A Power Grid Change Sensor in Dynamic Reactive Power Compensation

Abstract

The utility model relates to the technical field of reactive power compensation, and discloses a power grid change sensor in dynamic reactive power compensation, including a reactive power compensation controller and a capacitor group, wherein the capacitor adopts a thyristor switching capacitor, and the reactive power compensation controller includes a single chip microcomputer, a voltage measurement conversion module, a current measurement conversion module, an analog-to-digital conversion module, a power factor angle measurement module, a communication interface module, a reset module, a pulse drive circuit and a composite switch, wherein the single chip microcomputer is respectively connected to the analog-to-digital conversion module, the power factor angle measurement module, the communication interface module, the reset module and the pulse drive circuit, wherein the analog-to-digital conversion module is connected to the voltage measurement conversion module and the current measurement conversion module, and the pulse drive circuit is connected to the composite switch. The utility model improves the load power factor in the power system, reduces the equipment capacity, and reduces the power loss, thereby ensuring the stability of the power system and improving the power transmission capacity.

Description

Technical Field

[0001] The utility model relates to the technical field of reactive power compensation, in particular to a power grid change sensor in dynamic reactive power compensation. Background Art

[0002] With the development of power systems, various loads are continuously connected to the power systems. The impact of impact reactive loads on the power grid is becoming more and more serious, which significantly reduces the power quality of the power grid. Reactive power compensation is one of the important means to improve power quality.

[0003] In low-voltage power grids, as the use of inductive loads such as motors gradually increases, the power supply efficiency gradually decreases. In order to improve the power factor of the power grid and improve the quality of the power grid, it is necessary to compensate for the reactive power of the low-voltage power grid. The traditional static reactive power compensation method cannot monitor the quality of the power grid in real time, and cannot dynamically compensate for the reactive power of the low-voltage power grid according to the changes in parameters. The compensation effect cannot achieve the expected goal, and capacitors often burn out. Therefore, it is of great significance to use dynamic reactive power compensation technology to improve the power factor of the power grid and improve the quality of the low-voltage power grid. Utility Model Content

[0004] The utility model provides a power grid change sensor in dynamic reactive power compensation, which improves the load power factor in the power system, reduces the equipment capacity, and reduces the power loss, thereby ensuring the stability of the power system and improving the power transmission capacity.

[0005] The utility model provides a power grid change sensor in dynamic reactive power compensation, comprising a reactive power compensation controller and a capacitor group, wherein the capacitor adopts a thyristor switching capacitor, and the reactive power compensation controller comprises a single chip microcomputer, a voltage measurement conversion module, a current measurement conversion module, an analog-to-digital conversion module, a power factor angle measurement module, a communication interface module, a reset module, a pulse drive circuit and a composite switch, wherein the single chip microcomputer is respectively connected to the analog-to-digital conversion module, the power factor angle measurement module, the communication interface module, the reset module and the pulse drive circuit, the analog-to-digital conversion module is connected to the voltage measurement conversion module and the current measurement conversion module, and the pulse drive circuit is connected to the composite switch;

[0006] The single-chip microcomputer detects reactive power during operation, obtains the grid line voltage, load phase current and power factor measurement circuit through the voltage measurement conversion module, the current measurement conversion module and the power factor angle measurement module, and then calculates reactive power to obtain reactive power shortage. The single-chip microcomputer performs identification and analysis and controls the capacitor bank to issue a switching command output, so that the pulse drive circuit receives the command and then controls the composite switch to realize the switching start / shutdown operation.

[0007] Furthermore, the voltage measurement conversion module includes a voltage transformer, and the current measurement conversion module includes a current transformer; the maximum voltage rating of the current transformer output is 7.07V, and the peak voltage is 10V; the voltage transformer output voltage rating is The peak voltage is

[0008] When measuring current and voltage, reactive power compensation performs coupling operation in the current transformer and the voltage transformer, and then transmits the result to the single chip microcomputer.

[0009] Furthermore, the analog-to-digital conversion module is designed with three ports, namely a chip select terminal, a serial data input terminal, and an input / output clock terminal. The three ports are connected to the microcontroller in a three-wire SPI serial connection mode to achieve communication between various components.

[0010] Furthermore, the power factor value of the power factor angle measurement module is extracted and calculated through a three-phase load, a phase current signal is extracted from one phase, and a line voltage signal is extracted from the other two phases. The angle between the phase current and the line voltage is set to θ. The principle of θ is the angle between the phase current leading the line voltage. The power factor angle measurement module uses the phase difference principle between the phase current and the line voltage.

[0011] Furthermore, the communication interface module realizes communication with the upper machine position, and adopts RS-323 standard interface to transmit interface information of various devices, including serial transmission data terminal equipment and data communication equipment;

[0012] When the host computer sends a command to the single chip microcomputer, the corresponding serial interface of the single chip microcomputer transmits data to the host computer according to the communication protocol requirements, thereby realizing the communication between the controller and the host computer.

[0013] Furthermore, it also includes a display module, the display module is connected to the single chip microcomputer, and the display module is designed into two parts, namely a working status display circuit and a voltage, current and power factor display circuit;

[0014] The working status display circuit controls 8 light-emitting diodes through the ULN2003 display driver to achieve the display requirements. 4 of them are responsible for the system overvoltage display, undervoltage display, power factor leading and lagging display, and the other 4 are responsible for realizing the capacitor bank switching status display. The 8 diodes represent 8 groups of capacitors. When a capacitor executes the switching instruction, the corresponding indicator light will light up.

[0015] The voltage, current and power factor display circuit uses the MAX7219 display driver to control four LED displays. Each display image requires a button to realize screen switching.

[0016] Furthermore, the reset module includes a timer, a serial E2PROM and a voltage detection current, and is uniformly packaged. The circuit of the reset module adopts a 3-wire SPI interface, and the programming and reading and writing links adopt a software protocol;

[0017] When performing a reset operation, the reset signal output pin RESET is used. When the chip is performing power detection and circuit detection, if it finds that the actual power supply is lower than the rated working voltage, RESET switches to a high level state and waits for the power to recover before switching to the initial state to reset the system, thereby realizing the independent protection mode of the microcontroller.

[0018] Furthermore, it also includes an alarm module, which is connected to the single-chip microcomputer and includes an LED flashing alarm light and a buzzer alarm.

[0019] Furthermore, it also includes a heat dissipation module, which is connected to the single-chip microcomputer and includes an isolating switch, a driving circuit and a heat dissipation fan.

[0020] The beneficial effects of the utility model are:

[0021] The utility model includes a reactive power compensation controller and a capacitor group. The capacitor adopts a thyristor switching capacitor, which can be assembled on the low-voltage side bus of the distribution transformer in a centralized compensation manner to achieve the function of compensating reactive power. When the single-chip microcomputer is running, it detects reactive power, obtains the grid line voltage, load phase current and power factor measurement circuit through the voltage measurement conversion module, the current measurement conversion module and the power factor angle measurement module, and then calculates the reactive power to obtain the reactive power shortage. The single-chip microcomputer identifies and analyzes and controls the capacitor group to issue a switching command output, so that the pulse drive circuit receives the command, and then controls the composite switch to achieve the switching start / shutdown operation. Improve the load power factor in the power system, reduce the equipment capacity, and reduce the power loss, thereby ensuring the stability of the power system and improving the power transmission capacity. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The utility model is a schematic diagram of the structure of the power grid change sensor in the dynamic reactive power compensation.

[0023] The realization of the purpose, functional features and advantages of the utility model will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0025] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back...) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0026] In addition, the descriptions of "first", "second", etc. in the present utility model are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in this field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present utility model.

[0027] It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0028] like Figure 1 As shown, the utility model provides a power grid change sensor in dynamic reactive power compensation, including a reactive power compensation controller and a capacitor bank, wherein the capacitor adopts a thyristor switching capacitor, and the reactive power compensation controller includes a single chip microcomputer, a voltage measurement conversion module, a current measurement conversion module, an analog-to-digital conversion module, a power factor angle measurement module, a communication interface module, a reset module, a pulse drive circuit and a composite switch, wherein the single chip microcomputer is respectively connected to the analog-to-digital conversion module, the power factor angle measurement module, the communication interface module, the reset module and the pulse drive circuit, wherein the analog-to-digital conversion module is connected to the voltage measurement conversion module and the current measurement conversion module, and the pulse drive circuit is connected to the composite switch;

[0029] The single-chip computer detects reactive power during operation, obtains the grid line voltage, load phase current and power factor measurement circuit through the voltage measurement conversion module, current measurement conversion module and power factor angle measurement module, and then calculates reactive power. In order to clearly observe the voltage value, current value and power factor value, a four-digit digital display circuit is configured to display the relevant values, and a keyboard circuit is used to switch the display content. The specific control process is: calculate the reactive power shortage → controller identification analysis → control the capacitor bank → issue a switching instruction → control the single-chip computer I / O port output → pulse drive circuit receives instructions → control the thyristor switching on / off → realize the switching start / off operation.

[0030] Design of thyristor trigger drive circuit: After completing the switching operation, the controller needs to trigger the thyristor through a high-frequency trigger pulse. To achieve impact-free switching, it is necessary to use a TSC pulse trigger device to ensure that the power supply voltage is consistent with the pre-charge voltage of the capacitor. When the trigger device is driven, it will control the conduction and switching of the thyristor, thereby controlling the switching on and off of the capacitor. In the design stage, it should be noted that the capacitor voltage is a dynamic value, so it is necessary to monitor the actual voltage across the thyristor before the switching operation begins. If it exceeds the set voltage peak, it is necessary to reduce the voltage and obtain a three-phase synchronous voltage after reducing the voltage. At this time, the voltage needs to flow through the filter circuit to obtain the input signal, and at the same time send instructions to the pulse trigger board. The single-chip control system performs logical judgment on the pulse trigger device circuit and outputs two control signals to control the switching operation of the thyristor. In this process, the isolation amplifier part is used to amplify the power of the two signals, thereby optimizing the thyristor trigger function.

[0031] The voltage measurement conversion module includes a voltage transformer, and the current measurement conversion module includes a current transformer; the maximum voltage rating of the current transformer output is 7.07V, and the peak voltage is 10V; the voltage transformer output voltage rating is The peak voltage is It can be seen that the AC voltage output by the current transformer and the voltage transformer floats within the range of ±10V. During the current and voltage signal processing, the operation can be completed through the simulator. When measuring the current and voltage, the reactive power compensation performs a coupling operation in the current transformer and the voltage transformer, and then transmits it to the single chip microcomputer.

[0032] The analog-to-digital conversion module is designed with three ports, namely, the chip selection terminal, the serial data input terminal, and the input / output clock terminal. The three ports are connected to the single-chip microcomputer in a three-wire SPI series mode to realize communication between the components. The three ports of the A / D converter are mainly provided by pins P1.0, P1.1, and P1.2, and pin P1.3 is separately set to receive the conversion data converted by the chip. The line of the three-wire SPI needs to be configured with an optical coupler isolation measure to ensure the effective isolation of the analog part and the digital part, thereby improving the circuit accuracy. The AC voltage flows through the voltage transformer and the AC current flows through the current transformer. After the conversion is completed, it can be converted into a weak signal in the microcomputer processing link. After flowing through the rectifier and filter circuit, the conversion of the AC quantity to the DC quantity is realized. At this time, the DC quantity can be directly converted by A / D (using the TLC2543 chip), thereby converting the analog quantity into a digital quantity and then transmitting it to the CPU. In order to save costs, a 12-bit data acquisition system can be selected, which mainly completes the acquisition of 11 analog signals in 11 input channels. The TLC2543 chip of the A / D converter directly inputs electrical energy by voltage, so the signal acquisition channel can also realize direct voltage input, while the current input requires the installation of a resistor at the interface to convert it into voltage before input.

[0033] The power factor value of the power factor angle measurement module is extracted and calculated through the three-phase load. Since the three-phase load is unbalanced, it is necessary to extract the phase current signal in one phase and the line voltage signal in the other two phases. The angle between the phase current and the line voltage is set to θ. The principle of θ is the angle between the phase current leading the line voltage, and there is a linear relationship between θ and φ. The power factor measurement circuit designed in this link uses the principle of the phase difference (θ) between the phase current and the line voltage.

[0034] The communication interface module realizes the communication with the upper machine, and adopts the RS-323 standard interface to transmit the interface information of various devices, including serial transmission data terminal equipment and data communication equipment; the serial communication port is connected with the serial transmission data terminal equipment and the data communication equipment. Since the logic levels of the three are different, it is necessary to set the logic zero level value, and the range is +5~+15V. If the RS-323 driver wants to connect to the level, it is necessary to convert the level to the RS-323 level and further convert it to the logic zero level. At this time, the communication interface line is connected to the 9-core RS-323 socket, and a three-wire wiring method is set, in which one line is grounded. In the actual communication link, when the upper machine sends an instruction to the single-chip microcomputer, the corresponding serial interface of the single-chip microcomputer transmits the data to the upper machine according to the communication protocol requirements, thereby realizing the communication between the controller and the upper machine.

[0035] The reset module includes a timer, a serial E2PROM and a voltage detection current, and is uniformly packaged to reduce the circuit board area and reduce the system operation space. The reset module circuit adopts a 3-wire SPI interface, and the programming and reading and writing links adopt a software protocol to further reduce the information flow at the I / O interface. When performing a reset operation, the reset signal output pin RESET is used. At this time, when the chip is performing power supply detection and circuit detection, if it is found that the actual power supply is lower than the rated working voltage, RESET switches to a high level state, waits for the power supply to recover, and then switches to the initial state to reset the system, thereby realizing the independent protection mode of the single-chip microcomputer.

[0036] The utility model also includes a display module, which is connected to the single-chip computer. The display module is designed into two parts, namely a working state display circuit and a voltage, current and power factor display circuit; the working state display circuit controls 8 light-emitting diodes through a ULN2003 display driver to achieve display requirements, 4 of which are responsible for overvoltage display, undervoltage display, and power factor leading and lagging display of the system, and the other 4 are responsible for realizing the switching state display of the capacitor group. The 8 diodes represent 8 groups of capacitor groups. When a capacitor executes a switching instruction, the corresponding indicator light will light up; the voltage, current and power factor display circuit uses a MAX7219 display driver to control 4 LED displays, and each display image needs to be set with a button to realize screen switching.

[0037] The utility model also comprises an alarm module, which is connected to the single chip computer and comprises an LED flashing alarm light and a buzzer alarm. When a circuit fails, the alarm device is controlled to work.

[0038] The utility model also includes a heat dissipation module, which is connected to the single-chip microcomputer and includes an isolating switch, a driving circuit and a heat dissipation fan. When the temperature is detected to exceed the set value, a high pulse signal is automatically sent to trigger the isolating switch to open, control the driving circuit to drive the heat dissipation fan to work, and can automatically adjust the wind speed according to the temperature value to achieve intelligent variable frequency speed regulation; the driving circuit adopts a three-phase full-bridge driving circuit; the heat dissipation fan adopts a brushless DC motor.

[0039] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, device, article or method including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, device, article or method. In the absence of further restrictions, an element defined by the sentence "includes a ..." does not exclude the presence of other identical elements in the process, device, article or method including the element.

[0040] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the contents of the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A power grid change sensor in dynamic reactive power compensation, characterized in that: It includes a reactive power compensation controller and a capacitor bank, wherein the capacitor adopts a thyristor switching capacitor, and the reactive power compensation controller includes a single chip microcomputer, a voltage measurement conversion module, a current measurement conversion module, an analog-to-digital conversion module, a power factor angle measurement module, a communication interface module, a reset module, a pulse drive circuit and a composite switch, wherein the single chip microcomputer is respectively connected to the analog-to-digital conversion module, the power factor angle measurement module, the communication interface module, the reset module and the pulse drive circuit, wherein the analog-to-digital conversion module is connected to the voltage measurement conversion module and the current measurement conversion module, and the pulse drive circuit is connected to the composite switch; The single-chip microcomputer detects reactive power during operation, obtains the grid line voltage, load phase current and power factor measurement circuit through the voltage measurement conversion module, the current measurement conversion module and the power factor angle measurement module, and then calculates reactive power to obtain reactive power shortage. The single-chip microcomputer performs identification and analysis and controls the capacitor bank to issue a switching command output, so that the pulse drive circuit receives the command and then controls the composite switch to realize the switching start / shutdown operation.

2. The grid change sensor in dynamic reactive power compensation according to claim 1, characterized in that: The voltage measurement conversion module includes a voltage transformer, and the current measurement conversion module includes a current transformer; the maximum voltage rating of the current transformer output is 7.07V, and the peak voltage is 10V; the voltage transformer output voltage rating is The peak voltage is When measuring current and voltage, reactive power compensation performs coupling operation in the current transformer and the voltage transformer, and then transmits the result to the single chip microcomputer.

3. The grid change sensor in dynamic reactive power compensation according to claim 1, characterized in that: The analog-to-digital conversion module is designed with three ports, namely a chip selection terminal, a serial data input terminal, and an input / output clock terminal. The three ports are respectively connected to the single-chip microcomputer in a three-wire SPI series connection mode to realize communication between various components.

4. The grid change sensor in dynamic reactive power compensation according to claim 1, characterized in that: The power factor value of the power factor angle measurement module is extracted and calculated through the three-phase load, the phase current signal is extracted from one phase, and the line voltage signal is extracted from the other two phases. The angle between the phase current and the line voltage is set to θ. The principle of θ is the angle between the phase current leading the line voltage. The power factor angle measurement module uses the phase difference principle between the phase current and the line voltage.

5. The grid change sensor in dynamic reactive power compensation according to claim 1, characterized in that: The communication interface module realizes communication with the upper machine position, and adopts RS-323 standard interface to transmit interface information of various devices, including serial transmission data terminal equipment and data communication equipment; When the host computer sends a command to the single chip microcomputer, the corresponding serial interface of the single chip microcomputer transmits data to the host computer according to the communication protocol requirements, thereby realizing the communication between the controller and the host computer.

6. The grid change sensor in dynamic reactive power compensation according to claim 1, characterized in that: It also includes a display module, which is connected to the single chip microcomputer and is designed to be composed of two parts, namely a working status display circuit and a voltage, current and power factor display circuit; The working status display circuit controls 8 light-emitting diodes through the ULN2003 display driver to achieve the display requirements. 4 of them are responsible for the system overvoltage display, undervoltage display, power factor leading and lagging display, and the other 4 are responsible for realizing the capacitor bank switching status display. The 8 diodes represent 8 groups of capacitors. When a capacitor executes the switching instruction, the corresponding indicator light will light up. The voltage, current and power factor display circuit uses the MAX7219 display driver to control four LED displays. Each display image requires a button to realize screen switching.

7. The grid change sensor in dynamic reactive power compensation according to claim 1, characterized in that: The reset module includes a timer, a serial E2PROM and a voltage detection current, and is uniformly packaged. The circuit of the reset module adopts a 3-wire SPI interface, and the programming and reading and writing links adopt a software protocol; When performing a reset operation, the reset signal output pin RESET is used. When the chip is performing power detection and circuit detection, if it finds that the actual power supply is lower than the rated working voltage, RESET switches to a high level state and waits for the power to recover before switching to the initial state to reset the system, thereby realizing the independent protection mode of the microcontroller.

8. The grid change sensor in dynamic reactive power compensation according to claim 1, characterized in that: It also includes an alarm module, which is connected to the single-chip microcomputer and includes an LED flashing alarm light and a buzzer alarm.

9. The grid change sensor in dynamic reactive power compensation according to claim 1, characterized in that: It also includes a heat dissipation module, which is connected to the single-chip microcomputer and includes an isolating switch, a driving circuit and a heat dissipation fan.

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