CN-122000973-A - Voltage cooperative control method based on AC small signal synchronization and local controller

CN122000973ACN 122000973 ACN122000973 ACN 122000973ACN-122000973-A

Abstract

The application provides a voltage cooperative control method based on alternating current small signal synchronization, which is applied to a local controller of each converter device, and is characterized in that a fundamental current component, an orthogonal component and an alternating current small signal current component of the fundamental current component are obtained through obtaining capacitance voltage and output current, fundamental voltage references are synthesized based on the fundamental current and the capacitance voltage, virtual impedance voltage drops are calculated, estimated voltage of a target converter device node is determined, alternating current small signal active power is calculated by utilizing the small signal current and a preset voltage reference, the estimated voltage average value of the node is further calculated, a voltage compensation value is generated through PI adjustment, the alternating current small signal frequency references are determined, the target small signal voltage references are synthesized, and finally the fundamental voltage references, the virtual impedance voltage drops and the small signal references are synthesized into total voltage references, and a modulating wave control converter device is generated through a voltage current loop. Therefore, the node voltage amplitude deviation can be effectively eliminated.

Inventors

WANG QINGBIN
MA MING
CHEN ZHENGLUN
Luo Jiezhou
YANG YUN
ZHAO XIANZHONG
WANG YUXI

Assignees

广东电网有限责任公司云浮供电局

Dates

Publication Date: 20260508
Application Date: 20260211

Claims (10)

1. The voltage cooperative control method based on the synchronization of alternating current small signals is characterized by being applied to a local controller of each converter device, and comprises the following steps of: acquiring capacitance voltage and output current of a connected target variable-current device, and separating the capacitance voltage and the output current from the output current to obtain an alternating current small-signal current component, a fundamental current component and orthogonal components thereof; Based on the capacitor voltage and the fundamental current component, synthesizing a fundamental voltage reference after controlling frequency modulation and voltage regulation through sagging, and calculating virtual impedance voltage drop based on the fundamental current component and orthogonal components thereof; determining node estimated voltage of the target converter equipment, calculating active power of an alternating current small signal by utilizing the alternating current small signal current component and a preset alternating current small signal voltage reference, and calculating a node estimated voltage average value according to the active power of the alternating current small signal and the node estimated voltage; PI regulation is carried out on the node estimated voltage average value and the rated node voltage, after a voltage compensation value is generated, an alternating current small signal frequency reference is determined by utilizing the voltage compensation value, and a target alternating current small signal voltage reference is synthesized according to the alternating current small signal frequency reference and the alternating current small signal voltage amplitude; And after the fundamental voltage reference, the virtual impedance voltage drop and the target alternating current small signal voltage reference are synthesized into a total voltage reference, generating a modulation wave through a voltage-current loop, wherein the modulation wave is used for controlling the target variable current equipment.
2. The method according to claim 1, wherein the step of separating an ac small signal current component, a fundamental current component, and a quadrature component thereof from the output current comprises: inputting the output current into a quadrature signal generator which is arranged in parallel and is based on second-order generalized integral; carrying out band-pass filtering on the output current at the fundamental angular frequency by using a first orthogonal signal generator to obtain the fundamental current component and the orthogonal component thereof; and carrying out band-pass filtering on the output current at an alternating small signal angular frequency reference position by using a second orthogonal signal generator to obtain the alternating small signal current component.
3. The method according to claim 1, wherein the step of calculating a virtual impedance drop based on the fundamental current component and the quadrature component thereof comprises: The virtual impedance drop is calculated using the following formula: Wherein, the 、 And Respectively represent the virtual impedance voltage drops An axial component, Axis component An axis component of the optical fiber, Representing the virtual resistance of the resistor, Representing the virtual inductance of the inductor, Representing the nominal frequency of the target variable current device, 、、 And Respectively represent the fundamental currents An axial component, An axial component, Axis component An axis orthogonal component.
4. The method for cooperative control of voltage based on synchronization of ac small signals according to claim 1, wherein the step of calculating the ac small signal active power by using the ac small signal current component and a preset ac small signal voltage reference comprises: the ac small signal active power is calculated using the following formula: Wherein, the Representing the active power of the alternating small signal, And Representing the alternating small signal current component Axis component An axis component of the optical fiber, And Representing the preset AC small signal voltage reference Axis component An axis component.
5. The method according to claim 1, wherein the step of calculating a node estimated voltage average value based on the ac small signal active power and the node estimated voltage comprises: the node estimated voltage average is calculated using the following formula: Wherein, the Representing the node estimated voltage average value, Representing the estimated voltage at the node in question, Representing the active power of the alternating small signal, Representing the cut-off angle frequency of the low-pass filter used for voltage estimation, And The weight coefficient is represented by a number of weight coefficients, Representing complex variables.
6. The method for cooperative control of voltages based on synchronization of ac small signals according to claim 1, wherein the step of PI-adjusting the node estimated voltage average value and the rated node voltage to generate a voltage compensation value comprises: the voltage compensation value is generated using the following formula: Wherein, the Representing the value of the voltage compensation to be described, Representing the voltage at the nominal node in question, Representing the node estimated voltage average value, And Representing the proportional and integral coefficients of PI regulation, Representing complex variables.
7. The method for cooperative control of voltage based on synchronization of ac small signals according to claim 1, wherein the step of determining the ac small signal frequency reference using the voltage compensation value comprises: The ac small signal frequency reference is determined using the following equation: Wherein, the Representing the ac small signal frequency reference, Represents the rated alternating current small signal angular frequency, Representing the sag factor of the ac small signal, Representing the voltage compensation value.
8. The method according to claim 1, wherein the step of synthesizing a target ac small signal voltage reference based on the ac small signal frequency reference and the ac small signal voltage amplitude comprises: the target ac small signal voltage reference is synthesized using the following formula: Wherein, the 、 And Respectively representing the target alternating current small signal voltage references An axial component, Axis component An axis component of the optical fiber, Representing the amplitude of the ac small signal voltage, Representing the ac small signal frequency reference.
9. The method for cooperative control of voltage based on synchronization of alternating current small signals according to claim 1, wherein the step of generating the modulation wave through the voltage-current loop comprises: comparing the total voltage reference with the capacitor voltage of the target variable current device to obtain a voltage deviation signal, and generating a current reference instruction according to the voltage deviation signal; comparing the current reference instruction with the inductance current of the target variable current device to obtain a current deviation signal, and generating a voltage control signal according to the current deviation signal; And performing pulse width modulation processing on the voltage control signal to generate the modulation wave.
10. A local controller is characterized by comprising one or more processors and a memory; Stored in the memory are computer readable instructions which, when executed by the one or more processors, perform the steps of the ac small signal synchronization-based voltage cooperative control method according to any one of claims 1 to 9.

Description

Voltage cooperative control method based on AC small signal synchronization and local controller Technical Field The application relates to the technical field of high-proportion distributed power supply distribution transformer area voltage cooperative control, in particular to a voltage cooperative control method based on alternating current small signal synchronization and a local controller. Background In a distribution transformer area of high-proportion distributed photovoltaic access, a distributed photovoltaic inverter and a power electronic transformer are generally adopted as converter equipment, the two converter equipment are connected in parallel and networked through a public bus, the two converter equipment are connected through the public bus to supply power for loads of public nodes, and each inverter and the power electronic transformer are provided with independent local controllers to realize self operation control. The public node plays a core role of supplying power to the load, and maintaining the voltage stability of the public node is important to guaranteeing the power supply reliability. Meanwhile, the power electronic transformer is increasingly applied to power distribution areas due to flexible operation modes and strong regulation and control capability. However, the power electronic transformer and the photovoltaic inverter in the transformer area are generally connected in parallel in a sagging control mode to perform networking operation, so that node voltage amplitude deviation is easily caused. Especially when the public node is connected with a nonlinear load or an unbalanced load, the distortion and the unbalance degree of the three-phase voltage are further aggravated, and the electric energy quality is seriously affected. Conventional control methods based on node voltage sampling typically transmit the voltage signal collected at the node to the local controller of each inverter via a communication line. Because the distributed power supply has scattered geographical positions, the mode has high dependence on communication links, not only increases the system construction and maintenance cost, but also leads the signal transmission process to be easily interfered by line noise and has poor engineering applicability. Another Proportional-integral regulator-based control method (PI-SVC) has significant limitations in node voltage estimation, although it does not rely on telecommunication. On one hand, the asynchronous starting time of PI-SVC in the parallel units can lead to different voltage compensation amounts in each regulator integration link so as to influence the voltage reference in droop control and cause the deterioration of reactive power distribution performance, and on the other hand, when the line impedance parameters are inaccurate, the estimation result of each device on the node voltage has deviation. Because the PI regulator has zero steady-state error characteristic, the integration link can continuously accumulate the compensation quantity until the estimated voltage reaches the rated value, and the estimated deviation can lead the compensation quantity of the output voltage of each device and reactive power to diverge, and even cause the system to be unstable in serious cases. In summary, in the existing node voltage control method, under the conditions of multi-source parallel connection and uncertain line impedance parameters, the common node voltage is difficult to accurately adjust, voltage amplitude deviation is easy to generate, and reactive power distribution and system stability are further affected. Disclosure of Invention The application aims to solve the technical defects, in particular to the technical defects that the common node voltage is difficult to accurately adjust and the voltage amplitude deviation is easy to generate under the conditions of multi-source parallel connection and uncertain line impedance parameters in the existing node voltage control method. In a first aspect, the present application provides a voltage cooperative control method based on synchronization of alternating current small signals, which is applied to a local controller of each converter device, and the method includes: acquiring capacitance voltage and output current of a connected target variable-current device, and separating an alternating current small-signal current component, a fundamental current component and orthogonal components thereof from the output current; based on the capacitor voltage and the fundamental current component, synthesizing fundamental voltage reference after controlling frequency modulation and voltage regulation through sagging, and calculating virtual impedance voltage drop based on the fundamental current component and orthogonal components thereof; Determining node estimated voltage of target converter equipment, calculating active power of an alternating current small signal by utilizing an alternating current small s