Visual on-load voltage regulation tap switch control system, equipment and medium

Abstract

The invention relates to a visual on-load voltage regulation tap switch control system, device and medium, which comprises a single chip microcomputer control circuit, the single chip microcomputer control circuit is connected with a signal processing circuit and a power supply circuit, and the signal processing circuit is connected with a voltage zero cross detection circuit, a voltage sensor and a data acquisition unit. The voltage zero-cross detection circuit, the voltage sensor, the data acquisition unit and the power supply circuit are all connected with the isolation reduction transformer, and the isolation reduction transformer is connected with the low-voltage side voltage of the distribution transformer; the single-chip microcomputer control circuit is further connected with a switch position sensor, a communication circuit, a switch drive circuit and a thyristor trigger circuit. The communication circuit is in communication connection with a remote computer through an RS485. The method has the advantages of realizing automatic voltage regulation conversion, stabilizing voltage, accurately setting visual parameters and realizing non-impact voltage regulation.

Description

Technical Field

[0001] This invention belongs to the field of tap changer technology, specifically relating to a visualized on-load tap changer control system, equipment, and medium. Background Technology

[0002] Voltage is a crucial quality indicator in power systems. During normal operation, fluctuations in the power supply voltage and changes in load size cause frequent variations in the system's supply voltage. In severe cases, this can affect the normal operation of electrical equipment, directly impacting production and daily life. An effective solution is to use control equipment to control the on-load tap changer. When the supply voltage changes, the supply voltage can be stabilized by adjusting the tap position of the primary winding of the power transformer (in an on-load tap-changing power supply system). The on-load tap changer controller, a key piece of equipment in an on-load tap-changing power supply system, is the command and control center of the system, and its performance directly affects the reliable operation of the system. Generally speaking, the transformer... The voltage between adjacent taps of a transformer ranges from hundreds to thousands of volts, and the current on the taps ranges from tens of amperes to over a thousand amperes. The capacity of the power electronic devices constituting the tap changer can range from several kilowatts to 10 MW. Therefore, the choice of power electronic components varies depending on the application and voltage regulation requirements. However, existing control systems cannot achieve a voltage regulation process without transients or impacts in the voltage and current waveforms by controlling the on and off times of the power electronic devices. Therefore, it is essential to provide a visualized on-load tap changer control system, equipment, and medium that enables automatic voltage regulation, stable voltage, precise setting of visualized parameters, and impact-free voltage regulation. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a visualized on-load tap changer control system, equipment and medium that realizes automatic voltage regulation and conversion, stable voltage, precise setting of visualized parameters, and shock-free voltage regulation.

[0004] The objective of this invention is achieved as follows: Firstly, a visualized on-load tap changer control system includes a microcontroller control circuit. This microcontroller control circuit is connected to a signal processing circuit and a power supply circuit. The signal processing circuit is connected to a zero-crossing voltage detection circuit, a voltage sensor, and a data acquisition unit. The zero-crossing voltage detection circuit, voltage sensor, data acquisition unit, and power supply circuit are all connected to an isolation step-down transformer, which is connected to the low-voltage side of the distribution transformer. The microcontroller control circuit is also connected to a switch position sensor, a communication circuit, a switch drive circuit, and a thyristor trigger circuit. The communication circuit establishes a communication connection with a remote computer using RS485.

[0005] The voltage zero-crossing detection circuit consists of an optocoupler 4N25 and a NAND gate 74LS00. It is used to utilize the zero-crossing triggering characteristic of the thyristor to send an interrupt request to the microcontroller when the grid voltage crosses zero, and send a trigger signal to the thyristor triggering circuit to complete the effective conduction of the tap changer.

[0006] The data acquisition unit uses a 12-bit serial switched capacitor successive approximation analog-to-digital converter (TLC2543) to complete data acquisition. The data acquisition unit acquires the AC voltage on the secondary side of the distribution transformer after it has been stepped down by the isolation step-down transformer. After being shaped, filtered and divided into DC voltage signals, the DC voltage signals are converted into digital signals by the AD converter (TLC2543) and input to the signal processing circuit.

[0007] The triggering circuit of the thyristor adopts a zero-crossing triggering circuit with the MOC3061 chip as the core. The MOC3061 is driven by the negative logic of ULN2003 to achieve the purpose of triggering the thyristor. The triggering circuit of the thyristor adopts a gate turn-off thyristor.

[0008] The microcontroller is bidirectionally connected to a reset circuit and an LCD display, which uses an LCM12864ZK LCD module.

[0009] The microcontroller control circuit uses a PIC16F877 microcontroller chip; the switch position detection circuit uses 11 optocouplers connected to the PIC16F877 and is connected to a remote computer via a MAX485 communication interface to display the switch position.

[0010] The system is a contactless on-load tap-changing system based on a dynamic model. It adopts a time-domain contactless on-load tap-changing transformer dynamic model and uses the TLM method to solve the on-load tap-changing process with transition resistance, determine the time of no-impact tap-changing, and realize no-impact tap-changing.

[0011] The dynamic model of the time-domain contactless on-load tap-changing transformer specifically includes the following steps:

[0012] Step 1: Dynamic model of transformer core: The hysteresis phenomenon of transformer core is modeled based on Jiles-Atherton theory;

[0013] Step 2: Solving the dynamic transformer model using the TLM method: The TLM (Transmission Line Model) method is used to solve the dynamic model, and the results are time-domain values.

[0014] Step 3: Dynamic on-load voltage regulation process: 3.1: Voltage regulating winding engagement process; 3.2: Voltage regulating winding disengagement process.

[0015] In a second aspect, an electronic device includes a processor and a memory, the memory storing computer programs and / or instructions, which, when executed by the processor, realize the automatic voltage regulation switching function of the on-load tap changer based on the visualized on-load tap changer control system described above.

[0016] Thirdly, a computer-readable storage medium stores a computer program and / or instructions, which, when executed by a processor, realize the automatic voltage regulation switching function of the on-load tap changer based on the visualized on-load tap changer control system described above.

[0017] The beneficial effects of this invention are as follows: This invention provides a visualized on-load tap changer control system, equipment, and medium. In use, this invention employs a PIC16F877 microcontroller to control and regulate the on-load tap changer, enabling automatic voltage regulation and stabilization. The signal is converted from analog to digital via a voltage transformer and signal conditioning circuit, then compared with set parameters. The PIC determines the appropriate action to drive the switch mechanism. The switch position sensor is connected to the PIC and transmits the data to a remote computer via a MAX485, displaying the current switch position, real-time voltage value, and total tap changer action count. This invention allows for tap change operations without interrupting the load, enabling the tap changer to meet the needs of various transformers and ensuring the quality of the on-load tap changer output voltage. This invention offers advantages such as automatic voltage regulation, stable voltage, precise parameter setting, and shock-free voltage regulation. Attached Figure Description

[0018] Figure 1 This is a block diagram of the system composition structure of the present invention.

[0019] Figure 2 This is a circuit diagram for the voltage zero-crossing detection of the present invention.

[0020] Figure 3 This is a circuit diagram for measuring voltage according to the present invention.

[0021] Figure 4 This is a circuit diagram for the switch position detection of the present invention.

[0022] Figure 5 This is a circuit diagram of a liquid crystal display according to the present invention.

[0023] Figure 6 This is a schematic diagram of the communication circuit of the present invention.

[0024] Figure 7 This is a schematic diagram illustrating the connection method between the tap changer and the transformer according to the present invention.

[0025] Figure 8 This is a system schematic diagram of the present invention.

[0026] Figure 9 This is a diagram showing the hysteresis loop and differential magnetic susceptibility curve of the present invention.

[0027] Figure 10 The inductor element model and equivalent circuit diagram of the present invention are shown.

[0028] Figure 11 This is a schematic diagram of the voltage regulating winding process of the present invention.

[0029] Figure 12 This is a TLM circuit diagram of the transformer voltage regulation according to the present invention.

[0030] Figure 13 This is a schematic diagram of the voltage and current waveforms during the dynamic engagement of the voltage regulating winding according to the present invention.

[0031] Figure 14 This is a waveform diagram of the impact current during the voltage regulation process of the present invention.

[0032] Figure 15 The voltage and current waveforms during the dynamic withdrawal of the voltage regulating winding are shown in the figure. Detailed Implementation

[0033] The present invention will be further described below with reference to the embodiments and / or accompanying drawings.

[0034] Example 1

[0035] like Figures 1-6 As shown, a visualized on-load tap changer control system includes a microcontroller control circuit. This microcontroller control circuit is connected to a signal processing circuit and a power supply circuit. The signal processing circuit is connected to a zero-crossing voltage detection circuit, a voltage sensor, and a data acquisition unit. The zero-crossing voltage detection circuit, voltage sensor, data acquisition unit, and power supply circuit are all connected to an isolation step-down transformer, which is connected to the low-voltage side of the distribution transformer. The microcontroller control circuit is also connected to a switch position sensor, a communication circuit, a switch drive circuit, and a thyristor trigger circuit. The communication circuit uses RS485 to establish a communication connection with a remote computer.

[0036] The voltage zero-crossing detection circuit consists of an optocoupler 4N25 and a NAND gate 74LS00. It is used to utilize the zero-crossing triggering characteristic of the thyristor to send an interrupt request to the microcontroller when the mains voltage crosses zero, and send a trigger signal to the thyristor triggering circuit to complete the effective conduction of the tap changer. This avoids the surge voltage that may be generated when the tap changer switches at any time of AC power supply voltage switching.

[0037] In this embodiment, the voltage zero-crossing detection circuit: To avoid potential surge voltages that could damage the switching devices due to tap changers switching at any time during AC power supply voltage switching, the zero-crossing triggering characteristic of the thyristor is utilized. When the mains voltage crosses zero, an interrupt request is sent to the microcontroller, which in turn sends a trigger signal to the thyristor triggering circuit, thus ensuring the tap changer is effectively turned on. The voltage zero-crossing detection circuit of this invention mainly consists of an optocoupler 4N25 and a NAND gate 74LS00, with the specific connection method as follows... Figure 2 As shown;

[0038] Its working principle is as follows: AC power is directly applied to two anti-parallel LEDs through current-limiting resistor R3. During the positive and negative half-cycles of the AC voltage sine wave, the LEDs conduct alternately, thereby causing the optocouplers to alternately saturate and turn off. When both optocouplers are on or any one of them is on, the output signal of the NAND gate 74LS00 is high. When the optocouplers are off, the input signals of the NAND gate 74LS00 are all high voltages, and its output is low.

[0039] The data acquisition unit uses a 12-bit serial switched capacitor successive approximation analog-to-digital converter (TLC2543) to complete data acquisition. The AC voltage on the secondary side of the distribution transformer is stepped down by an isolation step-down transformer, acquired by the data acquisition unit, and converted into a DC voltage signal through shaping, filtering, and voltage division. After conversion by the TLC2543 AD converter, the converted digital signal is input to the microcontroller, which then performs data processing and system control.

[0040] In this embodiment, the data acquisition unit uses a 12-bit serial switched capacitor successive approximation analog-to-digital converter (TLC2543) to complete the data acquisition work. The AC voltage on the secondary side of the distribution transformer is stepped down by the isolation step-down transformer, acquired by the data acquisition unit, and converted into a DC voltage signal through shaping, filtering, and voltage division processes. After conversion by the TLC2543 AD converter, the converted digital signal is input to the signal processing circuit and then sent to the microcontroller, which then performs data processing and system control.

[0041] The triggering circuit of the thyristor adopts a zero-crossing triggering circuit with the MOC3061 chip as the core. The gate resistor of the thyristor can improve the anti-interference capability. The MOC3061 is driven by the negative logic of the ULN2003. After the data of the data acquisition unit is compared with the reference value of the voltage zero-crossing detection circuit, the microcontroller sends a control signal to the ULN2003 to drive the MOC3061 chip, thereby achieving the purpose of triggering the thyristor. The triggering circuit of the thyristor adopts a gate-turn-off thyristor.

[0042] In this embodiment, the thyristor triggering circuit adopts a zero-crossing triggering circuit based on the MOC3061 chip. The gate resistor of the thyristor can improve the anti-interference capability. The MOC3061 is driven by the negative logic of the ULN2003. After comparing the data of the data acquisition unit with the reference value of the voltage zero-crossing detection circuit, the microcontroller sends a control signal to the ULN2003 to drive the MOC3061 chip, thereby achieving the purpose of triggering the thyristor. The advantages of this triggering method are: the thyristor output is a sine wave with no waveform distortion, less electromagnetic interference, and no noise.

[0043] As a feasible implementation method, a gate turn-off thyristor (GTO) is used as an automatic voltage regulating device for on-load tap changers. The characteristic that the GTO can be controlled by the gate to achieve rapid switching of transformer taps is utilized. This type of tap changer does not require a transition resistor to limit the circulating current during the tap change process, which simplifies the circuit, reduces costs, and improves the safety and reliability of operation.

[0044] The microcontroller is bidirectionally connected to a reset circuit and an LCD display.

[0045] The microcontroller control circuit uses a PIC16F877 microcontroller chip; the switch position detection circuit uses 11 optocouplers connected to the PIC16F877 and is connected to a remote computer via a MAX485 communication interface to display the switch position; the LCD display uses an LCM12864ZK LCD module.

[0046] In this embodiment, the PIC16F877 microcontroller chip uses its pins to interact with an external display, sets parameters through the liquid display, and directly connects to a human-machine interface or computer to transmit the parameters to a remote computer, providing data for remote monitoring and unattended operation.

[0047] As a feasible implementation, the voltage detection circuit measures the signal voltage. It converts the acquired analog signal into a digital signal via a PIC microcontroller A / D module, then compares it with a pre-set voltage reference value using a PC microcontroller programmable, thereby driving the motor and controlling gear shifting. Because the transformer operates in a harsh environment with many interference signals, and the microcontroller itself lacks filtering capabilities, a filtering circuit is necessary. Furthermore, since the signal is AC while the microcontroller operates on DC voltage, a rectifier circuit is required to convert the AC voltage to DC. Simultaneously, to meet the microcontroller's maximum operating voltage, the output voltage value needs to be limited; therefore, a limiting circuit is indispensable. A +5V Zener diode is used as needed, and its circuit diagram is shown below. Figure 3 As shown.

[0048] As a specific and feasible implementation, the switch position detection circuit: During transformer operation, to help operators monitor the on-site operation, the current switch position must be provided and displayed, offering tap changer adjustment information. If the tap changer is adjusted upwards or downwards when it is already at its highest or lowest position, it will damage the transformer tap changer. In this case, the output should be locked to minimize control failure. In this invention, 11 optocoupler circuits are connected to a PIC (Picture Control Unit). The switch position is determined by PIC logic control, and the switch position is displayed by connecting to a host computer via a MAX485 communication interface. The circuit schematic is shown below. Figure 4 As shown.

[0049] As a specific implementation method, the display circuit is mainly used to set and display parameters, including voltage reference value, measurement accuracy, sampling time, limit voltage, and other parameters. This invention uses an LCM12864ZK LCD display module, and implements logic control through software programming. To make operation more convenient, four switch buttons are added to the circuit, which also use logic control to select and adjust parameters. The schematic diagram is shown below. Figure 5 As shown.

[0050] As a specific and feasible implementation method, the communication circuit is used to realize point-to-point communication between the PIC microcontroller and the computer, such as... Figure 6 As shown, it is used to display parameters such as real-time voltage value, tap changer position, total number of tap changer actions, and voltage standard value on site, and simultaneously output alarm information; however, since the PIC microcontroller itself does not have an RS485 communication interface, an external communication interface is required to realize the communication function.

[0051] This invention relates to a visualized on-load tap changer control system, equipment, and medium. In use, this invention employs a PIC16F877 microcontroller to control and regulate the on-load tap changer, enabling automatic voltage regulation and stabilization. The signal is converted from analog to digital via a voltage transformer and signal conditioning circuit, then compared with preset parameters. The PIC determines the appropriate action to control the switch drive mechanism. The switch position sensor is connected to the PIC and transmits the data to a remote computer via a MAX485 for display, allowing operators to see the switch's current position, real-time voltage value, and total tap changer action. The PIC-controlled LCD displays the information... The invention allows for on-site setting of voltage reference values, voltage limits, calculation accuracy, switch action intervals, sampling rates, etc., enabling visualized adjustment. It incorporates an optocoupler isolation circuit in the position detection circuit and a filter circuit in the measurement circuit to improve anti-interference capabilities. The PIC (Polyionized Component Interchange) performs voltage sampling and calculation, detects switches and limit positions, stores data, controls gear shifting and protection, provides alarms, and communicates with a human-machine interface or computer. The invention uses an LCM12864ZK LCD module for precise parameter setting, and employs button settings for easy parameter adjustment. This invention offers advantages such as automatic voltage regulation, stable voltage, visualized and precise parameter setting, and shock-free voltage regulation.

[0052] Example 2

[0053] like Figures 7-15 As shown, a visualized on-load tap changer control system includes a microcontroller control circuit. This microcontroller control circuit is connected to a signal processing circuit and a power supply circuit. The signal processing circuit is connected to a zero-crossing voltage detection circuit, a voltage sensor, and a data acquisition unit. The zero-crossing voltage detection circuit, voltage sensor, data acquisition unit, and power supply circuit are all connected to an isolation step-down transformer, which is connected to the low-voltage side of the distribution transformer. The microcontroller control circuit is also connected to a switch position sensor, a communication circuit, a switch drive circuit, and a thyristor trigger circuit. The communication circuit uses RS485 to establish a communication connection with a remote computer.

[0054] In this embodiment, the structure and working principle of the on-load tap changer are as follows: For applications commonly used in power distribution systems... Distribution transformers, whose taps can reach a maximum voltage of Because the gate turn-off thyristor (GTO) has a withstand voltage of over 2000V, two GTOs connected in reverse parallel can be independently and directly connected between each winding tap and the neutral point of the transformer, serving as the actuating element of the on-load tap changer. Since the GTO has controllable turn-off characteristics, it can switch rapidly under computer control. Therefore, the tap changer circuit does not need a transition resistor to limit circulating current, thus simplifying the circuit and improving operational reliability. The connection method between the tap changer and the transformer is as follows: Figure 7 As shown.

[0055] Assuming that the turn-off thyristor group GT02 was originally on while the rest of the GTO groups were off, now, due to a decrease in load or an increase in grid voltage, the transformer output voltage has risen beyond the allowable range. To reduce the transformer output voltage to the allowable range, the number of turns on the primary side of the transformer should be increased, meaning the turn-off thyristor currently on should be changed from GT02 to GT03. The process is as follows:

[0056] Normally, at the zero-crossing point when the GTO of the GT02 group changes from being subjected to reverse voltage to being subjected to forward voltage, a positive control voltage is applied between its gate and cathode to keep it continuously conducting; when it is necessary to change the tap from... Become When the GTO voltage of GTO3 group crosses zero from the negative half-cycle to the positive half-cycle, the control circuit applies a positive voltage control signal between its cathode and gate to turn it on. Subsequently, a negative pulse control signal is applied between the gate and cathode of the response element of GT02 group to turn it off. This completes a tap change and voltage adjustment, restoring the output voltage to the allowable range and achieving the purpose of stabilizing the output voltage, thus realizing the automatic voltage regulation function.

[0057] As a specific and feasible implementation method, its working principle diagram is as follows: Figure 8 As shown, the microcontroller main control chip first acquires the secondary voltage of the transformer through the rectifier filter circuit and the AD conversion circuit, and then compares it with the internally set voltage baseline value. Based on the deviation from the required value, it determines the turn-off thyristor that should be activated. At the same time, it detects whether the grid voltage has crossed zero. When the voltage crosses zero, the microcontroller sends a control signal to the GTO group to control the GTO group's conduction and cutoff, safely and reliably completing the adjustment of the tap changer, stabilizing the output voltage, and displaying the working status of the GTO. It also uses a digital display to monitor voltage changes in real time and understand the operation of the transformer tap changer. However, its working voltage is 3.3V and 1.8V, while the working voltage of other components is usually 5V. Therefore, after the transformer secondary voltage is regulated, a level conversion chip must be used to make it reach the effective working voltage for tap changer control.

[0058] In the entire tap changer control device, the GTO drive circuit is the key part to ensure the safe and reliable operation of the tap changer. As can be seen from the GTO's turn-on and turn-off process, the GTO gate drive circuit should provide a positive trigger pulse and a reverse turn-off pulse, and the timing of the two pulses should be controllable. The positive pulse should have a certain width, and a certain current should be maintained after conduction to reduce the voltage drop of the GTO conduction tube. The leading edge of the reverse turn-off current pulse should have a certain steepness to reduce the GTO turn-off time. Therefore, this invention adopts a direct-coupled drive circuit.

[0059] In summary, this invention samples, filters, and calculates voltage and current, then controls the opening and closing of tap changers and displays their operating status based on the analysis and comparison of specific data, ultimately achieving a stable output of the load voltage. First, it determines whether the input voltage exceeds the limit based on a preset voltage reference value. Second, if the voltage is within the acceptable range, the device does not adjust. Third, if the voltage exceeds the limit, it compares it with the reference value, and determines which tap changers should be opened and closed based on the different comparison results, then performs the corresponding adjustment. If the lowest (highest) adjustment level is reached, a lockout output is issued.

[0060] The system is a contactless on-load tap-changing system based on a dynamic model. It adopts a time-domain contactless on-load tap-changing transformer dynamic model and uses the TLM method to solve the on-load tap-changing process with transition resistance, determine the time of no-impact tap-changing, and realize no-impact tap-changing.

[0061] The dynamic model of the time-domain contactless on-load tap-changing transformer specifically includes the following steps:

[0062] Step 1: Dynamic model of transformer core: The hysteresis phenomenon of transformer core is modeled based on Jiles-Atherton theory;

[0063] In this embodiment, the Jiles-Atherton ferromagnetic hysteresis principle is used to measure the magnetic field strength of the transformer core. With magnetization The relationship between magnetization and iron core hysteresis characteristics is used to reflect the magnetic hysteresis properties of the iron core. This theory assumes that the magnetization intensity... Irreversible components With reversible components The sum of these is for the purpose of finding Introducing the concept of non-hysteresis magnetization, which involves no resistance during magnetization and has no effect on the movement of magnetic domains, the differential permeability can be described as: ,in, The non-hysteresis magnetization intensity; The saturation magnetization; The average field parameter reflects the coupling between magnetic domains; Parameters characterizing the shape of the non-magnetic magnetization curve; Parameters reflecting the restraining effect of magnetic domains on motion; is the reversible magnetization coefficient, with a value between 0 and 1; the following 5 parameters can be obtained experimentally. The parameter reflects the direction of change of magnetic field strength over time.

[0064] The above equation is generally solved using numerical methods such as the fourth-order Runge-Kutta method, which allows us to determine... The changing pattern, let ,when When the value approaches 0, numerical computation may fail to converge. Therefore, when... When, rewritten as .

[0065] like Given an alternating magnetic field, the hysteresis loop can be determined by following the law of change. Figure 9 for Starting from 0, the variation patterns of the hysteresis loop and differential magnetic susceptibility within the range of -500 to 500 A are shown. , , , , As can be seen from the differential magnetic susceptibility curve, the differential magnetic susceptibility is positive; the differential magnetic susceptibility is the largest at the coercive point (i.e., the intersection of the principal hysteresis loop and the horizontal axis).

[0066] Step 2: Solving the dynamic transformer model using the TLM method: The TLM (Transmission Line Model) method is used to solve the dynamic model, and the results are time-domain values.

[0067] In this embodiment, the TLM method is an analysis method that discretizes time. By establishing the equivalent inductance and capacitance of the transmission line model, the problem to be solved is discretized and transformed into the solution of a linear circuit, avoiding calculus calculations, as detailed below:

[0068] A lumped nonlinear element (inductor or capacitor) can be replaced by a discrete lossless transmission line model, where the transmission line length, inductance per unit length, capacitance per unit length, and transmission time are respectively... and ,in It is also the time step for solving the problem; there are two TLM models for inductors and capacitors, called the series (Link) model and the parallel (Stub) model, respectively. In the dynamic transformer model, the nonlinear element adopts the Stub model; Figure 10 This is a model of an inductor element and its equivalent circuit. Figure 10 (a) is a value The inductor and its transmission line are modeled using a stub. To highlight the characteristic that the inductor stores the most energy when the current is maximum, the stub model terminal of the inductor is considered as a short circuit. The voltage wave will undergo total reflection upon incident, and the time required for total reflection is... ,inductance Therefore, the wave speed of the transmission line is: We can obtain: The characteristic impedance of the transmission line is The capacitance introduced into the model is called the model error capacitance. This value is proportional to the square of the time step of the problem to be solved, so as long as Small enough, error capacitance It is very small; in actual inductors always have inter-turn capacitance. From this perspective, the TLM model is closer to the actual situation than the ideal circuit model of inductors.

[0069] According to the theory of lossless transmission lines, the current and voltage on the transmission line are transmitted as traveling waves. The magnitudes of the current and voltage on the transmission line are the superposition of the incident and reflected waves. Thevenin equivalent circuits can be constructed as follows: Figure 10 As shown in (b), therefore: , where superscript and These represent the incident wave and the reflected wave, respectively, with subscripts indicating the direction of the wave. Indicates the first indivual time.

[0070] Step 3: Dynamic on-load tap changing process: 3.1: Tap changing winding energization process;

[0071] In this embodiment, with Figure 11 The on-load tap-changing transformer model shown is used to study the tap-changing winding connection process. The switches in the figure are all composed of anti-parallel thyristors. The original operating mode is the primary winding. The operation and control system require the voltage regulating winding to be... Investment.

[0072] 3.11: System operating status before voltage regulation: The system is already running stably before voltage regulation, and at this time the thyristor switch... With the switch closed and all other switches open, the equation for this operating state is: ,in, Symbols introduced for ease of description , Permeability of free space; The cross-sectional area of ​​the iron core; The length of the magnetic circuit of the iron core; These are the primary winding voltage, the regulating winding voltage, and the secondary winding voltage, respectively. These are the primary winding electromotive force, the voltage regulating winding electromotive force, and the secondary winding electromotive force, respectively. This refers to the power supply voltage. Its amplitude; for The initial phase angle of the voltage at the instant of closing; These are the primary winding current, the voltage regulating winding current, and the secondary winding current, respectively. These are the number of turns in the primary winding, the number of turns in the voltage regulating winding, and the number of turns in the secondary winding, respectively. The resistance and inductance of the primary winding; For the secondary winding resistance and inductance; For the load resistor and inductor; The description refers to a power electronic switch composed of anti-parallel thyristors. Electrical characteristics; for The gate trigger pulse voltage of the thyristor is the same for the two anti-parallel thyristors.

[0073] To facilitate the solution, the above equation is converted into an equivalent TLM circuit, such as... Figure 12 As shown in the figure A resistor used to represent the on / off characteristics of a thyristor; .

[0074] In the initial state, all components have no stored energy, meaning the initial value of all incident voltages is 0, and the iron core has no residual magnetism. Pick The value at time, according to the TLM method, is determined by the time step. The current and voltage variation curves can be obtained by solving sequentially; the following describes the process from the first... To find the result of the first step The process of taking steps.

[0075] a. Calculate the incident voltage using the above formula, for example, to find the first... Step inductance The incident voltage is: ;

[0076] b. According to the first Step Use the value to solve for the current in the circuit ;

[0077] c. According to Find the new The value is then used to find the new value. Value, then press the new one. The current is obtained by solving the circuit. ;

[0078] d. If or , ( (For the maximum allowable error), then correct. and Determine the size, then return to step c;

[0079] e. until and When the error is less than the allowable value, the first value is calculated. The instantaneous current value of the step.

[0080] 3.12: Circulating current is connected in the voltage regulating winding: In If the primary voltage of the transformer rises, the control system, after data acquisition and processing, issues a signal indicating that the voltage regulating winding needs to be engaged. The instructions; in When the voltage regulating winding is engaged Close the power electronic switch The equation for this operating state is: ,in, for The thyristor gate trigger pulse voltage; since the regulating winding and the main winding are made of the same material and have the same electrical characteristics, only the number of turns differs. Therefore, the equation obtained according to the running equation formula in 3.11 is... The current and voltage values ​​at time t are the initial values ​​of the above equation.

[0081] 3.13: Elimination of circulating current during voltage regulation: Blocking power electronic switches The trigger pulse, in When the current crosses zero, Natural shutdown; flowing through The current is Therefore, after the latching trigger pulse, when the condition is met... At that time, the equation describing the running state becomes: .

[0082] 3.14: Voltage regulation transition resistor deactivation: In Time-triggered power electronic switch This causes the voltage regulation transition resistor to disengage, and the equation describing the operating state is: Thus, one voltage regulation process is complete. The solution steps for voltage regulation steps 3.12 to 3.14 are similar to those in 3.11 and will not be repeated here. The obtained voltage and current waveforms of the on-load voltage regulation process of the energized voltage regulating winding are as follows: Figure 13 As shown in the figure; from top to bottom, the waveforms are: primary voltage waveform, primary current waveform, secondary voltage waveform, secondary current waveform, voltage regulating winding waveform, and voltage regulating transition resistor current waveform.

[0083] exist Before that moment, the voltages on the primary and secondary sides of the transformer had stabilized. The voltage of the regulating winding and the voltage of the primary winding had different amplitudes but the same variation pattern. The currents on the primary and secondary sides also remained stable and varied sinusoidally. The regulating transition resistor was not engaged, and no current flowed through it. At a certain moment, the primary voltage of the transformer rises. To maintain a stable load voltage, on-load tap regulation is required. After data acquisition, processing, and judgment, the control system issues a tap regulation command. Always close the power electronic switch Because resistive elements are used to suppress voltage regulation surges, power electronic switches... The triggering and conduction timing should be selected at the zero-crossing moment of the voltage regulating winding (the same time as the zero-crossing moment of the primary winding voltage), so that the current flowing before and after triggering and conduction is... The current will not change abruptly, such as... Figure 13 As shown; it is important to note After the circuit is triggered, the current direction across the transition resistor is opposite to the voltage direction. This is because... Figure 11 middle The positive direction is defined as from left to right; the next step is to lock. The trigger pulse flows through The current is ,exist At that moment, the value should be zero. Natural shutdown, at the moment of shutdown It will reverse, becoming the same as the main winding current. The same; in order to clearly illustrate this process, Figure 13 The turn-off time is delayed by one cycle; this process will cause the current to... There is a mutation, but this mutation affects the current. The impact is very small and can be ignored; finally, in time Crossing zero, towards A trigger pulse is sent to disengage the voltage regulation transition resistor; at this point, one voltage regulation process is complete.

[0084] Depend on Figure 13 It can be seen that before and after dynamic voltage regulation ( and Transformer secondary voltage Maintaining stability means the load voltage remains stable; during dynamic voltage regulation, the waveforms of the primary and secondary current and voltage on both sides of the transformer remain continuous without any impact changes; from the start of the primary system voltage change to the end of the dynamic voltage regulation process, the shortest regulation time is 3 cycles (60ms); there is current on the voltage regulation transition resistor ( The flow time is 2 cycles, so the power consumption of the transition resistor is very small.

[0085] In the voltage regulation process described above, the switching of power electronic switches occurs at the zero-crossing moments of voltage or current, which are easy to determine. If the timing of voltage regulation is inaccurate, it will cause impacts on the voltage and current waveforms. Figure 14 The image shows the direction An incorrect trigger pulse timing causes an impact on the primary side current waveform.

[0086] 3.2: Voltage regulating winding disengagement process.

[0087] In this embodiment, it is still based on Figure 11 The circuit shown is used to study the voltage regulating winding disengagement process; assuming the system is already running stably before voltage regulation, at this time the thyristor switch... and Close the circuit, and open all others; voltage regulating winding. Once operational; using the same solution method as in Section 3.1, the voltage and current waveforms during the voltage regulation process can be obtained as follows: Figure 15 As shown in the figure; from top to bottom, the waveforms are: primary voltage waveform, primary current waveform, secondary voltage waveform, secondary current waveform, voltage regulating winding waveform, and voltage regulating transition resistor current waveform.

[0088] a. in When the primary power supply voltage of the transformer drops, the control system, after data acquisition and processing, issues a signal that the voltage regulating winding needs to be disconnected. The instructions;

[0089] b. Locking out power electronic switches The trigger pulse, in the flow When the current is zero ( Figure 15 middle (Time) Naturally shut off, voltage regulation transition resistor Investment;

[0090] c. During periods without impact ( Figure 15 middle (At any time), to power electronic switches A trigger pulse is sent to close the voltage regulating winding. quit;

[0091] d. Interlocking power electronic switch and The trigger pulse, in the current When crossing zero ( Figure 15 middle At that moment, the two power electronic switches naturally turn off, and the voltage regulating winding... It returns to an unloaded state, preparing for the next voltage adjustment.

[0092] Towards Timing of the initial trigger pulse The determination needs to be solved based on the operating state equation of the voltage regulating system; since at this moment the voltage regulating winding... Voltage It is near zero, so it can be selected. The time corresponding to the zero crossing is The initial value is obtained by iteratively solving. .

[0093] In summary, the time-domain contactless on-load tap-changing transformer dynamic model of this invention uses Jiles-Atherton theory to solve the nonlinear problem caused by transformer core hysteresis and considers the abrupt change in transformer parameters caused by the switching of the tap-changing winding. The dynamic model is solved using the transmission line model (TLM) method, and the results are time-domain values. The dynamic model is suitable for studying the contactless on-load tap-changing process with transition resistance, and its tap changer is composed of thyristors. By selecting an appropriate thyristor switching time, impact-free tap-changing can be achieved, that is, the current and voltage waveforms remain continuous and smooth during the switching of the transition resistance and the tap-changing winding.

[0094] This invention provides a visualized on-load tap changer control system, equipment, and medium. In use, the invention employs a power electronic component (GTO) as the actuator for the on-load tap changer, utilizing its gate turn-off characteristic to achieve rapid tap switching, improving transformer voltage stability and the ability to start motors. The control device, based on single-chip microcomputer control technology, can safely and reliably control the GTO's conduction and turn-off, with fast data processing speed, high accuracy, and low power consumption. This invention offers advantages such as small size, frequent operation, fast response speed, and high safety, making it suitable for existing distribution transformers. The invention also includes a time-domain contactless on-load tap-changing transformer dynamic model. This model considers the nonlinearity caused by transformer core hysteresis and the changes in transformer parameters caused by winding variations during voltage regulation. Using this dynamic model, the on-load tap-changing process with transition resistance can be solved using the TLM method, determining the moment of impact-free voltage regulation. This dynamic model is also suitable for studying problems related to on-load tap-changing processes without transition resistance. This invention offers advantages such as automatic voltage regulation conversion, stable voltage, visualized and precise parameter setting, and impact-free voltage regulation.

[0095] Example 3

[0096] An electronic device includes a processor and a memory, the memory storing computer programs and / or instructions, which, when executed by the processor, realize the automatic voltage regulation switching function of the on-load tap changer based on the visualized on-load tap changer control system described above, and can also play a role in stabilizing the voltage.

[0097] As one possible implementation, a bus may also be included, which is used to connect the components.

[0098] The memory stores computer-executable programs / instructions; the processor executes the computer-executable programs / instructions stored in the memory.

[0099] The memory and processor are electrically connected directly or indirectly to enable data transmission or interaction. For example, these components can be electrically connected to each other through one or more communication buses or signal lines, such as bus connections. The memory stores computer-executable programs / instructions that implement data access control methods, including at least one software functional module that can be stored in the memory in the form of software or firmware. The processor executes various functional applications and data processing by running the software programs and modules stored in the memory.

[0100] The memory can be, but is not limited to, random access memory (RAM), read-only memory (ROM), programmable read-only memory (PROM), erasable read-only memory (EPROM), electrically erasable read-only memory (EEPROM), etc.; wherein, the memory is used to store programs, and the processor executes the programs / instructions after receiving them; furthermore, the software programs and modules in the aforementioned memory may also include an operating system, which may include various software components and / or drivers for managing system tasks (such as memory management, storage device control, power management, etc.), and can communicate with various hardware or software components to provide an operating environment for other software components.

[0101] The processor can be an integrated circuit chip with signal processing capabilities; the processor mentioned above can be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it can implement or execute the methods disclosed in the embodiments of this invention; the general-purpose processor can be a microprocessor or any conventional processor, etc.

[0102] Example 4

[0103] A computer-readable storage medium storing a computer program and / or instructions, which, when executed by a processor, realize the automatic voltage regulation switching function of the on-load tap changer based on the visualized on-load tap changer control system described above, and can also play a role in stabilizing the voltage.

[0104] The computer-readable storage medium is any available medium that a computing device can store, or a data storage device such as a server or data center that integrates one or more available media.

[0105] The available media can be magnetic media (e.g., floppy disks, hard disks, magnetic tapes), optical media (e.g., DVDs), or semiconductor media (e.g., solid-state drives).

[0106] Those skilled in the art will understand that all or part of the steps of the above-described method embodiments can be implemented by hardware related to program instructions. The aforementioned program / instructions can be stored in a computer-readable storage medium. When executed, the program / instructions perform the steps of the above-described method embodiments; and the aforementioned storage medium includes various media capable of storing program code, such as ROM, RAM, magnetic disks, or optical disks.

Claims

1. A visual on-load tap changer control system comprising a single-chip microcomputer control circuit, characterized in that: The single-chip microcomputer control circuit is connected with a signal processing circuit and a power supply circuit, the signal processing circuit is connected with a voltage zero-crossing detection circuit, a voltage sensor and a data acquisition unit, the voltage zero-crossing detection circuit, the voltage sensor, the data acquisition unit and the power supply circuit are connected with an isolation step-down transformer, the isolation step-down transformer is connected with a low-voltage side voltage of a distribution transformer, the single-chip microcomputer control circuit is further connected with a switch position sensor, a communication circuit, a switch driving circuit and a thyristor triggering circuit, and the communication circuit is connected with a remote computer through RS485 communication.

2. The visualized on-load tap changer control system of claim 1, wherein: The voltage zero-crossing detection circuit is composed of a photo-coupler 4N25 and a NAND gate 74LS00, and is used for sending an interrupt request to the single-chip microcomputer at the voltage zero-crossing point of the power grid by using the zero-crossing triggering characteristic of the thyristor, and sending a triggering signal to the thyristor triggering circuit to complete the effective conduction of the tap changer.

3. The visualized on-load tap changer control system of claim 2, wherein: The data acquisition unit adopts a 12-bit serial switched capacitor successive approximation analog-to-digital converter TLC2543 to complete data acquisition, acquires the alternating voltage on the secondary side of the distribution transformer after being stepped down by the isolation step-down transformer, and converts the alternating voltage into a direct current voltage signal through shaping, filtering and voltage division, and then converts the direct current voltage signal into a digital signal through the AD converter TLC2543 and inputs the digital signal into the signal processing circuit.

4. The visualized on-load tap changer control system of claim 3, wherein: The triggering circuit of the thyristor adopts a zero-crossing triggering circuit with an MOC3061 chip as the core, the MOC3061 is driven by the negative logic of an ULN2003, and the purpose of triggering the thyristor is achieved, and the triggering circuit of the thyristor adopts a gate turn-off thyristor.

5. The visualized on-load tap changer control system of claim 1, wherein: The single-chip microcomputer is bidirectionally connected with a reset circuit and a liquid crystal display, and the liquid crystal display adopts an LCM12864ZK liquid crystal display module.

6. The visualized on-load tap changer control system of claim 5, wherein: The single-chip microcomputer control circuit adopts a PIC16F877 single-chip microcomputer chip, the switch position detection circuit adopts 11 photoelectric coupling circuits connected with the PIC16F877, and is connected with a remote computer through a MAX485 communication interface to display the switch position.

7. The visualized on-load tap changer control system of claim 1, wherein: The system is a dynamic model-based non-contact on-load voltage regulating system, adopts a time-domain non-contact on-load voltage regulating transformer dynamic model, solves the on-load voltage regulating process containing a transition resistance through a TLM method, determines a non-shock voltage regulating time, and realizes non-shock voltage regulation.

8. The visualized on-load tap changer control system of claim 7, wherein: The time-domain non-contact on-load voltage regulating transformer dynamic model specifically includes the following steps: Step 1: transformer core dynamic model: a model is constructed based on the Jiles-Atherton theory for the magnetic hysteresis phenomenon of the transformer core; Step 2: TLM method for solving the dynamic transformer model: a TLM method, i.e., a transmission line model method, is used to solve the dynamic model, and the obtained result is a time-domain value; Step 3: dynamic on-load voltage regulating process: 3.1: regulating winding input process; 3.2: regulating winding exit process.

9. An electronic device, comprising: The processor and the memory are included, the memory stores a computer program and / or instructions, and the program and / or instructions are executed by the processor to realize the conversion function of the automatic voltage regulation of the on-load tap changer based on the visualized on-load voltage regulating tap changer control system according to any one of claims 1-8. 10.A computer readable storage medium storing a computer program and / or instructions, characterized in that: The program and / or instructions, when executed by the processor, implement the conversion function of the on-load tap changer automatic voltage regulation based on the visualization of the on-load tap changer control system according to any one of claims 1-8.

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