, and for those skilled in the art, other drawings can also be obtained according to these drawings without creative labor.

[0017] Figure 1 It is the connection diagram of the utility model.

[0018] Fig. 1, small power grid simulation source, 2, load, 3, small power DC source, 4, grid-connected inverter, 5, isolation transformer, 6, high power feedback PCS, 7, small capacity power grid. CONCRETE IMPLEMENTATION

[0019] In order to make the above-mentioned purposes, features and advantages of the present application more apparent, understandable and easy to understand, the specific embodiments of the present application will be described in detail below with reference to the drawings. In the following description, a large number of specific details are set forth in order to provide a thorough understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the spirit of the present application. Therefore, the present application is not limited by the specific embodiments disclosed below.

[0020] The conventional experimental platform for low-voltage ride-through test of the wind power grid-connected inverter 4 in the laboratory is composed of a small-capacity power grid 7, a small-power grid simulation source 1, a load 2, and a small-power DC source 3, and the functions of each part are as follows:

[0021] The small-power grid simulation source 1 is a power grid disturbance device for testing the grid-connected inverter 4 and other devices, which can meet the test requirements of overvoltage, undervoltage, overfrequency, underfrequency, and low-voltage ride-through (zero ride-through) of the tested devices.

[0022] The load 2 is composed of a resistor R, an inductor L, or a capacitor C, and is used to consume the energy output by the tested device.

[0023] The small-power DC source 3 is a DC power supply with voltage and current limiting functions.

[0024] The tested device (grid-connected inverter 4) has an energy flow direction from the DC side to the AC side.

[0025] If the small-power grid simulation source 1 has no feedback function, the power relationship of each device must be ensured as follows:

[0026] The rated power of the small-power grid simulation source 1 is greater than or equal to the input power of the load 2, which is greater than or equal to the operating power of the grid-connected inverter 4.

[0027] If the small-power grid simulation source 1 has a feedback function, the load 2 can be omitted, but the power relationship must still be met as follows:

[0028] The rated power of the small-power grid simulation source 1 is greater than or equal to the operating power of the grid-connected inverter 4.

[0029] Therefore, the capacity of all devices in the experimental platform must be greater than or equal to the operating power of the tested device (i.e., the grid-connected inverter 4).

[0030] When a high-power wind power grid-connected inverter 4 is tested, in order to solve the problem of insufficient capacity of the experimental platform, an isolation transformer 5 and a high-power feedback PCS 6 are added to the experimental platform, as shown in Figure 1 The high-power feedback PCS 6 is an energy storage converter. The high-power feedback PCS 6 is required to work in a rectification state, and the performance of fault ride-through is good, and the power recovery time is faster than that of the tested device (i.e., the grid-connected inverter 4). The specific working mode is set as follows:

[0031] The grid-connected inverter 4 in the conventional wind power system works in a constant voltage mode at the DC side, the small power DC source 3 can be set to work in a current limiting and voltage limiting mode, and the large power feedback PCS 6 also works in a constant voltage mode at the DC side. If the power to be tested of the grid-connected inverter 4 is P4, the constant voltage point of the DC is V4 (V4 is the voltage at the input side of the grid-connected inverter), and the AC working voltage point is V4ac, the voltage limiting point of the small power DC source 3 is set to V3 (V3 is the voltage at the output side of the small power DC source), the current limiting point is set to I3, the constant voltage point of the large power feedback PCS 6 is set to V6 (V6 is the voltage at the output side of the large power feedback PCS), the AC current limiting point is set to I6ac, and the parameters are set to satisfy V6>V3>V4.

[0032] When working in a steady state, the power of the small power DC source 3 is P3=V4*I3, the power of the large power feedback PCS 6 is P6≈V4ac*I6ac*1.73, the power relationship is P3+P6=P4, the bus voltage is V4, and the small power DC source 3 and the large power feedback PCS 6 both work in a current limiting state.

[0033] When entering a fault ride-through, the large power feedback PCS 6 stops active output, if the grid-connected inverter 4 to be tested reduces or stops active output, if the grid-connected power is less than P3, the small power DC source 3 enters a voltage limiting state, the DC bus is equal to the voltage limiting point V3, otherwise the DC bus is still equal to the constant voltage point V4; in a recovery time period when entering the fault ride-through, the power recovery speed of the large power feedback PCS 6 is faster than the recovery speed of the grid-connected inverter 4 to be tested, the large power feedback PCS 6 enters a DC constant voltage state, and the DC bus is equal to the voltage limiting point V6; when the power of the grid-connected inverter 4 to be tested recovers to the power to be tested P4, the DC bus is equal to the voltage limiting point V4 in a steady state working state.

[0034] The above is only a preferred embodiment of the present application, and does not limit the present application in any form. Any person skilled in the art can make many possible changes and modifications to the technical solution of the present application, or modify it into equivalent embodiments with equivalent changes, without departing from the scope of the technical solution of the present application, by using the disclosed methods and technical contents. Therefore, any equivalent changes made to the shape, structure and principle of the present application, without departing from the technical solution of the present application, should be covered by the protection scope of the present application.

Claims

1. A high-power low-voltage ride-through test device based on an alternating current analog source experimental platform, characterized in that, The small power grid simulation source (1), the small power DC source (3), the isolation transformer (5) and the high-power feedback PCS (6) are included. The input end of the small power DC source (3) is connected to the small-capacity power grid (7), the output end of the small power DC source (3) is electrically connected to the input end of the measured device, the output end of the measured device is electrically connected to the input end of the isolation transformer (5), the output end of the isolation transformer (5) is electrically connected to the input end of the high-power feedback PCS (6), and the output end of the high-power feedback PCS (6) is electrically connected to the input end of the measured device. The input end of the small power grid simulation source (1) is connected to the small-capacity power grid (7), and the output end of the small power grid simulation source (1) is electrically connected to the input end of the isolation transformer (5). The DC constant voltage point of the measured device in the DC side constant voltage mode is V4, the voltage limiting point of the small power DC source (3) is V3, and the DC constant voltage point of the high-power feedback PCS (6) is V6, wherein V6>V3>V4.

2. The low voltage ride through test device based on the alternating current analog source experimental platform of claim 1, wherein, The small-capacity power grid (7) is electrically connected to the AC input end of the small power DC source (3), the DC output end of the small power DC source (3) is electrically connected to the DC input end of the measured device, the AC output end of the measured device is electrically connected to the input end of the isolation transformer (5), the output end of the isolation transformer (5) is electrically connected to the AC input end of the high-power feedback PCS (6), and the DC output end of the high-power feedback PCS (6) is electrically connected to the DC input end of the measured device.

3. The low voltage ride through test device based on the alternating current analog source experimental platform of claim 1, wherein, The small-capacity power grid (7) is electrically connected to the AC input end of the small power grid simulation source (1), the AC output end of the small power grid simulation source (1) is electrically connected to the input end of the isolation transformer (5), the output end of the isolation transformer (5) is electrically connected to the AC input end of the high-power feedback PCS (6), and the DC output end of the high-power feedback PCS (6) is electrically connected to the DC input end of the measured device.

4. The low voltage ride through test device based on AC analog source experimental platform of claim 1, wherein, The small power grid simulation source (1) is also connected to the load (2), and the AC output end of the measured device is electrically connected to the load (2).

5. The low voltage ride through test device based on AC analog source experimental platform of claim 1, wherein, The measured device is a grid-connected inverter (4) in a DC side constant voltage mode.

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