Transformer disconnection detection method, reactive power compensation control device and reactive power compensation system

Abstract

The application provides a kind of mutual inductor broken line detection method, reactive power compensation control equipment and reactive power compensation system, it is related to reactive power compensation technical field.The mutual inductor broken line detection method includes: in the case where it is detected that grid current is less than preset current threshold and duration is greater than preset length, the secondary mutual inductor of reactive power compensation system is detected for broken line;In the case where it is detected that secondary mutual inductor is not in broken line state, the primary mutual inductor of reactive power compensation system is detected for broken line;In the case where secondary mutual inductor is in broken line state or primary mutual inductor is in broken line state, alarm is started;Wherein, primary mutual inductor is connected with the bus of grid, and secondary mutual inductor is connected between the output end of primary mutual inductor and mutual inductor input end of reactive power compensation control equipment.The scheme of the application can realize the broken line detection of the mutual inductor of reactive power compensation system, avoid the problem of not compensation or overcompensation caused by the broken line of mutual inductor.

Description

Technical Field

[0001] This application relates to the field of reactive power compensation technology, and in particular to a method for detecting open circuits in current transformers, a reactive power compensation control device, and a reactive power compensation system. Background Technology

[0002] A reactive power compensation system (VCS) is a control system that improves voltage stability by coordinating and controlling reactive power compensation devices to regulate reactive power voltage in a regional power grid. During the operation of a VCS, the reactive power compensation control equipment needs to collect grid voltage and current signals to calculate the current reactive power of the grid. Based on this, it calculates the reactive power capacity that needs compensation and then formulates a switching strategy to execute capacitor switching actions.

[0003] In reactive power compensation systems, instrument transformers play a crucial role in sensing the grid status and providing control data. By proportionally transforming high voltage and large current signals into low voltage and small current signals, they provide critical real-time data for the controller to accurately calculate and switch reactive power. If an instrument transformer is disconnected, the reactive power compensation system may fail to compensate or overcompensate. Therefore, how to detect disconnections in instrument transformers is particularly important and is a technical problem that urgently needs to be solved. Summary of the Invention

[0004] This application provides a method for detecting open circuit in a current transformer, a reactive power compensation control device, and a reactive power compensation system, so as to realize the detection of open circuit in the current transformer of the reactive power compensation system and avoid the problems of non-compensation or overcompensation caused by open circuit in the current transformer.

[0005] In a first aspect, this application provides a method for detecting open circuit in a current transformer, applied to a reactive power compensation control device in a reactive power compensation system. The method for detecting open circuit in a current transformer includes: If the grid current is detected to be less than the preset current threshold and the duration is greater than the preset duration, the secondary transformer of the reactive power compensation system is disconnected. If the secondary current transformer is not found to be disconnected, the primary current transformer of the reactive power compensation system is tested for disconnection. An alarm is triggered if either the secondary current transformer or the primary current transformer is disconnected. The primary current transformer is connected to the busbar of the power grid, and the secondary current transformer is connected between the output terminal of the primary current transformer and the current transformer input terminal of the reactive power compensation control device.

[0006] In one optional design, the disconnection detection of the secondary transformer in the reactive power compensation system includes: Input a high-level signal and a low-level signal to the detection signal input terminal of the secondary transformer detection circuit, respectively; When the high-level signal is input to the detection signal input terminal, the DC component of the output signal of the secondary transformer detection circuit is obtained to obtain the first DC quantity; When the low-level signal is input to the detection signal input terminal, the DC component of the output signal of the secondary transformer detection circuit is obtained to obtain the second DC component. Determine the difference in DC flow rate between the first DC flow rate and the second DC flow rate; If the DC-DC difference is greater than a preset threshold, the secondary current transformer is determined to be in a disconnected state; if the DC-DC difference is less than or equal to the preset threshold, the secondary current transformer is determined to be not in a disconnected state. The secondary transformer detection circuit includes a detection signal input terminal, a bias signal input terminal, a sampling resistor, a pull-up resistor, a bias resistor, and a differential operational amplifier circuit. The positive differential input terminal of the differential operational amplifier circuit is connected to the first output terminal of the secondary transformer, and the negative differential input terminal of the differential operational amplifier circuit is connected to the second output terminal of the secondary transformer. The pull-up resistor is connected between the positive differential input terminal and the detection signal input terminal. The sampling resistor is connected between the positive differential input terminal and the negative differential input terminal. The bias signal input terminal is used to input a target bias voltage to the signal path where the positive differential input terminal of the differential operational amplifier circuit is located through the bias resistor.

[0007] In one optional design, the differential operational amplifier circuit includes the positive differential input terminal, the negative differential input terminal, the first operational amplifier, the third resistor, the fourth resistor, the fifth resistor, the sixth resistor, the eighth resistor, the ninth resistor, the first capacitor, and the second capacitor. The third and fifth resistors are connected in series between the negative differential input terminal and the negative input terminal of the first operational amplifier; the fourth and sixth resistors are connected in series between the positive differential input terminal and the positive input terminal of the first operational amplifier; the series junction of the third and fifth resistors is connected to ground through the first capacitor; the series junction of the fourth and sixth resistors is connected to ground through the second capacitor; the eighth resistor is connected between the negative input terminal and the output terminal of the first operational amplifier; the output terminal of the first operational amplifier is connected to the signal output terminal of the differential operational amplifier circuit through the ninth resistor. One end of the bias resistor is connected to the bias signal input terminal, and the other end is connected to the positive input terminal of the first operational amplifier.

[0008] In an optional design, the secondary transformer detection circuit further includes a bias voltage generation circuit; The reference terminal of the bias voltage generating circuit is used to input a reference voltage, and the output terminal of the bias voltage generating circuit is connected to the bias signal input terminal. The bias voltage generating circuit is used to generate the target bias voltage based on the reference voltage.

[0009] In one alternative design, the bias voltage generating circuit includes the reference terminal, a second operational amplifier, a tenth resistor, an eleventh resistor, a third capacitor, and a fourth capacitor. The tenth resistor is connected between the reference terminal and the positive input terminal of the second operational amplifier; the eleventh resistor and the third capacitor are connected in parallel between the positive input terminal of the second operational amplifier and ground; the negative input terminal of the second operational amplifier is connected to the output terminal of the second operational amplifier; the output terminal of the second operational amplifier serves as the output terminal of the bias voltage generation circuit and is connected to the bias signal input terminal, and is connected to ground through the fourth capacitor.

[0010] In one optional design, the disconnection detection of the primary transformer in the reactive power compensation system includes: Determine the target capacitor adjustment amount; The capacitors of the reactive power compensation system are adjusted based on the target capacitance adjustment amount. Determine whether the effective value of the grid current changes after adjusting the capacitor; Under the circumstances of change, it is determined that the primary current transformer is not in a disconnected state; If no changes occur, it is determined that the primary transformer is in a disconnected state.

[0011] In one alternative design, determining the target capacitance adjustment amount includes: The input current of the primary transformer is determined based on the transformation ratio of the primary transformer and the secondary transformer and the current of the secondary transformer; The target capacitance adjustment amount is determined based on the input voltage of the primary transformer, the input current of the primary transformer, and the preset rate of change.

[0012] In one optional design, adjusting the capacitor of the reactive power compensation system based on the target capacitance adjustment includes: Check if there are any capacitors online in the power grid; When there are capacitors online in the power grid, the capacitor corresponding to the target capacitance adjustment amount is disconnected from the online capacitors; When there are no capacitors online in the power grid, a capacitor corresponding to the target capacitance adjustment amount is connected to the power grid.

[0013] Secondly, this application provides a reactive power compensation control device, including a memory and a processor. The memory stores a computer program that can run on the processor. When the processor executes the computer program, it implements the steps of the current transformer disconnection detection method as described in any of the first aspects above.

[0014] Thirdly, this application provides a reactive power compensation system, including a primary current transformer, a secondary current transformer, at least one capacitor, and a reactive power compensation control device as described in the second aspect above. The primary current transformer is connected to the bus of the power grid, the secondary current transformer is connected between the output terminal of the primary current transformer and the current transformer input terminal of the reactive power compensation control device, each of the at least one capacitor is connected to the power grid, and the reactive power compensation control device is connected to the at least one capacitor.

[0015] The instrument transformer disconnection detection method, reactive power compensation control device, and reactive power compensation system provided in this application perform disconnection detection on the secondary instrument transformer of the reactive power compensation system when the reactive power compensation control device detects that the grid current is less than a preset current threshold and the duration is greater than a preset time. If the secondary instrument transformer is not detected to be disconnected, the primary instrument transformer of the reactive power compensation system is detected to be disconnected. An alarm is activated if either the secondary or primary instrument transformer is disconnected. The primary instrument transformer is connected to the grid bus, and the secondary instrument transformer is connected between the output terminal of the primary instrument transformer and the input terminal of the reactive power compensation control device. In this way, when a low current condition occurs, the reactive power compensation control device initiates instrument transformer disconnection detection, detecting the primary instrument transformer circuit from its own secondary instrument transformer circuit, thus realizing instrument transformer disconnection detection and activating an alarm upon detection of a disconnection for appropriate handling, avoiding problems of non-compensation or overcompensation caused by instrument transformer disconnection. Furthermore, by conducting graded testing on the secondary and primary current transformers, it is easier to locate the current transformer with a broken wire, making the fault diagnosis more precise. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the reactive power compensation system provided in the embodiments of this application; Figure 2 A schematic flowchart of the current transformer open circuit detection method provided in the embodiments of this application; Figure 3 This is one of the flowcharts illustrating the method for detecting open circuits in the secondary current transformers of a reactive power compensation system in this application embodiment; Figure 4This is one of the structural schematic diagrams of the secondary transformer detection circuit provided in the embodiments of this application; Figure 5 This is a second schematic diagram of the secondary transformer detection circuit provided in the embodiments of this application; Figure 6 This is a schematic diagram of the bias voltage generating circuit 50 provided in an embodiment of this application; Figure 7 This is the third schematic diagram of the secondary transformer detection circuit provided in the embodiments of this application; Figure 8 This is the second flowchart illustrating the method for detecting open circuits in the secondary current transformer of a reactive power compensation system in this application embodiment. Figure 9 This is one of the flowcharts illustrating the method for detecting open circuits in the primary transformer of a reactive power compensation system in this application embodiment; Figure 10 This is the second flowchart illustrating the method for detecting open circuits in the primary transformer of a reactive power compensation system in this application embodiment. Detailed Implementation

[0017] In this application, "at least one" means one or more, and "more than one" means two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can mean: A alone, A and B simultaneously, or B alone. A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, or c alone can mean: a alone, b alone, c alone, a combination of a and b, a combination of a and c, a combination of b and c, or a, b, and c. a, b, and c can be single or multiple. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0018] The terms “center,” “longitudinal,” “lateral,” “up,” “down,” “left,” “right,” “front,” and “rear,” etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0019] The terms "connected" and "connected" should be interpreted broadly. For example, in circuit structures, "connected" or "connected" can refer not only to physical connections but also to electrical or signal connections. This could be a direct connection (physical connection) or an indirect connection via at least one intermediate component, as long as the circuit is connected. It could also refer to the internal connection between two components. Similarly, a signal connection can refer to a connection via a circuit or a medium, such as radio waves. Those skilled in the art will understand the specific meaning of these terms in this application based on the specific circumstances.

[0020] A reactive power compensation system (VCS) is a control system that improves voltage stability by coordinating and controlling reactive power compensation devices to regulate reactive power voltage in a regional power grid. During the operation of a VCS, the reactive power compensation control equipment needs to collect grid voltage and current signals to calculate the current reactive power of the grid. Based on this, it calculates the reactive power capacity that needs compensation and then formulates a switching strategy to execute capacitor switching actions.

[0021] Figure 1 A schematic diagram of the reactive power compensation system provided in an embodiment of this application is shown. This reactive power compensation system can be applied to a power grid. Hereinafter, the power grid requiring reactive power compensation will be referred to as the power grid. The power grid can be, for example, as shown below. Figure 1 The three-phase three-wire power grid shown is Figure 1 The example provided is a three-phase, three-wire power grid, but this does not constitute a limitation of this application. (See also...) Figure 1 As shown, the reactive power compensation system may include a primary current transformer 11, a secondary current transformer 12, at least one capacitor, and a reactive power compensation control device 13. The primary current transformer 11 is connected to the busbar of the power grid. The secondary current transformer 12 is connected between the output terminal of the primary current transformer 11 and the current transformer input terminal of the reactive power compensation control device 13. Each of the at least one capacitor is connected to the power grid, and the reactive power compensation control device 13 is connected to at least one capacitor. UA, UB, and UC represent the three phases of the power grid. The current transformer input terminal of the reactive power compensation control device 13 may include a positive current transformer input terminal IB+ and a negative current transformer input terminal IB-.

[0022] Capacitors, also known as capacitor banks, smart capacitors, etc., can be configured in practical applications based on the actual site conditions. For example, in... Figure 1 In this context, at least one capacitor includes capacitor 1, capacitor 2, ..., capacitor N, for a total of N capacitors (N is an integer greater than or equal to 1). It is understandable that... Figure 1The examples provided are merely illustrative and do not constitute a limitation on the number of at least one capacitor in this disclosure. Each of the at least one capacitor is connected to the power grid, and the reactive power compensation control device 13 is connected to each of the at least one capacitor. The reactive power compensation control device 13 can connect or disconnect the capacitor from the power grid by controlling a relay inside the capacitor. Figure 1 The example illustrates that: the reactive power compensation control device 13 is connected to the first port RJ45_A of the first capacitor via a serial interface (COM port), the second port RJ45_B of the first capacitor is connected to the first port RJ45_A of the second capacitor, ... The second port RJ45_B of the capacitor is connected to the first port RJ45_A of the Nth capacitor. It can be understood that, for ease of field wiring, the first port RJ45_A and the second port RJ45_B of each capacitor can be shorted, thus allowing the reactive power compensation control device 13 to be connected to each capacitor respectively. Figure 1 The wiring method of the reactive power compensation control device 13 with at least one capacitor is only an example and does not constitute a limitation of this application.

[0023] Reference Figure 1 As shown, in an industrial power distribution network, the downstream of the reactive power compensation system consists of factory load equipment and photovoltaic grid-connected equipment. The reactive power compensation control device 13 measures the voltage and current signals of the power grid to calculate parameters such as the effective value of the grid voltage, the effective value of the current, reactive power, active power, and power factor. Based on at least one parameter from these calculations, a reactive power compensation strategy is formed to control the switching operation of capacitors, thereby achieving the purpose of reactive power compensation for the power grid. However, if the current transformer circuit of the reactive power compensation system malfunctions, i.e., a disconnection occurs, the reactive power compensation control device 13 will be unable to calculate the corresponding power signal value, resulting in a state where reactive power cannot be detected. Consequently, it will be unable to control the switching of capacitors, i.e., it will be unable to effectively compensate for the reactive power of the power grid. In a four-quadrant compensation system with a photovoltaic power grid, if the photovoltaic active power is equivalent to the active power used, and multiple capacitors in the reactive power compensation system are already connected to the grid, a disconnection of the current transformer during reactive power compensation will prevent the timely disconnection of the compensation capacitors, leading to the danger of overcompensation of the power grid. Therefore, if a current transformer disconnects, the reactive power compensation system may fail to compensate or overcompensate, which can cause significant damage to the power grid. Thus, how to detect disconnections in current transformers is crucial and is a pressing technical problem that needs to be solved.

[0024] Based on this, this application provides a method for detecting open circuits in a current transformer applied to a reactive power compensation control device 13. Combined with... Figure 1As shown, the reactive power compensation control device 13 can detect a disconnection in the secondary transformer 12 of the reactive power compensation system when the grid current is detected to be less than a preset current threshold for a duration greater than a preset time. If the secondary transformer 12 is not detected to be disconnected, it continues to detect a disconnection in the primary transformer 11 of the reactive power compensation system. An alarm is triggered when either the secondary transformer 12 or the primary transformer 11 is disconnected. By detecting a disconnection in the transformers and triggering an alarm when a transformer is disconnected, timely appropriate action can be taken, avoiding problems of non-compensation or overcompensation caused by transformer disconnection, thus improving the operational reliability of the reactive power compensation system.

[0025] The following is combined Figures 2-10 The present application provides a detailed description of the current transformer open circuit detection method. This current transformer open circuit detection method can be applied to, for example... Figure 1 The reactive power compensation control device 13 shown in the reactive power compensation system can be a microcontroller with data processing capabilities or a device containing a processor.

[0026] Figure 2 This paper illustrates a flowchart of the current transformer open circuit detection method provided in an embodiment of this application. (Refer to...) Figure 2 As shown, the current transformer open circuit detection method may include the following steps 210-240.

[0027] Step 210: If the grid current is detected to be less than the preset current threshold and the duration is greater than the preset duration, perform a disconnection detection on the secondary transformer of the reactive power compensation system.

[0028] The preset current threshold is a pre-set current reference value used to determine whether the grid current is at a low level. The preset duration is a pre-set time length used to determine whether the state of the grid current being lower than the preset current threshold has lasted for a period of time.

[0029] If the grid current is less than the preset current threshold and the duration is greater than the preset time, the grid current detected by the reactive power compensation control device 13 can be considered to be in a low current state. At this time, the transformer disconnection detection logic is entered to determine whether the entire transformer circuit is disconnected. Specifically, the secondary transformers of the reactive power compensation system are first disconnected to determine whether they are in a disconnected state. If the secondary transformer is not detected to be in a disconnected state, step 220 is executed; if the secondary transformer is detected to be in a disconnected state, step 230 is executed.

[0030] For example, a secondary current transformer detection circuit can be used to detect whether a secondary current transformer is disconnected. This detection circuit may include a detection signal input terminal, a bias signal input terminal, a sampling resistor, a pull-up resistor, a bias resistor, and a differential operational amplifier circuit. The positive differential input terminal of the differential operational amplifier circuit is connected to the first output terminal of the secondary current transformer, and the negative differential input terminal is connected to the second output terminal. The pull-up resistor is connected between the positive differential input terminal and the detection signal input terminal. The sampling resistor is connected between the positive and negative differential input terminals. The bias signal input terminal is used to input a target bias voltage into the signal path where the positive differential input terminal of the differential operational amplifier circuit is located, through the bias resistor.

[0031] Specifically, a high-level signal and a low-level signal can be input to the detection signal input terminal of the secondary transformer detection circuit, respectively. The difference between the DC components of the output signal of the secondary transformer detection circuit after inputting the high-level signal and the low-level signal is greater than a preset threshold to determine whether the secondary transformer is disconnected.

[0032] Step 220: Perform a wire breakage detection on the primary transformer of the reactive power compensation system.

[0033] If the secondary current transformer is not detected to be in a disconnected state, continue to detect the disconnection of the primary current transformer in the reactive power compensation system. If the primary current transformer is also not in a disconnected state, proceed to step 240; if the primary current transformer is in a disconnected state, proceed to step 230.

[0034] For example, whether the primary transformer is disconnected can be determined by whether the effective value of the grid current changes after the capacitor of the reactive power compensation system is connected or disconnected.

[0035] Step 230: Activate the alarm.

[0036] An alarm is triggered when either the secondary or primary current transformer is disconnected. For example, an alarm message can be output, which may include at least one of the following: visual information, audible information, or graphical interface prompts. This ensures timely alerts when the primary and / or secondary current transformers are disconnected, prompting staff to address the fault promptly and ensuring the normal operation of the reactive power compensation system.

[0037] For example, the type of alarm message corresponding to the primary current transformer can be the same as or different from the type of alarm message corresponding to the secondary current transformer.

[0038] For example, the alarm message may also include transformer identification information to distinguish between primary and secondary transformers, such as setting different alarm sounds, setting different light signals, and outputting the transformer name. This allows the system to pinpoint which transformer is in a disconnected state.

[0039] Step 240: Reset the timer.

[0040] If the current transformer is not detected to be disconnected, the reactive power compensation control device 13 can clear the timing information used to time the duration when the grid current is less than the preset current threshold, and then re-perform the grid current detection and cumulative calculation of the duration when the grid current is less than the preset current threshold in step 210.

[0041] The transformer disconnection detection method provided in this application detects a disconnection in the secondary transformer of the reactive power compensation system when the reactive power compensation control equipment detects that the grid current is less than a preset current threshold for a duration greater than a preset time. If the secondary transformer is not detected to be disconnected, the primary transformer of the reactive power compensation system is also detected to be disconnected. An alarm is triggered if either the secondary or primary transformer is disconnected. In this way, when a low current condition occurs, the reactive power compensation control equipment initiates transformer disconnection detection, detecting both the secondary and primary transformer circuits. This achieves transformer disconnection detection and triggers an alarm upon detection, allowing for appropriate handling and avoiding problems of non-compensation or overcompensation caused by transformer disconnection. Furthermore, by performing graded detection on both the secondary and primary transformers, it is easier to locate the disconnected transformer, making the fault diagnosis more precise, and it avoids the influence of grid reactive power fluctuations during secondary transformer disconnection detection.

[0042] based on Figure 2 In one embodiment of the current transformer open circuit detection method corresponding to the embodiments, Figure 3 This illustration shows one of the flowcharts of a method for detecting open circuits in a secondary current transformer of a reactive power compensation system according to an embodiment of this application. (Refer to...) Figure 3 As shown, detecting open circuits in the secondary transformers of a reactive power compensation system may include the following steps 211-217.

[0043] Step 211: Input a high-level signal and a low-level signal to the detection signal input terminal of the secondary transformer detection circuit respectively.

[0044] The secondary current transformer detection circuit is used to detect whether the secondary current transformer is disconnected. Figure 4 This paper shows one of the structural schematic diagrams of a secondary transformer detection circuit provided in an embodiment of this application. (Refer to...) Figure 4As shown, the secondary transformer detection circuit may include a detection signal input terminal DOUT_IN, a bias signal input terminal VREF_IN, a sampling resistor R1, a pull-up resistor R2, a bias resistor R7, and a differential operational amplifier circuit 40. The positive differential input terminal V+ of the differential operational amplifier circuit 40 is connected to the first output terminal of the secondary transformer 12, and the negative differential input terminal V- of the differential operational amplifier circuit 40 is connected to the second output terminal of the secondary transformer 12. The pull-up resistor R2 is connected between the positive differential input terminal V+ and the detection signal input terminal DOUT_IN of the differential operational amplifier circuit 40. The sampling resistor R1 is connected between the positive differential input terminal V+ and the negative differential input terminal V-. The bias signal input terminal VREF_IN is used to input the target bias voltage to the signal path where the positive differential input terminal V+ of the differential operational amplifier circuit 40 is located through the bias resistor R7.

[0045] The differential operational amplifier circuit 40 can acquire the current information of the secondary transformer 12 through the sampling resistor R1. The secondary transformer 12 outputs AC power. The negative voltage of the AC power can be boosted to a voltage greater than 0 by the target bias voltage input through the bias signal input terminal VREF_IN. That is, the differential signal output by the signal output terminal IB_IN of the differential operational amplifier circuit 40 is a signal greater than 0, which facilitates the acquisition of data by the subsequent reactive power compensation control equipment.

[0046] according to Figure 4 The secondary transformer detection circuit shown can use sampling resistor R1 to obtain the signals from the two output terminals of the secondary transformer 12 and input them to the two differential input terminals of the differential operational amplifier circuit 40 respectively. The detection signal input terminal DOUT_IN can be connected to the general purpose input / output (GPIO) port of the reactive power compensation control device, through which a high-level signal and a low-level signal are input to the detection signal input terminal DOUT_IN respectively. When a high-level signal and a low-level signal are input to the circuit through the detection signal input terminal DOUT_IN respectively, if the secondary transformer 12 is in an open-circuit state, the differential signal output from the signal output terminal IB_IN of the differential operational amplifier circuit 40 will be changed by the high-level signal and the low-level signal, and the difference in the DC component of the differential signal corresponding to the high-level signal and the low-level signal will be large; otherwise, the difference is small. Therefore, it can be determined whether the secondary transformer 12 is in an open-circuit state by inputting a high-level signal and a low-level signal to the detection signal input terminal DOUT_IN respectively, and by detecting whether there is a significant difference in the DC component of the differential signal output from the signal output terminal IB_IN of the differential operational amplifier circuit 40. Specifically, please refer to steps 212-217 below.

[0047] based on Figure 4 In one embodiment, Figure 5This is a second schematic diagram of the secondary transformer detection circuit provided in an embodiment of this application, with reference to... Figure 5 As shown, in Figure 4 Based on this, the secondary transformer detection circuit may also include a bias voltage generation circuit 50.

[0048] The reference terminal VREF of the bias voltage generation circuit 50 is used to input the reference voltage, and the output terminal of the bias voltage generation circuit 50 is connected to the bias signal input terminal VREF_IN.

[0049] The bias voltage generation circuit 50 is used to generate a target bias voltage based on the reference voltage input at the reference terminal VREF. This target bias voltage can be input to the signal path of the positive differential input terminal V+ of the differential operational amplifier circuit 40 through the bias resistor R7, so as to boost the negative voltage of the AC power output from the secondary transformer 12 to a voltage greater than 0.

[0050] For example, the target bias voltage generated by the bias voltage generation circuit 50 can be 0.5 times the reference voltage input at the reference terminal VREF.

[0051] For example, Figure 6 A schematic diagram of the bias voltage generating circuit 50 provided in an embodiment of this application is shown. (Refer to...) Figure 6 As shown, the bias voltage generation circuit 50 may include a reference terminal VREF, a second operational amplifier A2, a tenth resistor R10, an eleventh resistor R11, a third capacitor C3, and a fourth capacitor C4. The tenth resistor R10 is connected between the reference terminal VREF and the positive input terminal of the second operational amplifier A2. The eleventh resistor R11 and the third capacitor C3 are connected in parallel between the positive input terminal of the second operational amplifier A2 and ground GND. The negative input terminal of the second operational amplifier A2 is connected to the output terminal of the second operational amplifier A2. The output terminal of the second operational amplifier A2 serves as the output terminal of the bias voltage generation circuit 50 and is connected to the bias signal input terminal VREF_IN, and is also connected to ground GND through the fourth capacitor C4.

[0052] exist Figure 6 In the bias voltage generating circuit 50 shown, for example, the tenth resistor R10 and the eleventh resistor R11 can be selected to have the same resistance value.

[0053] For example, the second operational amplifier A2 can be an operational amplifier of model TLV9004.

[0054] For example, the reference voltage at the reference terminal VREF can be 3V.

[0055] according to Figure 6The bias voltage generation circuit 50 shown can be used in practical applications with an external power supply voltage of 3.3V. The reference voltage input at the reference terminal VREF is divided by the tenth resistor R10 and the eleventh resistor R11 and then input to the positive input terminal of the second operational amplifier A2. After being amplified by the second operational amplifier A2, a voltage signal of 0.5 times the reference voltage can be generated to obtain the target bias voltage.

[0056] based on Figure 4 In one embodiment, Figure 7 This is shown as the third schematic diagram of the secondary transformer detection circuit provided in the embodiment of this application, with reference to... Figure 7 As shown, the secondary transformer detection circuit may include a detection signal input terminal DOUT_IN, a bias signal input terminal VREF_IN, a sampling resistor R1, a pull-up resistor R2, a bias resistor R7, and a differential operational amplifier circuit 40. The positive differential input terminal V+ of the differential operational amplifier circuit 40 is connected to the first output terminal of the secondary transformer 12, and the negative differential input terminal V- of the differential operational amplifier circuit 40 is connected to the second output terminal of the secondary transformer 12. The pull-up resistor R2 is connected between the positive differential input terminal V+ and the detection signal input terminal DOUT_IN of the differential operational amplifier circuit 40, and the sampling resistor R1 is connected between the positive differential input terminal V+ and the negative differential input terminal V-.

[0057] The differential operational amplifier circuit 40 includes a positive differential input terminal V+, a negative differential input terminal V-, a first operational amplifier A1, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, an eighth resistor R8, a ninth resistor R9, a first capacitor C1, and a second capacitor C2. The third resistor R3 and the fifth resistor R5 are connected in series between the negative differential input terminal V- and the negative input terminal of the first operational amplifier A1. The fourth resistor R4 and the sixth resistor R6 are connected in series between the positive differential input terminal V+ and the positive input terminal of the first operational amplifier A1. The series connection of the fifth resistor R5 is connected to ground GND through the first capacitor C1; the series connection of the fourth resistor R4 and the sixth resistor R6 is connected to ground GND through the second capacitor C2; the eighth resistor R8 is connected between the negative input terminal and the output terminal of the first operational amplifier A1; the output terminal of the first operational amplifier A1 is connected to the signal output terminal IB_IN of the differential operational amplifier circuit 40 through the ninth resistor R9; one end of the bias resistor R7 is connected to the bias signal input terminal VREF_IN, and the other end is connected to the positive input terminal of the first operational amplifier A1.

[0058] according to Figure 7The secondary transformer detection circuit shown includes a differential filter circuit for the differential operational amplifier circuit 40, consisting of the third resistor R3, the first capacitor C1, the fourth resistor R4, and the second capacitor C2. This circuit filters the differential signal input to the differential operational amplifier circuit 40. The target bias voltage input at the bias signal input terminal VREF_IN can boost the signal output from the differential operational amplifier circuit 40, i.e., increase the target bias voltage. This boosts the negative AC voltage output from the secondary transformer 12 to a voltage greater than 0, facilitating data acquisition by subsequent reactive power compensation control equipment.

[0059] For example, the secondary transformer detection circuit may also include a fifth capacitor C5, which is connected between the signal output terminal IB_IN of the differential operational amplifier circuit 40 and ground GND. The fifth capacitor C5 and the ninth resistor R9 can form a filter circuit, which can filter the signal output from the signal output terminal IB_IN of the differential operational amplifier circuit 40 and improve the signal quality.

[0060] Step 212: Obtain the DC component of the output signal of the secondary transformer detection circuit when a high-level signal is input to the detection signal input terminal, and obtain the first DC quantity.

[0061] based on Figures 4-7 In any embodiment of the secondary transformer detection circuit, a high-level signal can be input to the detection signal input terminal DOUT_IN of the secondary transformer detection circuit. At this time, the DC component of the signal output terminal IB_IN of the differential operational amplifier circuit 40 is obtained, that is, the DC component of the output terminal signal of the secondary transformer detection circuit is obtained, and the first DC current can be obtained.

[0062] For example, the signal output from the signal output terminal IB_IN of the differential operational amplifier circuit 40 can be sampled, and the sampled data can be calculated using a Fast Fourier Transform (FFT) to obtain the DC component.

[0063] Step 213: Obtain the DC component of the output signal of the secondary transformer detection circuit when a low-level signal is input to the detection signal input terminal, and obtain the second DC component.

[0064] based on Figures 4-7 In any embodiment of the secondary transformer detection circuit, a low-level signal can be input to the detection signal input terminal DOUT_IN of the secondary transformer detection circuit. At this time, the DC component of the signal output terminal IB_IN of the differential operational amplifier circuit 40 is obtained, that is, the DC component of the output terminal signal of the secondary transformer detection circuit is obtained, and the second DC component can be obtained.

[0065] Step 214: Determine the difference between the first and second DC quantities.

[0066] After obtaining the first DC flow rate and the second DC component, the difference between the first DC flow rate and the second DC flow rate can be calculated to obtain the DC flow rate difference between the two.

[0067] Step 215: Determine whether the difference in direct current is greater than the preset threshold.

[0068] After obtaining the DC flow difference between the first DC flow rate and the second DC flow rate, the DC flow difference is compared with a preset threshold. If the DC flow difference is greater than the preset threshold, step 216 is executed; otherwise, step 217 is executed.

[0069] Step 216: Determine that the secondary current transformer is in an open circuit state.

[0070] If the difference between the current and voltage values ​​exceeds a preset threshold, it can be determined that the secondary current transformer is in a disconnected state, and an alarm can be triggered at this time.

[0071] Step 217: Confirm that the secondary current transformer is not in a disconnected state.

[0072] If the difference between the current and voltage values ​​is less than or equal to a preset threshold, it can be determined that the secondary current transformer is not in a disconnected state and can work normally.

[0073] In this way, by inputting high-level and low-level signals to the detection signal input terminal of the secondary transformer detection circuit, and by detecting whether the difference between the DC components of the output signal of the secondary transformer detection circuit after inputting the high-level and low-level signals is greater than a preset threshold, it can be determined whether the secondary transformer is disconnected. Thus, the secondary transformer detection circuit can be used to realize the disconnection detection of the secondary transformer.

[0074] based on Figure 3 The corresponding embodiment of the open circuit detection method for secondary current transformers, combined with Figures 4-7 The secondary transformer detection circuit of any embodiment, Figure 8 This illustrates the second flowchart of a method for detecting open circuits in the secondary current transformers of a reactive power compensation system, as shown in this embodiment of the application. Figure 8 As shown, detecting open circuits in the secondary transformers of a reactive power compensation system may include the following steps 801-811.

[0075] Step 801: Set the GPIO port connected to the detection signal input terminal DOUT_IN as an output GPIO port.

[0076] The GPIO port connecting the reactive power compensation control device to the detection signal input terminal DOUT_IN can be configured as an output GPIO port or a floating input GPIO port, i.e., a high-impedance state. When performing open-circuit detection on the secondary transformer, this GPIO port can be initially configured as an output GPIO port.

[0077] Step 802: Input a high-level signal to the detection signal input terminal DOUT_IN.

[0078] The reactive power compensation control device can input a high-level signal to the detection signal input terminal DOUT_IN through the output type GPIO port.

[0079] Step 803: Obtain the DC component of the output signal of the secondary transformer detection circuit to obtain the first DC flow rate.

[0080] After inputting a high-level signal to the detection signal input terminal DOUT_IN, the reactive power compensation control device samples the output signal of the secondary transformer detection circuit, and then performs FFT calculation on the sampled data to obtain the DC component of the output signal of the secondary transformer detection circuit, which can be denoted as the first DC component A.

[0081] For example, after inputting a high-level signal to the detection signal input terminal DOUT_IN, the reactive power compensation control device can collect 128 sampling points of the output signal of the secondary transformer detection circuit within 20 milliseconds, obtain 128 sampling point data, and then perform FFT calculation on the 128 sampling point data to obtain the first DC flow A.

[0082] Step 804: Input a low-level signal to the detection signal input terminal DOUT_IN.

[0083] The reactive power compensation control device can continue to input a low-level signal to the detection signal input terminal DOUT_IN through the output type GPIO port.

[0084] Step 805: Obtain the DC component of the output signal of the secondary transformer detection circuit to obtain the second DC component.

[0085] After the reactive power compensation control device inputs a low-level signal to the detection signal input terminal DOUT_IN, it can sample the output signal of the secondary transformer detection circuit, and then perform FFT calculation on the sampled data to obtain the DC component of the output signal of the secondary transformer detection circuit, which can be denoted as the second DC component B.

[0086] For example, after inputting a low-level signal to the detection signal input terminal DOUT_IN, the reactive power compensation control device can collect 128 sampling points of the output signal of the secondary transformer detection circuit within 20 milliseconds, obtain 128 sampling point data, and then perform FFT calculation on the 128 sampling point data to obtain the second DC quantity B.

[0087] Step 806: Set the GPIO port connected to the detection signal input terminal DOUT_IN to a high-impedance state.

[0088] After obtaining the first DC flow A and the second DC flow B, the reactive power compensation control device can set the GPIO port to a high-impedance state, that is, a floating input type GPIO port.

[0089] Step 807: Determine the difference between the first and second DC flow rates.

[0090] Step 808: Determine whether the difference in DC flow rate is greater than the preset threshold.

[0091] After obtaining the DC difference between the first and second DC quantities, the reactive power compensation control device compares this DC difference with a preset threshold. If the DC difference is greater than the preset threshold, step 809 is executed; otherwise, step 811 is executed.

[0092] Step 809: Determine that the secondary current transformer is in an open circuit state.

[0093] If the difference between the DC current and the DC current is found to be greater than the preset threshold, it means that the high-level and low-level signals input to the DOUT_IN terminal of the detection signal will change the external signal input to the secondary transformer detection circuit. Therefore, it can be determined that the secondary transformer is abnormal and is in a disconnected state.

[0094] Step 810: Activate the alarm.

[0095] If it is determined that the secondary transformer is in a disconnected state, the reactive power compensation control equipment can activate an alarm and output an alarm message to remind staff to handle the fault in a timely manner and ensure the normal operation of the reactive power compensation system.

[0096] Step 811: Confirm that the secondary current transformer is not in a disconnected state.

[0097] If the DC difference is determined to be less than or equal to the preset threshold, it means that the high-level and low-level signals input to the detection signal input terminal DOUT_IN will not interfere with the signal input from the secondary transformer to the secondary transformer detection circuit. The DC value of the signal is locked on the reference level signal, which indicates that the secondary transformer is not in a disconnected state and can work normally.

[0098] For example, when the secondary current transformer is not in a disconnected state, the GPIO port can be configured as a floating input GPIO port to restore the normal signal acquisition state.

[0099] In this way, by inputting high-level and low-level signals to the detection signal input terminal of the secondary transformer detection circuit, and by detecting whether the difference between the DC components of the output signal of the secondary transformer detection circuit after inputting the high-level and low-level signals is greater than a preset threshold, it can be determined whether the secondary transformer is disconnected. Thus, the secondary transformer detection circuit can be used to realize the disconnection detection of the secondary transformer.

[0100] based on Figure 2 In one embodiment of the current transformer open circuit detection method corresponding to the embodiments, Figure 9 This document illustrates one of the flowcharts for a method of detecting open circuits in a primary transformer of a reactive power compensation system, as shown in this embodiment of the application. Figure 9 As shown, detecting a broken wire in the primary transformer of a reactive power compensation system may include the following steps 910-950.

[0101] Step 910: Determine the target capacitor adjustment amount.

[0102] When performing open circuit detection on the primary transformer of the reactive power compensation system, the reactive power compensation control equipment can first determine the target capacitance adjustment amount for adjusting the capacitance of the capacitor in the reactive power compensation system.

[0103] For example, the reactive power compensation control device can determine the required target capacitor regulation amount by setting a preset adjustment amount; or it can determine the required target capacitor regulation amount according to preset rules, such as determining the required target capacitor regulation amount based on a preset rate of change that can bring to the grid current.

[0104] In one embodiment, determining the target capacitance adjustment amount may include: determining the input current of the primary transformer based on the ratio of the primary transformer and the secondary transformer and the current of the secondary transformer; and determining the target capacitance adjustment amount based on the input voltage of the primary transformer, the input current of the primary transformer, and a preset rate of change.

[0105] The transformation ratio between the primary and secondary current transformers can be set according to actual needs. The preset rate of change can be set based on experience or requirements, for example, it can be set to at least 3%.

[0106] For example, determining the input current of the primary transformer based on the transformation ratio of the primary and secondary transformers and the current of the secondary transformer can include: determining the input current of the primary transformer by multiplying the transformation ratio of the primary and secondary transformers and the current of the secondary transformer. This process can be expressed as the following formula (1): (1) Where In represents the input current of the primary transformer, M represents the transformation ratio of the primary transformer and the secondary transformer, and I2 represents the current of the secondary transformer.

[0107] For example, determining the target capacitance adjustment amount based on the input voltage of the primary transformer, the input current of the primary transformer, and a preset rate of change may include: determining an initial capacitance adjustment amount based on the input voltage and the input current of the primary transformer; and determining the target capacitance adjustment amount by multiplying the initial capacitance adjustment amount by the preset rate of change.

[0108] Specifically, based on the input voltage Un and input current In of the primary transformer, the initial capacitance adjustment Q0 can be determined using the following formula (2): (2) For example, assuming the user sets the transformation ratio M of the primary and secondary transformers to be 200, the determined input current In of the primary transformer is 1000A, the input voltage (i.e., the three-phase voltage) Un of the primary transformer is 400V, and the preset change rate is 3%, then the target capacitance adjustment amount can be determined by combining the above formula (2). The capacitance is 20.784 kvar. Therefore, the capacitance to be added or removed must be greater than or equal to 20.784 kvar.

[0109] Step 920: Adjust the capacitors of the reactive power compensation system based on the target capacitance adjustment amount.

[0110] Once the target capacitance adjustment amount is determined, the capacitance of the capacitor in the reactive power compensation system can be cut off or connected to the target capacitance adjustment amount to achieve capacitor adjustment.

[0111] Specifically, in one embodiment, adjusting the capacitors of the reactive power compensation system based on the target capacitance adjustment amount may include: detecting whether there are capacitors online in the power grid; if there are capacitors online in the power grid, removing the capacitor corresponding to the target capacitance adjustment amount from the online capacitors; and if there are no capacitors online in the power grid, connecting the capacitor corresponding to the target capacitance adjustment amount to the power grid.

[0112] It is understandable that one or more capacitors can be connected or disconnected, and the capacitance must be greater than or equal to the target capacitance adjustment.

[0113] Step 930: Determine whether the effective value of the grid current changes after adjusting the capacitor.

[0114] After adjusting the disconnection or connection of capacitors in the reactive power compensation system according to the target capacitance adjustment, it can be determined whether the effective value of the grid current changes before and after the adjustment. If it changes, proceed to step 940; if it does not change, proceed to step 950.

[0115] Step 940: Confirm that the primary transformer is not in a disconnected state.

[0116] If the effective value of the grid current changes before and after the adjustment, it indicates that the change in capacitance has affected the primary transformer. In this case, it can be determined that the primary transformer is normal and not in a disconnected state.

[0117] Step 950: Determine that the primary transformer is in an open-circuit state.

[0118] If the effective value of the grid current does not change before and after the adjustment, it means that the change in capacitance has no effect on the primary transformer. In this case, it can be determined that the primary transformer is in an open circuit state.

[0119] In this way, by adjusting the capacitance of the grid capacitor, the system can detect whether the primary transformer is in a disconnected state based on whether the effective value of the grid current changes before and after the adjustment, thus realizing the disconnection detection of the primary transformer.

[0120] based on Figure 9 The corresponding embodiment of the open circuit detection method for a primary current transformer Figure 10 This illustrates the second flowchart of a method for detecting open circuits in the primary transformer of a reactive power compensation system, as shown in this embodiment of the application. Figure 10 As shown, detecting a broken wire in the primary transformer of a reactive power compensation system may include the following steps 1001-1009.

[0121] Step 1001: Determine the target capacitor adjustment amount.

[0122] The specific method for determining the target capacitor adjustment amount in step 1001 can be referred to step 910 above, and will not be repeated here.

[0123] Step 1002: Check if there are any capacitors online in the power grid.

[0124] The reactive power compensation control equipment can first detect whether there are any capacitors online in the power grid, that is, whether there are any capacitors connected to the power grid. If there are capacitors online in the power grid, proceed to step 1003; otherwise, proceed to step 1004.

[0125] Step 1003: Remove the capacitor corresponding to the target capacitance adjustment from the online capacitors.

[0126] When there are capacitors online in the power grid, the reactive power compensation control equipment can disconnect the capacitor corresponding to the target capacitance adjustment from the online capacitors. That is, the capacitance of the disconnected capacitor is at least the target capacitance adjustment.

[0127] Step 1004: Connect the capacitor corresponding to the target capacitance adjustment amount to the power grid.

[0128] When there are no capacitors online in the power grid, the reactive power compensation control equipment can connect the capacitor corresponding to the target capacitance adjustment amount to the power grid, that is, continue to connect the capacitor with the capacitance corresponding to the target capacitance adjustment amount from the offline capacitors to the power grid.

[0129] Step 1005: Determine whether the effective value of the grid current has changed.

[0130] After executing step 1003 or step 1004, the reactive power compensation control device can determine whether the effective value of the grid current has changed after adjusting the capacitor's capacitance. If it has changed, then execute steps 1006-1007; otherwise, execute steps 1008-1009.

[0131] Step 1006: Confirm that the primary transformer is not in a disconnected state.

[0132] Step 1007: Restore the capacitors of the power grid to their initial state.

[0133] Once it is determined that the primary transformer is not in a disconnected state, i.e., the primary transformer is in a normal working state, by connecting or disconnecting the capacitor, the capacitor connection status of the power grid can be restored to the state before the primary transformer was detected as disconnected.

[0134] Step 1008: Determine that the primary transformer is in an open-circuit state.

[0135] Step 1009: Remove all in-line capacitors.

[0136] If it is determined that the primary transformer is in an open-circuit state, all online capacitors in the power grid can be disconnected and an alarm can be triggered to remind staff to handle the fault in a timely manner and ensure the normal operation of the reactive power compensation system.

[0137] In this way, by adjusting the capacitance of the grid capacitor, the system can detect whether the primary transformer is in a disconnected state based on whether the effective value of the grid current changes before and after the adjustment, thus realizing the disconnection detection of the primary transformer.

[0138] The transformer open circuit detection method provided in this application can, on the one hand, effectively determine whether there is an open circuit in the transformer circuit. If an open circuit is found, the reactive power compensation control equipment can promptly issue an alarm, guiding manual intervention to handle the fault in a timely manner, thus avoiding problems of undercompensation or overcompensation caused by transformer open circuits. On the other hand, by using two-stage transformer detection, the problem points of the transformers are refined, facilitating the troubleshooting and maintenance of system problems. Furthermore, in the case of a secondary transformer open circuit, detection can be performed without switching capacitors, reducing reactive power fluctuations in the system and achieving better reactive power compensation.

[0139] This application also provides a reactive power compensation control device, which may include a memory and a processor. The memory stores a computer program that can run on the processor. When the processor executes the computer program, it can implement the steps of the current transformer disconnection detection method provided in any of the above method embodiments, which will not be repeated here.

[0140] Based on the current transformer disconnection detection method described in any of the above embodiments, this application also provides a computer-readable storage medium. For example, a non-transitory computer-readable storage medium may be a read-only memory (ROM), a random access memory (RAM), a CD-ROM, magnetic tape, a floppy disk, or an optical data storage device, etc. This storage medium stores computer instructions for executing the current transformer disconnection detection method described in any of the above embodiments, which will not be elaborated further here.

[0141] Those skilled in the art will understand that all or part of the steps of the above embodiments can be implemented by hardware, or by a program instructing related hardware to implement them. The program can be stored in a computer-readable storage medium, such as a read-only memory, a disk, or an optical disk.

[0142] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the disclosure herein. This application is intended to cover any variations, uses, or adaptations thereof that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this application are indicated by the claims.

Claims

1. A method for detecting open circuit in a current transformer, characterized in that, The reactive power compensation control equipment applied to reactive power compensation systems includes a current transformer open circuit detection method comprising: If the grid current is detected to be less than the preset current threshold and the duration is greater than the preset duration, the secondary transformer of the reactive power compensation system is disconnected. If the secondary current transformer is not found to be disconnected, the primary current transformer of the reactive power compensation system is tested for disconnection. An alarm is triggered if either the secondary current transformer or the primary current transformer is disconnected. The primary current transformer is connected to the busbar of the power grid, and the secondary current transformer is connected between the output terminal of the primary current transformer and the current transformer input terminal of the reactive power compensation control device.

2. The method for detecting open circuits in a current transformer according to claim 1, characterized in that, The step of detecting open circuits in the secondary current transformers of the reactive power compensation system includes: Input a high-level signal and a low-level signal to the detection signal input terminal of the secondary transformer detection circuit, respectively; When the high-level signal is input to the detection signal input terminal, the DC component of the output signal of the secondary transformer detection circuit is obtained to obtain the first DC quantity; When the low-level signal is input to the detection signal input terminal, the DC component of the output signal of the secondary transformer detection circuit is obtained to obtain the second DC component. Determine the difference in DC flow rate between the first DC flow rate and the second DC flow rate; If the DC-DC difference is greater than a preset threshold, the secondary current transformer is determined to be in a disconnected state; if the DC-DC difference is less than or equal to the preset threshold, the secondary current transformer is determined to be not in a disconnected state. The secondary transformer detection circuit includes a detection signal input terminal, a bias signal input terminal, a sampling resistor, a pull-up resistor, a bias resistor, and a differential operational amplifier circuit. The positive differential input terminal of the differential operational amplifier circuit is connected to the first output terminal of the secondary transformer, and the negative differential input terminal of the differential operational amplifier circuit is connected to the second output terminal of the secondary transformer. The pull-up resistor is connected between the positive differential input terminal and the detection signal input terminal. The sampling resistor is connected between the positive differential input terminal and the negative differential input terminal. The bias signal input terminal is used to input a target bias voltage to the signal path where the positive differential input terminal of the differential operational amplifier circuit is located through the bias resistor.

3. The method for detecting open circuits in a current transformer according to claim 2, characterized in that, The differential operational amplifier circuit includes a positive differential input terminal, a negative differential input terminal, a first operational amplifier, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, an eighth resistor, a ninth resistor, a first capacitor, and a second capacitor. The third and fifth resistors are connected in series between the negative differential input terminal and the negative input terminal of the first operational amplifier; the fourth and sixth resistors are connected in series between the positive differential input terminal and the positive input terminal of the first operational amplifier; the series junction of the third and fifth resistors is connected to ground through the first capacitor; the series junction of the fourth and sixth resistors is connected to ground through the second capacitor; the eighth resistor is connected between the negative input terminal and the output terminal of the first operational amplifier; the output terminal of the first operational amplifier is connected to the signal output terminal of the differential operational amplifier circuit through the ninth resistor. One end of the bias resistor is connected to the bias signal input terminal, and the other end is connected to the positive input terminal of the first operational amplifier.

4. The method for detecting open circuits in a current transformer according to claim 2, characterized in that, The secondary transformer detection circuit also includes a bias voltage generation circuit. The reference terminal of the bias voltage generating circuit is used to input a reference voltage, and the output terminal of the bias voltage generating circuit is connected to the bias signal input terminal. The bias voltage generating circuit is used to generate the target bias voltage based on the reference voltage.

5. The current transformer open circuit detection method according to claim 4, characterized in that, The bias voltage generating circuit includes the reference terminal, the second operational amplifier, the tenth resistor, the eleventh resistor, the third capacitor, and the fourth capacitor; The tenth resistor is connected between the reference terminal and the positive input terminal of the second operational amplifier; the eleventh resistor and the third capacitor are connected in parallel between the positive input terminal of the second operational amplifier and ground; the negative input terminal of the second operational amplifier is connected to the output terminal of the second operational amplifier; the output terminal of the second operational amplifier serves as the output terminal of the bias voltage generation circuit and is connected to the bias signal input terminal, and is connected to ground through the fourth capacitor.

6. The method for detecting open circuit in a current transformer according to any one of claims 1 to 5, characterized in that, The step of detecting a disconnection in the primary transformer of the reactive power compensation system includes: Determine the target capacitor adjustment amount; The capacitors of the reactive power compensation system are adjusted based on the target capacitance adjustment amount. Determine whether the effective value of the grid current changes after adjusting the capacitor; Under the circumstances of change, it is determined that the primary current transformer is not in a disconnected state; If no changes occur, it is determined that the primary transformer is in a disconnected state.

7. The method for detecting open circuit in a current transformer according to claim 6, characterized in that, Determining the target capacitance adjustment amount includes: The input current of the primary transformer is determined based on the transformation ratio of the primary transformer and the secondary transformer and the current of the secondary transformer; The target capacitance adjustment amount is determined based on the input voltage of the primary transformer, the input current of the primary transformer, and the preset rate of change.

8. The method for detecting open circuit in a current transformer according to claim 6, characterized in that, The adjustment of the capacitor of the reactive power compensation system based on the target capacitance adjustment amount includes: Check if there are any capacitors online in the power grid; When there are capacitors online in the power grid, the capacitor corresponding to the target capacitance adjustment amount is disconnected from the online capacitors; When there are no capacitors online in the power grid, a capacitor corresponding to the target capacitance adjustment amount is connected to the power grid.

9. A reactive power compensation control device, comprising a memory and a processor, wherein the memory stores a computer program executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the current transformer disconnection detection method as described in any one of claims 1 to 8.

10. A reactive power compensation system, characterized in that, It includes a primary current transformer, a secondary current transformer, at least one capacitor, and the reactive power compensation control device as described in claim 9; The primary current transformer is connected to the bus of the power grid, the secondary current transformer is connected between the output terminal of the primary current transformer and the current transformer input terminal of the reactive power compensation control device, each of the at least one capacitor is connected to the power grid, and the reactive power compensation control device is connected to the at least one capacitor.

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