Energy acquisition circuit, sf6 gas density relay and high voltage primary equipment energy acquisition circuit and method

Abstract

The application discloses an energy acquisition circuit for converting a microampere current source into a low-voltage milliampere energy source, comprising a first charging capacitor C1, a voltage trigger circuit, a voltage reduction circuit, a freewheeling filter circuit and a second charging capacitor C3; the application further discloses an SF6 gas density relay energy acquisition circuit and method, and a high-voltage primary equipment energy acquisition circuit and method; the application directly acquires a microampere energy source from an alarm contact DC220V power supply of an SF6 gas density relay or a leakage current of high-voltage primary equipment through the energy acquisition circuit, thereby eliminating the need for the SF6 density relay or the high-voltage primary equipment to lay an independent power cable.

Description

Technical Field

[0001] The present invention relates to the technical field of energy acquisition, and in particular to an energy acquisition circuit, an SF6 gas density relay, and a high-voltage primary equipment energy acquisition circuit and method. Background Art

[0002] Traditional SF6 density relays use a pointer to indicate the SF6 gas pressure value at 20°C (the pressure value at 20°C is used in engineering projects to represent SF6 gas density), and output contact-type information in combination with set alarm and lockout values. Currently, there is a type of SF6 density relay with remote transmission capabilities, which requires an independent operating power supply, typically a 24V DC power supply. This equipment requires on-site trenching and laying of a large number of power cables, power supplies, and power terminal boxes during project implementation. This is a heavy workload and difficult to maintain later, especially posing safety risks for older substation facilities.

[0003] In addition, traditional lightning arresters are monitored by mechanical discharge counters, which indicate the arrester leakage current on site through a mechanical pointer ammeter and display the cumulative number of arrester discharge events on site through a mechanical counter, requiring staff to regularly record data for analysis. Currently, there is a portable tester at home and abroad that can measure the arrester leakage current online, but staff are still required to carry the tester to the site regularly for test work and manual data analysis. Currently, there is also an online monitoring device at home and abroad that replaces the mechanical discharge counter. It has the function of online monitoring of arrester leakage current and arrester discharge events and remote data transmission, but its equipment is bulky and requires the laying of independent power supply cables and communication cables. As a result, a large number of cables need to be laid on site during project implementation. The project implementation work is large and the subsequent maintenance is difficult. For old substations, the implementation safety risk is even higher. Summary of the Invention

[0004] In order to solve the problems existing in the prior art, the purpose of the present invention is to provide an energy acquisition circuit, an SF6 gas density relay and a high-voltage primary equipment energy acquisition circuit and method. The present invention can eliminate the need for laying independent power cables.

[0005] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is: an energy acquisition circuit for converting a microampere current source into a low-voltage milliampere energy, comprising a first charging capacitor C1, a voltage-type trigger circuit, a step-down circuit, a freewheeling filter circuit and a second charging capacitor C3. The output end of the microampere current source is connected to the two ends of the first charging capacitor C1, and is used to charge and store energy in the first charging capacitor C1. The first charging capacitor C1 is connected to the step-down circuit through the voltage-type trigger circuit. The voltage-type trigger circuit is periodically cut off and turned on according to the voltage of the first charging capacitor C1, and modulates the microampere current source into a high-voltage fixed-width pulse voltage source. The step-down circuit adjusts the high-voltage fixed-width pulse voltage source into a low-voltage pulse voltage source. The freewheeling filter circuit is used to rectify and filter the low-voltage pulse voltage source, and output a DC voltage to charge and store energy in the second charging capacitor C3, thereby obtaining a low-voltage milliampere energy.

[0006] As a further improvement of the present invention, the energy acquisition circuit also includes a voltage comparator U1 and a DC / DC converter U2. The second charging capacitor C3 is connected to the DC / DC converter U2. The voltage comparator U1 controls the enable end of the DC / DC converter U2 to start power supply adjustment and output a low-voltage milliampere energy with a stable supply voltage according to the voltage of the second charging capacitor C3.

[0007] As a further improvement of the present invention, the voltage-type trigger circuit is a voltage-triggered diode D2 , and the voltage-triggered diode D2 is connected in series between the first charging capacitor C1 and the input end of the step-down circuit.

[0008] As a further improvement of the present invention, the voltage-type trigger circuit includes a voltage-triggered diode D and a unidirectional thyristor or field-effect transistor Q. The unidirectional thyristor or field-effect transistor Q is connected in series between the first charging capacitor C1 and the input end of the step-down circuit. One end of the voltage-triggered diode D is connected to the common end of the first charging capacitor C1 and the unidirectional thyristor or field-effect transistor Q, and the other end of the voltage-triggered diode D is connected to the unidirectional thyristor or field-effect transistor Q1 through a resistor R, for controlling the conduction and cutoff of the unidirectional thyristor or field-effect transistor Q.

[0009] As a further improvement of the present invention, the step-down circuit includes a transformer T1, the freewheeling filter circuit includes a freewheeling diode D3 and a filter capacitor C2, the primary winding of the transformer T1 is connected in parallel between the output end of the voltage-type trigger circuit and the first charging capacitor C1, the secondary winding of the transformer T1 is connected in parallel with the filter capacitor C2, the freewheeling diode D3 is connected in series between the secondary winding output end of the transformer T1 and the filter capacitor C2, and the anode of the freewheeling diode D3 is connected to the secondary winding output end of the transformer T1, and the cathode of the freewheeling diode D3 is connected to the filter capacitor C2.

[0010] As a further improvement of the present invention, the step-down circuit includes an inductor T2 with a magnetic core, the freewheeling filter circuit includes a freewheeling diode D3 and a filter capacitor C2, the freewheeling diode D3 is connected in parallel between the output end of the voltage-type trigger circuit and the first charging capacitor C1, and the cathode of the freewheeling diode D3 is connected to the output end of the voltage-type trigger circuit, the anode of the freewheeling diode D3 is connected to the first charging capacitor C1, the filter capacitor C2 is connected in parallel with the freewheeling diode D3, and the inductor T2 is connected in series between the cathode of the freewheeling diode D3 and the filter capacitor C2.

[0011] As a further improvement of the present invention, the second charging capacitor C3 is a Faraday capacitor or a lithium-ion capacitor.

[0012] The present invention also provides an SF6 gas density relay energy acquisition circuit for converting a high-voltage constant-voltage source into a low-voltage milliampere-level energy source, including the energy acquisition circuit as described above, and also including a current limiting circuit. The current limiting circuit is arranged between the high-voltage constant-voltage source and the first charging capacitor C1, and is used to convert the high-voltage constant-voltage source into a microampere-level current source to charge and store energy in the first charging capacitor C1.

[0013] As a further improvement of the present invention, the energy acquisition circuit of the SF6 gas density relay also includes a bridge rectifier D1, which is arranged between the high voltage constant voltage source and the current limiting circuit, or the bridge rectifier D1 is arranged between the current limiting circuit and the first charging capacitor C1, for achieving positive and negative polarity matching of the power supply.

[0014] As a further improvement of the present invention, the current limiting circuit is a series constant current source I1 or a current limiting resistor.

[0015] The present invention also provides an SF6 gas density relay energy acquisition method, which adopts the SF6 gas density relay energy acquisition circuit as described above, connects the SF6 gas density relay energy acquisition circuit and the alarm contact of the SF6 gas density relay in parallel and then connects them to the power secondary system loop. The SF6 gas density relay energy acquisition circuit converts the high-voltage constant voltage source obtained from the power secondary system loop into a low-voltage milliampere-level energy and then supplies power to each circuit module of the electronic circuit part of the SF6 gas density relay.

[0016] The present invention also provides a high-voltage primary equipment energy acquisition circuit for converting an AC current source into a low-voltage milliampere-level energy source, including the energy acquisition circuit as described above, and also including a bridge rectifier D5. The bridge rectifier D5 is arranged between the AC current source and the first charging capacitor, and is used to rectify the AC leakage current of the high-voltage primary equipment into a DC current source through D5.

[0017] As a further improvement of the present invention, it also includes a protection circuit, which includes a zinc oxide resistor RV1, a wire-wound resistor R1 and a voltage-type trigger diode D4. The zinc oxide resistor RV1 is connected in series in the leakage current grounding loop of the high-voltage primary equipment. One end of the zinc oxide resistor RV1 is connected to one of the input ends of the bridge rectifier D5 via the wire-wound resistor R1, and the other end of the zinc oxide resistor RV1 is connected to the other input end of the bridge rectifier D5. The voltage-type trigger diode D4 is connected in parallel between the two input ends of the bridge rectifier D5.

[0018] As a further improvement of the present invention, the high-voltage primary equipment is a lightning arrester or a capacitor-type equipment.

[0019] The present invention also provides a method for obtaining energy from high-voltage primary equipment, which uses the high-voltage primary equipment energy acquisition circuit as described above, and connects the high-voltage primary equipment energy acquisition circuit in series to the high-voltage primary equipment leakage current grounding loop. The high-voltage primary equipment energy acquisition circuit obtains the leakage current with current source characteristics of the monitored high-voltage primary equipment, converts it into low-voltage milliampere-level energy, and then powers the circuit module.

[0020] The beneficial effects of the present invention are:

[0021] The present invention obtains microampere-level energy directly from the DC220V power supply of the alarm contact of the SF6 gas density relay or the leakage current of the high-voltage primary equipment through the energy acquisition circuit, eliminating the need to lay independent power cables for the SF6 density relay or the high-voltage primary equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic diagram of the SF6 gas density relay contact engineering application in Example 1;

[0023] Figure 2 Schematic diagram of the circuit structure of embodiment 1 of the present invention;

[0024] Figure 3 Schematic diagram of the circuit structure of embodiment 2 of the present invention. DETAILED DESCRIPTION

[0025] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0026] Example 1

[0027] In one embodiment, Figure 2 As shown, an energy acquisition circuit is used to convert a microampere current source into a low-voltage milliampere energy source, including a first charging capacitor C1, a voltage-type trigger circuit, a step-down circuit, a freewheeling filter circuit and a second charging capacitor C3. The output end of the microampere current source is connected to the two ends of the first charging capacitor C1, and is used to charge and store energy in the first charging capacitor C1. The first charging capacitor C1 is connected to the step-down circuit through the voltage-type trigger circuit. The voltage-type trigger circuit periodically cuts off and turns on the voltage of the first charging capacitor C1, modulating the microampere current source into a high-voltage fixed-width pulse voltage source. The step-down circuit adjusts the high-voltage fixed-width pulse voltage source into a low-voltage pulse voltage source. The freewheeling filter circuit is used to rectify and filter the low-voltage pulse voltage source, and output a DC voltage to charge and store energy in the second charging capacitor C3, thereby obtaining a low-voltage milliampere energy source.

[0028] In another embodiment, the energy acquisition circuit further includes a voltage comparator U1 and a DC / DC converter U2, the second charging capacitor C3 is connected to the DC / DC converter U2, and the voltage comparator U1 controls the enable end of the DC / DC converter U2 to start power adjustment and output a low-voltage milliampere energy with a stable supply voltage according to the voltage of the second charging capacitor C3.

[0029] In another embodiment, the voltage-type trigger circuit is a voltage-triggered diode D2 , and the voltage-triggered diode D2 is connected in series between the first charging capacitor C1 and the input end of the step-down circuit.

[0030] In another embodiment, the voltage-type trigger circuit includes a voltage-triggered diode D and a unidirectional thyristor or field-effect transistor Q. The unidirectional thyristor or field-effect transistor Q is connected in series between the first charging capacitor C1 and the input end of the step-down circuit. One end of the voltage-triggered diode D is connected to the common end of the first charging capacitor C1 and the unidirectional thyristor or field-effect transistor Q. The other end of the voltage-triggered diode D is connected to the unidirectional thyristor or field-effect transistor Q1 through a resistor R, and is used to control the conduction and cutoff of the unidirectional thyristor or field-effect transistor Q.

[0031] In another embodiment, the step-down circuit includes a transformer T1, the freewheeling filter circuit includes a freewheeling diode D3 and a filter capacitor C2, the primary winding of the transformer T1 is connected in parallel between the output end of the voltage-type trigger circuit and the first charging capacitor C1, the secondary winding of the transformer T1 is connected in parallel with the filter capacitor C2, the freewheeling diode D3 is connected in series between the secondary winding output end of the transformer T1 and the filter capacitor C2, and the anode of the freewheeling diode D3 is connected to the secondary winding output end of the transformer T1, and the cathode of the freewheeling diode D3 is connected to the filter capacitor C2.

[0032] In another embodiment, the step-down circuit includes an inductor T2 with a magnetic core, the freewheeling filter circuit includes a freewheeling diode D3 and a filter capacitor C2, the freewheeling diode D3 is connected in parallel between the output end of the voltage-type trigger circuit and the first charging capacitor C1, and the cathode of the freewheeling diode D3 is connected to the output end of the voltage-type trigger circuit, the anode of the freewheeling diode D3 is connected to the first charging capacitor C1, the filter capacitor C2 is connected in parallel with the freewheeling diode D3, and the inductor T2 is connected in series between the cathode of the freewheeling diode D3 and the filter capacitor C2.

[0033] In another embodiment, the second charging capacitor C3 is a Faraday capacitor or a lithium-ion capacitor.

[0034] This embodiment also provides an SF6 gas density relay energy acquisition circuit for converting a high-voltage constant-voltage source into a low-voltage milliampere-level energy source, including the energy acquisition circuit as described above, and also including a current limiting circuit. The current limiting circuit is arranged between the high-voltage constant-voltage source and the first charging capacitor C1, and is used to convert the high-voltage constant-voltage source into a microampere-level current source to charge and store energy in the first charging capacitor C1.

[0035] In another embodiment, the SF6 gas density relay energy acquisition circuit further includes a bridge rectifier D1, wherein the bridge rectifier D1 is arranged between the high voltage constant voltage source and the current limiting circuit, or the bridge rectifier D1 is arranged between the current limiting circuit and the first charging capacitor C1, for achieving polarity matching of the positive and negative poles of the power supply.

[0036] In another embodiment, the current limiting circuit is a series constant current source I1 or a current limiting resistor.

[0037] This embodiment also provides an SF6 gas density relay energy acquisition method, which uses the SF6 gas density relay energy acquisition circuit as described above, connects the SF6 gas density relay energy acquisition circuit and the alarm contact of the SF6 gas density relay in parallel and then connects them to the power secondary system loop. The SF6 gas density relay energy acquisition circuit converts the high-voltage constant voltage source obtained from the power secondary system loop into a low-voltage milliampere-level energy and then supplies power to each circuit module of the SF6 gas density relay electronic circuit part.

[0038] The principle of the SF6 gas density relay including the energy acquisition circuit of this embodiment is further explained below:

[0039] like Figure 1 As shown in the figure, in actual engineering applications, the alarm and locking contacts of the SF6 gas density relay are connected to an intermediate relay or measurement and control device via a DC220V power supply to transmit pressure status information. The alarm contact of the SF6 density relay MK1 and the coil of the 1ZJ intermediate relay are connected in series to the DC220V power supply. When the SF6 gas pressure is at normal values, the alarm contact is open. At this time, the 1ZJ intermediate relay control coil is not energized and the intermediate relay is not energized. The voltage across the alarm contact is equal to the DC220V voltage. When the SF6 gas leaks and the pressure drops to the set alarm value, the alarm contact closes, the 1ZJ intermediate relay control coil is energized, and the intermediate relay is energized, transmitting the low SF6 gas pressure alarm. The voltage across the alarm contact is approximately DC0V, and the intermediate relay control coil drives the pull-in current of several milliamperes. The alarm contact of the SF6 density relay MK2 and the measurement and control device are connected in series to the DC220V power supply. Its operation is similar to the aforementioned intermediate relay, and the measurement and control device input drive current is several milliamperes.

[0040] The SF6 gas density relay is designed to obtain microampere-level energy directly from the DC220V power supply of the alarm contact, eliminating the need to lay independent power cables. Figure 2 As shown, the energy harvesting circuit and alarm contact are connected in parallel to the power secondary system circuit. The energy harvesting circuit mainly consists of a series constant current source I1, a bridge rectifier D1, a first charging capacitor C1, a voltage triggering diode D2, a transformer T1, a freewheeling diode D3, a filter capacitor C2, a second charging capacitor C3, a voltage comparator U1, and a DC / DC converter U2.

[0041] Series constant current source I1 converts a 220V DC voltage source into a microampere-level current source. It can also be a simple current-limiting resistor. In the circuit, series constant current source I1 can be connected in series before or after bridge rectifier D1. In engineering applications, the alarm contacts of the SF6 density relay do not distinguish between positive and negative DC polarity. Bridge rectifier D1 automatically matches the polarity. Series constant current source I1 and bridge rectifier D1 are connected in series to a 220V DC voltage source. After matching the power supply polarity, they output a microampere-level constant current with a maximum voltage of 220V. This microampere-level constant current charges the first charging capacitor C1.

[0042] Voltage-type trigger circuit A1 or A2, A1 is composed of a voltage-triggered device, such as a voltage-triggered diode D2; A2 is composed of a voltage-triggered device D and a unidirectional thyristor or field-effect transistor Q. After the voltage-triggered device D is triggered, the unidirectional thyristor or field-effect transistor Q is controlled to conduct through a resistor R. When the voltage of the first charging capacitor C1 is lower than the conduction threshold of the voltage-type trigger circuit A1 or A2, the voltage-type trigger circuit A1 or A2 is turned off. When the voltage of the first charging capacitor C1 is higher than the conduction threshold of the voltage-type trigger circuit A1 or A2, the voltage-type trigger circuit A1 or A2 is turned on, and the first charging capacitor C1 supplies energy to the primary winding of the transformer T1, and the primary winding of the transformer T1 consumes the energy stored in the first charging capacitor C1. When the voltage of the first charging capacitor C1 drops to the cut-off threshold of the voltage-type trigger circuit A1 or A2, the voltage-type trigger circuit A1 or A2 is turned off, and the first charging capacitor C1 stops supplying energy to the primary winding of the transformer T1. The above-mentioned microampere-level constant current continues to charge the first charging capacitor C1, forming a switching oscillation operation over and over again, modulating the constant DC voltage source into a fixed-width pulse voltage source to drive the transformer T1 to form a high-frequency switching power supply regulation circuit. The series constant current source I1, the bridge rectifier D1, the first charging capacitor C1, the voltage-type trigger circuit A1 or A2, and the primary winding of the transformer T1 constitute a fixed pulse width high-frequency transformer. The transformer T1 is designed as an isolated step-down high-frequency transformer. When isolation is not required, the transformer T1 can be designed as an inductor T2 with a magnetic core to form a non-isolated power supply. Its switching frequency is adjusted by the first charging capacitor C1, and the secondary output voltage is adjusted by the transformer T1 ratio, converting high-voltage microampere energy into low-voltage milliampere energy.

[0043] A freewheeling diode D3 and filter capacitor C2 form a freewheeling filter circuit, rectifying and filtering the high-frequency pulse voltage from the secondary output of transformer T1. The resulting DC voltage charges the second charging capacitor C3, a farad capacitor or lithium-ion capacitor, to store energy. When the SF6 density relay is first connected to the system and initially stores energy, the voltage on the second charging capacitor C3 is too low to support operation. A voltage comparator U1 identifies the voltage on the second charging capacitor C3. When the voltage reaches a certain threshold, the comparator controls the EN enable terminal of the DC / DC converter U2 to enable power regulation. The Buck-Boost automatic step-up / step-down DC / DC converter U2 regulates the output to a constant voltage, which supplies power to the entire digital circuit. The primary current of the energy harvesting circuit is in the microampere range, while the charging current on the second charging capacitor C3 is in the milliampere range. Under normal circumstances, the SF6 pressure is at the rated value, the alarm contact is open, and the energy acquisition circuit works normally. At this time, a microampere current flows through the intermediate relay, but it is far lower than its action threshold current and is therefore not affected. When the SF6 pressure is lower than the set alarm value, the alarm contact closes and the intermediate relay is activated. At this time, the energy acquisition circuit cannot work normally, and the energy supply circuit continues to work by relying on the energy stored in the second charging capacitor C3.

[0044] Example 2

[0045] In one embodiment, Figure 3 As shown, an energy acquisition circuit is used to convert a microampere current source into a low-voltage milliampere energy source, including a first charging capacitor C1, a voltage-type trigger circuit, a step-down circuit, a freewheeling filter circuit and a second charging capacitor C3. The output end of the microampere current source is connected to the two ends of the first charging capacitor C1, and is used to charge and store energy in the first charging capacitor C1. The first charging capacitor C1 is connected to the step-down circuit through the voltage-type trigger circuit. The voltage-type trigger circuit periodically cuts off and turns on the voltage of the first charging capacitor C1, modulating the microampere current source into a high-voltage fixed-width pulse voltage source. The step-down circuit adjusts the high-voltage fixed-width pulse voltage source into a low-voltage pulse voltage source. The freewheeling filter circuit is used to rectify and filter the low-voltage pulse voltage source, and output a DC voltage to charge and store energy in the second charging capacitor C3, thereby obtaining a low-voltage milliampere energy source.

[0046] In another embodiment, the energy acquisition circuit further includes a voltage comparator U1 and a DC / DC converter U2, the second charging capacitor C3 is connected to the DC / DC converter U2, and the voltage comparator U1 controls the enable end of the DC / DC converter U2 to start power adjustment and output a low-voltage milliampere energy with a stable supply voltage according to the voltage of the second charging capacitor C3.

[0047] In another embodiment, the voltage-type trigger circuit is a voltage-triggered diode D2 , and the voltage-triggered diode D2 is connected in series between the first charging capacitor C1 and the input end of the step-down circuit.

[0048] In another embodiment, the voltage-type trigger circuit includes a voltage-triggered diode D and a unidirectional thyristor or field-effect transistor Q. The unidirectional thyristor or field-effect transistor Q is connected in series between the first charging capacitor C1 and the input end of the step-down circuit. One end of the voltage-triggered diode D is connected to the common end of the first charging capacitor C1 and the unidirectional thyristor or field-effect transistor Q. The other end of the voltage-triggered diode D is connected to the unidirectional thyristor or field-effect transistor Q1 through a resistor R, and is used to control the conduction and cutoff of the unidirectional thyristor or field-effect transistor Q.

[0049] In another embodiment, the step-down circuit includes a transformer T1, the freewheeling filter circuit includes a freewheeling diode D3 and a filter capacitor C2, the primary winding of the transformer T1 is connected in parallel between the output end of the voltage-type trigger circuit and the first charging capacitor C1, the secondary winding of the transformer T1 is connected in parallel with the filter capacitor C2, the freewheeling diode D3 is connected in series between the secondary winding output end of the transformer T1 and the filter capacitor C2, and the anode of the freewheeling diode D3 is connected to the secondary winding output end of the transformer T1, and the cathode of the freewheeling diode D3 is connected to the filter capacitor C2.

[0050] In another embodiment, the step-down circuit includes an inductor T2 with a magnetic core, the freewheeling filter circuit includes a freewheeling diode D3 and a filter capacitor C2, the freewheeling diode D3 is connected in parallel between the output end of the voltage-type trigger circuit and the first charging capacitor C1, and the cathode of the freewheeling diode D3 is connected to the output end of the voltage-type trigger circuit, the anode of the freewheeling diode D3 is connected to the first charging capacitor C1, the filter capacitor C2 is connected in parallel with the freewheeling diode D3, and the inductor T2 is connected in series between the cathode of the freewheeling diode D3 and the filter capacitor C2.

[0051] In another embodiment, the second charging capacitor C3 is a Faraday capacitor or a lithium-ion capacitor.

[0052] This embodiment also provides a high-voltage primary device energy acquisition circuit for converting an AC current source into a low-voltage milliampere-level energy source, including the energy acquisition circuit as described above, and also including a bridge rectifier D5. The bridge rectifier D5 is arranged between the AC current source and the first charging capacitor, and is used to rectify the AC leakage current of the high-voltage primary device into a DC current source through D5.

[0053] In another embodiment, a protection circuit is further included, which includes a zinc oxide resistor RV1, a wire-wound resistor R1 and a voltage-type trigger diode D4. The zinc oxide resistor RV1 is connected in series in the leakage current grounding loop of the high-voltage primary equipment. One end of the zinc oxide resistor RV1 is connected to one of the input ends of the bridge rectifier D5 via the wire-wound resistor R1, and the other end of the zinc oxide resistor RV1 is connected to the other input end of the bridge rectifier D5. The voltage-type trigger diode D4 is connected in parallel between the two input ends of the bridge rectifier D5.

[0054] In another embodiment, the high-voltage primary equipment is a lightning arrester or a capacitor-type equipment.

[0055] This embodiment also provides a method for obtaining energy from a high-voltage primary device, which uses the high-voltage primary device energy acquisition circuit as described above, and connects the high-voltage primary device energy acquisition circuit in series to the high-voltage primary device leakage current grounding loop. The high-voltage primary device energy acquisition circuit obtains the leakage current with current source characteristics of the monitored high-voltage primary device, converts it into low-voltage milliampere-level energy, and then powers the circuit module.

[0056] The following uses a lightning arrester as an example to further explain the principle of the high-voltage primary equipment of the energy acquisition circuit of this embodiment:

[0057] For example Figure 3 As shown, the arrester, with its constant current source characteristics, leaks current into the circuit from port 1 and out of the circuit from port 2. Zinc oxide resistor RV1 protects the circuit when the arrester is discharging. Its normal state is high impedance, preventing the arrester's leakage current from flowing through RV1. However, when the arrester is discharging, zinc oxide resistor RV1 conducts current through RV1, thereby protecting the subsequent circuitry. Wirewound resistor R1 possesses both resistance and inductance characteristics. Normally, the arrester's leakage current flows through it, generating a small terminal voltage that does not affect circuit operation. However, when the arrester is discharging, the inductance of the wirewound resistor prevents the current from increasing, while its resistance generates a higher terminal voltage, further protecting the subsequent circuitry. Voltage-type trigger diode D4 is normally high impedance in its cutoff state. When the arrester is discharging, any remaining voltage energy after the wirewound resistor's protection causes it to conduct, releasing energy to protect the subsequent circuitry. Decoupling filter capacitor C1 provides decoupling and filtering to eliminate ripple interference.

[0058] The AC leakage current of the lightning arrester is rectified by D2 into a DC constant current source, and then converted into a low-voltage milliampere-level energy through the energy acquisition circuit, and then powered for the circuit module, such as the circuit module of the monitoring device of the high-voltage primary equipment. The working principle of its energy acquisition circuit is the same as that of Example 1.

[0059] The above-described embodiments merely represent specific implementations of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, and all such variations and improvements fall within the scope of protection of the present invention.

Claims

1. An energy acquisition circuit, characterized in that: It is used to convert a microampere current source into a low-voltage milliampere energy source, including a first charging capacitor C1, a voltage-type trigger circuit, a step-down circuit, a freewheeling filter circuit and a second charging capacitor C3. The output end of the microampere current source is connected to the two ends of the first charging capacitor C1 to charge and store energy for the first charging capacitor C1. The first charging capacitor C1 is connected to the step-down circuit through the voltage-type trigger circuit. The voltage-type trigger circuit periodically cuts off and turns on the voltage of the first charging capacitor C1 to modulate the microampere current source into a high-voltage fixed-width pulse voltage source. The step-down circuit converts the high-voltage The pulse voltage source with a fixed voltage width is adjusted to a low-voltage pulse voltage source, and the freewheeling filter circuit is used to rectify and filter the low-voltage pulse voltage source, and output a DC voltage to charge and store energy for the second charging capacitor C3, thereby obtaining a low-voltage milliampere-level energy; the energy acquisition circuit also includes a voltage comparator U1 and a DC / DC converter U2, the second charging capacitor C3 is connected to the DC / DC converter U2, and the voltage comparator U1 controls the enable end of the DC / DC converter U2 to start power adjustment and output a low-voltage milliampere-level energy with a stable supply voltage according to the voltage of the second charging capacitor C3.

2. The energy harvesting circuit according to claim 1, wherein: The voltage-type trigger circuit is a voltage-triggered diode D2 , and the voltage-triggered diode D2 is connected in series between the first charging capacitor C1 and the input end of the step-down circuit.

3. The energy harvesting circuit according to claim 1, wherein: The voltage-type trigger circuit includes a voltage-triggered diode D and a unidirectional thyristor or field-effect transistor Q. The unidirectional thyristor or field-effect transistor Q is connected in series between the first charging capacitor C1 and the input end of the step-down circuit. One end of the voltage-triggered diode D is connected to the common end of the first charging capacitor C1 and the unidirectional thyristor or field-effect transistor Q. The other end of the voltage-triggered diode D is connected to the unidirectional thyristor or field-effect transistor Q through a resistor R, and is used to control the conduction and cutoff of the unidirectional thyristor or field-effect transistor Q.

4. The energy harvesting circuit according to claim 1, 2 or 3, characterized in that: The step-down circuit includes a transformer T1, and the freewheeling filter circuit includes a freewheeling diode D3 and a filter capacitor C2. The primary winding of the transformer T1 is connected in parallel between the output end of the voltage-type trigger circuit and the first charging capacitor C1, the secondary winding of the transformer T1 is connected in parallel with the filter capacitor C2, and the freewheeling diode D3 is connected in series between the output end of the secondary winding of the transformer T1 and the filter capacitor C2, with the anode of the freewheeling diode D3 connected to the output end of the secondary winding of the transformer T1, and the cathode of the freewheeling diode D3 connected to the filter capacitor C2.

5. The energy harvesting circuit according to claim 1, 2 or 3, characterized in that: The step-down circuit includes an inductor T2 with a magnetic core, and the freewheeling filter circuit includes a freewheeling diode D3 and a filter capacitor C2. The freewheeling diode D3 is connected in parallel between the output end of the voltage-type trigger circuit and the first charging capacitor C1, and the cathode of the freewheeling diode D3 is connected to the output end of the voltage-type trigger circuit, the anode of the freewheeling diode D3 is connected to the first charging capacitor C1, the filter capacitor C2 is connected in parallel with the freewheeling diode D3, and the inductor T2 is connected in series between the cathode of the freewheeling diode D3 and the filter capacitor C2.

6. The energy harvesting circuit according to claim 1, wherein: The second charging capacitor C3 is a Faraday capacitor or a lithium-ion capacitor.

7. An SF6 gas density relay energy acquisition circuit, characterized in that: Used to convert a high-voltage constant-voltage source into a low-voltage milliampere-level energy, including the energy acquisition circuit according to any one of claims 1 to 6, and also including a current limiting circuit, wherein the current limiting circuit is arranged between the high-voltage constant-voltage source and the first charging capacitor C1, and is used to convert the high-voltage constant-voltage source into a microampere-level current source to charge and store energy in the first charging capacitor C1.

8. The SF6 gas density relay energy acquisition circuit according to claim 7, characterized in that: The SF6 gas density relay energy acquisition circuit also includes a bridge rectifier D1, which is arranged between the high voltage constant voltage source and the current limiting circuit, or the bridge rectifier D1 is arranged between the current limiting circuit and the first charging capacitor C1, for achieving positive and negative polarity matching of the power supply.

9. The SF6 gas density relay energy acquisition circuit according to claim 7 or 8, characterized in that: The current limiting circuit is a series constant current source I1 or a current limiting resistor.

10. A method for obtaining energy from an SF6 gas density relay, characterized in that: The SF6 gas density relay energy acquisition circuit as described in any one of claims 7 to 9 is adopted, and the SF6 gas density relay energy acquisition circuit and the alarm contact of the SF6 gas density relay are connected in parallel and then connected to the power secondary system circuit. The SF6 gas density relay energy acquisition circuit converts the high voltage constant voltage source obtained from the power secondary system circuit into a low voltage milliampere level energy and then supplies power to each circuit module of the electronic circuit part of the SF6 gas density relay.

11. A high-voltage primary equipment energy acquisition circuit, characterized in that: Used to convert an AC current source into a low-voltage milliampere-level energy source, including the energy acquisition circuit as described in any one of claims 1 to 6, and also including a bridge rectifier D5, wherein the bridge rectifier D5 is arranged between the AC current source and the first charging capacitor, and is used to rectify the AC leakage current of the high-voltage primary device into a DC current source through D5.

12. The high-voltage primary equipment energy acquisition circuit according to claim 11, characterized in that: It also includes a protection circuit, which includes a zinc oxide resistor RV1, a wire-wound resistor R1 and a voltage-type trigger diode D4. The zinc oxide resistor RV1 is connected in series in the leakage current grounding loop of the high-voltage primary equipment. One end of the zinc oxide resistor RV1 is connected to one of the input ends of the bridge rectifier D5 via the wire-wound resistor R1, and the other end of the zinc oxide resistor RV1 is connected to the other input end of the bridge rectifier D5. The voltage-type trigger diode D4 is connected in parallel between the two input ends of the bridge rectifier D5.

13. The high-voltage primary equipment energy acquisition circuit according to claim 11 or 12, characterized in that: The high-voltage primary equipment is a lightning arrester or a capacitor type equipment.

14. A method for obtaining energy from high-voltage primary equipment, characterized in that: A high-voltage primary equipment energy acquisition circuit as described in any one of claims 11 to 13 is used, and the high-voltage primary equipment energy acquisition circuit is connected in series to the high-voltage primary equipment leakage current grounding loop. The high-voltage primary equipment energy acquisition circuit acquires the leakage current with current source characteristics of the monitored high-voltage primary equipment, converts it into low-voltage milliampere-level energy, and then powers the circuit module.

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