An electromagnetic valve circuit of an energy equipment and an online diagnosis method for its safety state

Abstract

The present invention discloses an electromagnetic valve circuit for energy equipment and an online diagnosis method for its safety status, belonging to the field of industrial control network security of energy equipment, including: an equipment connection step of connecting an online detection device in parallel to a corresponding position in the electromagnetic valve circuit according to the working type of the electromagnetic valve; a calibration step of calibrating the initial value of the detection circuit in the online detection device; a parameter configuration step of storing the calibration values of each detection channel and the state truth table of all electromagnetic valves of the energy equipment under various working conditions; an online diagnosis step of using the online detection device to detect the electromagnetic valve circuit and its safety status, and combining the detection results with the state truth table to vote on the safety status of the energy equipment; a status warning step of performing real-time warning on possible network attacks or illegal operations. The present invention accesses the detection probe to the object to be measured in a parallel manner, and real-time detects the safety status of the electromagnetic valve and its control circuit, reducing the risk of increasing the system fault points of the object to be measured.

Description

Technical Field

[0001] The present invention relates to the field of industrial control network security for energy equipment, and particularly to an electromagnetic valve circuit of energy equipment and an online diagnosis method for its safety state. Background Art

[0002] With the promulgation and implementation of a series of laws and regulations such as the "Network Security Law", the "Data Security Law", the "Personal Information Protection Law", and the "Regulations on the Security Protection of Critical Information Infrastructure", network security has penetrated into all walks of life. At present, the network security protection for industrial control systems is to strengthen the industrial control network by deploying devices such as firewalls, threat detection systems, and host guards, and adopting mechanisms such as configuring white lists and filtering communication messages at the information layer. This method has a certain positive effect on network security protection, but it cannot effectively prevent illegal operation instructions sent by legitimate industrial control devices, thereby damaging the process flow and destroying energy equipment, cannot prevent malicious human manipulation of energy equipment, and even more cannot prevent security incidents caused by the failure and out-of-control of the control loop of the energy equipment itself.

[0003] The electromagnetic valve is a key control component of energy equipment (steam turbines, gas turbines, wind turbines), mainly realizing electro-hydraulic signal conversion, operating condition switching, emergency shutdown, etc. There are two existing detection methods for electromagnetic valves and their control circuits. One is to arrange maintenance personnel for regular inspections, and the other is to connect an electromagnetic valve monitoring module in series in the control circuit. However, the inspection by maintenance engineers can only disassemble and measure the electromagnetic valve and its control circuit to check for faults before the energy equipment starts and after it stops. During the normal production process of the energy equipment, only the appearance of the electromagnetic valve can be used to judge its quality, and the internal fault information of the electromagnetic valve and its control circuit cannot be truly grasped, resulting in the phenomenon of "refusal to act" of the electromagnetic valve for control instructions in test conditions or emergency shutdown conditions.

[0004] In the prior art, such as the patent No. CN205808433U, named "A Device for Detecting the Working State of an Electromagnetic Valve", which provides a method for online detecting the working state of a small-power electromagnetic valve based on the principle of detecting whether the electromagnetic valve is in the open or closed state by using the change in inductance when the electromagnetic valve is in the open and closed states. This solution has the following disadvantages: ① It is required to connect the detection device in series in the electromagnetic valve circuit. Since the detection device itself has a probability of failure, the failure rate of the entire electromagnetic valve circuit is increased; ② By converting 220VAC to 24VDC to provide drive power supply for the electromagnetic valve, only small-power electromagnetic valves can be driven, and large-power and high-voltage-level energy equipment electromagnetic valves (35W / 220VDC) cannot be driven.

[0005] For another example, Patent No. CN103148280A, with the title "Online Monitoring Equipment for Solenoid Valve Failures", provides a solution that uses online detection of the drive current of BTS power devices to determine the working state of the solenoid valve. This solution has the following disadvantages: ① Similar to Patent No. CN205808433U, it requires the detection device to be connected in series to the solenoid valve circuit. Since the detection device itself has a probability of failure, it increases the failure rate of the entire solenoid valve circuit; ② By detecting the drive current of the BTS power device, only the on / off state of the solenoid valve coil can be detected, and the true working state of the iron core driven by the solenoid valve coil cannot be determined.

[0006] In addition, energy equipment (such as steam turbines, gas turbines, wind turbines, etc.) has many solenoid valves with different functions. For example, high-pressure shut-off solenoid valves for emergency shutdown, test solenoid valves for daily valve activity tests, and fast-closing solenoid valves for quickly closing the regulating valve to prevent equipment overspeed. These solenoid valves must work strictly according to the on / off logic truth tables of each working condition of the unit, otherwise serious safety accidents and huge economic losses will occur. Summary of the Invention

[0007] The present invention aims to solve the problem of the lack of systematic and comprehensive state monitoring of solenoid valves in the prior art, and proposes a solenoid valve circuit for energy equipment and an online diagnosis method for its safety state. By using the state truth tables of solenoid valves in energy equipment under various working conditions, security events such as network attacks and social engineering attacks against energy equipment are voted on to achieve the inherent safety of energy equipment.

[0008] In order to achieve the above invention purpose, the technical solution of the present invention is as follows:

[0009] A solenoid valve circuit for energy equipment and an online diagnosis method for its safety state, including the following steps:

[0010] Equipment connection step, including connecting the detection probes of the online detection device in parallel to the corresponding positions in the solenoid valve circuit according to the working type of the solenoid valve;

[0011] Calibration step, including forcing the control instruction of the relay cabinet to control the solenoid valve to be powered on or off to calibrate the initial value of the detection circuit in the online detection device;

[0012] Parameter configuration step, including storing the calibration values of each detection channel and the state truth tables of all solenoid valves in energy equipment under various working conditions;

[0013] Online diagnosis step, including using the online detection device to detect the solenoid valve circuit and its safety state, and combining the detection results with the state truth table to vote on the safety state of the energy equipment;

[0014] A status warning step, including transmitting the safety status of energy equipment to other network security systems through a communication protocol, and performing real-time warning if there is a network attack or illegal operation.

[0015] Further, in the equipment connection step, when the working type of the solenoid valve is normally energized, the detection probe is connected in parallel downstream of the fuse in the solenoid valve circuit; when the working type of the solenoid valve is normally de-energized, the detection probe is connected in parallel upstream of the fuse in the solenoid valve circuit.

[0016] Further, the implementation of detecting the solenoid valve circuit and its safety status by using the on-line detection device includes:

[0017] Step a: Use a high-voltage detection circuit to detect whether the solenoid valve circuit is energized, while shielding the discharge detection and phase detection, and output the detection result;

[0018] Step b: If the solenoid valve circuit loses power, at the moment of power loss, use a discharge detection circuit to detect the discharge time of the solenoid valve to judge the working state of the solenoid valve spool;

[0019] Step c: After the solenoid valve circuit finishes discharging, use a phase detection circuit to input an excitation source to the solenoid valve circuit to detect its phase difference, so as to obtain the solenoid valve inductive reactance according to the phase difference to judge whether the solenoid valve coil is intact.

[0020] Further, in step a, the high-voltage detection circuit is connected in parallel to the solenoid valve circuit. The high-voltage detection circuit includes an optocoupler U27, a thyristor IRF2, and an optocoupler U29; the optocoupler U27 converts the low-voltage HVPWM signal into a control circuit connection and inputs a gate control signal for driving the thyristor IRF2 with high voltage into the circuit, thereby reducing the voltage of the solenoid valve circuit; then drive the optocoupler U29 through a filter circuit and transmit the high-voltage detection signal into the FPGA / MCU circuit.

[0021] Further, in step b, at the moment when the solenoid valve loses power, the solenoid valve, the freewheeling diode D33 and the cement resistor R66 in the discharge detection circuit form a discharge loop, pass through a π-type filter circuit, and then through a sampling resistor R69 and an instrumentation amplifier, and transmit the discharge charge into the FPGA / MCU circuit for A / D conversion to calculate the discharge charge and the working state of the solenoid valve spool.

[0022] Further, the phase detection circuit includes an optocoupler U28 and a thyristor IRF1; the G pin of the thyristor IRF1 is connected to the PHYPWM control pin and is used to access a PWM excitation signal to the solenoid valve in a power-off state; the optocoupler U28 is connected to the thyristor IRF1 and is also connected to the CAPSIG terminal, and is used to transmit the PWM signal of the solenoid valve circuit into the FPGA / MCU circuit. The FPGA / MCU circuit calculates the inductive reactance of the solenoid valve through the phase difference between the input excitation signal and the feedback PWM signal.

[0023] Further, the first pin of the optocoupler U27 is connected to the 3.3V input power supply through the R63 resistor; the second pin is connected to the HVPWM control pin and is used to adjust the pulse to control the on-off state of the light-emitting diode in the optocoupler U27; the third pin is connected to the HVDCN through the resistor R67; the fourth pin is connected to the D pin of the thyristor IRF2.

[0024] Further, the first pin of the optocoupler U29 is connected to the resistor R73, the second pin is connected to the HVDCN, and the optocoupler U29 is driven through a filter circuit composed of an inductor L2 and a capacitor C26 to control the on-off state of its light-emitting diode; the fourth pin is connected to the HVSIG and is used to transmit the signal into the FPGA / MCU circuit.

[0025] Further, the D pin of the thyristor IRF1 is connected to the diode D35, the first pin of the optocoupler U28 is connected to the S pin of the thyristor IRF1, and the fourth pin is connected to the CAPSIG terminal.

[0026] Further, the first pin of the instrumentation amplifier is connected to the resistor R71, the fourth pin is connected to the HVDCP through the resistor R70, and the seventh pin is connected to the AISIG terminal.

[0027] In summary, the present invention has the following advantages:

[0028] 1. The present invention accesses the detection probe to the object to be measured in a parallel manner, and real-time detects the safety state of the solenoid valve and its control circuit, reducing the risk of increasing the system fault points of the object to be measured.

[0029] 2. The present invention detects the voltage of the object to be measured under the energized condition of the solenoid valve; under the power-off condition of the solenoid valve, a low-voltage excitation signal is input to the object to be measured to actively measure the inductance of the object to be measured, so as to obtain the solenoid valve circuit and its installation state, and realize the monitoring of the operating state of the solenoid valve.

[0030] 3. The present invention can combine the energized / power-off operation truth table of the solenoid valve under various working conditions, comprehensively monitor the operating state of the solenoid valve system, and give a real-time warning of network attacks or human malicious forced signal behaviors initiated by the working state of the solenoid valve. Description of the Drawings

[0031] Figure 1 It is a schematic diagram of the solenoid valve circuit for energy equipment;

[0032] Figure 2 It is a schematic diagram of the layout of detection points for normally de-energized solenoid valves according to the present invention;

[0033] Figure 3 It is a schematic diagram of the layout of detection points for normally energized solenoid valves according to the present invention;

[0034] Figure 4 It is the detection process of the safety state of the energy equipment according to the present invention;

[0035] Figure 5 It is the detection process of the solenoid valve and its control circuit according to the present invention;

[0036] Figure 6 It is the circuit block diagram of the on-line diagnostic device in the embodiment of the present invention;

[0037] Figure 7 It is the high-voltage detection circuit diagram of the on-line diagnostic device in the embodiment of the present invention;

[0038] Figure 8 It is the phase detection circuit diagram of the on-line diagnostic device in the embodiment of the present invention;

[0039] Figure 9 It is the discharge detection circuit diagram of the on-line diagnostic device in the embodiment of the present invention;

[0040] In the figure:

[0041] CT1, high-voltage detection circuit, CT2, alarm output circuit, CT3, phase detection circuit, CT4, discharge detection circuit, CT5, storage circuit, CT6, FPGA / MCU circuit, CT7, communication circuit, CT8, power supply circuit. Detailed Embodiments

[0042] In order to more clearly illustrate the present invention, the present invention will be further described below in conjunction with preferred embodiments and drawings. Those skilled in the art should understand that the specific content described below is illustrative rather than restrictive, and should not be used to limit the protection scope of the present invention.

[0043] Embodiment 1

[0044] Energy equipment (such as steam turbines, gas turbines, wind turbines, etc.) usually includes high-pressure shut-off solenoid valves, mechanical shutdown solenoid valves, quick-close solenoid valves, and valve activity test solenoid valves, as Figure 1As shown in the figure, the control instructions are transmitted to the on-site solenoid valve through the relays, fuses, and cables in the relay cabinet, thereby controlling the safe operation of the energy equipment. When the energy equipment is operating normally, the solenoid valves are divided into two types: normally energized and normally de-energized.

[0045] Taking a steam turbine as an example, in order to prevent equipment damage caused by steam turbine overspeed, there are usually electrical overspeed protection and mechanical overspeed protection in the steam turbine control system. Among them, mechanical overspeed is the last protection system to prevent the failure of electrical overspeed protection. When mechanical overspeed occurs, the steam turbine shuts down safely. During the daily operation of the steam turbine, in order to verify the reliability of mechanical overspeed, an oil injection test and a mechanical overspeed test are regularly carried out. That is, when the isolation solenoid valve is energized and the steam turbine speed is higher than the mechanical overspeed protection value, or when the oil injection test solenoid valve is energized, the mechanical overspeed protection acts. At this time, although the mechanical overspeed protection acts, the unit still operates normally. Therefore, the isolation solenoid valve is prohibited from being energized during normal operation, otherwise the mechanical overspeed protection will fail. It can be seen from this that if the isolation solenoid valve is energized under other working conditions, the unit will be in a very dangerous state.

[0046] If the fast closing solenoid valve is energized under the operating condition of the steam turbine generating electricity at full load, the steam turbine governor valve will close completely, steam cannot enter the steam turbine, and the steam turbine generator will become an electric motor, resulting in a safety accident of reverse power operation.

[0047] If the steam turbine needs to enter the emergency shutdown condition, but the high-pressure shut-off solenoid valve is energized and the fast closing solenoid valve is de-energized, the steam turbine cannot shut down, leading to a greater safety accident.

[0048] In short, if the operating states of these solenoid valves are attacked by network attacks or maliciously manipulated by humans, it will cause major safety accidents to the energy equipment.

[0049] Therefore, in order to detect the entire control loop of the fuse, cable, solenoid valve and the working state of the solenoid valve in real time, the present invention proposes a solenoid valve circuit of energy equipment and an online diagnosis method for its safety state, and the detection probe is connected in parallel to the detection point upstream or downstream of the fuse to realize the real-time detection of the safety state of the solenoid valve and its control loop, as Figure 2 , Figure 3 shown.

[0050] As Figure 5 shown, in this step, the process of detecting the solenoid valve circuit and its safety state includes:

[0051] Step a: Connect the detection probe in parallel to the solenoid valve circuit;

[0052] Step b: Detect whether the solenoid valve circuit is energized, and use the detection result as the input of the state truth table to output the current state of the solenoid valve;

[0053] Step c: If the solenoid valve circuit loses power, start the discharge detection at the moment of power loss, and obtain the working state of the solenoid valve spool by detecting the discharge time of the solenoid valve;

[0054] Step d: After the solenoid valve circuit finishes discharging, start the phase detection, input an excitation source into the solenoid valve circuit to detect its phase difference, and then obtain the inductive reactance of the solenoid valve according to the phase difference to determine whether the solenoid valve coil is intact.

[0055] In the above steps, if the current state of the solenoid valve, the working state of the solenoid valve spool, and the state of the solenoid valve coil are detected to be abnormal, an alarm is issued in a timely manner.

[0056] In the present invention, the detection probe is connected to the object to be measured in a parallel manner, reducing the risk of increasing the system fault points of the object to be measured; under the energized condition of the solenoid valve, the voltage of the object to be measured is detected; under the power-off condition of the solenoid valve, a low-voltage excitation signal is input to the object to be measured to actively measure the inductance of the object to be measured, thereby reducing the risk of the detection device interfering with the control system of the object to be measured.

[0057] Embodiment 2

[0058] An energy equipment solenoid valve circuit and its online diagnosis method for safety status proposed by the present invention can detect the states of multiple solenoid valves simultaneously. Combining with the solenoid valve operation truth table, the system comprehensively monitors the operation state of the solenoid valve and gives a real-time warning of network attacks or human malicious forced signal behaviors initiated by the working state of the solenoid valve.

[0059] Specifically, as Figure 4 shown, the specific steps of applying this method to the energy equipment safety status detection process are as follows:

[0060] Equipment connection step: According to the working type of the solenoid valve (always energized / always de-energized), connect the detection probe in parallel to the detection point upstream or downstream of the fuse in the solenoid valve circuit; as Figure 2 , Figure 3 shown in the detection points, when the working type of the solenoid valve is always energized, the detection point is located downstream of the fuse; when the working type of the solenoid valve is always de-energized, the detection point is located upstream of the fuse;

[0061] Calibration step: Force the control command of the relay cabinet to control the command of switch K11 in the solenoid valve circuit ( Figure 1 ), so that the solenoid valve is energized / de-energized, and calibrate the A / D code value of the discharge detection circuit and the PWM phase difference of the phase detection circuit in the online diagnosis device;

[0062] Parameter configuration steps: Calibration values of A / D code for the discharge detection circuits of each detection channel, PWM phase difference calibration values for the phase detection circuit, and the state truth table of all solenoid valves of the configured energy equipment under various working conditions are stored in the storage chip; Table 1 below is an example of the solenoid valve energized state truth table:

[0063] Table 1 Solenoid valve energized state truth table

[0064]

[0065] Online detection steps: Detect the solenoid valve circuit and its safety status, and combine the detection results with the state truth table to vote on the safety status of the energy equipment;

[0066] State warning steps: Transmit the safety status of the energy equipment to other network security systems through the communication protocol. If there is a network attack or illegal operation, give a real-time warning through the alarm circuit.

[0067] Specifically, according to the solenoid valve circuit and its safety status detection steps mentioned in Embodiment 1:

[0068] Step a: Detect whether the solenoid valve circuit is energized, and use the detection result as the input of the solenoid valve state truth table to output the current state of the solenoid valve;

[0069] In this embodiment, a high-voltage detection circuit CT1 is used to detect whether the solenoid valve circuit is energized (that is, to judge whether K11 in Figure 1 is closed). As shown in Figure 7 , the high-voltage detection circuit CT1 includes an optocoupler U27 (TPL281), a thyristor IRF2 (IRF_SI2312), and an optocoupler U29 (TPL281). The content in the brackets represents the device model, which is only for example. Simple model replacements based on the above principles are within the scope of protection of this application.

[0070] Among them, the first pin of the optocoupler U27 (model TPL281) is connected to the 3.3V input power supply through the resistor R63; the second pin is connected to the HVPWM control pin, which is used to adjust the pulse to control the on-off state of the light-emitting diode in the optocoupler U27; the third pin is connected to HVDCN through the resistor R67, and the fourth pin is connected to the D pin of the thyristor IRF2 (IRF_SI2312), which is used to convert the low-voltage HVPWM (frequency 10KHz, duty cycle 4.5%) into a gate control signal for the thyristor IRF2 that is connected to the control circuit and inputs high-voltage drive 220VDC to the circuit, thereby reducing the 220VDC control loop voltage to 10VDC. The first pin of the optocoupler U29 (TPL281) is connected to the resistor R73, the second pin is connected to HVDCN, and drives the optocoupler U29 through the filter circuit composed of the inductor L2 and the capacitor C26 to control the on-off state of its light-emitting diode; the fourth pin of the optocoupler U29 (TPL281) is connected to the HVSIG terminal, which is used to transmit the signal into the FPGA / MCU circuit CT6.

[0071] Step b: If the solenoid valve circuit loses power, start the discharge detection at the moment of power loss (0ms), and obtain the working state of the solenoid valve spool by detecting the discharge time of the solenoid valve.

[0072] In this embodiment, the discharge detection circuit CT4 is used to start the discharge detection. The discharge detection circuit is used when Figure 1 K11 in is disconnected instantaneously to measure the discharge time of the solenoid valve.

[0073] As Figure 9 shown, the discharge detection circuit CT4 includes the instrumentation amplifier AD8211. Among them, the first pin of the instrumentation amplifier AD8211 is connected to the resistor R71, and the fourth pin is connected to HVDCP through the resistor R70 to receive the differential signal. When the solenoid valve loses power instantaneously, the solenoid valve, the freewheeling diode D33, and the cement resistor R66 (100 ohms, power 1W) form a discharge loop, and a π-type filter circuit is formed through the inductor L1, the capacitor C23, and the capacitor C24; then, through the sampling resistor R69 and the instrumentation amplifier AD8211, the discharge charge is transmitted into the FPGA / MCU circuit CT6 for A / D conversion to calculate the discharge charge and the working state of the iron core of the solenoid valve.

[0074] The seventh pin of the instrumentation amplifier AD8211 is connected to the AISIG terminal, and the discharge charge is transmitted into the FPGA / MCU circuit CT6 for A / D conversion to calculate the discharge charge and the working state of the spool of the solenoid valve.

[0075] Step c: After the solenoid valve circuit discharges for 1000 ms (the discharge time depends on the specific situation), start phase detection, input an excitation source to the solenoid valve circuit to detect its phase difference, and then obtain the solenoid valve inductive reactance based on the phase difference to determine whether the solenoid valve coil is intact.

[0076] In this step, a phase detection circuit CT3 outputs a PWM wave (excitation source) to the solenoid valve to detect its PWM phase difference.

[0077] As Figure 8 shown, the phase detection circuit CT3 includes an optocoupler U28 (TPL281) and a thyristor IRF1 (IRF_SI2312). The fuse F2 is connected to the 5V input power supply to protect the input power supply; the D pin of the thyristor IRF1 (IRF_SI2312) is connected to the diode D35, and the G pin is connected to the PHYPWM control pin to connect a PWM excitation signal (peak value 5VDC, frequency 100Hz, duty cycle 50%) to the solenoid valve in the power-off state. The first pin of the optocoupler U28 (TPL281) is connected to the S pin of the thyristor IRF1 (IRF_SI2312), and the fourth pin is connected to the CAPSIG terminal to transmit the PMW signal of the solenoid valve circuit to the FPGA / MCU circuit CT6. The FPGA / MCU circuit CT6 calculates the inductive reactance of the solenoid valve through the phase difference between the input PHYPWM excitation signal and the feedback CAPSIG signal.

[0078] In this embodiment, as Figure 6 shown, the high-voltage detection circuit CT1, the phase detection circuit CT3, and the discharge detection circuit CT4 are all connected to the FPGA / MCU circuit CT6, and the FPGA / MCU circuit CT6 enables the logic control of the entire online diagnostic device.

[0079] Furthermore, the FPGA / MCU circuit CT6 is also connected to an alarm output circuit CT2, a storage circuit CT5, a communication circuit CT7, and a power supply circuit CT8. In this embodiment, the alarm output circuit CT2 is used to output the alarm signal after voting by the FPGA / MCU circuit CT6; the storage circuit CT5 is used to store the on / off true value table of the solenoid valve under various operating conditions of the energy equipment and the configuration information of the entire device; the communication circuit CT7 is used to communicate with other devices and collect the operating condition information of the energy equipment; the alarm output circuit CT2, the FPGA / MCU circuit CT6, the high-voltage detection circuit CT1, the storage circuit CT5, the communication circuit CT7, the phase detection circuit CT3, and the discharge detection circuit CT4 are all connected to the power supply circuit CT8 to achieve power supply.

[0080] The above are only the preferred embodiments of the present invention, and do not impose any form of limitation on the present invention. Any simple modification or equivalent change made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. An online diagnostic method for the safety status of a solenoid valve circuit of energy equipment, characterized in that: The steps include: The equipment connection step includes connecting the detection probe of the online detection device in parallel to the corresponding position in the solenoid valve circuit according to the working type of the solenoid valve; The calibration step includes forcing the relay cabinet to control the solenoid valve to be energized or de-energized so as to calibrate the initial value of the detection circuit in the online detection device; The parameter configuration step includes storing the calibration values ​​of each detection channel and the state truth table of all solenoid valves of the energy equipment under various working conditions; The online diagnosis step includes using an online detection device to detect the solenoid valve circuit and its safety status, and combining the detection results with the state truth table to determine the safety status of the energy equipment; Status warning step, including transmitting the security status of energy equipment to other network security systems through communication protocols, and issuing real-time warnings if there is a network attack or illegal operation; In the online diagnosis step, the use of an online detection device to detect the solenoid valve circuit and its safety status includes: Step a, using a high-voltage detection circuit to detect whether the solenoid valve circuit is energized, shielding discharge detection and phase detection at the same time, and outputting the detection result; Step b: If the solenoid valve circuit loses power, at the moment of power failure, a discharge detection circuit is used to detect the discharge time of the solenoid valve to determine the working state of the solenoid valve core; Step c: after the solenoid valve circuit is discharged, a phase detection circuit is used to input an excitation source into the solenoid valve circuit to detect its phase difference, so as to obtain the inductive reactance of the solenoid valve according to the phase difference and thus determine whether the solenoid valve coil is intact.

2. The method for online diagnosis of the safety status of a solenoid valve circuit of energy equipment according to claim 1 is characterized in that: In the equipment connection steps, when the working type of the solenoid valve is normally energized, connect the detection probe in parallel to the downstream of the fuse in the solenoid valve circuit; when the working type of the solenoid valve is normally de-energized, connect the detection probe in parallel to the upstream of the fuse in the solenoid valve circuit.

3. The method for online diagnosis of the safety status of a solenoid valve circuit of energy equipment according to claim 1 is characterized in that: In step a, the high-voltage detection circuit is connected in parallel to the solenoid valve circuit, and the high-voltage detection circuit includes a photocoupler U27, a thyristor IRF2 and a photocoupler U29; the photocoupler U27 converts the low-voltage HVPWM signal into a control circuit connection and inputs a high-voltage gate control signal of the thyristor IRF2 into the circuit, thereby reducing the voltage of the solenoid valve circuit; the photocoupler U29 is then driven by the filter circuit, and the high-voltage detection signal is transmitted to the FPGA / MCU circuit.

4. The method for online diagnosis of the safety status of a solenoid valve circuit of energy equipment according to claim 1 is characterized in that: In step b, when the solenoid valve loses power, the solenoid valve and the freewheeling diode D33 and cement resistor R66 in the discharge detection circuit form a discharge circuit, which passes through the π-type filter circuit, and then through the sampling resistor R69 and the instrument amplifier to transmit the discharged electricity to the FPGA / MCU circuit for A / D conversion to calculate the discharged electricity and the working status of the valve core of the solenoid valve.

5. The method for online diagnosis of the safety status of a solenoid valve circuit of energy equipment according to claim 1 is characterized in that: The phase detection circuit includes a photocoupler U28 and a thyristor IRF1; the G pin of the thyristor IRF1 is connected to the PHYPWM control pin, and is used to connect the PWM excitation signal to the solenoid valve in the power-off state; the photocoupler U28 is connected to the thyristor IRF1 and is also connected to the CAPSIG end, and is used to transmit the PWM signal of the solenoid valve loop to the FPGA / MCU circuit, and the FPGA / MCU circuit calculates the inductive reactance of the solenoid valve by the phase difference between the input excitation signal and the feedback PWM signal.

6. The method for online diagnosis of the safety status of a solenoid valve circuit of energy equipment according to claim 3 is characterized in that: The first pin of the photocoupler U27 is connected to the input power supply through the resistor R63; the second pin is connected to the HVPWM control pin for adjusting the pulse, thereby controlling the switching state of the light-emitting diode in the photocoupler U27; the third pin is connected to HVDCN through the resistor R67; and the fourth pin is connected to the D pin of the thyristor IRF2.

7. The method for online diagnosis of the safety status of a solenoid valve circuit of energy equipment according to claim 3 is characterized in that: The first pin of the photocoupler U29 is connected to the resistor R73, and the second pin is connected to HVDCN. The filter circuit composed of the inductor L2 and the capacitor C26 drives the photocoupler U29 to control the switching state of its light-emitting diode; the fourth pin is connected to HVSIG to transmit the signal to the FPGA / MCU circuit.

8. The method for online diagnosis of the safety status of a solenoid valve circuit of energy equipment according to claim 5 is characterized in that: The D pin of the thyristor IRF1 is connected to the diode D35, the first pin of the photocoupler U28 is connected to the S pin of the thyristor IRF1, and the fourth pin is connected to the CAPSIG terminal.

9. The method for online diagnosis of the safety status of a solenoid valve circuit of energy equipment according to claim 4, characterized in that: The first pin of the instrument amplifier is connected to the resistor R71, the fourth pin is connected to the HVDCP via the resistor R70, and the seventh pin is connected to the AISIG terminal.

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