Reactive compensation method and system, control equipment and storage medium

Abstract

The invention provides a reactive compensation method and system, control equipment and a storage medium, and relates to the technical field of electric power, and the method comprises the steps: obtaining a synchronous rotation angle; obtaining a current three-phase voltage and a current three-phase current, and based on a phase-locked loop algorithm, performing calculation according to the synchronous rotation angle, the current three-phase voltage and the current three-phase current to obtain a current reactive power; the method comprises the following steps: detecting a current capacitor voltage, acquiring the current capacitor voltage, detecting a potential point equal to the current capacitor voltage in voltage value on a power grid side to obtain an equipotential point, and determining a current equipotential point according to a time interval between two adjacent equipotential points; when the current reactive power is greater than or equal to the current capacitance capacity of the capacitor side, recording and obtaining target action time and a target equipotential point based on a judgment strategy according to the current moment, the mechanical delay time and the current equipotential point; and after the target action time is delayed, a relay control signal is output, and the capacitor is put into a power grid side at a target equipotential point for reactive compensation, so that rapid reactive compensation response is provided.

Description

Technical Field

[0001] The present application relates to the field of electric power technology, and in particular to a reactive power compensation method, system, control device and storage medium. Background Art

[0002] In the scenario where the power grid outputs AC power, it is usually necessary to perform reactive power compensation on the power grid. The full name of reactive power compensation is reactive power compensation. It plays a role in improving the power factor of the power grid in the power supply system, reducing the loss of the power supply transformer and transmission lines, improving the power supply efficiency, and improving the power supply environment. Therefore, reactive power compensation devices play an indispensable and important role in the power supply system.

[0003] Reactive power compensation is usually achieved by adding capacitors to the power grid. The voltage on the grid side is a sinusoidal signal with a frequency of 50HZ, or 20 milliseconds (ms). The traditional reactive power compensation method is to detect the voltage zero crossing point and the current zero crossing point within a cycle (i.e. 20ms), and then calculate the phase difference between the voltage zero crossing point and the current zero crossing point, and calculate the reactive power based on the phase difference. Adding capacitors to the power grid means that when there is a demand for capacitors, the capacitors are added to the grid after the internal charge is discharged, that is, when the charge is zero, by detecting the voltage zero crossing point on the grid side, and then adding capacitors to the grid side at the voltage zero crossing point on the grid side.

[0004] In the traditional reactive power compensation method, the reactive power calculation process and the capacitor input and removal action response are relatively slow, which makes the traditional reactive power compensation method operate for a long time and cannot form a fast reactive power compensation response. Summary of the invention

[0005] The present application provides a reactive power compensation method, system, control device and storage medium to provide a fast reactive power compensation response.

[0006] In a first aspect, the present application provides a reactive power compensation method, the reactive power compensation method comprising: Get the synchronous rotation angle; Obtain the current three-phase voltage and the current three-phase current on the grid side, and calculate based on the phase-locked loop algorithm according to the synchronous rotation angle, the current three-phase voltage and the current three-phase current to obtain the current reactive power; and obtain the current capacitor voltage on the capacitor side, detect the potential point equal to the voltage value of the current capacitor voltage on the grid side, obtain the equipotential point, and determine the current equipotential point according to the time interval between two adjacent equipotential points, wherein the equipotential point includes a rising edge equipotential point and a falling edge equipotential point; When the current reactive power is greater than or equal to the current capacitance of the capacitor side, the current time is recorded, and according to the current time, the mechanical delay time and the current equipotential point, a target action time and a target equipotential point are obtained based on a determination strategy; Taking the current moment as the starting point, a relay control signal is output after delaying the target action time, so that the capacitor on the capacitor side is connected to the grid side at the target equipotential point to perform reactive power compensation on the grid side.

[0007] In a possible design, acquiring the synchronous rotation angle includes: Obtain the three-phase voltage on the grid side in real time; The phase-locked loop is used to perform phase locking to obtain the synchronous rotation angle.

[0008] In a possible design, the phase-locked loop algorithm is used to calculate the current reactive power according to the synchronous rotation angle, the current three-phase voltage, and the current three-phase current, including: Performing Clarke coordinate transformation on the current three-phase voltage to obtain a first voltage coordinate component and a second voltage coordinate component; Performing Clarke coordinate transformation on the current three-phase current to obtain a first current coordinate component and a second current coordinate component; Using the synchronous rotation angle, performing Park coordinate transformation on the first voltage coordinate component and the second voltage coordinate component to obtain a third voltage coordinate component and a fourth voltage coordinate component; Using the synchronous rotation angle, performing Park coordinate transformation on the first current coordinate component and the second current coordinate component to obtain a third current coordinate component and a fourth current coordinate component; According to the formula , calculate the current reactive power, where Q is the current reactive power, is the third voltage coordinate component, is the fourth voltage coordinate component, is the third current coordinate component, is the fourth current coordinate component.

[0009] In a possible design, the acquiring the current capacitor voltage on the capacitor side, detecting a potential point on the grid side that is equal to the voltage value of the current capacitor voltage, and obtaining the equipotential point includes: Get the current capacitor voltage on the capacitor side; At the potential point where the rising edge of the sine wave on the grid side is equal to the voltage value of the current capacitor voltage, the rising edge equipotential point is obtained; The falling edge equipotential point is obtained at the potential point where the falling edge of the sine wave on the grid side is equal to the voltage value of the current capacitor voltage.

[0010] In a possible design, determining the current isoelectric point according to the time interval between two adjacent isoelectric points includes: Acquire two adjacent rising edge equipotential points to obtain a first rising edge equipotential point and a second rising edge equipotential point; Calculate the time interval between the first rising edge equipotential point and the second rising edge equipotential point to obtain a first time interval; Acquire two adjacent falling edge equipotential points to obtain a first falling edge equipotential point and a second falling edge equipotential point; Calculate the time interval between the first falling edge equipotential point and the second falling edge equipotential point to obtain a second time interval; If the first time interval and the second time interval are both equal to the interval threshold, it is determined that the equipotential point is in a stable state, and the process returns to the execution step of obtaining two adjacent rising edge equipotential points to obtain a first rising edge equipotential point and a second rising edge equipotential point. Each time the process returns to the execution step of obtaining two adjacent rising edge equipotential points to obtain a first rising edge equipotential point and a second rising edge equipotential point, the second rising edge equipotential point or the second falling edge equipotential point of the current detection cycle is correspondingly updated to the first rising edge equipotential point or the first falling edge equipotential point of the next detection cycle. The first rising edge equipotential point or the first falling edge equipotential point is determined as the current equipotential point.

[0011] In a possible design, the target action time and the target isoelectric point are obtained based on the determination strategy according to the current moment, the mechanical delay time and the current isoelectric point, including: Calculate the time difference between the first rising edge equipotential point and the current moment to obtain a rising edge interval; Calculate the time difference between the first falling edge equipotential point and the current moment to obtain a falling edge interval; Calculate the sum of the rising edge interval and the mechanical delay time to obtain the rising edge time; Calculate the sum of the falling edge interval and the mechanical delay time to obtain the falling edge time; According to the rising edge time and the falling edge time, based on a determination strategy, the target action time and the target equipotential point are obtained.

[0012] In a possible design, obtaining the target action time and the target equipotential point based on the rising edge time and the falling edge time based on a determination strategy includes: Under the condition that the rising edge time is less than or equal to 20 milliseconds, and the falling edge time is less than or equal to 20 milliseconds: If the rising edge time is greater than or equal to the falling edge time, the target equipotential point is the next rising edge equipotential point adjacent to the current equipotential point, and the target action time is the difference between 20 milliseconds and the rising edge time; If the rising edge time is less than the falling edge time, the target equipotential point is the next falling edge equipotential point adjacent to the current equipotential point, and the target action time is the difference between 20 milliseconds and the falling edge time; Under the condition that the rising edge time is less than or equal to 20 milliseconds, and the falling edge time is greater than 20 milliseconds: the target equipotential point is the next rising edge equipotential point adjacent to the current equipotential point, and the target action time is the difference between 20 milliseconds and the rising edge time; Under the condition that the rising edge time is greater than 20 milliseconds, and the falling edge time is less than or equal to 20 milliseconds: the target equipotential point is the next falling edge equipotential point adjacent to the current equipotential point, and the target action time is the difference between 20 milliseconds and the falling edge time; Under the condition that the rising edge time is greater than 20 milliseconds, and the falling edge time is greater than 20 milliseconds: If the rising edge time is greater than or equal to the falling edge time, the target equipotential point is the second rising edge equipotential point separated from the current equipotential point, and the target action time is the difference between 40 milliseconds and the rising edge time; If the rising edge time and is less than the falling edge time and, the target equipotential point is the second falling edge equipotential point separated from the current equipotential point, and the target action time is the difference between 40 milliseconds and the falling edge time and.

[0013] In a second aspect, the present application provides a reactive power compensation system, the system comprising: a control circuit, a secondary current transformer, a grid-side bus, a relay, and a capacitor; The secondary current transformer, the grid-side bus, the relay and the capacitor are all electrically connected to the control circuit, and the control circuit is used to implement the method steps described in the first aspect.

[0014] In a third aspect, the present application provides a control device, comprising: a memory and a processor, wherein the memory stores a computer program that can be run on the processor, and is characterized in that when the processor executes the program, the method steps described in the first aspect are implemented.

[0015] In a fourth aspect, the present application provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the method steps described in the first aspect.

[0016] Beneficial effects of the embodiments of the present application: In an embodiment of the present application, by calculating the current reactive power in real time and detecting the current equipotential point in real time, when the current reactive power is greater than or equal to the current capacitance of the capacitor side, that is, when the capacitor needs to be put into operation, the equipotential point closest to the current moment, that is, the target equipotential point, is determined according to the current moment, the mechanical delay time of the relay and the current equipotential point, and the target action time is calculated. Taking the current moment as the starting point, the relay control signal is output after delaying the target action time, so that the capacitor on the capacitor side is put into operation on the power grid side at the target equipotential point, and reactive compensation is performed on the power grid side to provide a fast reactive compensation response.

[0017] The beneficial effects provided in the above-mentioned second aspect and various possible designs of the above-mentioned second aspect can refer to the beneficial effects brought about by the above-mentioned first aspect and various possible implementation methods of the first aspect, and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application, and for ordinary technicians in this field, other embodiments can also be obtained based on these drawings.

[0019] Figure 1 A schematic diagram of the topological structure of the reactive power compensation system according to an embodiment of the present application; Figure 2 A flowchart of a reactive power compensation method provided in an embodiment of the present application; Figure 3 A schematic diagram of a sine wave voltage signal and capacitor voltage equipotential points within a cycle provided by an embodiment of the present application; Figure 4 A schematic diagram of the time relationship of an isoelectric point provided in an embodiment of the present application; Figure 5 A determination strategy diagram provided for an embodiment of the present application. DETAILED DESCRIPTION

[0020] In this application, "at least one" means one or more, and "plurality" means two or more. "And / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone, where A and B can be singular or plural. The character " / " generally indicates that the objects associated before and after are in an "or" relationship. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, at least one of a, b, or c alone can mean: a alone, b alone, c alone, a and b in combination, a and c in combination, b and c in combination, or a, b, and c in combination, where a, b, and c can be single or multiple. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0021] The directions or positional relationships indicated by terms such as "center", "longitudinal", "lateral", "up", "down", "left", "right", "front", and "back" are based on the directions or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present application and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present application.

[0022] The terms "connected" and "connected" should be understood in a broad sense. For example, the "connected" or "connected" of a circuit structure can refer to not only physical connection, but also electrical connection or signal connection. For example, it can be directly connected, that is, physically connected, or indirectly connected through at least one intermediate element, as long as the circuit is connected, or it can be the internal connection of two elements; signal connection can refer to signal connection through a circuit or through a media medium, such as radio waves. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0023] In order to clearly understand the scheme in this application, the reactive power compensation system is first introduced, see Figure 1 , Figure 1 It is a schematic diagram of the topological structure of the reactive power compensation system. Figure 1 As shown, the reactive power compensation system may include: a control circuit, a secondary current transformer, a grid-side bus, a relay, and a capacitor.

[0024] Among them, see Figure 1The grid-side busbar includes a first phase line A, a second phase line B, a third phase line C and a neutral line N. For the mains power, the AC voltage value between the first phase line A and the second phase line B is 380VAC, the AC voltage value between the first phase line A and the third phase line C is 380VAC, and the AC voltage value between the second phase line B and the third phase line C is 380VAC; the AC voltage value between the first phase line A and the neutral line N is 220VAC, the AC voltage value between the second phase line B and the neutral line N is 220VAC, and the AC voltage value between the third phase line C and the neutral line N is 220VAC.

[0025] Typically, a primary current transformer is provided on the grid-side busbar, and the primary current transformer is electrically connected to the secondary current transformer and the grid-side busbar, respectively, to achieve the conversion of the grid-side current value, and transmit the converted current value to the secondary current transformer. In an example, the input current of the primary current transformer may be 100A (ampere), and the output current of the primary current transformer may be 5A.

[0026] The secondary current transformer transforms the current output by the primary current transformer again and transmits the converted current to the control circuit. The control circuit can collect the three-phase current on the grid side through the secondary current transformer and the primary current transformer. In an example, the input current of the secondary current transformer can be 0A~5A, and the output current of the secondary current transformer can be 0A~100mA (milliamperes).

[0027] The control circuit is electrically connected to the first phase line A, the second phase line B, the third phase line C and the neutral line N, and is used to collect the three-phase voltage (i.e., UA, UB, UC) on the grid side. The control circuit is also electrically connected to the capacitor, and is used to collect the voltage value of the capacitor (i.e., UA-C, UB-C, UC-C).

[0028] The control circuit may further include a relay drive circuit for outputting a relay control signal to drive the relay to close or open, so that the capacitor is connected to or disconnected from the grid side.

[0029] Based on the above-mentioned reactive power compensation system, in order to provide a fast reactive power compensation response, an embodiment of the present application provides a reactive power compensation method, which includes: obtaining a synchronous rotation angle; obtaining a current three-phase voltage and a current three-phase current on the grid side, and calculating based on a phase-locked loop algorithm according to the synchronous rotation angle, the current three-phase voltage and the current three-phase current to obtain a current reactive power; obtaining the current capacitor voltage on the capacitor side at the same time, detecting a potential point equal to the voltage value of the current capacitor voltage on the grid side, obtaining an equipotential point, and determining the current equipotential point according to the time interval between two adjacent equipotential points, wherein the equipotential point includes a rising edge equipotential point and a falling edge equipotential point; when the current reactive power is greater than or equal to the current capacitor capacity on the capacitor side, recording the current moment, and obtaining a target action time and a target equipotential point based on a determination strategy according to the current moment, the mechanical delay time and the current equipotential point; taking the current moment as the starting point, outputting a relay control signal after delaying the target action time, so that the capacitor on the capacitor side is put into the grid side at the target equipotential point to perform reactive power compensation on the grid side.

[0030] In an embodiment of the present application, by calculating the current reactive power in real time and detecting the current equipotential point in real time, when the current reactive power is greater than or equal to the current capacitance of the capacitor side, that is, when the capacitor needs to be put into operation, the equipotential point closest to the current moment, that is, the target equipotential point, is determined according to the current moment, the mechanical delay time of the relay and the current equipotential point, and the target action time is calculated. Taking the current moment as the starting point, the relay control signal is output after delaying the target action time, so that the capacitor on the capacitor side is put into operation on the power grid side at the target equipotential point, and reactive compensation is performed on the power grid side to provide a fast reactive compensation response.

[0031] The following describes the reactive power compensation method provided by the present application in conjunction with specific embodiments. Figure 2 , Figure 2 A flowchart of a reactive power compensation method provided in an embodiment of the present application is shown in FIG. Figure 2 As shown, the reactive power compensation method includes: S1, obtain the synchronous rotation angle.

[0032] The control circuit may include a processor for implementing the reactive power compensation method in the present application. The voltage on the grid side is a sinusoidal signal having a frequency of 50 Hz, i.e., 20 ms, and the synchronous rotation angle is the phase angle of the sinusoidal signal. In an example, the synchronous rotation angle of the three-phase voltage can be extracted by detecting the three-phase voltage on the grid side and performing phase-locked calculation using a phase-locked loop algorithm.

[0033] S2, obtain the current three-phase voltage and the current three-phase current on the grid side, and calculate based on the phase-locked loop algorithm according to the synchronous rotation angle, the current three-phase voltage and the current three-phase current to obtain the current reactive power; and obtain the current capacitor voltage on the capacitor side, detect the potential point equal to the voltage value of the current capacitor voltage on the grid side, obtain the equipotential point, and determine the current equipotential point according to the time interval between two adjacent equipotential points, wherein the equipotential point includes the rising edge equipotential point and the falling edge equipotential point.

[0034] In order to calculate the reactive power in real time, it is necessary to collect the three-phase voltage and three-phase current on the grid side in real time to obtain the current three-phase voltage and the current three-phase current. Based on the phase-locked loop algorithm, the coordinate transformation calculation is performed according to the synchronous rotation angle, the current three-phase voltage and the current three-phase current to obtain the current reactive power.

[0035] When calculating the current reactive power, it is also necessary to synchronously detect the equipotential point. The internal voltage of the capacitor on the capacitor side can be regarded as a DC voltage signal. As time goes by, the voltage of the capacitor will slowly drop to 0V. Figure 3 , Figure 3 It is a schematic diagram of the equipotential points of the sinusoidal voltage signal and the capacitor voltage within one cycle, as shown in Figure 3 As shown in the figure, in one cycle of the sine wave voltage signal on the grid side, the capacitor voltage and the sine wave voltage signal have two equipotential points. Figure 3 The single-phase voltage is used as an example for explanation, that is, the sinusoidal voltage signal UA between the first phase line A and the neutral line N, the period of the sinusoidal voltage signal UA is 20ms, and UA-C is the current capacitance voltage of the capacitor on the capacitor side. The two equipotential points are equipotential point 1 and equipotential point 2.

[0036] See also Figure 3 , obtain the current capacitor voltage on the capacitor side, compare the current capacitor voltage with the voltage on the grid side, and detect a potential point on the grid side that is equal to the voltage value of the current capacitor voltage to obtain an equipotential point. In addition, by comparing the difference between the current capacitor voltage and the voltage on the grid side, it can be determined whether the equipotential point is a rising edge equipotential point or a falling edge equipotential point. For example, if the difference between the current capacitor voltage and the voltage on the grid side is first positive and then negative, the equipotential point where the current capacitor voltage is equal to the voltage on the grid side is the rising edge equipotential point; if the difference between the current capacitor voltage and the voltage on the grid side is first negative and then positive, the equipotential point where the current capacitor voltage is equal to the voltage on the grid side is the falling edge equipotential point. Figure 3 In the figure, equipotential point 1 is the equipotential point along the rising edge, and equipotential point 2 is the equipotential point along the falling edge.

[0037] Since the period of the sinusoidal voltage signal is 20ms, equipotential points will appear cyclically in continuous periods. According to the time interval between two adjacent equipotential points, the state of the equipotential points can be continuously judged to determine the current equipotential point. The next equipotential point can be inferred from the current equipotential point to prepare for the subsequent capacitor input. The current equipotential point will be explained in detail in the subsequent embodiments.

[0038] It should be noted that the calculation of the current reactive power and the detection of the equipotential point are performed simultaneously and are a continuous process.

[0039] S3, when the current reactive power is greater than or equal to the current capacitance of the capacitor side, the current time is recorded, and according to the current time, the mechanical delay time and the current equipotential point, the target action time and the target equipotential point are obtained based on the determination strategy.

[0040] The current capacitance of the capacitor on the capacitor side is in var (var), for example, the current capacitance is 1Kvar (var). The current reactive power is compared with the current capacitance of the capacitor side in real time. When the current reactive power is greater than or equal to the current capacitance of the capacitor side, it is considered that the capacitor needs to be put into operation. At this time, the current moment is recorded, and based on the current moment, the mechanical delay time and the current equipotential point, the mechanical delay time is a fixed mechanical delay during the relay closure process, and the mechanical delay time needs to be taken into account when calculating the target action time. The next equipotential point can be inferred from the current equipotential point.

[0041] In this way, according to the current moment, mechanical delay time and current equipotential point, based on the judgment strategy, the fastest target equipotential point that can be put into use as well as the time required for the target equipotential point to arrive, that is, the target action time, can be obtained.

[0042] S4, starting from the current moment, outputs a relay control signal after delaying the target action time, so that the capacitor on the capacitor side is connected to the grid side at the target equipotential point to perform reactive power compensation on the grid side.

[0043] After obtaining the target action time and target equipotential point, taking the current time as the starting point, the relay control signal is output after delaying the target action time. After receiving the relay control signal, the relay is energized, the relay contacts are closed, and the capacitor on the capacitor side is connected to the grid side at the target equipotential point to realize reactive power compensation on the grid side.

[0044] The prior art is to put the capacitor into operation at zero point, while the present application is to put the capacitor on the capacitor side into operation at the equipotential point, which can be any voltage value of the capacitor. The present application does not limit the specific voltage value of the equipotential point.

[0045] In an embodiment of the present application, by calculating the current reactive power in real time and detecting the current equipotential point in real time, when the current reactive power is greater than or equal to the current capacitance of the capacitor side, that is, when the capacitor needs to be put into operation, the equipotential point closest to the current moment, that is, the target equipotential point, is determined according to the current moment, the mechanical delay time of the relay and the current equipotential point, and the target action time is calculated. Taking the current moment as the starting point, the relay control signal is output after delaying the target action time, so that the capacitor on the capacitor side is put into operation on the power grid side at the target equipotential point, and reactive compensation is performed on the power grid side to provide a fast reactive compensation response.

[0046] In a possible embodiment, the above step S1 includes: S11, obtain the three-phase voltage on the grid side in real time.

[0047] After power-on, the control circuit collects the three-phase voltage and three-phase current on the grid side, and after obtaining the three-phase voltage on the grid side, extracts the synchronous rotation angle θ from the three-phase voltage.

[0048] S12, using a phase-locked loop to perform phase locking to obtain a synchronous rotation angle.

[0049] Since the output of the phase locked loop (PLL) is unstable, it is often necessary to wait for a period of time, also known as the locking time. The locking time can be 3-5 cycles (i.e. 60ms~100ms). Until the output of the phase locked loop is stable, the phase locked loop can be used for phase locking to obtain the synchronous rotation angle θ.

[0050] In a possible embodiment, in the above step S2, the step of calculating the current reactive power may include: S21, performing Clarke coordinate transformation on the current three-phase voltage to obtain a first voltage coordinate component and a second voltage coordinate component.

[0051] Get the current three-phase voltage, that is , , , perform Clarke coordinate transformation on the current three-phase voltage, convert the three-phase stationary coordinate system into the components under the two-phase stationary coordinate system (αβ), and obtain the first voltage coordinate component , the second voltage coordinate component .

[0052] The coordinate transformation formula is: , .

[0053] S22, performing Clarke coordinate transformation on the current three-phase current to obtain a first current coordinate component and a second current coordinate component.

[0054] Get the current three-phase current, that is , , , perform Clarke coordinate transformation on the current three-phase current, convert the three-phase stationary coordinate system into components under the two-phase stationary coordinate system (αβ), and obtain the first current coordinate component , the second current coordinate component .

[0055] The coordinate transformation formula is: , .

[0056] S23, using the synchronous rotation angle, performing Park coordinate transformation on the first voltage coordinate component and the second voltage coordinate component to obtain a third voltage coordinate component and a fourth voltage coordinate component.

[0057] Using the synchronous rotation angle θ output by the phase-locked loop, the two-phase stationary coordinate system (αβ) is transformed into a dq rotating coordinate system synchronized with the power grid by Park coordinate transformation to obtain the third voltage coordinate component and the fourth voltage coordinate component .

[0058] The coordinate transformation formula is: , .

[0059] S24, using the synchronous rotation angle, performing Park coordinate transformation on the first current coordinate component and the second current coordinate component to obtain a third current coordinate component and a fourth current coordinate component.

[0060] Using the synchronous rotation angle θ output by the phase-locked loop, the two-phase stationary coordinate system (αβ) is transformed into a dq rotating coordinate system synchronized with the power grid by Park coordinate transformation to obtain the third current coordinate component and the fourth current coordinate component .

[0061] The coordinate transformation formula is: , .

[0062] S25, according to the formula , calculate the current reactive power, where Q is the current reactive power, is the third voltage coordinate component, is the fourth voltage coordinate component, is the third current coordinate component, is the fourth current coordinate component.

[0063] In an embodiment of the present application, based on a phase-locked loop algorithm, coordinate transformation is performed according to the synchronous rotation angle, the current three-phase voltage, and the current three-phase current, and the current reactive power can be calculated.

[0064] In a possible embodiment, in the above step S2, the step of obtaining the isoelectric point includes: S26, obtaining the current capacitor voltage on the capacitor side.

[0065] S27, at the potential point where the rising edge of the sine wave on the grid side is equal to the voltage value of the current capacitor voltage, a rising edge equipotential point is obtained.

[0066] S28, obtaining a falling edge equipotential point at a potential point where the falling edge of the sine wave on the grid side is equal to the voltage value of the current capacitor voltage.

[0067] The current capacitor voltage on the capacitor side is obtained, and the current capacitor voltage is compared with the voltage on the grid side. A potential point equal to the voltage value of the current capacitor voltage can be detected on the grid side to obtain an equipotential point. By comparing the difference between the current capacitor voltage and the voltage on the grid side, it can be determined whether the equipotential point is a rising edge equipotential point or a falling edge equipotential point.

[0068] Specifically, if the difference between the current capacitor voltage and the voltage on the grid side is first positive and then negative, the rising edge equipotential point is obtained at the potential point where the rising edge of the sinusoidal wave on the grid side is equal to the voltage value of the current capacitor voltage; if the difference between the current capacitor voltage and the voltage on the grid side is first negative and then positive, the falling edge equipotential point is obtained at the potential point where the falling edge of the sinusoidal wave on the grid side is equal to the voltage value of the current capacitor voltage.

[0069] In a possible embodiment, in the above step S2, the step of determining the current isoelectric point includes: S29, acquiring two adjacent rising edge equipotential points to obtain a first rising edge equipotential point and a second rising edge equipotential point.

[0070] See also Figure 4 , Figure 4 A schematic diagram of the relationship between isoelectric points and time is provided in the embodiment of the present application, such as Figure 4 As shown, the rising edge equipotential point is marked as T U , the sine wave signal on the grid side is continuous, obtain two adjacent rising edge equipotential points, and obtain the first rising edge equipotential point T U0 and the second rising edge equipotential point T U1 .

[0071] S210, calculating the time interval between the first rising edge equipotential point and the second rising edge equipotential point to obtain a first time interval.

[0072] Calculate the first rising edge equipotential point T U0 and the second rising edge equipotential point T U1 The first time interval ΔT is obtained U =T U1 -T U0 .

[0073] S211, acquiring two adjacent falling edge equipotential points to obtain a first falling edge equipotential point and a second falling edge equipotential point.

[0074] See also Figure 4 , mark the falling edge equipotential point as T D The sine wave signal on the grid side is continuous. Two adjacent falling edge equipotential points are obtained to obtain the first falling edge equipotential point T D0 and the second falling edge equipotential point T D1 .

[0075] S212, calculating the time interval between the first falling edge equipotential point and the second falling edge equipotential point to obtain a second time interval.

[0076] Calculate the first falling edge equipotential point T D0 and the second falling edge equipotential point T D1 The second time interval ΔT is obtained D =T D1 -T D0 .

[0077] S213, if the first time interval and the second time interval are both equal to the interval threshold, it is determined that the equipotential point is in a stable state, and the execution step is returned: two adjacent rising edge equipotential points are obtained to obtain the first rising edge equipotential point and the second rising edge equipotential point. Each time the execution step is returned: two adjacent rising edge equipotential points are obtained to obtain the first rising edge equipotential point and the second rising edge equipotential point, the second rising edge equipotential point or the second falling edge equipotential point of the current detection cycle is updated to the first rising edge equipotential point or the first falling edge equipotential point of the next detection cycle.

[0078] The theoretical value of the interval threshold is the period of the sine wave, which is equal to 20ms. In actual project applications, the interval threshold may have a deviation of about 20ms, such as 20ms±1ms.

[0079] If the first time interval ΔT U and the second time interval ΔT DIf both are equal to the interval threshold, it is determined that the equipotential point is in a stable state, that is, the rising edge equipotential point or the falling edge equipotential point is in a correct stable state. Detecting the state of the equipotential point is an ongoing process. After determining that the equipotential point is in a stable state, continue to return to the execution step: obtain two adjacent rising edge equipotential points, obtain the first rising edge equipotential point and the second rising edge equipotential point, and continue to determine whether the equipotential point is in a stable state.

[0080] The process of determining that the equipotential point is in a stable state is considered as a detection cycle. After a detection cycle, the second rising edge equipotential point T of the current detection cycle needs to be U1 Or the second falling edge equipotential point T D1 , corresponding to the first rising edge equipotential point T of the next detection cycle U0 Or the first falling edge equipotential point T D0 That is, after determining that the equipotential point is in a stable state, the second rising edge equipotential point T U1 Replaced by the first rising edge equipotential point T U0 , the second falling edge equipotential point T D1 Replaced by the first falling edge equipotential point T D0 , continue the process of detecting the next rising edge equipotential point or falling edge equipotential point, and determining whether the equipotential point is in a stable state.

[0081] S214, determining the first rising edge equipotential point or the first falling edge equipotential point as the current equipotential point.

[0082] After the equipotential point is determined to be in a stable state, the second rising edge equipotential point T U1 Replaced by the first rising edge equipotential point T U0 , the second falling edge equipotential point T D1 Replaced by the first falling edge equipotential point T D0 , then there is always the first rising edge equipotential point T U0 Or the first falling edge equipotential point T D0 , then the first rising edge equipotential point T that exists after the update U0 Or the first falling edge equipotential point T D0 Determine the current isoelectric point.

[0083] In the embodiment of the present application, the equipotential point is determined to be in a stable state and the first rising edge equipotential point or the first falling edge equipotential point is determined as the current equipotential point. This is so that when the capacitor needs to be put into operation, the next equipotential point closest to the current moment can be calculated with the correct equipotential point for the capacitor to be put into operation, so as to provide a fast reactive compensation response.

[0084] In a possible embodiment, the above step S3 includes: S31, calculating the time difference between the first rising edge equipotential point and the current time to obtain the rising edge interval.

[0085] When the current reactive power is greater than or equal to the current capacitance of the capacitor side, the capacitor needs to be put into operation. At this time, it is necessary to calculate that the upcoming rising edge equipotential point or falling edge equipotential point is the fastest relay closure action time point, and the capacitor needs to be put into operation at this time point.

[0086] The current equipotential point is the first rising edge equipotential point T U0 Or the first falling edge equipotential point T D0 .

[0087] Therefore, it is necessary to calculate the first rising edge equipotential point T U0 The time difference with the current time is used to obtain the rising edge interval ΔT UB .

[0088] S32, calculating the time difference between the first falling edge equipotential point and the current time, and obtaining the falling edge interval.

[0089] Similarly, calculate the first falling edge equipotential point T D0 The time difference with the current time is used to obtain the falling edge interval ΔT DB .

[0090] S33, calculating the sum of the rising edge interval and the mechanical delay time to obtain the rising edge time.

[0091] The mechanical delay time is a fixed mechanical delay in the process of relay closure. The mechanical delay time needs to be taken into account when calculating the target action time. When the type of relay is determined, the mechanical delay time is also a fixed value. The mechanical delay time is expressed as T j .

[0092] In this way, the rising edge interval ΔT is calculated UB With mechanical delay time T j The sum of the rising edge time and ΔT UM That is, ΔT UM= ΔT UB +T j .

[0093] S34, calculating the sum of the falling edge interval and the mechanical delay time to obtain the falling edge time.

[0094] Similarly, calculate the falling edge interval ΔT DB With mechanical delay time T j The sum of the falling edge time and ΔT DM . That is, ΔT DM=ΔT DB +T j .

[0095] S35, obtaining the target action time and the target equipotential point according to the rising edge time and the falling edge time based on the determination strategy.

[0096] According to the rising edge time and ΔT UM , falling edge time and ΔT DM Based on the judgment strategy, the target equipotential point and target action time of the capacitor that can be put into use closest to the current moment can be calculated.

[0097] In one possible embodiment, see Figure 5 , Figure 5 A determination strategy diagram is provided for an embodiment of the present application, such as Figure 5 As shown, the above step S35 may include: S351, at the rising edge time ΔT UM Less than or equal to 20 milliseconds, and the falling edge time and ΔT DM Less than or equal to 20 milliseconds: If the rising edge time is ΔT UM Greater than or equal to the falling edge time and ΔT DM , the target equipotential point is the next rising edge equipotential point adjacent to the current equipotential point, and the target action time is the difference between 20 milliseconds and the rising edge time.

[0098] If the rising edge time is ΔT UM Less than the falling edge time and ΔT DM , the target equipotential point is the next falling edge equipotential point adjacent to the current equipotential point, and the target action time is the difference between 20 milliseconds and the falling edge time.

[0099] First, make a time condition judgment: compare the rising edge time and ΔT UM and the falling edge time and ΔT DM The relationship between the rise time and ΔT UM ≦20 milliseconds, and the falling edge time is ΔT DM When ≦20 milliseconds, it is considered that the target equipotential point closest to the current moment that can be used to put the capacitor into operation is the rising edge equipotential point or the falling edge equipotential point in the current cycle.

[0100] Secondly, make auxiliary judgment: compare the rising edge time and ΔT UM and the falling edge time and ΔT DM Since the rise time and ΔT UM Or the falling edge time and ΔT DMThe longer the time is, the shorter the time for the next equipotential point to arrive. Therefore, if the rising edge time is equal to ΔT UM ≧Falling edge time and ΔT DM , the judgment result is: the target equipotential point is the next rising edge equipotential point adjacent to the current equipotential point, that is, the capacitor is put into operation at the next rising edge equipotential point. And the target action time is 20ms-ΔT UM , the relay is in (20ms-ΔT UM ) time and then the suction action will be performed.

[0101] If the rising edge time is ΔT UM <Falling edge time and ΔT DM , the judgment result is: the target equipotential point is the next falling edge equipotential point adjacent to the current equipotential point, that is, the capacitor is put into operation at the next falling edge equipotential point. And the target action time is 20ms-ΔT DM , the relay is in (20ms-ΔT DM ) time and then the suction action will be performed.

[0102] S352, at the rising edge time ΔT UM Less than or equal to 20 milliseconds, and the falling edge time and ΔT DM If it is greater than 20 milliseconds: the target equipotential point is the next rising edge equipotential point adjacent to the current equipotential point, and the target action time is the difference between 20 milliseconds and the rising edge time.

[0103] Similarly, if the rising edge time and ΔT UM Or the falling edge time and ΔT DM If the rising edge time is greater than 20 milliseconds, the equipotential point is considered to be in the next cycle. UM ≦20 milliseconds, and the falling edge time is ΔT DM When the value is >20 milliseconds, it is considered that the target equipotential point that can be used to put the capacitor into operation is the rising edge equipotential point in the current cycle, and no auxiliary judgment is required.

[0104] The judgment result is: the target equipotential point is the next rising edge equipotential point adjacent to the current equipotential point, that is, the capacitor is put into operation at the next rising edge equipotential point, and the target action time is 20ms-ΔT UM , the relay is in (20ms-ΔT UM ) time and then the suction action will be performed.

[0105] S353, at the rising edge time ΔT UM Greater than 20 milliseconds, and the falling edge time and ΔT DMIf it is less than or equal to 20 milliseconds: the target equipotential point is the next falling edge equipotential point adjacent to the current equipotential point, and the target action time is the difference between 20 milliseconds and the falling edge time.

[0106] Similarly, during the rising edge time and ΔT UM >20ms, and the falling edge time is ΔT DM When ≦20 milliseconds, it is considered that the target equipotential point that can be used to put the capacitor in is the falling edge equipotential point in the current cycle, and no auxiliary judgment is required.

[0107] The result is: the target equipotential point is the next falling equipotential point adjacent to the current equipotential point, that is, the capacitor is put into operation at the next rising equipotential point, and the target action time is 20ms-ΔT DM , the relay is in (20ms-ΔT DM ) time and then the suction action will be performed.

[0108] S354, at the rising edge time ΔT UM Greater than 20 milliseconds, and the falling edge time and ΔT DM Under the condition of more than 20 milliseconds: If the rising edge time is ΔT UM Greater than or equal to the falling edge time and ΔT DM , the target equipotential point is the second rising edge equipotential point separated from the current equipotential point, and the target action time is the difference between 40 milliseconds and the rising edge time.

[0109] If the rising edge time is ΔT UM Less than the falling edge time and ΔT DM , the target equipotential point is the second falling edge equipotential point separated from the current equipotential point, and the target action time is the difference between 40 milliseconds and the falling edge time.

[0110] First, make a time condition judgment: compare the rising edge time and ΔT UM and the falling edge time and ΔT DM The relationship between the rise time and ΔT UM >20ms, and the falling edge time is ΔT DM When the value is greater than 20 milliseconds, it is considered that the target equipotential point closest to the current moment that can be used to put the capacitor into operation is the rising edge equipotential point or the falling edge equipotential point in the next cycle.

[0111] Secondly, make auxiliary judgment: compare the rising edge time and ΔT UM and the falling edge time and ΔT DM Since the rise time and ΔT UM Or the falling edge time and ΔTDM The longer the time is, the shorter the time for the next equipotential point to arrive. Therefore, if the rising edge time is equal to ΔT UM ≧Falling edge time and ΔT DM , the judgment result is: the target equipotential point is the second rising edge equipotential point separated from the current equipotential point, that is, the capacitor is put into operation at the second rising edge equipotential point. And the target action time is 40ms-ΔT UM , the relay is in (40ms-ΔT UM ) time and then the suction action will be performed.

[0112] If the rising edge time is ΔT UM <Falling edge time and ΔT DM , the judgment result is: the target equipotential point is the second falling edge equipotential point separated from the current equipotential point, that is, the capacitor is put into operation at the second falling edge equipotential point. And the target action time is 40ms-ΔT DM , the relay is in (40ms-ΔT DM ) time and then the suction action will be performed.

[0113] The present application also provides a reactive power compensation system. Figure 1 , the system includes: a control circuit, a secondary current transformer, a grid-side bus, a relay and a capacitor; The secondary current transformer, the grid-side busbar, the relay and the capacitor are all electrically connected to the control circuit, and the control circuit is used to implement the above-mentioned reactive power compensation method steps.

[0114] The embodiment of the present application further provides a control device, including: a memory and a processor, the memory stores a computer program that can be run on the processor, and the processor implements the above-mentioned reactive power compensation method steps when executing the program.

[0115] The memory may include a random access memory (RAM) or a non-volatile memory, such as at least one disk memory. Optionally, the memory may also be at least one storage device located away from the aforementioned processor.

[0116] The above-mentioned processor can be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it can also be a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components.

[0117] In another embodiment provided in the present application, a computer-readable storage medium is provided, in which a computer program is stored. When the computer program is executed by a processor, any of the methods described in the above embodiments is implemented.

[0118] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When implemented by software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the process or function described in the embodiment of the present invention is generated in whole or in part. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions may be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions may be transmitted from one website site, computer, server or data center to another website site, computer, server or data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium may be any available medium that a computer can access or a data storage device such as a server or data center that includes one or more available media integrated. The available medium may be a magnetic medium (e.g., a floppy disk, a hard disk, a tape), an optical medium (e.g., a DVD), or a semiconductor medium (e.g., a solid-state drive Solid State Disk (SSD)), etc.

[0119] Finally, it should be noted that the above embodiments are only specific implementation methods of the present application, but the protection scope of the present application is not limited thereto, and any changes or substitutions within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A reactive power compensation method, characterized in that: The reactive power compensation method comprises: Get the synchronous rotation angle; Obtain the current three-phase voltage and the current three-phase current on the grid side, and calculate based on the phase-locked loop algorithm according to the synchronous rotation angle, the current three-phase voltage and the current three-phase current to obtain the current reactive power; and obtain the current capacitor voltage on the capacitor side, detect the potential point equal to the voltage value of the current capacitor voltage on the grid side, obtain the equipotential point, and determine the current equipotential point according to the time interval between two adjacent equipotential points, wherein the equipotential point includes a rising edge equipotential point and a falling edge equipotential point; When the current reactive power is greater than or equal to the current capacitance of the capacitor side, the current time is recorded, and according to the current time, the mechanical delay time and the current equipotential point, a target action time and a target equipotential point are obtained based on a determination strategy; Taking the current moment as the starting point, a relay control signal is output after delaying the target action time, so that the capacitor on the capacitor side is connected to the grid side at the target equipotential point to perform reactive power compensation on the grid side.

2. The reactive power compensation method according to claim 1, characterized in that: The obtaining of the synchronous rotation angle comprises: Obtain the three-phase voltage on the grid side in real time; The phase-locked loop is used to perform phase locking to obtain the synchronous rotation angle.

3. The reactive power compensation method according to claim 1, characterized in that: The phase-locked loop algorithm is used to calculate the current reactive power according to the synchronous rotation angle, the current three-phase voltage and the current three-phase current, including: Performing Clarke coordinate transformation on the current three-phase voltage to obtain a first voltage coordinate component and a second voltage coordinate component; Performing Clarke coordinate transformation on the current three-phase current to obtain a first current coordinate component and a second current coordinate component; Using the synchronous rotation angle, performing Park coordinate transformation on the first voltage coordinate component and the second voltage coordinate component to obtain a third voltage coordinate component and a fourth voltage coordinate component; Using the synchronous rotation angle, performing Park coordinate transformation on the first current coordinate component and the second current coordinate component to obtain a third current coordinate component and a fourth current coordinate component; According to the formula , calculate the current reactive power, where Q is the current reactive power, is the third voltage coordinate component, is the fourth voltage coordinate component, is the third current coordinate component, is the fourth current coordinate component.

4. The reactive power compensation method according to claim 1, characterized in that: The obtaining of the current capacitor voltage on the capacitor side, detecting a potential point on the grid side that is equal to the voltage value of the current capacitor voltage, and obtaining an equipotential point includes: Get the current capacitor voltage on the capacitor side; At the potential point where the rising edge of the sine wave on the grid side is equal to the voltage value of the current capacitor voltage, the rising edge equipotential point is obtained; The falling edge equipotential point is obtained at the potential point where the falling edge of the sine wave on the grid side is equal to the voltage value of the current capacitor voltage.

5. The reactive power compensation method according to claim 1, characterized in that: Determining the current isoelectric point according to the time interval between two adjacent isoelectric points includes: Acquire two adjacent rising edge equipotential points to obtain a first rising edge equipotential point and a second rising edge equipotential point; Calculate the time interval between the first rising edge equipotential point and the second rising edge equipotential point to obtain a first time interval; Acquire two adjacent falling edge equipotential points to obtain a first falling edge equipotential point and a second falling edge equipotential point; Calculate the time interval between the first falling edge equipotential point and the second falling edge equipotential point to obtain a second time interval; If the first time interval and the second time interval are both equal to the interval threshold, it is determined that the equipotential point is in a stable state, and the process returns to the execution step of obtaining two adjacent rising edge equipotential points to obtain a first rising edge equipotential point and a second rising edge equipotential point. Each time the process returns to the execution step of obtaining two adjacent rising edge equipotential points to obtain a first rising edge equipotential point and a second rising edge equipotential point, the second rising edge equipotential point or the second falling edge equipotential point of the current detection cycle is correspondingly updated to the first rising edge equipotential point or the first falling edge equipotential point of the next detection cycle. The first rising edge equipotential point or the first falling edge equipotential point is determined as the current equipotential point.

6. The reactive power compensation method according to claim 5, characterized in that: The step of obtaining the target action time and the target isoelectric point based on the current moment, the mechanical delay time and the current isoelectric point based on the determination strategy includes: Calculate the time difference between the first rising edge equipotential point and the current moment to obtain a rising edge interval; Calculate the time difference between the first falling edge equipotential point and the current moment to obtain a falling edge interval; Calculate the sum of the rising edge interval and the mechanical delay time to obtain the rising edge time; Calculate the sum of the falling edge interval and the mechanical delay time to obtain the falling edge time; According to the rising edge time and the falling edge time, based on a determination strategy, the target action time and the target equipotential point are obtained.

7. The reactive power compensation method according to claim 6, characterized in that: The step of obtaining the target action time and the target equipotential point based on the rising edge time and the falling edge time and the determination strategy comprises: Under the condition that the rising edge time is less than or equal to 20 milliseconds, and the falling edge time is less than or equal to 20 milliseconds: If the rising edge time is greater than or equal to the falling edge time, the target equipotential point is the next rising edge equipotential point adjacent to the current equipotential point, and the target action time is the difference between 20 milliseconds and the rising edge time; If the rising edge time is less than the falling edge time, the target equipotential point is the next falling edge equipotential point adjacent to the current equipotential point, and the target action time is the difference between 20 milliseconds and the falling edge time; Under the condition that the rising edge time is less than or equal to 20 milliseconds, and the falling edge time is greater than 20 milliseconds: the target equipotential point is the next rising edge equipotential point adjacent to the current equipotential point, and the target action time is the difference between 20 milliseconds and the rising edge time; Under the condition that the rising edge time is greater than 20 milliseconds, and the falling edge time is less than or equal to 20 milliseconds: the target equipotential point is the next falling edge equipotential point adjacent to the current equipotential point, and the target action time is the difference between 20 milliseconds and the falling edge time; Under the condition that the rising edge time is greater than 20 milliseconds, and the falling edge time is greater than 20 milliseconds: If the rising edge time is greater than or equal to the falling edge time, the target equipotential point is the second rising edge equipotential point separated from the current equipotential point, and the target action time is the difference between 40 milliseconds and the rising edge time; If the rising edge time and is less than the falling edge time and, the target equipotential point is the second falling edge equipotential point separated from the current equipotential point, and the target action time is the difference between 40 milliseconds and the falling edge time and.

8. A reactive power compensation system, characterized in that: The system comprises: a control circuit, a secondary current transformer, a grid-side bus, a relay and a capacitor; The secondary current transformer, the grid-side bus, the relay and the capacitor are all electrically connected to the control circuit, and the control circuit is used to implement the method steps as described in any one of claims 1-7.

9. A control device comprising: A memory and a processor, wherein the memory stores a computer program that can be run on the processor, and wherein the processor implements the method steps described in any one of claims 1 to 7 when executing the program.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the method steps according to any one of claims 1 to 7 are implemented.

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