Discharge counter and counting method for direct current valve lightning arrester

Abstract

The invention relates to a discharge counter, in particular to a discharge counter for a direct-current valve lightning arrester and a counting method. The technical problem that safe operation of a direct-current valve lightning arrester is easily affected when internal parts of an existing discharge counting device break down is mainly solved. The discharge counter comprises an inductive charging module, an energy storage capacitor, an emission control circuit and an optical fiber emitter. The induction end of the induction type charging module is arranged on the peripheral side of the direct current valve lightning arrester, and the output high end and the output low end are correspondingly connected to the two ends of the energy storage capacitor. An input high end and an input low end of the emission control circuit are respectively connected to two ends of the energy storage capacitor, and an output high end and an output low end of the emission control circuit are respectively connected to an input high end and an input low end of the optical fiber emitter; and the output end of the optical fiber transmitter is connected with external valve base equipment. According to the invention, the insulation performance of a traditional counter can be maintained, and the problem that the safety operation of the direct current valve lightning arrester and the whole converter valve is endangered due to the fault of the discharge counter can be solved.

Description

Technical Field

[0001] This invention relates to a discharge counter, specifically to a discharge counter and counting method for a DC valve surge arrester. Background Technology

[0002] In DC power transmission projects, converter valves are the core equipment for converting AC to DC power. They are usually composed of components such as thyristors or IGBTs. To protect the safe operation of these components, DC valve surge arresters and discharge counters are installed next to them.

[0003] The DC valve surge arrester and its associated discharge counter require very high insulation (tens to hundreds of kilovolts). Currently, discharge counters use optical fibers to transmit the discharge count remotely, and there are two common schemes. The first scheme mainly consists of an air discharge gap composed of upper and lower discharge electrodes, a resistor, and an optical fiber. The tip of the optical fiber is directly opposite the discharge gap. When no discharge occurs, the leakage current of the surge arrester flows through the internal resistor. When the DC valve surge arrester actuates, the gap discharges, emitting a spark. This spark is transmitted via the optical fiber to the remote valve base equipment, thus counting one discharge. The second scheme mainly consists of a nonlinear resistor, a current-limiting resistor, a rectifier, an energy storage capacitor, and an optical fiber transmitter. When no discharge occurs, the leakage current of the surge arrester flows through the current-limiting resistor, the rectifier circuit, and the energy storage capacitor. When the DC valve surge arrester operates, the nonlinear resistor is turned on, and the voltage inside the discharge counter is limited to the residual voltage of the nonlinear resistor, which plays a role in current leakage and protection. This residual voltage simultaneously passes through the current limiting resistor and the rectifier circuit to charge the energy storage capacitor. Then, the energy storage capacitor drives the fiber optic transmitter to send an optical pulse to the remote valve base device through the optical fiber, thereby realizing one discharge count.

[0004] In both of the above schemes, the discharge current must flow through the inside of the discharge counter. Once the internal components of the discharge counter fail, it will affect the safe operation of the DC valve surge arrester, and thus affect the reliability of the entire converter valve. Summary of the Invention

[0005] The purpose of this invention is to solve the technical problem that existing discharge counting schemes for DC valve surge arresters can easily affect the safe operation of the DC valve surge arrester and thus the reliability of the entire converter valve when the internal components of the discharge counter fail. Therefore, this invention provides a discharge counter and counting method for DC valve surge arresters.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A discharge counter for DC valve surge arresters, characterized by: Includes an inductive charging module, an energy storage capacitor C1, a transmission control circuit, and an optical fiber transmitter F; There are N inductive charging modules, where N≥1; The sensing terminals of N inductive charging modules are respectively set on the periphery of the DC valve arrester, and the high-end and low-end output terminals are respectively connected to the high-end and low-end of the energy storage capacitor C1. The inductive charging module is used to generate an induced current when a discharge current occurs in the DC valve arrester, and output it to the energy storage capacitor C1 for charging. The high-end and low-end inputs of the transmission control circuit are connected to the high-end and low-end of the energy storage capacitor C1, respectively, and the high-end and low-end outputs are connected to the high-end and low-end inputs of the fiber optic transmitter F, respectively. The transmission control circuit is used to output current to the fiber optic transmitter F when the voltage across the energy storage capacitor C1 is greater than the trigger voltage. The output of the fiber optic transmitter F is connected to an external valve base device to transmit optical pulses to the valve base device when it receives current, thereby achieving discharge counting.

[0007] Furthermore, the inductive charging module includes a feedthrough high-frequency coil T and a discharge resistor RE; A through-hole high-frequency coil T is sleeved around the periphery of the DC valve surge arrester to generate an induced current when a discharge current occurs in the DC valve surge arrester; The two ends of the energy dissipation resistor RE are connected to the high-end and low-end outputs of the through-hole high-frequency coil T, respectively. The energy discharge resistor RE is used to discharge the induced current when it is less than or equal to a set threshold; and to output the induced current to the energy storage capacitor C1 when it is greater than the set threshold.

[0008] Furthermore, the number of turns of the through-hole high-frequency coil T is 50.

[0009] Furthermore, the inductive charging module also includes a TVS diode and a rectifier bridge D; The two ends of the TVS tube and the high and low input terminals of the rectifier bridge D are connected in parallel with the high and low terminals of the discharge resistor RE, respectively, and are connected to the high and low output terminals of the feedthrough high-frequency coil T. The high-end and low-end inputs of the rectifier bridge D are connected to the high-end and low-end outputs of the feedthrough high-frequency coil T, respectively, and are also connected to the high-end and low-end of the energy storage capacitor C1, respectively. The discharge resistor RE is used to output the induced current to the energy storage capacitor C1 via the rectifier bridge D when the induced current is greater than the set threshold.

[0010] Furthermore, N>1; After the high-end outputs of N inductive charging modules are connected together, they are all connected to the high-end of the energy storage capacitor C1. The low-end outputs of N inductive charging modules are connected together and then connected to the low-end of the energy storage capacitor C1.

[0011] Furthermore, the transmit control circuit includes trigger resistors R1, R2, and R3, current-limiting resistor R4, thyristor SCR1, and voltage regulator chip LDO1; One end of the trigger resistor R1 and the input terminal of the voltage regulator chip LDO1 are respectively connected to the high end of the energy storage capacitor C1; The other end of trigger resistor R1 and one end of trigger resistor R2 are respectively connected to one end of trigger resistor R3; The other end of the trigger resistor R3 is connected to the gate of the thyristor SCR1; The output of the voltage regulator chip LDO1 is connected to one end of the current-limiting resistor R4; The other end of the current-limiting resistor R4 and the anode of the thyristor SCR1 are connected to the high-end and low-end inputs of the fiber optic transmitter F, respectively. Thyristor SCR1 is used to turn on when the voltage across trigger resistor R3 reaches its turn-on voltage; The other end of the trigger resistor R2, the GND terminal of the voltage regulator chip LDO1, and the cathode of the thyristor SCR1 are respectively connected to the low end of the energy storage capacitor C1.

[0012] Furthermore, the transmission control circuit also includes a charging resistor R5, a trigger resistor R6, a trigger capacitor C2, and a thyristor SCR2; One end of the charging resistor R5 and the anode of the thyristor SCR2 are respectively connected to the output terminal of the voltage regulator chip LDO1; The other end of the charging resistor R5 is connected to one end of the trigger resistor R6 and one end of the trigger capacitor C2, respectively. The other end of the trigger resistor R6 is connected to the gate of the thyristor SCR2; the thyristor SCR2 is used to turn on when the voltage of the trigger capacitor C2 is greater than its gate trigger voltage. The other end of the trigger capacitor C2 and the cathode of the thyristor SCR2 are respectively connected to the low end of the energy storage capacitor C1.

[0013] Furthermore, the output of the fiber optic transmitter F is connected to an external valve base device via an optical fiber.

[0014] Meanwhile, the present invention also provides a discharge counting method for DC valve surge arresters, which uses the aforementioned discharge counter for DC valve surge arresters, and is characterized by including the following steps: Step 1: The inductive charging module generates an induced current based on the discharge current on the DC valve surge arrester. When the induced current is greater than the set threshold, it outputs the induced current to the energy storage capacitor C1 for charging and then executes Step 2; when the induced current is less than the set threshold, it discharges the current. Step 2: Output current to the transmission control circuit through the energy storage capacitor C1; Step 3: When the voltage across the energy storage capacitor C1 is greater than the trigger voltage, the transmission control circuit outputs current to the fiber optic transmitter F and executes step 4; when the voltage is less than the trigger voltage, the current is discharged. Step 4: The optical fiber transmitter F transmits optical pulses to the external valve base device based on the received current to achieve discharge counting.

[0015] Furthermore, it also includes step 5: when the fiber optic transmitter F sends out optical pulses, it simultaneously charges the trigger capacitor C2 through the voltage regulator chip LDO1. When the charging voltage reaches the gate trigger voltage of the thyristor SCR2, the thyristor SCR2 turns on and the thyristor SCR1 turns off, and the fiber optic transmitter F stops sending optical pulses. In order to control the pulse width of the optical pulses sent by the fiber optic transmitter F by controlling the charging time of the trigger capacitor C2.

[0016] The beneficial effects of this invention are: 1. This invention uses an inductive charging module to generate induced current through electromagnetic induction. The induced current is then output to the fiber optic transmitter F via the energy storage capacitor C1 and the transmission control circuit to achieve discharge counting. Since the discharge current does not pass through the inside of the discharge counter, this maintains the insulation performance of the traditional counter and solves the problem that a failure of the discharge counter could endanger the safe operation of the DC valve surge arrester and the entire converter valve.

[0017] 2. The transmission control circuit of the present invention can generate a single optical pulse signal with a fixed width, which improves the reliability of signal transmission and makes it easier for the valve base (receiving) device to identify the authenticity of the signal based on the optical pulse width. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the composition structure of an embodiment of the present invention; Figure 2 This is a schematic diagram of the circuit structure of an embodiment of the present invention; Figure 3 This is a schematic diagram of the circuit structure of the inductive charging module in an embodiment of the present invention; Figure 4 This is a schematic diagram of the circuit structure of the transmission control circuit in an embodiment of the present invention. Detailed Implementation

[0019] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and embodiments. 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.

[0020] This invention provides a discharge counter for a DC valve surge arrester, such as... Figure 1 and Figure 2 As shown, the discharge counter mainly includes an inductive charging module, an energy storage capacitor C1, a transmission control circuit, and an optical fiber transmitter F.

[0021] The number of inductive charging modules is N, where N≥1. However, considering that using multiple inductive charging modules can improve the width and transmission power of the optical pulse, in this embodiment, N>1, that is... Figure 1 The inductive charging module 1, inductive charging module 2, ..., inductive charging module n are described.

[0022] Optionally, in some embodiments, the number of inductive charging modules may be set to one.

[0023] For details, see Figure 2 and Figure 3 The aforementioned N inductive charging modules each include a through-hole high-frequency coil T, a discharge resistor RE, a TVS diode, and a rectifier bridge D.

[0024] The through-type high-frequency coil T has 50 turns. The through-type high-frequency coil T is sleeved around the periphery of the DC valve surge arrester; the two ends of the energy dissipation resistor RE, the two ends of the TVS diode, and the high and low input terminals of the rectifier bridge D are respectively connected to the high and low output terminals of the through-type high-frequency coil T. After the high and low output terminals of the rectifier bridge D in the N inductive charging modules are connected accordingly, the connected nodes are respectively connected to the high and low terminals of the energy storage capacitor C1.

[0025] See Figure 2 and Figure 4 The transmit control circuit includes trigger resistors R1, R2, R3, and R6, current-limiting resistor R4, charging resistor R5, trigger capacitor C2, thyristor SCR1, thyristor SCR2, and low-power linear voltage regulator chip LDO1.

[0026] The voltage regulator chip LDO1 is model HT7550. One end of trigger resistor R1 and the input terminal of voltage regulator chip LDO1 are connected to the high end of energy storage capacitor C1, respectively; the other end of trigger resistor R1 and one end of trigger resistor R2 are connected to one end of trigger resistor R3, respectively; the other end of trigger resistor R3 is connected to the gate of thyristor SCR1; the output terminal of voltage regulator chip LDO1 is connected to one end of current limiting resistor R4, one end of charging resistor R5, and the anode of thyristor SCR2, respectively; the other end of current limiting resistor R4 and the anode of thyristor SCR1 are connected to the high end and low end of input of fiber optic transmitter F, respectively; the other end of charging resistor R5 is connected to one end of trigger resistor R6 and one end of trigger capacitor C2, respectively; the other end of trigger resistor R6 is connected to the gate of thyristor SCR2; the other end of trigger resistor R2, the GND terminal of voltage regulator chip LDO1, the cathode of thyristor SCR1, the other end of trigger capacitor C2, and the cathode of thyristor SCR2 are connected to the low end of energy storage capacitor C1, respectively.

[0027] The output of the fiber optic transmitter F is connected to an external valve base device via an optical fiber. Upon receiving current, it transmits a fixed-width optical pulse through the optical fiber to the valve base device, thereby achieving discharge counting. When using: Step 1: When the DC valve surge arrester does not discharge, because the leakage current of the DC valve surge arrester is very small, it flows through the through hole of the through-hole high-frequency coil T, and induces a small induced current in the secondary coil. It is directly discharged through the energy discharge resistor RE and will not charge the energy storage capacitor C1.

[0028] When the DC valve surge arrester discharges, the discharge current is very large and flows through the through hole of the through-hole high-frequency coil T, inducing a large induced current in the secondary coil. This induced current charges the energy storage capacitor C1 after passing through the rectifier bridge D.

[0029] Step 2: Output current to the transmission control circuit through the energy storage capacitor C1.

[0030] Step 3: In the transmission control circuit, when the voltage across the trigger resistor R3 exceeds the gate trigger voltage of the thyristor SCR1 in the voltage divider network composed of trigger resistors R1, R2 and R3, the thyristor SCR1 is turned on. The current is regulated by the voltage regulator chip LDO1 and then discharges to the fiber optic transmitter F and the current limiting resistor R4 in a constant current manner.

[0031] If the voltage across trigger resistor R3 does not reach the gate trigger voltage of thyristor SCR1, the energy storage capacitor C1 will slowly discharge through trigger resistors R1 and R2 until the voltage is 0.

[0032] Step 4: The fiber optic transmitter F transmits optical pulses to the external valve base device via the optical fiber. At the same time, the current flowing through the voltage regulator chip LDO1 charges the trigger capacitor C2 through the charging resistor R5. When the voltage on the trigger capacitor C2 reaches the gate trigger voltage of the thyristor SCR2, the thyristor SCR2 turns on and the thyristor SCR1 turns off, completing one discharge count.

[0033] Step 5: When the fiber optic transmitter F transmits optical pulses, it simultaneously charges the trigger capacitor C2 through the voltage regulator chip LDO1. When the charging voltage reaches the gate trigger voltage of the thyristor SCR2, SCR2 turns on, SCR1 turns off, and the fiber optic transmitter F stops transmitting optical pulses. Since the discharge time of the surge arrester is in the microsecond range, the charging time of the energy storage capacitor C1 is also in the microsecond range, which is negligible compared to the charging time of the trigger capacitor C2 (millisecond range). Therefore, the pulse width of the optical pulse is the time it takes for the trigger capacitor C2 to charge to the gate trigger voltage of the thyristor SCR2, i.e., a fixed pulse width. Thus, by controlling the charging time of the trigger capacitor C2, the pulse width of the optical pulses transmitted by the fiber optic transmitter F can be controlled. The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions within the technical scope disclosed in the present invention should be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A discharge counter for a DC valve surge arrester, characterized in that: Includes an inductive charging module, an energy storage capacitor C1, a transmission control circuit, and an optical fiber transmitter F; The inductive charging module comprises N units, where N ≥ 1; The sensing terminals of the N inductive charging modules are respectively disposed on the periphery of the DC valve arrester, and the high-end and low-end output terminals are respectively connected to the high-end and low-end of the energy storage capacitor C1; the inductive charging module is used to generate an induced current when a discharge current occurs in the DC valve arrester, and output it to the energy storage capacitor C1 for charging. The high-end and low-end inputs of the transmission control circuit are connected to the high-end and low-end of the energy storage capacitor C1, respectively, and the high-end and low-end outputs are connected to the high-end and low-end inputs of the fiber optic transmitter F, respectively. The transmission control circuit is used to output current to the fiber optic transmitter F when the voltage on the energy storage capacitor C1 is greater than the trigger voltage. The output end of the fiber optic transmitter F is connected to an external valve base device, and is used to transmit optical pulses to the valve base device when receiving current, so as to realize discharge counting.

2. A discharge counter for a DC valve surge arrester according to claim 1, characterized in that: The inductive charging module includes a through-type high-frequency coil T and a discharge resistor RE; The through-hole high-frequency coil T is sleeved on the periphery of the DC valve arrester and is used to generate an induced current when a discharge current occurs in the DC valve arrester. The two ends of the energy dissipation resistor RE are respectively connected to the high-end and low-end outputs of the through-hole high-frequency coil T; The energy-discharging resistor RE is used to discharge the induced current when it is less than or equal to a set threshold. When the induced current exceeds the set threshold, it is output to the energy storage capacitor C1.

3. A discharge counter for a DC valve surge arrester according to claim 2, characterized in that: The number of turns of the through-hole high-frequency coil T is 50.

4. A discharge counter for a DC valve surge arrester according to claim 2 or 3, characterized in that: The inductive charging module also includes a TVS diode and a rectifier bridge D; The two ends of the TVS tube and the high and low input terminals of the rectifier bridge D are connected in parallel with the high and low terminals of the discharge resistor RE, respectively, and are connected to the high and low output terminals of the feedthrough high-frequency coil T. The high-end and low-end inputs of the rectifier bridge D are respectively connected to the high-end and low-end outputs of the feedthrough high-frequency coil T, and are also respectively connected to the high-end and low-end of the energy storage capacitor C1. The energy leakage resistor RE is used to output the induced current to the energy storage capacitor C1 through the rectifier bridge D when the induced current is greater than a set threshold.

5. A discharge counter for a DC valve surge arrester according to claim 1, characterized in that: N>1； After the high-end outputs of the N inductive charging modules are connected together, they are all connected to the high-end of the energy storage capacitor C1. After the low-end outputs of N inductive charging modules are connected together, they are all connected to the low end of the energy storage capacitor C1.

6. A discharge counter for a DC valve surge arrester according to claim 1 or 5, characterized in that: The launch control circuit includes trigger resistor R1, trigger resistor R2, trigger resistor R3, current limiting resistor R4, thyristor SCR1, and voltage regulator chip LDO1; One end of the trigger resistor R1 and the input terminal of the voltage regulator chip LDO1 are respectively connected to the high end of the energy storage capacitor C1; The other end of the trigger resistor R1 and one end of the trigger resistor R2 are respectively connected to one end of the trigger resistor R3; The other end of the trigger resistor R3 is connected to the gate of the thyristor SCR1; The output terminal of the voltage regulator chip LDO1 is connected to one end of the current limiting resistor R4; The other end of the current-limiting resistor R4 and the anode of the thyristor SCR1 are respectively connected to the high-end and low-end inputs of the fiber optic transmitter F. The thyristor SCR1 is used to turn on when the voltage across the trigger resistor R3 reaches its gate trigger voltage. The other end of the trigger resistor R2, the GND terminal of the voltage regulator chip LDO1, and the cathode of the thyristor SCR1 are respectively connected to the low end of the energy storage capacitor C1.

7. A discharge counter for a DC valve surge arrester according to claim 6, characterized in that: The launch control circuit also includes a charging resistor R5, a trigger resistor R6, a trigger capacitor C2, and a thyristor SCR2; One end of the charging resistor R5 and the anode of the thyristor SCR2 are respectively connected to the output terminal of the voltage regulator chip LDO1; The other end of the charging resistor R5 is connected to one end of the trigger resistor R6 and one end of the trigger capacitor C2, respectively. The other end of the trigger resistor R6 is connected to the gate of the thyristor SCR2; the thyristor SCR2 is used to turn on when the voltage of the trigger capacitor C2 is greater than its gate trigger voltage. The other end of the trigger capacitor C2 and the cathode of the thyristor SCR2 are respectively connected to the low end of the energy storage capacitor C1.

8. A discharge counter for a DC valve surge arrester according to claim 1, characterized in that: The output end of the fiber optic transmitter F is connected to an external valve base device via an optical fiber.

9. A discharge counting method for a DC valve surge arrester, employing the discharge counter for a DC valve surge arrester as described in any one of claims 1-8, characterized in that, Includes the following steps: Step 1: The inductive charging module generates an induced current based on the discharge current on the DC valve surge arrester. When the induced current is greater than the set threshold, it outputs the induced current to the energy storage capacitor C1 for charging and then executes Step 2; when the induced current is less than the set threshold, it discharges the current. Step 2: Output current to the transmission control circuit through the energy storage capacitor C1; Step 3: When the voltage across the energy storage capacitor C1 is greater than the trigger voltage, the transmission control circuit outputs current to the fiber optic transmitter F and executes step 4; when the voltage is less than the trigger voltage, the current is discharged. Step 4: Based on the received current, the fiber optic transmitter F transmits optical pulses to the external valve base device to achieve discharge counting.

10. The discharge counting method for a DC valve surge arrester according to claim 9, characterized in that, It also includes step 5: When optical pulses are transmitted to the outside through the optical fiber transmitter F, the trigger capacitor C2 is charged through the voltage regulator chip LDO1. When the charging voltage reaches the gate trigger voltage of the thyristor SCR2, the thyristor SCR2 turns on and the thyristor SCR1 turns off, and the optical fiber transmitter F stops transmitting optical pulses. The pulse width of the optical pulses transmitted by the optical fiber transmitter F can be controlled by controlling the charging time of the trigger capacitor C2.

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