A high-temperature superconducting phase modifier superconducting rotor quench segmented protection circuit

Abstract

The application discloses a high-temperature superconducting phase modifier superconducting rotor quench segmented protection circuit and belongs to the technical field of superconducting motors. The circuit comprises a grounding circuit Gnd, an excitation power supply DC, direct-current special thyristors D1-D2, superconducting coils L1-L6, a PLC that can be coded and the like. The internal logic of the PLC comprises a rising edge flip-flop, a comparison unit, a delay unit, a timer and the like. When a single or multiple superconducting coils of the superconducting rotor occur quench failure, the protection process is divided into two stages. In the first stage, the main loop switch between the superconducting coils of each pole and the excitation power supply is disconnected, and the commutation switch and the special direct-current circuit breaker are closed to shunt. In the second stage, the direct-current circuit breaker is disconnected, and the current is transferred to the energy-moving resistor to dissipate. The superconducting rotor quench segmented protection circuit can realize reliable protection of the superconducting coils under the working conditions of cooling system failure, electromagnetic interference impact and the like, maximally protects the safety of the superconducting phase modifier and prevents rotor quench failure from occurring or expanding.

Description

Technical Field

[0001] This invention belongs to the field of superconducting motor technology and relates to a high-temperature superconducting camera superconducting rotor quench segment protection circuit. Background Technology

[0002] With the rapid development of new power systems, the proportion of new energy sources such as wind power and photovoltaics has exceeded 35%. Consequently, the demand for voltage support and inertial response from synchronous condensers (SCDCs) in the power grid is increasing. Increasing the single-unit power capacity of SCDCs can significantly enhance their voltage support and inertial response capabilities, directly improving grid stability. Applying high-temperature superconducting tape to the rotor excitation windings of SCDCs can increase power density to more than five times that of traditional copper windings, representing a core path to achieving megawatt-level SCDCs. As early as 2003, AMSC in the United States put a ±8 Mvar superconducting SCDC into operation on the Tennessee grid, and the Guangdong power grid in my country completed a 300 kvar prototype verification in 2020. However, when encountering grid short circuits or cooling failures, superconducting coils can lose their superconducting characteristics within milliseconds. If protection is not timely, local hotspots will heat up at an extremely high rate, leading to winding burnout or even equipment explosion, becoming a current technical bottleneck for high-temperature superconducting SCDCs.

[0003] Domestic and international research institutions have conducted preliminary explorations into quench protection for superconducting tuners. Domestic scholars, such as Wang Qiang, have designed a composite sensor to monitor changes in the rotor's magnetic field and temperature, proposing a threshold-based early warning mechanism. Internationally, Johnson Michael's team has developed an active protection system based on the rate of change of magnetic flux, achieving rapid response to quench ingress in a small superconducting tuner rotor in a laboratory environment.

[0004] However, existing research mostly focuses on single-parameter monitoring or simple protection logic design, which is insufficient to cope with complex superconducting rotor quench faults such as cooling system failure and electromagnetic interference. At the same time, traditional protection schemes generally suffer from contradictory device performance issues, requiring the same device to have both low conduction loss and high breaking capacity. This leads to low system reliability and cannot prevent local quench from spreading to adjacent areas. Summary of the Invention

[0005] Purpose of the invention: This invention proposes a segmented protection circuit for superconducting rotor quenching in a high-temperature superconducting phase converter. It can reliably protect the superconducting coil under conditions such as cooling system failure and electromagnetic interference, solve the technical contradiction of balancing low conduction loss and high breaking capacity in a single device, and maximize the protection of equipment safety and prevent the occurrence or spread of rotor quenching faults.

[0006] Technical solution: The present invention proposes a high-temperature superconducting camera superconducting rotor quench protection circuit, including a grounding line Gnd, an excitation power supply DC, DC dedicated thyristors D1 to D2, a programmable logic controller PLC, multiple main circuit switches, multiple main circuit ammeters, multiple superconducting coils, and multiple protection circuit units. The grounding line Gnd is connected in series with the negative terminal of the excitation power supply DC. The DC dedicated thyristor D1 and DC dedicated thyristor D2 are connected in reverse parallel and then connected in parallel with the excitation power supply DC. The superconducting coils are connected in series, and the main circuit switch and the main circuit ammeter are connected in series between two adjacent superconducting coils. The protection circuit unit is connected in parallel across the two ends of the superconducting coil; The number of main circuit switches, main circuit ammeters, protection circuit units, and superconducting coils are all the same, and they correspond one-to-one. Each set of main circuit switches, main circuit ammeters, protection circuit units, and superconducting coils constitutes a unit module. The protection circuit unit includes a voltmeter, a converter circuit, a converter switch, and an energy-displacement resistor connected in parallel with the converter circuit; A voltmeter is connected in parallel across the two ends of the superconducting coil; The converter circuit and the converter switch are connected in series and then connected to both ends of the superconducting coil; The converter circuit includes a DC circuit breaker, a converter circuit ammeter, and a fuse connected in series; the DC circuit breaker is a TM30 model. The programmable logic controller (PLC) receives signals from all ammeters and voltmeters and outputs control signals to each switch, circuit breaker, and fuse.

[0007] Furthermore, when the PLC detects a quenching fault in the rotor of the high-temperature superconducting phase converter through the signal output by the voltmeter, the PLC controls the conduction of thyristors D1 and D2 to form a low-impedance path, short-circuiting the excitation power supply DC, and allowing the current to be discharged through the thyristor circuit.

[0008] Furthermore, the PLC detects a quench fault in the rotor of the high-temperature superconducting camera by the signal output from the voltmeter. Specifically, when the PLC receives the voltmeter signal rising from below 0.5V to above 0.5V, the rising edge trigger, which is initially set to 0, triggers and latches the signal. After a delay, the PLC outputs a rotor quench fault signal, which includes a first rotor quench fault signal and a second rotor quench fault signal.

[0009] Furthermore, the PLC inverts the first signal of the quench fault from each unit module and inputs it into an OR logic gate, then outputs control signal C1 to turn off the main circuit switch. The PLC inputs the quench fault signals of each unit module into the logic gate and outputs the control signal C2 to close the commutator switch.

[0010] Furthermore, the PLC executes a two-stage protection logic: First stage: When the output of the voltmeter in any unit module continuously exceeds the threshold voltage for a set duration, the SR latch is set; Second stage: When the output of the main circuit ammeter in any unit module is lower than the threshold current for a set duration, the SR latch is reset; The output signal of the SR latch is generated by an OR logic gate to generate a control signal C3, which controls the DC circuit breaker to close in the first stage and open in the second stage.

[0011] Furthermore, the PLC receives signals from the converter circuit ammeters in each protection circuit unit. When the current value of the converter circuit ammeter exceeds the upper limit threshold, the PLC sets the corresponding SR latch. The output signal of the SR latch corresponding to the ammeter of each converter circuit is passed through the OR logic gate to generate the control signal C4 to disconnect the fuse. After troubleshooting, the SR latch is reset via an external switch to allow manual closure of the fuse.

[0012] Furthermore, the main circuit switch adopts a high-current turn-off thyristor switch, which normally conducts the operating current and reliably turns off under low current through the gate turn-off signal.

[0013] Furthermore, both the converter switch and the DC circuit breaker adopt parallel enhanced IGBT modules to turn off large currents in the μs range.

[0014] Furthermore, in the event of a rotor quench fault, the main circuit switch is in a high-temperature or under-drive state, and the DC circuit breaker operates at a low temperature. The conduction voltage drop of the DC circuit breaker is significantly lower than that of the main circuit switch, and the current is actively distributed to the converter circuit to transfer the current on the main circuit switch in order to meet its breaking requirements.

[0015] Beneficial effects: This superconducting rotor quench segmented protection circuit uses thyristors to bear the continuous operating current of the equipment and IGBTs to realize the rapid transfer of rotor quench fault current, effectively solving the technical contradiction that a single power device cannot simultaneously achieve low conduction loss and high breaking capacity, and significantly improving the reliability of system operation; and by rapidly isolating and directionally discharging energy from the superconducting coil that has experienced a quench fault, it achieves electrical isolation of the superconducting coil that has not experienced a quench fault, effectively preventing the spread of local quench energy to adjacent areas, thereby maximizing equipment safety and suppressing the expansion of rotor quench fault.

[0016] (1) The superconducting rotor quench segment protection circuit can achieve the coordinated division of labor between thyristors and IGBTs. That is, the thyristor carries the main current with ultra-low conduction loss, and the IGBT quickly disconnects when the rotor quench fault occurs, thus avoiding the high cost problem caused by pursuing low loss and high breaking capacity of a single device at the same time.

[0017] (2) The two-stage protection mechanism can accurately cut off the rotor quench fault coil in a very short time. Combined with the segmented protection strategy, the quench energy diffusion range can be limited to the area around the rotor quench fault coil, reducing the temperature rise of adjacent coils and extending the equipment life. Attached Figure Description

[0018] Figure 1 This is a circuit diagram of the rotor segment protection circuit of the present invention; Figure 2 This is the PLC internal logic diagram of the rotor segment protection circuit of the present invention; Figure 3 This is a schematic diagram of the normal circuit current state of the rotor segment protection circuit of the present invention; Figure 4 This is a schematic diagram of the first stage of the rotor overrun fault state of the rotor segment protection circuit of the present invention. Figure 5 This is a schematic diagram of the second stage of the rotor overrun fault state of the rotor segment protection circuit of the present invention. Figure 6 This is the protection circuit and PLC internal logic diagram of the present invention. Detailed Implementation

[0019] like Figure 1 and 5 As shown, the high-temperature superconducting phase converter rotor overrun protection technology proposed in this invention includes a grounding line Gnd, an excitation power supply DC, DC dedicated thyristors D1~D2, superconducting coils L1~L6, main circuit switches SW1-1~SW1-6, converter switches SW2-1~SW2-6, dedicated DC circuit breakers CB1~CB6, fuses EF1~EF6, energy transfer resistors R1~R6, converter circuit ammeters A21~A26, main circuit ammeters A11~A16, voltmeters V1~V6, and a pre-coded PLC. The grounding line Gnd is connected in series with the negative terminal of the excitation power supply DC to establish a low impedance reference potential; The DC dedicated thyristor D1 and DC dedicated thyristor D2 are connected in reverse parallel and then connected in parallel with the excitation power supply DC to form a low impedance path in the event of a quench fault. Each dedicated DC circuit breaker is connected in series with a corresponding fuse and a corresponding converter circuit ammeter to form a converter circuit. Each converter switch is connected in series with its corresponding converter circuit, and each energy transfer resistor is connected in parallel with its corresponding converter circuit to form a protection circuit unit; The protection circuit unit consists of multiple units, which are connected in parallel to the two ends of each superconducting coil. Each superconducting coil is connected in series with the corresponding main circuit switch and the corresponding main circuit ammeter. Each voltmeter is connected in parallel to the two ends of each superconducting coil, forming a unit module. The unit modules are connected in series to form a chain structure, which is connected in series with the excitation power supply to form the main circuit. The encoded PLC directly controls each main circuit switch, each converter switch, each dedicated DC circuit breaker, and each fuse. The DC-specific thyristors D1 and D2 adopt a modular packaging structure. When the system detects a quench failure in the rotor of the high-temperature superconducting camera, the DC-specific thyristors D1 and D2 are quickly triggered to conduct, forming a low-impedance path. This short-circuits the excitation power supply DC, so that the DC current no longer flows through the superconducting coil, but is instead discharged through the short-circuit loop formed by the thyristors. The main circuit switch adopts a high-current turn-off thyristor switch, which can conduct a large current under normal conditions and can reliably turn off at low current through a gate turn-off signal. The protection circuit unit functions in the event of one or more faults; Both the converter switch and the dedicated DC circuit breaker adopt parallel enhanced IGBT modules, which can carry transient pulse large current and turn off large current in μs-level time. The main circuit switch operates at high temperature / insufficient drive during rotor quench faults, while the dedicated DC circuit breaker (TM30) operates at low temperature during rotor quench faults. The dedicated DC circuit breaker (TM30) has a significantly lower on-state voltage drop than the main circuit switch, actively distributing current to the converter circuit and diverting current from the main circuit switch to meet its breaking requirements. The dedicated DC circuit breaker (TM30) used in this invention supports front / rear board wiring and is retrofittable; rated current 500A; patented arc extinguishing technology, minimizing arc flash. like Figure 2 As shown, the encoded PLC can receive the current signal output by the ammeter and the voltage signal output by the voltmeter in the circuit. After logic operations, these signals are output as control signals, which control each switch. like Figure 2 As shown in (a), when a rotor quench fault occurs due to cooling system failure, electromagnetic interference, or other reasons, the coded PLC receives a voltage signal measured by a voltmeter that rises from below 0.5V to above 0.5V. The rising edge trigger, initially at 0, triggers and latches the signal. After a delay, it outputs the first rotor quench fault signal C11-C61 and the second rotor quench fault signal C12-C62. Figure 2As shown in (d), the rotor overrun fault first signals C11 to C61 of each unit module are inverted and input as an "OR" logic signal, and output as a control signal C1 to control the main circuit switch, which is disconnected in the event of a rotor overrun fault; the rotor overrun fault second signals C12 to C62 of each unit module are input as an "OR" logic signal, and output as a control signal C2 to control the converter switch, which is closed in the event of a rotor overrun fault.

[0020] like Figure 2 As shown in (b), when a rotor quench fault occurs due to cooling system failure, electromagnetic interference, or other reasons, the segmented protection circuit of the coded PLC executes the protection process: First stage: After the voltage signal output by each voltmeter is greater than 3V and the running time is greater than 0.05s, the set terminal of the SR latch is set; Second stage: After the current signal output by each main circuit ammeter is lower than 100A for a period of time, the reset terminal of the SR latch is set. Figure 2 As shown in (d), the third rotor overrun fault signal C13 to C63 output by the SR latch of each unit module is input into the "OR" logic signal, and the output control signal C3 controls the dedicated DC circuit breaker (TM30) so that it closes in the first stage and opens in the second stage when the rotor overrun fault occurs. like Figure 2 As shown in (c), when the current signal output by the converter circuit ammeter exceeds 400A, the coded PLC sets the SR latch. After troubleshooting, an external single-pole double-throw switch is manually used to set the SR latch's reset pin. Figure 2 As shown in (d), the fourth rotor overrun fault signal C14 to C64 output by the SR latch of each unit module is input into the "OR" logic, and the output control signal C4 controls the fuse so that the fuse opens when the converter circuit current exceeds 400A, and the fuse can be manually closed after the rotor overrun fault is cleared. During normal operation, the superconducting excitation coils L1 to L6 of the superconducting phase converter rotor are powered by the excitation power supply through the main circuit switch, and the current flow path is as follows: Figure 3 As shown.

[0021] When a quench fault occurs in a single or multiple superconducting excitation poles, the protection process is executed efficiently in two stages: The first stage rapidly disconnects the main circuit switch connecting each pole coil, and simultaneously closes the converter switch to form a converter circuit with the dedicated DC circuit breaker (TM30). The current flow path is as follows: Figure 4 As shown; in the second stage, the DC circuit breaker is disconnected, and the current is transferred to the energy transfer resistor for dissipation. The current flow path is as follows. Figure 5 As shown.

[0022] The above description is merely a preferred form of the superconducting camera of the present invention. The scope of protection of the present invention is not limited to the above-described form of the superconducting camera. Any equivalent modifications or variations made by those skilled in the art based on the disclosure of the present invention should be included within the scope of protection set forth in the claims.

Claims

1. A high-temperature superconducting camera superconducting rotor quench protection circuit, characterized in that: It includes grounding line Gnd, excitation power supply DC, DC dedicated thyristor D1~D2, programmable logic controller PLC, multiple main circuit switches, multiple main circuit ammeters, multiple superconducting coils, and multiple protection circuit units. The grounding line Gnd is connected in series with the negative terminal of the excitation power supply DC. The DC dedicated thyristor D1 and DC dedicated thyristor D2 are connected in reverse parallel and then connected in parallel with the excitation power supply DC. The superconducting coils are connected in series, and the main circuit switch and the main circuit ammeter are connected in series between two adjacent superconducting coils. The protection circuit unit is connected in parallel across the two ends of the superconducting coil; The number of main circuit switches, main circuit ammeters, protection circuit units and superconducting coils are all the same and correspond one-to-one. Each group of main circuit switches, main circuit ammeters, protection circuit units and superconducting coils constitutes a unit module. The unit modules are connected in series to form a chain structure, and this chain structure is connected in series with the excitation power supply to form the main circuit. The protection circuit unit includes a voltmeter, a converter circuit, a converter switch, and an energy-displacement resistor connected in parallel with the converter circuit; A voltmeter is connected in parallel across the superconducting coil. The converter circuit and the converter switch are connected in series and then connected in parallel across the superconducting coil. The converter circuit includes a DC circuit breaker, a converter circuit ammeter, and a fuse connected in series. The programmable logic controller (PLC) receives signals from all ammeters and voltmeters and outputs control signals to each switch, circuit breaker, and fuse.

2. The high-temperature superconducting camera superconducting rotor quench protection circuit according to claim 1, characterized in that, When the PLC detects a quenching fault in the rotor of the high-temperature superconducting phase converter through the signal output by the voltmeter, the PLC controls the thyristors D1 and D2 to conduct, forming a low-impedance path, short-circuiting the excitation power supply DC, and allowing the current to be discharged through the thyristor circuit.

3. The high-temperature superconducting camera superconducting rotor quench protection circuit according to claim 2, characterized in that, The PLC detects a rotor quenching fault in the high-temperature superconducting camera by the signal output from the voltmeter. Specifically, when the PLC receives the voltmeter signal rising from below 0.5V to above 0.5V, the rising edge trigger, which is initially set to 0, triggers and latches the signal. After a delay, the PLC outputs a rotor quenching fault signal, which includes a first rotor quenching fault signal and a second rotor quenching fault signal.

4. The high-temperature superconducting camera superconducting rotor quench protection circuit according to claim 3, characterized in that, The PLC inverts the first signal of the queuing fault from each unit module and inputs it into an OR logic gate, then outputs control signal C1 to turn off the main circuit switch. The PLC inputs the second signal of the quench fault of each unit module into the logic gate and outputs the control signal C2 to close the commutator switch.

5. The high-temperature superconducting camera superconducting rotor quench protection circuit according to claim 1, characterized in that, The PLC executes a two-stage protection logic: Phase 1: When the output of the voltmeter in any unit module continuously exceeds the threshold voltage for a set duration, the SR latch is set. Second stage: When the output of the main circuit ammeter in any unit module is lower than the threshold current and the set time is reached, the SR latch is reset. The output signal of the SR latch is generated into a control signal C3 through an OR logic gate, which controls the DC circuit breaker to close in the first stage and open in the second stage.

6. The high-temperature superconducting camera superconducting rotor quench protection circuit according to claim 1, characterized in that, The PLC receives signals from the converter circuit ammeters in each protection circuit unit. When the current value of the converter circuit ammeter exceeds the upper limit threshold, the PLC sets the corresponding SR latch. The output signal of the SR latch corresponding to the ammeter of each converter circuit is passed through the OR logic gate to generate the control signal C4 to disconnect the fuse. After troubleshooting, the SR latch is reset via an external switch to allow manual closure of the fuse.

7. The high-temperature superconducting camera superconducting rotor quench protection circuit according to claim 1, characterized in that, The main circuit switch adopts a high-current turn-off thyristor switch, which normally conducts the operating current and reliably turns off under low current through the gate turn-off signal.

8. The high-temperature superconducting camera superconducting rotor quench protection circuit according to claim 1, characterized in that, Both the converter switch and the DC circuit breaker use parallel enhanced IGBT modules to turn off large currents in the μs range.

9. The high-temperature superconducting camera superconducting rotor quench protection circuit according to claim 1, characterized in that, When the rotor fails to quench, the main circuit switch is in a high temperature or insufficient drive state, and the DC circuit breaker is operating at a low temperature. The conduction voltage drop of the DC circuit breaker is significantly lower than that of the main circuit switch. The current is actively distributed to the converter circuit, and the current on the main circuit switch is transferred to meet its breaking requirements.

10. The high-temperature superconducting camera superconducting rotor quench protection circuit according to claim 1, characterized in that, The DC circuit breaker is model TM30.

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