CN-121984316-A - Control method and device for three-phase inverter

CN121984316ACN 121984316 ACN121984316 ACN 121984316ACN-121984316-A

Abstract

The application provides a control method and a control device of a three-phase inverter. The control method comprises the steps of obtaining a negative sequence voltage component and a negative sequence current component at a public connection node in a current control period, inputting a negative sequence direct-axis current given value and a negative sequence alternating-axis current given value at the public connection node or an inversion node in a negative sequence synchronous rotation coordinate system according to the negative sequence voltage component, the negative sequence current component, a grid connection requirement and an equivalent capacitance value of a filter, inputting a first negative sequence direct-axis current, a first negative sequence alternating-axis current and a first negative sequence direct-axis voltage fed back by the negative sequence direct-axis current given value and a previous control period into a first negative sequence current control loop, controlling the first negative sequence direct-axis voltage, and inputting the negative sequence direct-axis current, the first negative sequence direct-axis current and the first negative sequence alternating-axis voltage fed back by the negative sequence direct-axis current given value and the previous control period into a second negative sequence current control loop, and controlling the first negative sequence direct-axis voltage.

Inventors

PENG QIANQIAN
HUANG MUXIN
YI LONGQIANG
XIE PEIQIN

Assignees

厦门科华数能科技有限公司

Dates

Publication Date: 20260505
Application Date: 20260130

Claims (10)

1. The control method of the three-phase inverter is characterized in that the three-phase inverter comprises a filter, one end of the filter is connected with an inversion node in the three-phase inverter, and the other end of the filter is connected with a power grid at a common connection node, and the method comprises the following steps: in the current control period, acquiring a negative sequence voltage component and a negative sequence current component at the public connection node; according to the negative sequence voltage component, the negative sequence current component, the grid connection requirement and the equivalent capacitance value of the filter, a negative sequence direct-axis current given value and a negative sequence quadrature-axis current given value at the public connection node or the inversion node in a negative sequence synchronous rotation coordinate system are established, wherein the negative sequence synchronous rotation coordinate system is established according to the opposite phases of positive sequence phases obtained by a positive sequence phase-locked loop; Inputting the negative sequence direct-axis current given value and the first negative sequence direct-axis current, the first negative sequence quadrature-axis current and the first negative sequence direct-axis voltage at the public connection node or the inversion node fed back in the previous control period into a first negative sequence current control loop, and controlling the first negative sequence direct-axis voltage at the public connection node or the inversion node; And inputting the negative sequence quadrature axis current given value and the first negative sequence direct axis current, the first negative sequence quadrature axis current and the first negative sequence quadrature axis voltage at the public connection node or the inversion node fed back in the previous control period into a second negative sequence current control loop, and controlling the first negative sequence quadrature axis voltage at the public connection node or the inversion node.
2. The control method according to claim 1, wherein the negative-sequence direct-axis current given value and negative-sequence quadrature-axis current given value at the common connection node or the inversion node in a negative-sequence synchronous rotation coordinate system according to the negative-sequence voltage component, the negative-sequence current component, a grid-connected requirement, and an equivalent capacitance value of the filter, comprises: Obtaining a negative sequence reactive current at the public connection node according to a gain coefficient specified by the grid connection requirement and the negative sequence voltage component; Transforming the negative sequence voltage component to obtain a second negative sequence quadrature axis voltage and a second negative sequence direct axis voltage at the public connection node under the negative sequence synchronous rotation coordinate system; and obtaining a negative sequence direct-axis current given value and a negative sequence quadrature-axis current given value at the public connection node according to the negative sequence reactive current, the second negative sequence quadrature-axis voltage and the second negative sequence direct-axis voltage.
3. The control method according to claim 2, wherein the obtaining a negative-sequence direct-axis current given value and a negative-sequence quadrature-axis current given value at the common connection node from the negative-sequence reactive current and the second negative-sequence quadrature-axis voltage, the second negative-sequence direct-axis voltage, comprises: Obtaining an included angle between the negative sequence voltage component and a negative sequence straight axis coordinate axis in the negative sequence synchronous rotation coordinate according to the second negative sequence quadrature axis voltage and the second negative sequence straight axis voltage; And obtaining a negative sequence direct-axis current given value and a negative sequence quadrature-axis current given value at the public connection node according to the negative sequence reactive current and the included angle.
4. A control method according to claim 2 or 3, characterized in that the method further comprises: obtaining a negative sequence direct-axis current given value at the inversion node according to the negative sequence direct-axis current given value at the public connection node, the second negative sequence quadrature-axis voltage, the equivalent capacitance value and a rotation angular velocity corresponding to the negative sequence synchronous rotation coordinate system; and obtaining the negative sequence quadrature axis current given value at the inversion node according to the negative sequence quadrature axis current given value at the public connection node, the second negative sequence direct axis voltage, the equivalent capacitance value and the rotation angular velocity corresponding to the negative sequence synchronous rotation coordinate system.
5. The control method according to claim 4, wherein the obtaining the negative-sequence direct-axis current given value at the inversion node from the negative-sequence direct-axis current given value at the common connection node, the second negative-sequence quadrature-axis voltage, the equivalent capacitance value, and the rotational angular velocity corresponding to the negative-sequence synchronous rotational coordinate system includes: taking the product of the rotation angular velocity, the equivalent capacitance value and the second negative sequence quadrature axis voltage as a direct axis capacitance current between the inversion node and the common connection node; And taking the difference between the negative sequence direct-axis current given value at the common connection node and the direct-axis capacitance current as the negative sequence direct-axis current given value at the inversion node.
6. The control method according to claim 2, wherein the obtaining the negative-sequence quadrature-axis current given value at the inversion node from the negative-sequence quadrature-axis current given value at the common connection node, the second negative-sequence direct-axis voltage, the equivalent capacitance value, and the rotational angular velocity corresponding to the negative-sequence synchronous rotational coordinate system includes: Taking the product of the rotation angular velocity, the equivalent capacitance value and the second negative sequence direct-axis voltage as a quadrature-axis capacitance current between the inversion node and the common connection node; and taking the sum of the negative sequence quadrature axis current given value at the public connection node and the quadrature axis capacitance current as the negative sequence quadrature axis current given value at the inversion node.
7. The control method of claim 4, wherein the first negative sequence current control loop comprises a first PI controller, wherein the filter comprises an equivalent inductance value, and wherein the method further comprises: Inputting a first difference value between a negative sequence direct-axis current given value at the public connection node or the inversion node and the first negative sequence direct-axis current into the first PI controller to obtain a first output value; Determining a product among the equivalent inductance value, the rotation angular velocity corresponding to the negative sequence synchronous rotation coordinate system and the first negative sequence quadrature axis current as a first product; And adding the first output value to the first product and then adding the first negative sequence direct-axis voltage to be used as the output of the first negative sequence current control loop in the current control period.
8. The control method of claim 7, wherein the second negative sequence current control loop comprises a second PI controller; The method further comprises the steps of: Inputting a second difference value between a negative sequence quadrature axis current given value at the public connection node or the inversion node and the first negative sequence quadrature axis current into the second PI controller to obtain a second output value; Determining a product among the equivalent inductance value, the rotational angular velocity and the first negative sequence direct-axis current as a second product; and subtracting the second product from the second output value, and adding the first negative-sequence direct-axis voltage to serve as the output of the second negative-sequence current control loop in the current control period.
9. The control method according to claim 8, characterized in that the method further comprises: acquiring a positive sequence voltage component and a positive sequence current component at the public connection node; According to the positive sequence voltage component, the positive sequence current component and the equivalent capacitance value of the filter, a positive sequence direct-axis current given value and a positive sequence quadrature-axis current given value at the public connection node or the inversion node in a positive sequence synchronous rotation coordinate system are established, wherein the positive sequence synchronous rotation coordinate system is established according to a positive sequence phase obtained by a positive sequence phase-locked loop; Inputting the positive sequence direct-axis current, the positive sequence quadrature-axis current and the positive sequence direct-axis voltage at the public connection node or the inversion node fed back by the given value of the positive sequence direct-axis current and the previous control period into a first positive sequence current control loop, and controlling the positive sequence direct-axis voltage of the public connection node or the inversion node; And inputting the given value of the orthogonal axis current, the orthogonal axis voltage fed back in the previous control period into a second orthogonal axis current control loop, and controlling the orthogonal axis voltage of the common connection node or the inversion node.
10. The control device of the three-phase inverter is characterized in that the three-phase inverter comprises a filter, one end of the filter is connected with an inversion node in the three-phase inverter, and the other end of the filter is connected with a power grid at a common connection node, and the device comprises: the data acquisition module is used for acquiring a negative sequence voltage component and a negative sequence current component at the public connection node in the current control period; The negative sequence synchronous rotation coordinate system is established according to opposite phases of positive sequence phases obtained by a positive sequence phase-locked loop, the negative sequence direct-axis current given value and a first negative sequence direct-axis current, a first negative sequence direct-axis current and a first negative sequence direct-axis voltage at the public connection node or the inversion node fed back in a previous control period are input into a first negative sequence current control loop, the first negative sequence direct-axis voltage at the public connection node or the inversion node is controlled, the negative sequence direct-axis current given value and the first negative sequence direct-axis current, the first negative sequence direct-axis current and the first negative sequence direct-axis voltage at the inversion node are fed back in a positive sequence phase-locked loop, and the public connection node or the first negative sequence direct-axis voltage at the inversion node is controlled.

Description

Control method and device for three-phase inverter Technical Field The application relates to the technical field of power systems, in particular to a control method and device of a three-phase inverter. Background The three-phase inverter is a core device for realizing bidirectional conversion and grid-connected control of electric energy, and is widely applied to the fields of photovoltaic power generation, energy storage systems and the like. Along with the large-scale access of new energy to a power grid, abnormal working conditions such as unbalanced voltage and the like frequently occur, and higher requirements are put forward on the dynamic response and control precision of the inverter under asymmetric conditions. At present, a control strategy based on a positive sequence synchronous rotation coordinate system is often adopted, and PI adjustment is performed by transforming a negative sequence current reference value into the positive sequence synchronous rotation coordinate system. However, since the negative sequence component appears as double frequency fluctuation in the positive sequence synchronous rotation coordinate system, it is difficult for the PI controller to realize the no-static-difference control, thereby generating steady-state error and current distortion. Another typical method is a double-sequence decoupling control strategy, i.e. positive and negative sequence synchronous rotation coordinate systems are established respectively, and independent control is performed in the respective coordinate systems. Although the control performance can be improved, the effect of the method is highly dependent on the precision and dynamic response speed of the negative sequence phase-locked loop, and when the voltage of the power grid drops or is unbalanced rapidly, control lag is easy to cause, and the requirement of a new standard on the rapid response of the negative sequence reactive current cannot be met. Disclosure of Invention The embodiment of the application provides a control method and a control device for a three-phase inverter, which can avoid the steady-state error problem caused by frequency doubling components in the traditional scheme, and can effectively cope with the rapid dynamic change when a power grid is unbalanced because of not depending on a negative sequence phase-locked loop, thereby meeting the requirement of a new standard on the output of the negative sequence reactive current of the inverter and reducing the influence of the voltage unbalance of the power grid. The technical scheme of the embodiment of the application is realized as follows: The embodiment of the application provides a control method of a three-phase inverter, which comprises a filter, wherein one end of the filter is connected with an inversion node in the three-phase inverter, the other end of the filter is connected with a power grid and is connected with a public connection node, in a current control period, a negative sequence voltage component and a negative sequence current component at the public connection node are obtained, according to the negative sequence voltage component, the negative sequence current component, a grid connection requirement and an equivalent capacitance value of the filter, a negative sequence direct-axis current given value and a negative sequence alternating-axis current given value at the public connection node or the inversion node in a negative sequence synchronous rotation coordinate system are input into a first negative sequence current control loop, the negative sequence direct-axis current given value and the first negative sequence direct-axis current at the public connection node or the inversion node fed back by a first negative sequence direct-axis current given value and a previous control period are established according to opposite phases of a positive sequence phase obtained by the positive sequence phase-locked loop, and the first negative sequence direct-axis current given value and the first negative sequence direct-axis current at the public connection node or the inversion node are input into the first negative sequence direct-axis current control loop, and the first negative sequence direct-axis current at the first negative sequence current given value or the first negative sequence direct-axis current at the public connection node or the inversion node is connected with the first negative sequence direct-axis current at the first negative sequence direct-axis current given value or the first negative sequence direct-axis current at the first negative sequence control node. The embodiment of the application provides a control device of a three-phase inverter, which comprises a filter, wherein one end of the filter is connected with an inversion node in the three-phase inverter, the other end of the filter is connected with a power grid and is connected with a public connection node, the device comprises a data acquisition module, an adju