Redundancy control circuit and method for passive relay protection device

Abstract

The invention discloses a redundancy control circuit and method for a passive relay protection device, and belongs to the technical field of relay protection, and the control circuit comprises a current sampling loop, a main control chip, and a hardware redundancy overcurrent protection system. Wherein the current sampling loop is used for converting a three-phase current of a power grid into a sampling voltage signal and respectively inputting the sampling voltage signal into the main control chip and the hardware redundancy overcurrent protection system; the main control chip is used for realizing software protection of a power grid according to an input sampling voltage signal; and the hardware redundancy overcurrent protection system is used for realizing hardware redundancy protection of the power grid according to the input sampling voltage signal. According to the invention, based on the existing software protection process of the relay protection device, a redundant hardware protection loop is additionally designed, so that when a line fails, a software system can be effectively prevented from downtime.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of relay protection, more particularly to a passive type relay protection device redundancy control circuit and method. BACKGROUND

[0002] The relay protection technology is an important part of the power grid system protection, and plays an important role in the control and protection of primary equipment.

[0003] The passive relay protection control device is mostly used in remote and primary equipment environment without on-site power supply, but at present, the passive relay protection device mostly relies on a simple software system for protection. When a short-circuit fault occurs in the primary line of the power grid, the current rapidly rises above the rated limit value, and the protection action is completely dependent on the software setting of the device to cut off the circuit. Once the device software system is dead and cannot normally operate, the protection cut-off cannot be realized, which is easy to cause damage to the primary equipment and even threatens the safety of the entire power system.

[0004] Therefore, how to fully guarantee the safety of the passive relay protection device is an urgent problem to be solved in the field. SUMMARY

[0005] Therefore, the present application provides a passive type relay protection device redundancy control circuit and method, which can directly trigger the protection action and cut off the circuit to protect the power distribution line safety and realize the safe and stable operation of the system through detecting that the current exceeds the rated limit value at the hardware level.

[0006] In order to achieve the above purpose, the present application adopts the following technical scheme: The present application first discloses a passive type relay protection device redundancy control circuit, comprising: a current sampling circuit, a main control chip, and a hardware redundancy overcurrent protection system; wherein the current sampling circuit is used for converting the three-phase current of the power grid into a sampling voltage signal and inputting the sampling voltage signal into the main control chip and the hardware redundancy overcurrent protection system respectively; the main control chip is used for realizing the software protection of the power grid according to the input sampling voltage signal; and the hardware redundancy overcurrent protection system is used for realizing the hardware redundancy protection of the power grid according to the input sampling voltage signal.

[0007] Preferably, the hardware redundancy overcurrent protection system comprises a voltage threshold upper limit setting module, a voltage threshold lower limit setting module, a first comparator U2A, a second comparator U2B, a triode Q1, and an output circuit relay; wherein the input end of the voltage threshold upper limit setting module receives the sampling voltage signal, the output end of the voltage threshold upper limit setting module inputs the same direction input end of the first comparator U2A, and the reverse input end of the first comparator U2A is connected with a first reference voltage; The input terminal of the voltage threshold lower limit setting module receives the sampled voltage signal, and the output terminal of the voltage threshold lower limit setting module is input to the inverting input terminal of the second comparator U2B. The non-inverting input terminal of the second comparator U2B is connected to the second reference voltage. The output terminals of the first comparator U2A and the second comparator U2B are both connected to the base of transistor Q1; the emitter of transistor Q1 is grounded; the drain of transistor Q1 is connected to one end of the coil of the output circuit relay; the other end of the coil of the output circuit relay is connected to the 5V power supply voltage through resistor R17.

[0008] Preferably, a first variable resistor R13 is also connected between the inverting input terminal of the first comparator U2A and the first reference voltage.

[0009] Preferably, a second variable resistor R14 is also connected between the non-inverting input terminal of the second comparator U2B and the second reference voltage.

[0010] Preferably, the voltage threshold upper limit setting module includes a fourth diode D4, a fifth diode D5, and a sixth diode D6. The anode of the fourth diode D4 receives the first phase AC sampling voltage signal UoA, the anode of the fifth diode D5 receives the second phase AC sampling voltage signal UoB, and the anode of the sixth diode D6 receives the third phase AC sampling voltage signal UoC. The cathodes of the fourth diode D4, the fifth diode D5, and the sixth diode D6 are interconnected to form the output terminal of the voltage threshold upper limit setting module. The voltage threshold lower limit setting module includes a seventh diode D7, an eighth diode D8, and a ninth diode D9. The cathode of the seventh diode D7 receives the first phase AC sampling voltage signal UoA, the cathode of the eighth diode D8 receives the second phase AC sampling voltage signal UoB, and the cathode of the ninth diode D9 receives the third phase AC sampling voltage signal UoC. The anodes of the seventh diode D7, the eighth diode D8, and the ninth diode D9 are interconnected to form the output terminal of the voltage threshold lower limit setting module.

[0011] Preferably, diodes D4, D5, D6, D7, D8, and D9 are 1N4148W low-voltage drop diodes.

[0012] This invention also discloses a redundancy control method for a passive relay protection device, comprising the following steps: Step 1: Collect the three-phase current of the power grid and convert it into a sampling voltage signal; Step 2: Input the acquired sampling voltage signal into the main control chip to realize software system protection of current. Step 3: Input the collected sampling voltage signal into the hardware redundancy overcurrent protection system to realize hardware redundancy protection of the power grid.

[0013] Furthermore, the hardware redundant overcurrent protection system described in step 3 includes a voltage threshold upper limit setting module, a voltage threshold lower limit setting module, a first comparator U2A, a second comparator U2B, a transistor Q1, and an output circuit relay; wherein, the input terminal of the voltage threshold upper limit setting module receives the sampled voltage signal, the output terminal of the voltage threshold upper limit setting module is input to the non-inverting input terminal of the first comparator U2A, and the inverting input terminal of the first comparator U2A is connected to the first reference voltage; The input terminal of the voltage threshold lower limit setting module receives the sampled voltage signal, and the output terminal of the voltage threshold lower limit setting module is input to the inverting input terminal of the second comparator U2B. The non-inverting input terminal of the second comparator U2B is connected to the second reference voltage. The output terminals of the first comparator U2A and the second comparator U2B are both connected to the base of transistor Q1; the emitter of transistor Q1 is grounded; the drain of transistor Q1 is connected to one end of the coil of the output circuit relay; the other end of the coil of the output circuit relay is connected to the 5V power supply voltage through resistor R17.

[0014] Furthermore, a first variable resistor R13 is connected between the inverting input terminal of the first comparator U2A and the first reference voltage; at the same time, a second variable resistor R14 is connected between the non-inverting input terminal of the second comparator U2B and the second reference voltage.

[0015] Furthermore, the voltage threshold upper limit setting module includes a fourth diode D4, a fifth diode D5, and a sixth diode D6. The anode of the fourth diode D4 receives the first phase AC sampling voltage signal UoA, the anode of the fifth diode D5 receives the second phase AC sampling voltage signal UoB, and the anode of the sixth diode D6 receives the third phase AC sampling voltage signal UoC. The cathodes of the fourth diode D4, the fifth diode D5, and the sixth diode D6 are interconnected to form the output terminal of the voltage threshold upper limit setting module. The voltage threshold lower limit setting module includes a seventh diode D7, an eighth diode D8, and a ninth diode D9. The cathode of the seventh diode D7 receives the first phase AC sampling voltage signal UoA, the cathode of the eighth diode D8 receives the second phase AC sampling voltage signal UoB, and the cathode of the ninth diode D9 receives the third phase AC sampling voltage signal UoC. The anodes of the seventh diode D7, the eighth diode D8, and the ninth diode D9 are interconnected to form the output terminal of the voltage threshold lower limit setting module.

[0016] As can be seen from the above technical solution, compared with the prior art, the present invention discloses a passive relay protection device redundant control circuit and method, which has the following beneficial effects: This invention is based on the existing software protection process of relay protection devices, and adds an additional redundant hardware protection loop. When a line fault occurs, it can effectively prevent damage to primary equipment or even the power system caused by the software system crashing and being unable to perform overcurrent protection. The control method is simple and the system stability is significantly improved. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of a sampling circuit provided in an embodiment of the present invention.

[0019] Figure 2 A circuit diagram of a hardware redundancy overcurrent protection system provided for an embodiment of the present invention.

[0020] Figure 3 The main control chip provided in this embodiment of the invention provides sampling and control output.

[0021] Figure 4 The main control flowchart provided for embodiments of the present invention. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] This invention first discloses a passive relay protection device redundant control circuit, including: a current sampling circuit, a main control chip, and a hardware redundant overcurrent protection system; wherein, the current sampling circuit is used to convert the three-phase current of the power grid into sampled voltage signals and input them to the main control chip and the hardware redundant overcurrent protection system respectively; the main control chip is used to implement software protection of the power grid based on the input sampled voltage signals; the hardware redundant overcurrent protection system is used to implement hardware redundant protection of the power grid based on the input sampled voltage signals.

[0024] For details, please refer to Figure 1In the current sampling circuit, the three-phase currents A, B, and C pass through the sampling resistor and the voltage follower to convert the three-phase currents A, B, and C into corresponding sampling voltages U0 (U0A, U0B, U0C), which are then input into the main control chip and the main control circuit of the hardware redundant overcurrent protection system.

[0025] refer to Figure 2 The hardware redundant overcurrent protection system includes a voltage threshold upper limit setting module, a voltage threshold lower limit setting module, a first comparator U2A, a second comparator U2B, a transistor Q1, and an output circuit relay. The input terminal of the voltage threshold upper limit setting module receives the sampled voltage signal U0, and the output terminal of the voltage threshold upper limit setting module is input to the non-inverting input terminal of the first comparator U2A. The inverting input terminal of the first comparator U2A is connected to the first reference voltage.

[0026] The input terminal of the voltage threshold lower limit setting module receives the sampled voltage signal U0, and the output terminal of the voltage threshold lower limit setting module is input to the inverting input terminal of the second comparator U2B. The non-inverting input terminal of the second comparator U2B is connected to the second reference voltage.

[0027] The output terminals of the first comparator U2A and the second comparator U2B are both connected to the base of transistor Q1; the emitter of transistor Q1 is grounded; the drain of transistor Q1 is connected to one end of the coil of the output circuit relay; the other end of the coil of the output circuit relay is connected to the 5V power supply voltage through resistor R17.

[0028] In addition, a first variable resistor R13 is connected between the inverting input of the first comparator U2A and the first reference voltage, which is used to change the upper limit U of the first reference voltage. max Meanwhile, a second variable resistor R14 is also connected between the non-inverting input terminal of the second comparator U2B and the second reference voltage, used to change the lower limit U of the second reference voltage. minx In this invention, both the first reference voltage and the second reference voltage are set to 5V.

[0029] For details, please refer to Figure 2The upper voltage threshold setting module includes a fourth diode D4, a fifth diode D5, and a sixth diode D6. The anode of the fourth diode D4 receives the first phase AC sampling voltage signal UoA, the anode of the fifth diode D5 receives the second phase AC sampling voltage signal UoB, and the anode of the sixth diode D6 receives the third phase AC sampling voltage signal UoC. The cathodes of the fourth diode D4, the fifth diode D5, and the sixth diode D6 are interconnected to form the output terminal of the upper voltage threshold setting module. Simultaneously, the lower voltage threshold setting module includes a seventh diode D7, an eighth diode D8, and a ninth diode D9. The cathode of the seventh diode D7 receives the first phase AC sampling voltage signal UoA, the cathode of the eighth diode D8 receives the second phase AC sampling voltage signal UoB, and the cathode of the ninth diode D9 receives the third phase AC sampling voltage signal UoC. The anodes of the seventh diode D7, the eighth diode D8, and the ninth diode D9 are interconnected to form the output terminal of the lower voltage threshold setting module.

[0030] like Figure 3 After the main control chip acquires the voltage values ​​U0 (U0A, U0B, U0C) of the three-phase current samples A, B, and C, it performs software system protection.

[0031] In this invention, the main control chip uses an existing internal threshold judgment method to determine abnormalities in the current sampling value and outputs a relay control signal, thereby realizing software protection for the passive relay protection control device.

[0032] In the implementation of this invention, while the main control chip performs software protection, the main control loop of the hardware redundant overcurrent protection system can simultaneously perform hardware-level system protection. The overcurrent protection current value range at the hardware system level is slightly larger than the protection current value range at the software system level.

[0033] This invention also discloses a redundancy control method for a passive relay protection device, the overall control flow of which is referenced below. Figure 4 This includes the following steps: Step 1: As Figure 1 As shown, in the current sampling circuit, the input three-phase currents A, B, and C pass through the sampling resistor and the voltage follower to convert the collected currents into corresponding sampling voltages U0 (U0A, U0B, U0C), which are then input into the main control chip and the main control circuit of the hardware redundant overcurrent protection system.

[0034] Step 2: As Figure 3 After the main control chip acquires the voltage values ​​U0 (U0A, U0B, U0C) of the three-phase current sampling of A, B, and C, it performs software system protection. At the same time, the main control circuit of the hardware redundant overcurrent protection system synchronously performs hardware-level system protection. The overcurrent protection current value range of the hardware system is slightly larger than that of the software system protection current value range.

[0035] Step 3: In the event of a main chip system failure, the main control circuit of the hardware redundancy overcurrent protection system will activate its protective action. The hardware redundancy overcurrent protection system, as shown in the example... Figure 2 As shown, the sampled voltages U0 (U0A, U0B, U0C) are input to the overcurrent protection system circuit. This protection circuit uses a 5V reference voltage as input and variable resistors R13 and R14 to set the upper limit Umax and lower limit Umin of the voltage threshold. The circuit uses comparators U2 (U2A, U2B) to convert the input sampled voltage U0 (U0A, U0B, U0C) into a single voltage. 0A U 0B U 0C The input three-phase sampling voltage U0 is compared with the voltage thresholds Umax and Umin. 0A U 0B U 0C The wave is a sinusoidal wave, therefore the peak U within the period is... 0max With the upper limit of the protection voltage threshold U max Comparison, trough U 0min Compared to the lower limit of the protection voltage threshold Umin, when all values ​​of the sampled voltage U0 within the sinusoidal period are within the protection voltage threshold range, comparators U2 (U2A, U2B) do not output voltage, transistor Q1 is not turned on, and protection is not triggered. When the sampled voltage U0 exceeds the upper limit of the protection voltage threshold Umax or falls below the lower limit Umin, the protection is triggered. min At this time, the comparator outputs a 5V voltage, and the transistor Q1 conducts after being energized by the voltage, driving the output circuit relay K1 to close the circuit and disconnect the primary circuit, thereby achieving overcurrent protection at the hardware level.

[0036] In the hardware redundant overcurrent protection system, diodes D4, D5, D6, D7, D8, and D9 are all 1N4148W low-dropout diodes, which have stronger conduction capability, lower forward voltage drop, less input voltage loss, and improved sampling voltage input accuracy. R13 and R14 are variable resistors. This hardware redundant overcurrent protection system circuit uses a 5V reference voltage input and the variable resistors R13 and R14; adjusting the values ​​of these two variable resistors changes the upper limit U of the reference voltage. max and lower limit U min The reference voltage threshold can be flexibly changed according to different protection needs. The circuit uses comparators U2 (U2A, U2B) to convert the input sampling voltage U0 (U 0A U 0B U 0C ) and voltage threshold U max U min The comparison is made because the input three-phase sampling voltage U0(U 0A U 0B U 0CThe wave is a sinusoidal wave, therefore the peak U within the period is... 0max With the upper limit of the protection voltage threshold U max Comparison, trough U 0min With the lower limit of the protection voltage threshold U min For comparison, when the sampled voltage U0 is within the protection voltage threshold range for all values ​​within the sinusoidal period, comparators U2 (U2A, U2B) do not output voltage, transistor Q1 is not turned on, and protection is not triggered. When the sampled voltage U0 exceeds the upper limit of the protection voltage threshold U... max Or below the lower threshold U min At this time, the comparator outputs a 5V voltage, and the transistor Q1 conducts after being energized by the voltage. The transistor Q1 is an NPN surface-mount silicon power switching transistor, which has the characteristics of higher reliability, low saturation voltage drop and fast switching. It avoids malfunctions and can respond faster, thereby driving the output circuit HF115 high-reliability relay K1 to quickly close the circuit and disconnect the primary circuit, thus realizing overcurrent protection at the hardware level.

[0037] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0038] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A passive type relay protection device redundancy control circuit, characterized by, The application relates to a current sampling circuit, a main control chip and a hardware redundant overcurrent protection system, wherein the current sampling circuit is used for converting three-phase currents of a power grid into sampling voltage signals and inputting the sampling voltage signals into the main control chip and the hardware redundant overcurrent protection system respectively; the main control chip is used for realizing software protection of the power grid according to the input sampling voltage signals; and the hardware redundant overcurrent protection system is used for realizing hardware redundant protection of the power grid according to the input sampling voltage signals. The hardware redundant overcurrent protection system comprises a voltage threshold upper limit setting module, a voltage threshold lower limit setting module, a first comparator U2A, a second comparator U2B, a triode Q1 and an output circuit relay; wherein the input end of the voltage threshold upper limit setting module receives the sampling voltage signal, the output end of the voltage threshold upper limit setting module inputs the same direction input end of the first comparator U2A, and the reverse direction input end of the first comparator U2A is connected with a first reference voltage; 2. The passive redundancy control circuit for a protective relay according to claim 1, wherein The input end of the voltage threshold lower limit setting module receives the sampling voltage signal, the output end of the voltage threshold lower limit setting module inputs the reverse direction input end of the second comparator U2B, and the same direction input end of the second comparator U2B is connected with a second reference voltage; The output ends of the first comparator U2A and the second comparator U2B are connected with the base of the triode Q1; the emitter of the triode Q1 is grounded; one end of the coil of the output circuit relay is connected with the drain of the triode Q1; and the other end of the coil of the output circuit relay is connected with a 5V power voltage through a resistor R17. The reverse direction input end of the first comparator U2A and the first reference voltage are further connected with a first variable resistor R13.

3. The passive redundancy control circuit for a protective relay according to claim 2, wherein The same direction input end of the second comparator U2B and the second reference voltage are further connected with a second variable resistor R14.

4. The passive redundant control circuit for a protective relay according to claim 2, wherein The voltage threshold upper limit setting module comprises a fourth diode D4, a fifth diode D5 and a sixth diode D6, the anode of the fourth diode D4 receives a first-phase alternating current sampling voltage signal UoA, the anode of the fifth diode D5 receives a second-phase alternating current sampling voltage signal UoB, the anode of the sixth diode D6 receives a third-phase alternating current sampling voltage signal UoC, the cathodes of the fourth diode D4, the fifth diode D5 and the sixth diode D6 are connected with each other to form the output end of the voltage threshold upper limit setting module; 5. The passive redundant control circuit for a protective relay according to claim 2, wherein The voltage threshold lower limit setting module comprises a seventh diode D7, an eighth diode D8 and a ninth diode D9, the cathode of the seventh diode D7 receives the first-phase alternating current sampling voltage signal UoA, the cathode of the eighth diode D8 receives the second-phase alternating current sampling voltage signal UoB, the cathode of the ninth diode D9 receives the third-phase alternating current sampling voltage signal UoC, the anodes of the seventh diode D7, the eighth diode D8 and the ninth diode D9 are connected with each other to form the output end of the voltage threshold lower limit setting module. The diodes D4, D5, D6, D7, D8 and D9 are 1N4148W low-voltage drop diodes.

6. The passive redundant control circuit for a protective relay according to claim 5, wherein, The application further discloses a method for realizing the hardware redundant overcurrent protection system.

7. A passive type relay protection device redundancy control method, characterized by, Step 1: converting three-phase currents of a power grid into sampling voltage signals; Step 2: inputting the collected sampling voltage signals into a main control chip to realize software system protection of the currents; ​ Step 3: input the collected sampling voltage signal into the hardware redundancy overcurrent protection system to realize hardware redundancy protection of the power grid.

8. The passive redundancy control method of claim 7, wherein, The hardware redundancy overcurrent protection system in step 3 comprises a voltage threshold upper limit setting module, a voltage threshold lower limit setting module, a first comparator U2A, a second comparator U2B, a triode Q1, and an output loop relay; wherein the input end of the voltage threshold upper limit setting module receives the sampling voltage signal, the output end of the voltage threshold upper limit setting module inputs the same direction input end of the first comparator U2A, and the reverse input end of the first comparator U2A is connected with a first reference voltage; the input end of the voltage threshold lower limit setting module receives the sampling voltage signal, the output end of the voltage threshold lower limit setting module inputs the reverse input end of the second comparator U2B, and the same direction input end of the second comparator U2B is connected with a second reference voltage; the output ends of the first comparator U2A and the second comparator U2B are both connected with the base of the triode Q1; the emitter of the triode Q1 is grounded; the drain of the triode Q1 is connected with one end of the coil of the output loop relay; the other end of the coil of the output loop relay is connected with a 5V power supply voltage through a resistor R17.

9. The passive redundancy control method of claim 8, wherein, the reverse input end of the first comparator U2A and the first reference voltage are further connected with a first variable resistor R13; at the same time, the same direction input end of the second comparator U2B and the second reference voltage are further connected with a second variable resistor R14.

10. The passive redundancy control method of claim 8, wherein, the voltage threshold upper limit setting module comprises a fourth diode D4, a fifth diode D5, and a sixth diode D6, the anode of the fourth diode D4 receives a first-phase alternating current sampling voltage signal UoA, the anode of the fifth diode D5 receives a second-phase alternating current sampling voltage signal UoB, the anode of the sixth diode D6 receives a third-phase alternating current sampling voltage signal UoC, the cathodes of the fourth diode D4, the fifth diode D5, and the sixth diode D6 are connected with each other to form the output end of the voltage threshold upper limit setting module; the voltage threshold lower limit setting module comprises a seventh diode D7, an eighth diode D8, and a ninth diode D9, the cathode of the seventh diode D7 receives the first-phase alternating current sampling voltage signal UoA, the cathode of the eighth diode D8 receives the second-phase alternating current sampling voltage signal UoB, the cathode of the ninth diode D9 receives the third-phase alternating current sampling voltage signal UoC, the anodes of the seventh diode D7, the eighth diode D8, and the ninth diode D9 are connected with each other to form the output end of the voltage threshold lower limit setting module.

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