Transformer substation operation maintenance monitoring system and method based on PLC

Abstract

The invention discloses a PLC-based transformer substation operation maintenance monitoring system and method. The system comprises a high-voltage bus, a low-voltage bus, a transformer, a high-voltage side circuit breaker, a low-voltage side circuit breaker and a PLC control system. The high-voltage bus is electrically connected with the high-voltage side of the transformer through the high-voltage side circuit breaker, and the low-voltage bus is electrically connected with the low-voltage side of the transformer through the low-voltage side circuit breaker; a high-voltage transformer group and a high-current transformer group are arranged between the high-voltage side circuit breaker and the transformer to acquire three-phase current and three-phase voltage of the high-voltage bus; the low-voltage bus is provided with a low-voltage transformer group and a low-current transformer group which are used for acquiring three-phase current and three-phase voltage of the low-voltage bus; the signal ends of the high-voltage transformer group, the high-current transformer group, the low-voltage transformer group and the low-current transformer group are in transmission connection with the signal input end of the PLC control system; and the PLC control system automatically controls the switching on and switching off of the high-voltage side circuit breaker and the low-voltage side circuit breaker based on the three-phase current and the three-phase voltage of the high-voltage bus and the low-voltage bus.

Description

Technical Field

[0001] This invention relates to the field of substation monitoring technology, and in particular to a PLC-based substation operation and maintenance monitoring system and method. Background Technology

[0002] The operation and maintenance of substations involves troubleshooting faults to achieve repair and maintenance. Common troubleshooting methods include fault information collection, on-site inspection, equipment testing, and actual machine inspection. Fault troubleshooting identifies and locates abnormal behaviors during equipment operation, typically involving methods such as Fault Mode Recognition (FMR) and Fault Tree Analysis (FTA). However, the standardization of existing online monitoring devices is low; products from different manufacturers differ in interfaces, communication protocols, and data parsing, causing challenges for system integration and maintenance. Furthermore, after collecting data such as current, voltage, and temperature, manual or computer analysis is required, followed by manual adjustments to the switching on and off of various devices within the substation before maintenance. When substation equipment malfunctions, it is difficult to promptly shut down the equipment to protect downstream loads or circuits. Summary of the Invention

[0003] Purpose of the invention: In order to overcome the shortcomings of the existing technology, the present invention provides a PLC-based substation operation and maintenance monitoring system and method. The PLC control system automatically controls the closing and opening of the high-voltage side circuit breaker and the low-voltage side circuit breaker by collecting the three-phase voltage and three-phase current through voltage transformers and current transformers, thereby improving the early warning and protection capabilities of equipment faults.

[0004] Technical Solution: To achieve the above objectives, the present invention provides a PLC-based substation operation and maintenance monitoring system, comprising a high-voltage busbar, a low-voltage busbar, a transformer, a high-voltage side circuit breaker, a low-voltage side circuit breaker, and a PLC control system. The high-voltage busbar is electrically connected to the high-voltage side of the transformer via the high-voltage side circuit breaker, and the low-voltage busbar is electrically connected to the low-voltage side of the transformer via the low-voltage side circuit breaker. A high-voltage transformer group and a high-current transformer group are installed between the high-voltage side circuit breaker and the transformer to collect the three-phase current and three-phase voltage of the high-voltage busbar, respectively. A low-voltage transformer group and a low-current transformer group are installed on the low-voltage busbar to collect the three-phase current and three-phase voltage of the low-voltage busbar, respectively. The signal terminals of the high-voltage transformer group, the high-current transformer group, the low-voltage transformer group, and the low-current transformer group are all connected to the signal input terminals of the PLC control system. The PLC control system automatically controls the closing and opening of the high-voltage side circuit breaker and the low-voltage side circuit breaker based on the three-phase current and three-phase voltage of the high-voltage busbar and the low-voltage busbar.

[0005] Furthermore, the high-voltage busbar includes a high-voltage A-phase line, a high-voltage B-phase line, and a high-voltage C-phase line; the high-voltage transformer group includes a first high-voltage transformer, a second high-voltage transformer, and a third high-voltage transformer; the first high-voltage transformer collects the high-voltage AB-phase voltage, the second high-voltage transformer collects the high-voltage BC-phase voltage, and the third high-voltage transformer collects the high-voltage AC-phase voltage; the high-current transformer group includes a first high-current transformer, a second high-current transformer, and a third high-current transformer; the first high-current transformer, the second high-current transformer, and the third high-current transformer respectively collect the current of the high-voltage A-phase line, the high-voltage B-phase line, and the high-voltage C-phase line.

[0006] Furthermore, the low-voltage busbar includes a low-voltage A-phase line, a low-voltage B-phase line, and a low-voltage C-phase line; the low-voltage transformer group includes a first low-voltage transformer, a second low-voltage transformer, and a third low-voltage transformer; the first low-voltage transformer collects the low-voltage AB-phase voltage, the second low-voltage transformer collects the low-voltage BC-phase voltage, and the third low-voltage transformer collects the low-voltage AC-phase voltage; the low-current transformer group includes a first low-current transformer, a second low-current transformer, and a third low-current transformer; the first low-current transformer, the second low-current transformer, and the third low-current transformer respectively collect the current of the low-voltage A-phase line, the low-voltage B-phase line, and the low-voltage C-phase line.

[0007] Furthermore, it also includes a temperature and humidity sensor and a U5 touchscreen; the temperature and humidity sensor detects the temperature and humidity of the transformer; the signal terminal of the temperature and humidity sensor is connected to the signal input terminal of the PLC control system to transmit the detected temperature and humidity to the PLC control system; the U5 touchscreen is communicatively connected to the PLC control system, and the operation of the PLC control system can be controlled by inputting parameters on the U5 touchscreen.

[0008] Furthermore, the low-voltage bus is electrically connected to the input terminal of the switching power supply, and the output terminal of the switching power supply is electrically connected to the power input terminals of the high-voltage transformer group, the high-current transformer group, the low-voltage transformer group, the low-current transformer group, the temperature and humidity sensor, and the PLC control system.

[0009] Furthermore, the PLC control system includes an internal CPU, an analog signal expansion module, a start control module, a stop control module, a reset control module, an emergency stop control module, and an alarm module. The input terminal of the analog signal expansion module serves as the signal input terminal of the PLC control system, and the output terminal of the analog signal expansion module is electrically connected to the I / O port of the internal CPU. The I / O port of the internal CPU is electrically connected to the input terminals of the start control module, stop control module, reset control module, emergency stop control module, and alarm module to control the operation of the start control module, stop control module, reset control module, emergency stop control module, and alarm module.

[0010] Furthermore, a working method for a PLC-based substation operation and maintenance monitoring system includes the following steps:

[0011] Step 1: The PLC control system outputs a high-voltage bus closing signal to control the high-voltage side circuit breaker to close. At this time, the high-voltage transformer group and the high-current transformer group are used to collect the three-phase voltage and three-phase current of the high-voltage bus, and compare whether the voltages of the high-voltage AB phase voltage, the high-voltage BC phase voltage and the high-voltage AC phase voltage are consistent, and determine whether the currents of the high-voltage A phase line, B phase line and C phase line exceed the set threshold range.

[0012] Step 2: When the voltages of high-voltage phase AB, high-voltage phase BC, and high-voltage phase AC are consistent, and the currents of high-voltage phase A, phase B, and phase C do not exceed the set threshold range, the PLC control system outputs a low-voltage bus closing signal to control the low-voltage side circuit breaker to close; conversely, the PLC control system outputs a high-voltage bus disconnection signal to control the high-voltage side circuit breaker to disconnect, and controls the alarm module to sound an alarm.

[0013] Step 3: Use low-voltage transformer group and low-current transformer group to collect three-phase voltage and three-phase current of low-voltage bus; compare whether the voltages of low-voltage AB phase voltage, low-voltage BC phase voltage and low-voltage AC phase voltage are consistent, and determine whether the current of low-voltage A phase line, B phase line and C phase line exceeds the set threshold range.

[0014] Step 4: When the voltages of low-voltage AB phase, low-voltage BC phase, and low-voltage AC phase are consistent, and the currents of low-voltage A phase, B phase, and C phase lines do not exceed the set threshold range, no action is taken to complete the transformer startup operation; otherwise, the PLC control system outputs high-voltage busbar tripping signals and low-voltage busbar tripping signals to control the high-voltage side circuit breaker and the low-voltage side circuit breaker to trip, and controls the alarm module to sound an alarm.

[0015] Furthermore, when the transformer starts up, the high-voltage busbar, low-voltage busbar, and transformer in the substation are monitored in real time. The PLC control system controls the high-voltage transformer group and the high-current transformer group to collect the three-phase voltage and three-phase current of the high-voltage busbar, controls the low-voltage transformer group and the low-current transformer group to collect the three-phase voltage and three-phase current of the low-voltage busbar, and controls the temperature and humidity sensor to collect the temperature and humidity of the transformer. The PLC control system uses the three-phase voltage and three-phase current of the high-voltage busbar, the three-phase voltage and three-phase current of the low-voltage busbar, and the temperature and humidity of the transformer to determine whether a fault has occurred in the substation, and performs automatic control and alarm.

[0016] Beneficial Effects: This invention provides a PLC-based substation operation and maintenance monitoring system and method. Voltage transformers and current transformers are installed on both the low-voltage and high-voltage busbars to collect high-voltage three-phase voltage and current, as well as low-voltage three-phase voltage and current. The PLC control system automatically controls the closing and opening of high-voltage and low-voltage side circuit breakers based on the high-voltage and low-voltage three-phase voltage and current. This protects the transformer and downstream loads from damage due to abnormal three-phase voltage and current. Simultaneously, it provides real-time and accurate online monitoring of transformer voltage and current, and improves early warning capabilities for equipment faults by enhancing data acquisition and processing algorithms. Attached Figure Description

[0017] Figure 1 This is a circuit connection diagram for voltage transformers and current transformers on a high-voltage busbar.

[0018] Figure 2 This is a circuit connection diagram for voltage transformers and current transformers on a low-voltage busbar.

[0019] Figure 3 This is a circuit connection diagram for a switching power supply.

[0020] Figure 4 This is a flowchart of a PLC-based substation operation and maintenance monitoring system. Detailed Implementation

[0021] The invention will now be further described with reference to the accompanying drawings.

[0022] like Figure 1-2 As shown, a PLC-based substation operation and maintenance monitoring system includes a high-voltage busbar 1, a low-voltage busbar 5, a transformer 3, a high-voltage side circuit breaker 2, a low-voltage side circuit breaker 4, and a PLC control system. The high-voltage busbar 1 is electrically connected to the high-voltage side of the transformer 3 through the high-voltage side circuit breaker 2, and the low-voltage busbar 5 is electrically connected to the low-voltage side of the transformer 3 through the low-voltage side circuit breaker 4. A high-voltage transformer group and a high-current transformer group are installed between the high-voltage side circuit breaker 2 and the transformer 3 to collect data from the high-voltage busbar 1. Three-phase current and three-phase voltage; the low-voltage bus 5 is equipped with a low-voltage transformer group and a low-current transformer group to collect the three-phase current and three-phase voltage of the low-voltage bus 5 respectively; the signal terminals of the high-voltage transformer group, high-current transformer group, low-voltage transformer group and low-current transformer group are all connected to the signal input terminal of the PLC control system. The PLC control system automatically controls the closing and opening of the high-voltage side circuit breaker 2 and the low-voltage side circuit breaker 4 based on the three-phase current and three-phase voltage of the high-voltage bus 1 and the low-voltage bus 5.

[0023] like Figure 1As shown, the high-voltage busbar 1 includes a high-voltage A-phase line, a high-voltage B-phase line, and a high-voltage C-phase line; the high-voltage transformer group includes a first high-voltage transformer 14, a second high-voltage transformer 15, and a third high-voltage transformer 16; the first high-voltage transformer 14 collects the high-voltage AB-phase voltage, the second high-voltage transformer 15 collects the high-voltage BC-phase voltage, and the third high-voltage transformer 16 collects the high-voltage AC-phase voltage; the high-current transformer group includes a first high-current transformer 11, a second high-current transformer 12, and a third high-current transformer 13; the first high-current transformer 11, the second high-current transformer 12, and the third high-current transformer 13 respectively collect the current of the high-voltage A-phase line, the high-voltage B-phase line, and the high-voltage C-phase line.

[0024] like Figure 1-2 As shown, the low-voltage busbar 5 includes a low-voltage A-phase line, a low-voltage B-phase line, and a low-voltage C-phase line; the low-voltage transformer group includes a first low-voltage transformer 24, a second low-voltage transformer 25, and a third low-voltage transformer 26; the first low-voltage transformer 24 collects the low-voltage AB-phase voltage, the second low-voltage transformer 25 collects the low-voltage BC-phase voltage, and the third low-voltage transformer 26 collects the low-voltage AC-phase voltage; the low-current transformer group includes a first low-current transformer 21, a second low-current transformer 22, and a third low-current transformer 23; the first low-current transformer 21, the second low-current transformer 22, and the third low-current transformer 23 respectively collect the current of the low-voltage A-phase line, the low-voltage B-phase line, and the low-voltage C-phase line. The high-voltage A-phase line, high-voltage B-phase line, and high-voltage C-phase line are respectively the L1-phase line, L2-phase line, and L3-phase line in the figure; the low-voltage A-phase line, low-voltage B-phase line, and low-voltage C-phase line are respectively the R-phase line, S-phase line, and T-phase line in the figure.

[0025] Both the high-voltage and low-voltage transformers employ CHVS-EHV type voltage sensors. These voltage sensors are measurement modules that utilize the closed-loop fluxgate principle to convert the measured voltage into a voltage signal proportional to the original voltage. They feature high precision, high linearity, high integration, small size, simple structure, long-term stable operation, and adaptability to various working environments. Both the high-current and low-current transformers employ SHDL100 type current sensors. These are Hall effect open-loop current sensors capable of measuring DC, AC, and pulse currents. The primary and secondary circuits are completely insulated, achieving zero differential loss. Both the high-voltage and low-voltage busbars use ZR-YJV type cables, which are flame-retardant cross-linked polyethylene insulated cables.

[0026] It also includes a temperature and humidity sensor and a U5 touchscreen. The temperature and humidity sensor detects the temperature and humidity of the transformer. The signal terminal of the temperature and humidity sensor is connected to the signal input terminal of the PLC control system, transmitting the detected temperature and humidity to the PLC control system. The U5 touchscreen is communicatively connected to the PLC control system, allowing control of the PLC control system's operation by inputting parameters on the U5 touchscreen. The U5 touchscreen uses the KTP400 basic touchscreen, a human-machine interface (HMI) device based on Microsoft Windows CE software, equipped with a 4-inch display and conventional touch technology, suitable for small to medium-sized automation or IT integration environments. The temperature and humidity sensor is a DB130 electronically protected temperature and humidity sensor with a measurement range of 0-100%RH-40-120 degrees Celsius. It includes a temperature sensing element and a humidity sensing element, and its main working principle is based on the changes in the electrical characteristics of the temperature and humidity sensing elements to measure the ambient temperature and humidity.

[0027] The U5 touchscreen communicates with the PLC control system to form a communication loop. This loop is responsible for transmitting signals generated by the touchscreen to the PLC control system for instruction transmission and execution. It includes power supply, signal transmission, and interfaces. Signal transmission is the core of the U5 touchscreen's communication loop. When a user operates the U5 touchscreen, the touchscreen converts these operations into electrical signals. These signals are transmitted to the PLC control system through the communication loop, where they are processed to execute corresponding instructions. Power supply is fundamental to the touchscreen's communication loop, providing a stable power supply to the touchscreen. The touchscreen's power supply is typically connected through a dedicated power interface to ensure normal operation.

[0028] like Figure 3 As shown, the low-voltage bus 5 is electrically connected to the input terminal of the switching power supply 6, and the output terminal of the switching power supply 6 is electrically connected to the power input terminals of the high-voltage transformer group, the high-current transformer group, the low-voltage transformer group, the low-current transformer group, the temperature and humidity sensor, and the PLC control system; the switching power supply can store electrical energy.

[0029] The PLC control system includes an internal CPU, analog signal expansion module, start control module, stop control module, reset control module, emergency stop control module, and alarm module. The input terminals of the analog signal expansion modules serve as signal input terminals for the PLC control system, and their output terminals are electrically connected to the I / O ports of the internal CPU. The I / O ports of the internal CPU are electrically connected to the input terminals of the start control module, stop control module, reset control module, emergency stop control module, and alarm module, controlling their operation. The PLC control system controls the alarm module to issue an alarm, notifying personnel to perform maintenance.

[0030] The analog quantity expansion module converts the received high-voltage AB-phase, high-voltage AC-phase, and high-voltage BC-phase voltages into analog values, and converts the received currents of the high-voltage A-phase, high-voltage B-phase, and high-voltage C-phase lines into analog values. It also converts the received low-voltage AB-phase, low-voltage AC-phase, and low-voltage BC-phase voltages into analog values, and converts the received currents of the low-voltage A-phase, low-voltage B-phase, and low-voltage C-phase lines into analog values. Simultaneously, it converts the received temperature and humidity into analog values. By converting all collected three-phase voltages, three-phase currents, temperature, and humidity into analog values, it enables the monitoring and control of field equipment. The analog quantity expansion module can collect and analyze analog signals such as current and voltage in real time to determine the transformer's operating status, thus unifying all data and standardizing communication protocols and data parsing.

[0031] A working method for a PLC-based substation operation and maintenance monitoring system includes the following steps:

[0032] Step 1: The PLC control system outputs a high-voltage bus closing signal to control the high-voltage side circuit breaker 2 to close. At this time, the high-voltage transformer group and the high-current transformer group are used to collect the three-phase voltage and three-phase current of the high-voltage bus 1, and compare whether the voltages of the high-voltage AB phase voltage, the high-voltage BC phase voltage and the high-voltage AC phase voltage are consistent, and determine whether the currents of the high-voltage A phase line, B phase line and C phase line exceed the set threshold range.

[0033] Step 2: When the voltages of high-voltage phase AB, high-voltage phase BC, and high-voltage phase AC are consistent, and the currents of high-voltage phase A, phase B, and phase C do not exceed the set threshold range, the PLC control system outputs a low-voltage bus closing signal to control the low-voltage side circuit breaker 4 to close. Conversely, when the voltages of high-voltage phase AB, high-voltage phase BC, and high-voltage phase AC are inconsistent, or any current among the high-voltage phase A, phase B, and phase C exceeds the set threshold range, the PLC control system outputs a high-voltage bus tripping signal to control the high-voltage side circuit breaker 2 to trip, and controls the alarm module to sound an alarm.

[0034] Step 3: Use low-voltage transformer group and low-current transformer group to collect three-phase voltage and three-phase current of low-voltage bus 5; compare whether the voltages of low-voltage AB phase voltage, low-voltage BC phase voltage and low-voltage AC phase voltage are consistent, and determine whether the current of low-voltage A phase line, B phase line and C phase line exceeds the set threshold range.

[0035] Step 4: When the voltages of low-voltage phases AB, BC, and AC are consistent, and the currents in low-voltage phases A, B, and C do not exceed the set threshold range, no action is taken, and the current flows through the transformer, completing the transformer's startup operation. Conversely, when the voltages of low-voltage phases AB, BC, and AC are inconsistent, and any current in low-voltage phases A, B, and C exceeds the set threshold range, the PLC control system outputs high-voltage busbar tripping signals and low-voltage busbar tripping signals to control high-voltage side circuit breaker 2 and low-voltage side circuit breaker 4 to trip, and controls the alarm module to sound an alarm, notifying personnel to perform maintenance. When the transformer is running and needs to be stopped, the PLC control system outputs high-voltage busbar tripping signals and low-voltage busbar tripping signals to control high-voltage side circuit breaker 2 and low-voltage side circuit breaker 4 to trip, thereby stopping the transformer operation.

[0036] The analog signal expansion module converts phase voltage and phase line current into analog signal values. Based on the converted phase voltage values, it determines whether the high-voltage and low-voltage phase voltages are consistent. Based on the converted phase line current values, it determines whether the high-voltage and low-voltage phase line currents exceed set threshold ranges. Specifically, it compares the high-voltage AB phase voltage, high-voltage BC phase voltage, and high-voltage AC phase voltage for consistency, and compares the low-voltage AB phase voltage, low-voltage BC phase voltage, and low-voltage AC phase voltage for consistency. A safe voltage threshold range is set for the phase voltage. When the phase voltage is within the safe voltage threshold range, the analog signal expansion module outputs an analog signal value U to the internal CPU. When the phase voltage is below the minimum value of the safe voltage threshold, the analog signal expansion module outputs an analog signal value U- to the internal CPU. When the phase voltage is above the maximum value of the safe voltage threshold, the analog signal expansion module outputs an analog signal value U+ to the internal CPU.

[0037] When comparing whether the voltages of high-voltage phase AB, high-voltage phase BC, and high-voltage phase AC are consistent, the analog conversion values ​​of these voltages can be compared. If all three voltages are U (analog conversion value), then they are consistent. Conversely, if any one of these voltages is U- (analog conversion value) or U+ (analog conversion value), then they are inconsistent.

[0038] When comparing whether the voltages of low-voltage AB phase, low-voltage BC phase, and low-voltage AC phase are consistent, the analog conversion values ​​of the low-voltage AB phase, low-voltage BC phase, and low-voltage AC phase voltages can be compared. When all three voltages are U analog conversion values, then the voltages are consistent. Conversely, when any one of the voltages is U- or U+ analog conversion values, then the voltages are inconsistent.

[0039] Alternatively, another method can be proposed to compare whether the voltages of high-voltage phase AB, high-voltage phase BC, and high-voltage phase AC are consistent. This involves subtracting each pair of voltages in each phase to obtain three differences. Each of these three differences is then compared to a voltage difference threshold. If any one of the three differences exceeds the threshold, the voltages of the high-voltage phase AB, high-voltage phase BC, and high-voltage phase AC are inconsistent. If none of the three differences exceed the threshold, the voltages of the high-voltage phase AB, high-voltage phase BC, and high-voltage phase AC are consistent. The method for comparing whether the voltages of low-voltage phase AB, low-voltage phase BC, and low-voltage phase AC are consistent is the same as that for comparing the voltages of the high-voltage phase AB, high-voltage phase BC, and high-voltage phase AC.

[0040] The process involves determining whether the currents of the high-voltage A-phase, B-phase, and C-phase lines, as well as the low-voltage A-phase, B-phase, and C-phase lines, exceed a set threshold range. A set threshold range is established for the currents of both the high-voltage and low-voltage phase lines. When the phase line current is within the set threshold range, the analog quantity expansion module outputs an I-analog conversion value to the internal CPU. When the phase line current is below the minimum value of the set threshold range, the analog quantity expansion module outputs an I-analog conversion value to the internal CPU, indicating an undercurrent. When the phase line current is above the maximum value of the set threshold range, the analog quantity expansion module outputs an I+analog conversion value to the internal CPU, indicating an overcurrent. Specifically, when determining whether the currents of the high-voltage A-phase, B-phase, and C-phase lines exceed the set threshold range, if the converted analog quantity values ​​are both I-analog conversion values ​​and I+analog conversion values, the phase line current is determined to exceed the set threshold range. If the converted analog quantity value is only I, the phase line current is determined to be within the set threshold range.

[0041] When the current of any one of the high-voltage phase lines A, B, and C is equal to the I + analog conversion value, it is determined that the current of the high-voltage phase lines A, B, and C exceeds the set threshold range, indicating that the phase current is too large, and the high-voltage side circuit breaker should be controlled to trip. When the current of any one of the high-voltage phase lines A, B, and C is equal to the I - analog conversion value, it is determined that the current of the high-voltage phase lines A, B, and C exceeds the set threshold range, indicating that the phase current is too small, and the high-voltage side circuit breaker should be controlled to trip. When the current of all three high-voltage phase lines A, B, and C is equal to the I analog conversion value, it is determined that the current of the high-voltage phase lines A, B, and C does not exceed the set threshold range.

[0042] When the current in any one of the low-voltage phases A, B, and C is equal to the I + analog-to-analog conversion value, it is determined that the current in all three phases exceeds the set threshold range, indicating an excessive phase current. The high-voltage and low-voltage circuit breakers should then be tripped. When the current in any one of the low-voltage phases A, B, and C is equal to the I - analog-to-analog conversion value, it is determined that the current in all three phases exceeds the set threshold range, indicating an excessive phase current. The high-voltage and low-voltage circuit breakers should then be tripped. When the current in all three phases is equal to the I analog-to-analog conversion value, it is determined that the current in all three phases does not exceed the set threshold range.

[0043] like Figure 4 As shown, when transformer 3 starts running, it monitors the high-voltage bus 1, low-voltage bus 5, and transformer 3 in the substation in real time. The PLC control system controls the high-voltage transformer group and the high-current transformer group to collect the three-phase voltage and three-phase current of the high-voltage bus 1, controls the low-voltage transformer group and the low-current transformer group to collect the three-phase voltage and three-phase current of the low-voltage bus 5, and controls the temperature and humidity sensor to collect the temperature and humidity of the transformer. The PLC control system determines whether a fault has occurred in the substation by using the three-phase voltage and three-phase current of the high-voltage bus 1, the three-phase voltage and three-phase current of the low-voltage bus 5, and the temperature and humidity of the transformer 3, and performs automatic control and alarm.

[0044] The PLC control system determines whether a fault has occurred in the substation by measuring the three-phase voltage and current of the high-voltage busbar, the three-phase voltage and current of the low-voltage busbar, and the temperature and humidity of the transformer, and performs automated control and alarm functions; including the following steps:

[0045] Step 1-1: Collect the three-phase voltage and three-phase current of the high-voltage bus and the low-voltage bus, as well as the temperature and humidity of the transformer, through the high-voltage transformer group, high-current transformer group, low-voltage transformer group, low-current transformer group and temperature and humidity sensor.

[0046] Steps 1-2: Input historical data of three-phase voltage and three-phase current of high-voltage bus, three-phase voltage and three-phase current of low-voltage bus, and temperature and humidity of transformer into deep learning network for training to obtain transformer fault prediction model.

[0047] Steps 1-3: Real-time acquisition of three-phase voltage and three-phase current of the high-voltage bus and low-voltage bus, as well as transformer temperature and humidity, are input into the transformer fault prediction model to predict whether a fault will occur in the transformer in the future cycle. If a fault exists, the high-voltage side circuit breaker and the low-voltage side circuit breaker are automatically controlled to trip, the alarm module is controlled to sound an alarm, and the cause of the fault is analyzed and transmitted to the touch screen for easy maintenance by staff. If no fault exists, the collected data is recorded in real time for subsequent data analysis.

[0048] When the current in the high-voltage A-phase, B-phase, and C-phase lines exceeds the set threshold range, the transformer temperature is checked for an increase. If the transformer temperature rises and exceeds the temperature threshold, the PLC control system directly controls the high-voltage and low-voltage circuit breakers to trip and issues an alarm, without using the transformer fault prediction model. If the transformer temperature does not rise or does not exceed the temperature threshold, the collected voltage, current, temperature, and humidity data are input into the transformer fault prediction model to predict whether a fault has occurred. If a fault occurs, the high-voltage and low-voltage circuit breakers are tripped and an alarm is issued.

[0049] When the current in the low-voltage A-phase, B-phase, and C-phase lines exceeds the set threshold range, the transformer temperature is checked for an increase. If the transformer temperature rises and exceeds the temperature threshold, the PLC control system directly controls the high-voltage and low-voltage circuit breakers to trip and issues an alarm, without using the transformer fault prediction model. If the transformer temperature does not rise or does not exceed the temperature threshold, the collected voltage, current, temperature, and humidity data are input into the transformer fault prediction model to predict whether a fault has occurred. If a fault occurs, the high-voltage and low-voltage circuit breakers are tripped and an alarm is issued.

[0050] When the transformer temperature exceeds the set maximum temperature threshold, the PLC control system directly controls the high-voltage side circuit breaker and the low-voltage side circuit breaker to trip and issues an alarm. When the transformer humidity exceeds the set maximum humidity threshold, the PLC control system directly controls the high-voltage side circuit breaker and the low-voltage side circuit breaker to trip and issues an alarm. This is to prevent damage to the transformer and downstream loads caused by excessive temperature or humidity.

[0051] The analog signal expansion module converts temperature and humidity into analog values. Based on the converted temperature value, it determines whether the transformer temperature exceeds a set maximum temperature threshold; based on the converted humidity value, it determines whether the transformer humidity exceeds a set maximum humidity threshold. A maximum temperature threshold is set, which can be 80 degrees Celsius. When the temperature is below the maximum threshold, the analog signal expansion module outputs a QF analog value to the internal CPU; when the temperature is above the maximum threshold, it outputs a QZ analog value. If the temperature is a QF value, the transformer temperature is below the set maximum temperature threshold, and no operation is performed. If the temperature is a QZ value, the transformer temperature exceeds the set maximum temperature threshold, and the PLC control system directly controls the high-voltage and low-voltage circuit breakers to trip and issues an alarm.

[0052] The humidity is set with a maximum humidity threshold. When the humidity is below the maximum humidity threshold, the analog quantity expansion module outputs an SF analog quantity conversion value to the internal CPU. When the humidity is above the maximum humidity threshold, the analog quantity expansion module outputs an SZ analog quantity conversion value to the internal CPU. When the humidity is converted to an SF analog quantity conversion value, the transformer humidity does not exceed the set maximum humidity threshold, and no operation is performed. When the humidity is converted to an SZ analog quantity conversion value, the transformer humidity exceeds the set maximum humidity threshold, and the PLC control system directly controls the high-voltage side circuit breaker and the low-voltage side circuit breaker to trip and issues an alarm.

[0053] The above description is merely a preferred embodiment of the present invention. Those skilled in the art can make several modifications and optimizations based on the above disclosure without departing from the basic principles described above. These modifications and optimizations should be considered within the scope of protection as understood by the present invention.

Claims

1. A PLC-based substation operation and maintenance monitoring system, characterized by: The utility model relates to a kind of high-voltage transformer control system, including high-voltage bus (1), low-voltage bus (5), transformer (3), high-voltage side circuit breaker (2), low-voltage side circuit breaker (4) and PLC control system;The high-voltage bus (1) is electrically connected the high-voltage side of transformer (3) by high-voltage side circuit breaker (2), and low-voltage bus (5) is electrically connected the low-voltage side of transformer (3) by low-voltage side circuit breaker (4);High-voltage mutual inductor group and high-current mutual inductor group are arranged between the high-voltage side circuit breaker (2) and transformer (3), and three-phase current and three-phase voltage of high-voltage bus (1) are collected respectively;Low-voltage mutual inductor group and low-current mutual inductor group are arranged in low-voltage bus (5), and three-phase current and three-phase voltage of low-voltage bus (5) are collected respectively;The signal end of high-voltage mutual inductor group, high-current mutual inductor group, low-voltage mutual inductor group and low-current mutual inductor group is all transmitted and connected the signal input end of PLC control system, and PLC control system is based on three-phase current and three-phase voltage of high-voltage bus (1) and low-voltage bus (5) to automatically control the closing and opening of high-voltage side circuit breaker (2) and low-voltage side circuit breaker (4).

2. The PLC-based substation operation and maintenance monitoring system according to claim 1, characterized in that: The high-voltage bus (1) includes high-voltage A-phase line, high-voltage B-phase line and high-voltage C-phase line;The high-voltage mutual inductor group includes first high-voltage mutual inductor (14), second high-voltage mutual inductor (15) and third high-voltage mutual inductor (16);First high-voltage mutual inductor (14) collects high-voltage A B-phase voltage, second high-voltage mutual inductor (15) collects high-voltage BC-phase voltage, and third high-voltage mutual inductor (16) collects high-voltage A C-phase voltage;The high-current mutual inductor group includes first high-current mutual inductor (11), second high-current mutual inductor (12) and third high-current mutual inductor (13);The first high-current mutual inductor (11), second high-current mutual inductor (12) and third high-current mutual inductor (13) collect the current of high-voltage A-phase line, high-voltage B-phase line and high-voltage C-phase line respectively.

3. The PLC-based substation operation and maintenance monitoring system according to claim 1, characterized in that: The low-voltage bus (5) includes low-voltage A-phase line, low-voltage B-phase line and low-voltage C-phase line;The low-voltage mutual inductor group includes first low-voltage mutual inductor (24), second low-voltage mutual inductor (25) and third low-voltage mutual inductor (26);First low-voltage mutual inductor (24) collects low-voltage A B-phase voltage, second low-voltage mutual inductor (25) collects low-voltage BC-phase voltage, and third low-voltage mutual inductor (26) collects low-voltage A C-phase voltage;The low-current mutual inductor group includes first low-current mutual inductor (21), second low-current mutual inductor (22) and third low-current mutual inductor (23);The first low-current mutual inductor (21), second low-current mutual inductor (22) and third low-current mutual inductor (23) collect the current of low-voltage A-phase line, low-voltage B-phase line and low-voltage C-phase line respectively.

4. The PLC-based substation operation and maintenance monitoring system according to claim 1, characterized in that: It further includes temperature and humidity sensor and U5 touch screen;The temperature and humidity sensor detects the temperature and humidity of transformer;The signal end of temperature and humidity sensor is transmitted and connected the signal input end of PLC control system, and the temperature and humidity detected are transmitted to PLC control system, The U5 touch screen is connected with the PLC control system, and the operation of the PLC control system can be controlled by inputting parameters on the U5 touch screen.

5. The PLC-based substation operation and maintenance monitoring system according to claim 1, characterized in that: The low-voltage bus (5) is electrically connected with the input end of the switching power supply (6), and the output end of the switching power supply (6) is electrically connected with the power input end of the high-voltage transformer group, the high-current transformer group, the low-voltage transformer group, the low-current transformer group, the temperature and humidity sensor and the PLC control system.

6. The PLC-based substation operation and maintenance monitoring system according to claim 1, characterized in that: The PLC control system comprises an internal CPU, an analog quantity expansion module, a start control module, a stop control module, a reset control module, an emergency stop control module and an alarm module; the input end of the analog quantity expansion module is used as the signal input end of the PLC control system, and the output end of the analog quantity expansion module is electrically connected with the I / O port of the internal CPU; the I / O port of the internal CPU is electrically connected with the input end of the start control module, the stop control module, the reset control module, the emergency stop control module and the alarm module, and controls the operation of the start control module, the stop control module, the reset control module, the emergency stop control module and the alarm module.

7. The working method of the PLC-based substation operation and maintenance monitoring system according to claims 1-6, characterized in that: The method comprises the following steps: Step one: the PLC control system outputs a high-voltage bus closing signal to control the closing of the high-voltage side circuit breaker (2); at this time, the high-voltage transformer group and the high-current transformer group are used to collect the three-phase voltage and three-phase current of the high-voltage bus (1), and whether the high-voltage AB phase voltage, the high-voltage BC phase voltage and the high-voltage AC phase voltage are consistent and whether the current of the high-voltage A phase line, the high-voltage B phase line and the high-voltage C phase line exceeds the set threshold range are judged; Step two: when the high-voltage AB phase voltage, the high-voltage BC phase voltage and the high-voltage AC phase voltage are consistent, and the current of the high-voltage A phase line, the high-voltage B phase line and the high-voltage C phase line does not exceed the set threshold range, the PLC control system outputs a low-voltage bus closing signal to control the closing of the low-voltage side circuit breaker (4); otherwise, the PLC control system outputs a high-voltage bus opening signal to control the opening of the high-voltage side circuit breaker (2), and controls the alarm module to alarm; Step three: the low-voltage transformer group and the low-current transformer group are used to collect the three-phase voltage and three-phase current of the low-voltage bus (5); whether the low-voltage AB phase voltage, the low-voltage BC phase voltage and the low-voltage AC phase voltage are consistent and whether the current of the low-voltage A phase line, the low-voltage B phase line and the low-voltage C phase line exceeds the set threshold range are judged; Step four: when the low-voltage AB phase voltage, the low-voltage BC phase voltage and the low-voltage AC phase voltage are consistent, and the current of the low-voltage A phase line, the low-voltage B phase line and the low-voltage C phase line does not exceed the set threshold range, no action is performed to complete the start of the transformer; otherwise, the PLC control system outputs a high-voltage bus opening signal and a low-voltage bus opening signal to control the opening of the high-voltage side circuit breaker (2) and the low-voltage side circuit breaker (4), and controls the alarm module to alarm.

8. The PLC-based substation operation and maintenance monitoring system according to claim 7, characterized in that: When the transformer (3) starts to operate, the high-voltage bus (1), the low-voltage bus (5) and the transformer (3) in the transformer substation are monitored in real time; the PLC control system controls the high-voltage mutual inductor group and the high-current mutual inductor group to collect the three-phase voltage and the three-phase current of the high-voltage bus (1), controls the low-voltage mutual inductor group and the low-current mutual inductor group to collect the three-phase voltage and the three-phase current of the low-voltage bus (5), and controls the temperature and humidity sensor to collect the temperature and humidity of the transformer; the PLC control system judges whether the transformer substation has a fault through the three-phase voltage and the three-phase current of the high-voltage bus (1), the three-phase voltage and the three-phase current of the low-voltage bus (5) and the temperature and humidity of the transformer (3), and performs automatic control and alarm.

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