Low-voltage dynamic reactive compensation system of submerged arc furnace

Abstract

The invention provides a low-voltage dynamic reactive compensation system for a submerged arc furnace. The low-voltage dynamic reactive compensation system comprises a monitoring module, a control module, a compensation module, a protection module and a communication module. Through the multi-factor dynamic weight compensation algorithm, the system can comprehensively consider the power factor, the harmonic distortion rate and the voltage fluctuation rate, the compensation capacity is dynamically adjusted in real time, the problems of lag, over-compensation or under-compensation of a traditional static compensation system are avoided, the compensation precision and the response speed are remarkably improved, and the system reliability is improved. The grading design of the basic capacitor bank and the adjusting capacitor bank is combined with coarse adjustment and fine adjustment strategies, the load fluctuation can be quickly responded, the timeliness and accuracy of compensation are ensured, and the method is particularly suitable for the working condition that the load of the submerged arc furnace fluctuates severely. And the power grid stability, the equipment safety and the energy efficiency level are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of reactive power compensation, and in particular to a low-voltage dynamic reactive power compensation system for an ore-fired furnace. Background Art

[0002] As core, high-energy-consuming equipment in industries like metallurgy and chemical engineering, submerged arc furnaces generate large amounts of inductive reactive power during operation, significantly reducing the power factor of the power grid. This, in turn, increases line losses, raises electricity costs, and threatens grid stability. Traditional reactive power compensation systems, which often use fixed capacitor banks for static compensation, struggle to adapt to the drastic load fluctuations of submerged arc furnaces. These systems are prone to problems such as compensation lag, overcompensation, or undercompensation, impacting energy efficiency optimization and equipment safety. Furthermore, the harmonic distortion and voltage fluctuations associated with submerged arc furnace operation, if not effectively suppressed, can lead to potential hazards such as harmonic resonance and equipment overheating, further exacerbating grid pollution and shortening equipment life.

[0003] While some existing dynamic compensation schemes can adjust capacitor switching based on power factor, they generally lack comprehensive consideration of multiple factors, including harmonic content and voltage fluctuation, resulting in insufficient compensation accuracy or a single response strategy. With the increasing demand for industrial intelligence and green production, submerged arc furnaces are placing higher demands on the dynamic response speed, multi-objective optimization capabilities, and intelligence level of reactive power compensation systems. Therefore, there is an urgent need for a new reactive power compensation system that can comprehensively evaluate multiple parameters, including power factor, harmonic distortion, and voltage fluctuations, dynamically adjust compensation strategies, and provide efficient protection and remote collaborative control capabilities. This will improve grid quality, reduce energy consumption, and ensure the long-term safe operation of equipment. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the defects of the prior art. The present invention proposes a low-voltage dynamic reactive power compensation system for a submerged arc furnace.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is a low-voltage dynamic reactive power compensation system for an electric arc furnace, comprising a monitoring module, a control module, a compensation module, a protection module and a communication module; The detection module is used to collect parameters including but not limited to voltage, current, power factor, temperature and harmonic distortion rate in real time; The control module includes a PLC controller and a compensation algorithm unit. The PLC controller is used to receive data from the monitoring module and perform calculations and decisions according to a preset algorithm. The compensation algorithm unit is used to calculate the required compensation capacity, group capacitors, and control the switching of capacitors. The compensation algorithm unit adopts a multi-factor dynamic weight compensation algorithm, which comprehensively considers power factor, harmonic distortion rate, and voltage fluctuation rate, and dynamically corrects the compensation capacity. It first inputs the real-time power factor , target power factor , total harmonic distortion and voltage fluctuation rate , ,in is the voltage value measured in real time, is the nominal voltage value of the system; then perform compensation capacity correction calculation and calculate the initial compensation capacity: ,in is the active power of the submerged arc furnace, , , and The tangent values ​​corresponding to the real-time and target power factors are used to calculate the comprehensive compensation demand coefficient. ,in , is the dynamic weight coefficient, satisfying , dynamically adjust according to working conditions and correct compensation capacity ,when When the compensation capacity increases, When , the compensation capacity needs to be reduced; The compensation module includes a basic capacitor bank, a regulating capacitor bank, and a switching unit. The basic capacitor bank and the regulating capacitor bank are used to grade the compensation capacity, quickly adjust the coarse and fine adjustments, and provide capacitive reactive power for the system. The switching unit uses a vacuum contactor to control the connection and disconnection of the capacitor bank. The protection module is used to ensure the safe operation of the system and suppress harmonic resonance; The communication module is used for collaborative control and remote management between devices.

[0006] Furthermore, the detection module includes a sensor unit, a data acquisition unit, and a harmonic analysis unit. Its sensors include a voltage transformer, a current transformer, a power factor sensor, and a temperature sensor. The voltage transformer is used to collect the three-phase voltage signal on the low-voltage side of the submerged arc furnace. The current transformer is used to collect the three-phase current signal on the low-voltage side of the submerged arc furnace. The power factor sensor is used to measure the power factor of the submerged arc furnace in real time. The temperature sensor is used to monitor the temperature of key equipment including but not limited to capacitors and reactors in real time. The data acquisition unit is used to convert the analog signal collected by the sensor into a digital signal and then transmit it to the control module.

[0007] Furthermore, the protection module includes an overvoltage and overcurrent protection unit, a temperature protection unit and a resonance suppression unit. The overvoltage and overcurrent protection unit is used to automatically cut off the connection of the capacitor group to protect the safety of the equipment when the system voltage or current exceeds the set threshold; the temperature protection unit is used to issue an alarm and take corresponding protection measures when the temperature of equipment such as capacitors and reactors is too high; the resonance suppression unit is used to monitor the resonance of the system in real time, and once a resonance tendency is detected, the relevant capacitor group is quickly cut off.

[0008] Furthermore, the communication module includes an ad hoc network communication unit and a remote monitoring interface. The ad hoc network communication unit performs data interaction and collaborative control between the compensation units through ad hoc network wireless communication ZigBee or LoRa; the remote monitoring interface is used to communicate with the host computer or cloud platform to realize remote monitoring and management.

[0009] Furthermore, the capacity of the basic capacitor bank is allocated in equal proportions, and the formula is: , covering the main compensation needs, adjusting the capacitor bank capacity to the smallest unit , n is the group number, used for fine-tuning, then the basic capacity group capacity is ; When the load fluctuates times / minute, automatically merge and adjust capacitor groups into larger capacity groups, when the load fluctuates times / minute, the minimum unit is the recovery adjustment capacitor bank.

[0010] Furthermore, the switching control logic includes a coarse adjustment stage and a fine adjustment stage. Calculate the number of basic capacitor banks required ; Calculate the remaining compensation , calculate the number of regulating capacitor banks required in the fine-tuning stage .

[0011] Furthermore, the dynamic weight coefficient is adjusted according to the working conditions: , the weight distribution is ;when , the weight distribution is ; , the weight distribution is .

[0012] Furthermore, the switching unit is configured with an inertial switching mechanism: if the change in compensation demand is less than 30% of the capacity of the current activated group, the response is delayed by 1-3 seconds.

[0013] Furthermore, the switching unit is configured to record the switching times of each group, and the group with the least switching times is used first.

[0014] Furthermore, the basic capacitor group and the regulating capacitor group are connected to the system in parallel, and each group of capacitors is controlled to be switched on and off by an independent vacuum contactor.

[0015] Compared with the prior art, the beneficial effects of the present invention include: through a multi-factor dynamic weight compensation algorithm, the system can comprehensively consider the power factor, harmonic distortion rate and voltage fluctuation rate, and dynamically adjust the compensation capacity in real time to avoid the lag, over-compensation or under-compensation problems of the traditional static compensation system, significantly improving the compensation accuracy and response speed. The hierarchical design of the basic capacitor group and the regulating capacitor group, combined with the coarse adjustment and fine adjustment strategies, can quickly respond to load fluctuations and ensure the timeliness and accuracy of compensation. It is particularly suitable for working conditions where the load of the electric arc furnace fluctuates violently. The system records the number of times each group of capacitors is switched on and off, and gives priority to the group with fewer switching times. By regularly detecting the capacity attenuation and temperature anomalies of the capacitor group, the number of times each group is used is balanced, and the service life of the equipment is extended. The present invention effectively solves the problem of reactive compensation in the operation of the electric arc furnace, improves the stability of the power grid, equipment safety and energy efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The disclosure of the present invention is illustrated with reference to the accompanying drawings. It should be understood that the drawings are for illustrative purposes only and are not intended to limit the scope of protection of the present invention. In the accompanying drawings, the same reference numerals are used to refer to the same components. Among them: Figure 1 The module diagram of a low-voltage dynamic reactive power compensation system for an electric arc furnace according to one embodiment of the present invention is schematically shown. DETAILED DESCRIPTION

[0017] It is easy to understand that according to the technical solution of the present invention, without changing the essential spirit of the present invention, a person skilled in the art can propose a variety of interchangeable structural modes and implementation modes. Therefore, the following specific embodiments and drawings are only exemplary descriptions of the technical solution of the present invention and should not be regarded as the entire invention or as a limitation or restriction of the technical solution of the present invention.

[0018] According to one embodiment of the present invention, Figure 1 A low-voltage dynamic reactive power compensation system for an electric arc furnace is characterized by comprising a monitoring module, a control module, a compensation module, a protection module and a communication module.

[0019] The detection module is used to collect parameters including but not limited to voltage, current, power factor, temperature and harmonic distortion rate in real time. The detection module includes a sensor unit, a data acquisition unit and a harmonic analysis unit. Its sensors include voltage transformers, current transformers, power factor sensors and temperature sensors. The voltage transformer is used to collect the three-phase voltage signal on the low-voltage side of the submerged arc furnace. The current transformer is used to collect the three-phase current signal on the low-voltage side of the submerged arc furnace. The power factor sensor is used to measure the power factor of the submerged arc furnace in real time. The temperature sensor is used to monitor the temperature of key equipment including but not limited to capacitors and reactors in real time. The data acquisition unit is used to convert the analog signal collected by the sensor into a digital signal and then transmit it to the control module.

[0020] The control module includes a PLC controller and a compensation algorithm unit. The PLC controller is used to receive data from the monitoring module and perform calculations and decisions according to the preset algorithm. The compensation algorithm unit is used to calculate the required compensation capacity, group capacitors, and control the switching of capacitors. The compensation algorithm unit adopts a multi-factor dynamic weight compensation algorithm, which comprehensively considers the power factor, harmonic distortion rate, and voltage fluctuation rate, and dynamically corrects the compensation capacity. It first inputs the real-time power factor , target power factor , total harmonic distortion and voltage fluctuation rate , ,in is the voltage value measured in real time, is the nominal voltage value of the system; then perform compensation capacity correction calculation and calculate the initial compensation capacity: ,in is the active power of the submerged arc furnace, , , and The tangent values ​​corresponding to the real-time and target power factors are used to calculate the comprehensive compensation demand coefficient. ,in , is the dynamic weight coefficient, satisfying , dynamically adjust according to working conditions and correct compensation capacity ,when When the compensation capacity increases, for example, when the harmonics are serious, additional suppression capacity is required. When the voltage is too high, the compensation capacity needs to be reduced, for example, to avoid overcompensation; The compensation module includes a basic capacitor bank, a regulating capacitor bank and a switching unit. The basic capacitor bank and the regulating capacitor bank are used for graded compensation capacity, rapid coarse adjustment and fine adjustment, and provide capacitive reactive power for the system. The switching unit uses a vacuum contactor to control the connection and removal of the capacitor bank. The capacity of the basic capacitor bank is allocated in geometric proportion, and the formula is: , covering the main compensation needs, adjusting the capacitor bank capacity to the smallest unit , n is the group number, used for fine-tuning, then the basic capacity group capacity is ; When the load fluctuates times / minute, automatically merge and adjust capacitor groups into larger capacity groups, when the load fluctuates times / minute, the recovery adjustment capacitor bank is the smallest unit, the switching control logic includes the coarse adjustment stage and the fine adjustment stage, the coarse adjustment stage is based on Calculate the number of basic capacitor banks required ; Calculate the remaining compensation , calculate the number of regulating capacitor banks required in the fine-tuning stage ; The protection module is used to ensure the safe operation of the system and suppress harmonic resonance. The protection module includes an overvoltage and overcurrent protection unit, a temperature protection unit, and a resonance suppression unit. The overvoltage and overcurrent protection unit is used to automatically cut off the connection of the capacitor bank to protect the safety of the equipment when the system voltage or current exceeds the set threshold. The temperature protection unit is used to issue an alarm and take corresponding protective measures when the temperature of equipment such as capacitors and reactors is too high. The resonance suppression unit is used to monitor the resonance of the system in real time, and once a resonance tendency is detected, the relevant capacitor bank is quickly disconnected.

[0021] The communication module is used for collaborative control and remote management between devices; the communication module includes an ad hoc network communication unit and a remote monitoring interface. The ad hoc network communication unit conducts data exchange and collaborative control between compensation units through ad hoc network wireless communication ZigBee or LoRa; the remote monitoring interface is used to communicate with the host computer or cloud platform to realize remote monitoring and management.

[0022] Dynamic weight coefficient is adjusted according to working conditions: , the weight distribution is ;when , the weight distribution is ; , the weight distribution is ; The switching unit is configured with an inertial switching mechanism: if the change in compensation demand is less than 30% of the capacity of the currently activated group, the response will be delayed by 1-3 seconds; the number of switching times of each group is recorded, and the group with the least number of times is used is given priority; the capacity attenuation and temperature anomalies of the capacitor group are regularly detected, and the number of times each group is used is balanced according to the switching history to extend the life of the equipment; the basic capacitor group and the regulating capacitor group are connected to the system in parallel, and each capacitor group is controlled by an independent vacuum contactor.

[0023] Specifically, the sensor unit collects parameters such as voltage, current, power factor, temperature, and harmonic distortion rate on the low-voltage side of the submerged arc furnace in real time. The data acquisition unit converts the analog signal into a digital signal, and the harmonic analysis unit performs real-time analysis of the harmonics, ultimately transmitting the data to the control module. The PLC controller receives the data from the monitoring module and makes calculations and decisions based on a preset compensation algorithm. The compensation algorithm unit uses a multi-factor dynamic weighted compensation algorithm, comprehensively considering power factor, harmonic distortion rate, and voltage fluctuation rate, and dynamically corrects the compensation capacity. The basic capacitor bank and the regulating capacitor bank are used to grade the compensation capacity, respectively, for rapid coarse adjustment and fine tuning. The switching unit uses a vacuum contactor to control the connection and removal of the capacitor group. The capacity of the basic capacitor group is distributed in proportion, and the capacity of the capacitor group is adjusted to the smallest unit. It is automatically merged or restored to the smallest unit according to the load fluctuation frequency. The overvoltage and overcurrent protection unit automatically cuts off the capacitor group when the system voltage or current exceeds the set threshold; the temperature protection unit issues an alarm and takes protective measures when the equipment temperature is too high; the resonance suppression unit monitors the system resonance in real time and quickly removes the relevant capacitor group; the self-organizing network communication unit realizes data interaction and collaborative control between the compensation units through ZigBee or LoRa wireless communication; the remote monitoring interface communicates with the host computer or cloud platform to realize remote monitoring and management.

[0024] The technical scope of the present invention is not limited to the contents of the above description. Those skilled in the art can make various deformations and modifications to the above embodiments without departing from the technical idea of ​​the present invention, and these deformations and modifications should all fall within the protection scope of the present invention.

Claims

1. A low-voltage dynamic reactive power compensation system for a submerged arc furnace, characterized in that: Including monitoring module, control module, compensation module, protection module and communication module; The detection module is used to collect parameters including but not limited to voltage, current, power factor, temperature and harmonic distortion rate in real time; The control module includes a PLC controller and a compensation algorithm unit. The PLC controller is used to receive data from the monitoring module and perform calculations and decisions according to a preset algorithm. The compensation algorithm unit is used to calculate the required compensation capacity, group capacitors, and control the switching of capacitors. The compensation algorithm unit adopts a multi-factor dynamic weight compensation algorithm, which comprehensively considers power factor, harmonic distortion rate, and voltage fluctuation rate, and dynamically corrects the compensation capacity. It first inputs the real-time power factor , target power factor , total harmonic distortion and voltage fluctuation rate , ,in is the voltage value measured in real time, is the nominal voltage value of the system; Then perform compensation capacity correction calculation to calculate the initial compensation capacity: ,in is the active power of the submerged arc furnace, , , and The tangent values ​​corresponding to the real-time and target power factors are used to calculate the comprehensive compensation demand coefficient. ,in , is the dynamic weight coefficient, satisfying , dynamically adjust according to working conditions and correct compensation capacity ,when When the compensation capacity increases, When , the compensation capacity needs to be reduced; The compensation module includes a basic capacitor bank, a regulating capacitor bank, and a switching unit. The basic capacitor bank and the regulating capacitor bank are used to grade the compensation capacity, quickly adjust the coarse and fine adjustments, and provide capacitive reactive power for the system. The switching unit uses a vacuum contactor to control the connection and disconnection of the capacitor bank. The protection module is used to ensure the safe operation of the system and suppress harmonic resonance; The communication module is used for collaborative control and remote management between devices.

2. The low-voltage dynamic reactive power compensation system for a submerged arc furnace according to claim 1, characterized in that: The detection module includes a sensor unit, a data acquisition unit, and a harmonic analysis unit. Its sensors include a voltage transformer, a current transformer, a power factor sensor, and a temperature sensor. The voltage transformer is used to collect the three-phase voltage signal on the low-voltage side of the submerged arc furnace. The current transformer is used to collect the three-phase current signal on the low-voltage side of the submerged arc furnace. The power factor sensor is used to measure the power factor of the submerged arc furnace in real time. The temperature sensor is used to monitor the temperature of key equipment including but not limited to capacitors and reactors in real time. The data acquisition unit is used to convert the analog signal collected by the sensor into a digital signal and then transmit it to the control module.

3. The low-voltage dynamic reactive power compensation system for a submerged arc furnace according to claim 1, characterized in that: The protection module includes an overvoltage and overcurrent protection unit, a temperature protection unit, and a resonance suppression unit. The overvoltage and overcurrent protection unit is used to automatically cut off the connection of the capacitor bank to protect the safety of the equipment when the system voltage or current exceeds the set threshold; the temperature protection unit is used to issue an alarm and take corresponding protective measures when the temperature of equipment such as capacitors and reactors is too high; the resonance suppression unit is used to monitor the resonance of the system in real time, and once a resonance tendency is detected, the relevant capacitor bank is quickly disconnected.

4. The low-voltage dynamic reactive power compensation system for a submerged arc furnace according to claim 1, characterized in that: The communication module includes an ad hoc network communication unit and a remote monitoring interface. The ad hoc network communication unit conducts data exchange and collaborative control between compensation units through ad hoc network wireless communication ZigBee or LoRa; the remote monitoring interface is used to communicate with the host computer or cloud platform to realize remote monitoring and management.

5. The low-voltage dynamic reactive power compensation system for a submerged arc furnace according to claim 1, characterized in that: The capacity of the basic capacitor bank is allocated in equal proportions, and the formula is: , covering the main compensation needs, adjusting the capacitor bank capacity to the smallest unit , n is the group number, used for fine-tuning, then the basic capacity group capacity is ; When the load fluctuates times / minute, automatically merge and adjust capacitor groups into larger capacity groups, when the load fluctuates times / minute, the minimum unit is the recovery adjustment capacitor bank.

6. The low-voltage dynamic reactive power compensation system for a submerged arc furnace according to claim 5, characterized in that: The switching control logic includes a coarse adjustment stage and a fine adjustment stage. Calculate the number of basic capacitor banks required ; Calculate the remaining compensation , calculate the number of regulating capacitor banks required in the fine-tuning stage .

7. The low-voltage dynamic reactive power compensation system for a submerged arc furnace according to claim 1, characterized in that: The dynamic weight coefficient is adjusted according to the working conditions: , the weight distribution is ;when , the weight distribution is ; , the weight distribution is .

8. The low-voltage dynamic reactive power compensation system for a submerged arc furnace according to claim 1, characterized in that: The switching unit is configured with an inertial switching mechanism: if the change in compensation demand is less than 30% of the current activation group capacity, the response is delayed by 1-3 seconds.

9. The low-voltage dynamic reactive power compensation system for a submerged arc furnace according to claim 1, characterized in that: The switching unit is configured to record the switching times of each group, and the group with the least switching times is used first.

10. The low-voltage dynamic reactive power compensation system for a submerged arc furnace according to claim 1, characterized in that: The basic capacitor group and the regulating capacitor group are connected to the system in parallel, and each group of capacitors is controlled by an independent vacuum contactor for switching.

Images