Electric furnace load electric energy quality treatment device based on star-connected chain type SVG (static var generator)
By using a star-connected SVG device and fiber optic connection control system, the power quality problem in electric furnace smelting was solved, the equipment footprint and cost were reduced, and load imbalance compensation and control system reliability were achieved.
Patent Information
- Application Number
- CN202520158125.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-23
- Publication Date
- 2026-01-30
- Estimated Expiration
- 2035-01-23
AI Technical Summary
Existing electric furnace smelting processes cause power quality problems such as excessive harmonics in the power grid, low power factor, voltage fluctuations, and flicker. In addition, traditional three-phase chain SVG devices have a large footprint and high cost.
The star-connected chain SVG device provides negative sequence and zero sequence current flow paths by connecting the secondary neutral point of the step-up transformer to the chain SVG branch in a star configuration. The control system, which is connected by optical fiber, reduces the equipment footprint and cost.
It achieves effective power quality management of electric furnace load, reduces equipment footprint and cost, and has load imbalance compensation function, improving the reliability and maintenance convenience of the control system.
Smart Images
Figure CN223858845U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to the technical field of electric energy quality treatment, especially relates to a kind of electric furnace load electric energy quality treatment device based on star-connected chain SVG. BACKGROUND
[0002] Compared with traditional steelmaking method, short process smelting technology represented by electric arc furnace steelmaking has higher furnace burden utilization rate, does not need to consume a large amount of fossil energy such as coal, and can reduce a large amount of waste gas emission, so it is beneficial to energy saving and environmental protection and reducing carbon emission and many other advantages.But the process of electric furnace smelting will produce frequent and sharp active power and reactive power impact on power supply network, resulting in a series of power quality problems such as harmonic overproof, serious low power factor, voltage fluctuation and flicker of power supply network.When the capacity of power supply network is small, the harmonic and flicker of public power network and other power quality problems may cause interference to the surrounding industrial users with high degree of automation, and even production accidents.Therefore, it is necessary to use electric energy quality comprehensive treatment device to comprehensively treat various electric energy quality problems in the operation process of electric furnace load, so as to ensure that the electric energy quality technical index of public power network meets the relevant requirements of national standard, and ensure the long-term safe and stable operation of power system.
[0003] The static var generator (hereinafter referred to as SVG) equipment based on full-controlled semiconductor power device is being widely used as electric furnace load electric energy quality treatment device because it can quickly and smoothly track the reactive power change of electric furnace load.But because of the three-phase imbalance characteristics of electric furnace load, the main one currently used is Figure 1 The DE three-phase chain SVG device based on angular connection topology structure has larger floor area and higher equipment cost. SUMMARY
[0004] The utility model aims at providing a kind of electric furnace load electric energy quality treatment device based on star-connected chain SVG, adopts star-connected chain SVG, effectively treats the electric energy quality in the operation process of electric furnace load, reduces the floor area of equipment.
[0005] To achieve the above-mentioned purpose, the utility model realizes through the following technical solutions:
[0006] The application discloses a star-connected chain SVG-based electric furnace load power quality treatment device, which comprises chain SVG branch a, chain SVG branch b and chain SVG branch c, one end of the chain SVG branch a, the chain SVG branch b and the chain SVG branch c is connected in series with a reactor, a soft start resistor and a power supply circuit breaker in sequence, the input end of the power supply circuit breaker is connected with the output end of the secondary side of a step-up transformer, a bypass contactor is connected in parallel with the soft start resistor, and the other end of the chain SVG branch a, the chain SVG branch b and the chain SVG branch c is connected in star mode; the power supply circuit breaker, the chain SVG branch a, the chain SVG branch b and the chain SVG branch c are connected with a control system respectively.
[0007] A voltage sensor and a current sensor are arranged between the reactor and the soft start resistor, the chain SVG branch a, the chain SVG branch b and the chain SVG branch c each comprise a plurality of SVG chain link modules connected in a head-tail mode, the SVG chain link module comprises an H-bridge power unit and a bypass unit connected in parallel with the H-bridge power unit, and the voltage sensor, the current sensor, the H-bridge power unit and the bypass unit are connected with the control system respectively.
[0008] The bypass unit comprises a bypass contactor, the bypass unit is used for short-circuiting a faulty H-bridge power unit, and the bypass contactor is connected with the control system.
[0009] The control system comprises a main control cabinet and a phase control cabinet, the main control cabinet and the phase control cabinet are connected through port optical fibers, and the A phase, the B phase and the C phase in the phase control cabinet are connected with the H-bridge power unit of the chain SVG branch a, the H-bridge power unit of the chain SVG branch b and the H-bridge power unit of the chain SVG branch c through port optical fibers.
[0010] The main control cabinet comprises an HMI man-machine interface, a PWM board one, a CPU board one, an analog quantity board and a digital quantity board, the HMI man-machine interface receives and displays signals of the control system, transmits the signals to the CPU board one and processes the signals through the CPU board one, the PWM board one is connected with a PWM board two of the phase control cabinet through optical fibers and is used for transmitting signals processed by the CPU board one to the phase control cabinet, the analog quantity board is connected with the voltage sensor and the current sensor through ports, and the digital quantity board is connected with the power supply circuit breaker through ports.
[0011] The phase control cabinet comprises the PWM board two, a CPU board two and a bus board, the PWM board two is connected with unit boards in the H-bridge power unit of the chain SVG branch a, the H-bridge power unit of the chain SVG branch b and the H-bridge power unit of the chain SVG branch c through interface optical fibers, the driving signals of the CPU board two and the signals of the CPU board one of the main control cabinet received by the PWM board two are transmitted to corresponding H-bridge power units, the bus board is connected with bypass boards in the corresponding H-bridge power units through port optical fibers, the bypass boards are connected with bypass contactors through port optical fibers, and the unit boards are connected with the bypass boards through port optical fibers.
[0012] The star connection of the other end of the chain SVG branch a, the chain SVG branch b and the chain SVG branch c is connected to the neutral point of the Y type connection of the secondary side of the step-up transformer through a disconnector, and a three-phase four-wire connection mode is formed.
[0013] The electric furnace load is connected to the primary side or the secondary side of the step-up transformer.
[0014] Compared with the prior art, the electric furnace load power quality treatment device has the advantages that:
[0015] 1. Compared with the angular chain SVG, the star chain SVG requires fewer power unit levels for the power valve group, reduces the equipment area and saves the cost.
[0016] 2. The neutral point of the star connection of the secondary side of the step-up transformer is connected to the input end of the disconnector, and the output end of the disconnector is connected to the star point of the chain SVG branch a, the chain SVG branch b and the chain SVG branch c, thereby forming a three-phase four-wire star connection topology, providing a closed path for the negative sequence and zero sequence current of the valve group (the valve group is composed of all power units in series), and enabling the star SVG device to realize the load unbalance compensation function.
[0017] 3. The disconnector can reliably disconnect the equipment during maintenance.
[0018] 4. The control system is connected to the chain SVG through an optical fiber, thereby improving the reliability of the control system, reducing the wiring, facilitating the maintenance and reducing the cost; the control system adopts a main control cabinet and a phase control cabinet, thereby facilitating the fault query and positioning. BRIEF DESCRIPTION OF DRAWINGS
[0019] Figure 1 is an electrical connection diagram of a conventional angular electric furnace load power quality treatment device.
[0020] Figure 2 is an electrical connection diagram of an electric furnace load power quality treatment device based on a star chain SVG Figure 1 .
[0021] Figure 3 is an electrical connection diagram of an electric furnace load power quality treatment device based on a star chain SVG Figure 2 .
[0022] Figure 4 is a signal connection schematic diagram of a power quality treatment device control system and primary equipment.
[0023] Figure 5 is a control system main control cabinet and phase control cabinet connection schematic diagram.
[0024] Figure 6 is the configuration diagram of the main control card of the card box.
[0025] Figure 7 is the configuration diagram of the card control card of the card box. DETAILED DESCRIPTION
[0026] The utility model will be described in detail below in conjunction with the drawings of the specification, but it should be pointed out that the implementation of the utility model is not limited to the following embodiments.
[0027] The following examples are implemented on the premise of the technical scheme of the utility model, and detailed implementation modes and specific operation processes are given, but the protection scope of the utility model is not limited to the following examples. The methods used in the following examples are all conventional methods unless otherwise specified.
[0028] Example 1
[0029] The existing three-phase chain SVG device of the corner joint topology structure is changed into the three-phase chain SVG device of the star joint topology structure, because the unit level of the same voltage grade corner joint equipment is 1.732 times of the star joint equipment, and the required power unit level of the power valve group of the star joint chain SVG is much less than that of the corner joint chain SVG. A furnace load power quality treatment device based on a star joint chain SVG, including chain SVG branch a, chain SVG branch b, chain SVG branch c, one end of the chain SVG branch a, the chain SVG branch b and the chain SVG branch c is connected in series with the reactor L, the soft start resistor R and the power supply circuit breaker QF in turn, the input end of the power supply circuit breaker QF is connected with the secondary side output end of the booster transformer T, and the other end of the chain SVG branch a, the chain SVG branch b and the chain SVG branch c is connected in star type; the star end of the chain SVG branch a, the chain SVG branch b and the chain SVG branch c is connected with the neutral point of the secondary side of the booster transformer T through the neutral line disconnector DS; the chain SVG branch a, the chain SVG branch b and the chain SVG branch c all include a plurality of SVG chain link modules connected in head and tail, the SVG chain link module includes an H-bridge power unit and a bypass unit connected in parallel with the H-bridge power unit, the bypass unit is used for short-circuiting the fault H-bridge power unit, the bypass unit includes a bypass contactor K, and the bypass contactor K is connected in parallel with the soft start resistor R; the voltage sensor and the current sensor are arranged between the reactor L and the soft start resistor R; the furnace load Electric furnace is connected with the primary side of the booster transformer T, as shown in Figure 2 , or the furnace load Electric furnace is connected with the secondary side of the booster transformer T, as shown in Figure 3 .
[0030] , as shown in Figures 4-6The control system comprises a main control cabinet and a phase control cabinet, the main control cabinet and the phase control cabinet are connected through port optical fibers, and A phase, B phase and C phase in the phase control cabinet are respectively connected with the H-bridge power unit of the chain SVG branch a, the H-bridge power unit of the chain SVG branch b and the H-bridge power unit of the chain SVG branch c through port optical fibers.
[0031] See Figure 4 , Figure 5 , Figure 7 The main control cabinet comprises an HMI man-machine interface, a PWM board one, a CPU board one, an analog quantity board and a digital quantity board, the HMI man-machine interface receives and displays signals of the control system, and transmits the signals to the CPU board one and processes the signals through the CPU board one, the PWM board one is connected with a PWM board two of the phase control cabinet through optical fibers, and is used for transmitting the signals processed by the CPU board one to the phase control cabinet, the analog quantity board is connected with voltage sensors and current sensors through ports, and the digital quantity board is connected with a power supply circuit breaker QF through a port.
[0032] The phase control cabinet comprises a PWM board two and a CPU board two, the PWM board two is connected with unit boards in the H-bridge power unit of the chain SVG branch a, the H-bridge power unit of the chain SVG branch b and the H-bridge power unit of the chain SVG branch c through interface optical fibers, and transmits the received control signals and driving signals of the CPU board one to the corresponding H-bridge power units. The CPU board two is connected with the PWM board two through a bus board, reads unit states and unit DC voltages of the corresponding H-bridge power units and uploads the signals to the HMI man-machine interface for display through a communication bus.
[0033] Working process
[0034] The normal operation control system closes the neutral point disconnector DS, and after the upper circuit breaker QF1 is closed, the device starts pre-charging soft start. When the minimum value of the DC voltage of each H-bridge power unit is greater than the set charging threshold, the device charging bypass contactor is closed to short the pre-charging resistor, and the device completes the soft start process. After that, each H-bridge power unit of the SVG device starts to operate, and the SVG device starts to compensate the electric furnace load. During operation, the HMI interface of the SVG device receives the device operation mode and control parameters set by the technical personnel and transmits them to the main control CPU board 1. At the same time, the analog board and the digital board collect the voltage, current and switch state signals of the power grid system and the electric furnace load. The above voltage, current and switch state signals are transmitted to the main control CPU board 1 for analysis and settlement, and the required reactive current instruction value, unbalanced current instruction value and harmonic current instruction value for the SVG device to compensate the electric furnace load are generated. The internal closed-loop control algorithm of the SVG device controls the output current of the device by collecting the SVG device output current signal, power grid voltage signal and DC voltage signal of each H-bridge power unit, and generates the control signal required for the device to compensate and operate. The main control PWM board 1 receives the control signal of the main control CPU board 1 and generates the IGBT drive signal of each H-bridge power unit, and transmits the IGBT drive signal of each H-bridge power unit to the phase control PWM board 2 through the optical fiber interface. The phase control PWM board 2 receives the IGBT drive signal of each H-bridge power unit of the main control PWM board 1 and forwards it to the corresponding H-bridge power unit control board. The H-bridge unit control board controls the action of each IGBT switch according to the corresponding IGBT drive signal, and finally makes the SVG device output the output current that meets the compensation requirements. Since the neutral point of the star-connected chain SVG is connected with the neutral point of the secondary side of the on-site main transformer or the step-up transformer, the star-connected chain SVG device has a closed loop for negative sequence and zero sequence current flow, so the star-connected device can effectively compensate the unbalanced electric furnace load. The phase control PWM board 2 also reads the running state data and DC voltage data of each H-bridge unit control board through optical fiber, and then outputs the above data to the phase control CPU board 2 through the bus board. The phase control CPU board 2 uploads the running state and DC voltage data of each H-bridge power unit to the HMI interface through the communication bus, which is used for displaying and monitoring the running state of each H-bridge power unit of the device. The output side of the H-bridge power unit is also connected with the unit bypass unit, which is used for automatically bypassing the faulty unit during the operation of the device, ensuring that the continuous operation of the device will not be affected by the failure of individual power units during normal operation, and ensuring the stability and reliability of long-term operation of the device.
[0035] Compared with the star-connected chain type SVG, the star-connected chain type SVG of the utility model needs much less power unit series of power valve group, reduces equipment floor space and saves cost; the neutral point of the star type connection of the secondary side of the step-up transformer is connected with the input end of the disconnecting switch, the output end of the disconnecting switch is connected with the star point of the chain type SVG branch a, the chain type SVG branch b and the chain type SVG branch c, and a three-phase four-wire star type connection topology is constituted, which provides a closed path for the negative sequence and zero sequence current circulation of the valve group (the valve group is composed of all power units in series), so that the star-connected SVG device can realize the load imbalance compensation function; the equipment can be reliably disconnected when the disconnecting switch is overhauled; the control system is connected with the chain type SVG through optical fibers, the reliability of the control system is improved, the wiring is less, maintenance is facilitated, and cost is reduced; the control system adopts a main control cabinet and a phase control cabinet, which facilitates fault inquiry and positioning.
Claims
1. A star-connected chain type SVG-based electric furnace load power quality treatment device, characterized in that, The chain SVG branch a, the chain SVG branch b and the chain SVG branch c are connected in series with the reactor, the soft start resistor and the power supply circuit breaker in sequence, the input end of the power supply circuit breaker is connected with the secondary side output end of the step-up transformer, the bypass contactor is connected in parallel with the soft start resistor, and the other ends of the chain SVG branch a, the chain SVG branch b and the chain SVG branch c are connected in star type; the power supply circuit breaker, the chain SVG branch a, the chain SVG branch b and the chain SVG branch c are connected with the control system respectively.
2. A star-connected chain type SVG based electric furnace load power quality management device according to claim 1, wherein, The voltage sensor and the current sensor are arranged between the reactor and the soft start resistor, the chain SVG branch a, the chain SVG branch b and the chain SVG branch c each comprise a plurality of SVG chain link modules connected in sequence, the SVG chain link module comprises an H-bridge power unit and a bypass unit connected in parallel with the H-bridge power unit, and the voltage sensor, the current sensor, the H-bridge power unit and the bypass unit are connected with the control system respectively.
3. A star-connected chain SVG-based electric furnace load power quality management device according to claim 2, characterized in that, The bypass unit comprises a bypass contactor, the bypass unit is used for short-circuiting the faulty H-bridge power unit, and the bypass contactor is connected with the control system.
4. A star-connected chain type SVG based electric furnace load power quality management device as claimed in claim 3 wherein, The control system comprises a main control cabinet and a phase control cabinet, the main control cabinet and the phase control cabinet are connected through port optical fibers, and the A phase, the B phase and the C phase in the phase control cabinet are connected with the H-bridge power unit of the chain SVG branch a, the H-bridge power unit of the chain SVG branch b and the H-bridge power unit of the chain SVG branch c through port optical fibers.
5. A star-connected chain SVG based electric furnace load power quality management device as claimed in claim 4 wherein, The main control cabinet comprises an HMI human-machine interface, a PWM board one, a CPU board one, an analog quantity board and a digital quantity board, the HMI human-machine interface receives and displays the signals of the control system, transmits the signals to the CPU board one and processes the signals through the CPU board one, the PWM board one is connected with a PWM board two of the phase control cabinet through optical fibers and is used for transmitting the signals processed by the CPU board one to the phase control cabinet, the analog quantity board is connected with the voltage sensor and the current sensor through ports, and the digital quantity board is connected with the power supply circuit breaker through ports.
6. A star-connected chain type SVG based electric furnace load power quality management device as claimed in claim 4 wherein, The phase control cabinet comprises the PWM board two, a CPU board two and a bus board, the CPU board two is connected with the PWM board two through the bus board, the PWM board two is connected with the unit boards in the H-bridge power unit of the chain SVG branch a, the H-bridge power unit of the chain SVG branch b and the H-bridge power unit of the chain SVG branch c through interface optical fibers, the driving signals of the CPU board two and the received CPU board one signals of the main control cabinet are transmitted to the corresponding H-bridge power units, the bus board is connected with the bypass boards in the corresponding H-bridge power units through port optical fibers, the bypass boards are connected with the bypass contactors through port optical fibers, and the unit boards are connected with the bypass boards through port optical fibers.
7. A star-connected chain type SVG based electric furnace load power quality management device as claimed in claim 1 wherein, The secondary side of the step-up transformer adopts Y type wiring, the neutral points of the star type connections of the other ends of the chain SVG branch a, the chain SVG branch b and the chain SVG branch c are connected with the neutral point of the Y type wiring of the secondary side of the step-up transformer through disconnectors, and a three-phase four-wire wiring mode is formed.
8. A star-connected chain type SVG based electric furnace load power quality management device as claimed in claim 1 wherein, The electric furnace load is connected with the primary side or the secondary side of the step-up transformer.