Direct-current test power supply capable of realizing alternating-current intrusion monitoring of direct-current loop

Abstract

The invention relates to a direct-current test power supply capable of realizing alternating-current intrusion monitoring of a direct-current loop, the power supply adopts alternating-current 220V input, a voltage-type direct-current source is formed by adopting bridge rectification and capacitor filtering, and the voltage range is DC280-DC332V; the power supply adopts four main power devices Q1-Q4, an anti-parallel diode and a parasitic capacitor to form a full-bridge arm; a power supply is connected with a rectifying circuit through a transformer containing a leakage inductor and an external resonant inductor L to form a full-bridge converter; an upper switch tube and a lower switch tube of two bridge arms of the full-bridge converter are in 180-degree complementary conduction, output voltage between the bridge arms is adjusted by adjusting a phase-shifting angle, and adjustment of the phase-shifting angle is also a basis for achieving soft switching. The device has the advantages of being reasonable in structure, providing a direct-current power supply, monitoring alternating-current voltage channeling, rapidly cutting off the direct-current power supply and giving an alarm in time.

Description

Technical Field

[0001] The invention belongs to the technical field of transformer substations, and in particular relates to a DC test power supply capable of realizing AC intrusion monitoring of a DC circuit. Background Art

[0002] In order to ensure the safe and stable operation of the primary equipment of the substation, various auxiliary electrical equipment needs to be configured in the station, such as various measurement and control devices, relay protection devices, fault recording devices, etc., collectively referred to as secondary equipment, and their electrical connection circuits are collectively referred to as secondary circuits. In order to realize their respective functions, the secondary circuits generally need to access the information source of the operating status of the primary equipment and the control power supply or operating power supply to ensure the operation of the secondary equipment. According to the nature of the power supply, the secondary circuit can be simply divided into AC circuit and DC circuit. The AC circuit is all the circuits powered by current transformers and voltage transformers. Its function is to collect the operating parameters of the relevant primary equipment for the secondary equipment to realize the primary system equipment. The DC circuit is the entire circuit connected between the positive and negative poles of the DC power supply. Its main functions are: to control the operation of equipment such as circuit breakers and switches; to indicate the operating status of primary and secondary equipment; to provide power for secondary devices, generally ±220V or ±110V; the grounding problem caused by AC entering the DC system is extremely harmful. Generally, the positive and negative poles of the DC circuit are mainly protection and circuit breaker control circuits. When the DC circuit is grounded, it may cause a short circuit in the control circuit, causing malfunction and refusal of protection and circuit breakers; AC entering the DC system causes grounding problems, mainly the AC power phase line Some locations are connected to the DC system bus or DC circuit wiring. The main feature is that the positive and negative poles to ground voltage can accurately detect the existence of AC voltage. The station AC power supply is connected to the ground with the PT neutral line. The AC phase line enters the DC system, which can cause the DC system to be grounded. Moreover, the harm of AC power entering the DC system is far greater than simple DC grounding. AC entering the DC circuit will cause the malfunction of the protection outlet intermediate relay or cause abnormal melting of the DC fuse, resulting in the refusal of protection. It may also cause the DC controlled equipment to start automatically, causing great harm to equipment and personnel. The reasons for AC entering the DC system Factors include staff wiring operation errors, cable wear and other factors. For substations, when the secondary circuit is under maintenance, due to factors such as personnel negligence, wiring errors, line wear and other factors, it is more likely to cause AC to DC. If the DC circuit is not checked after the maintenance work is completed and power is directly supplied to the equipment, accidents will occur. Such accidents happen from time to time, and substations currently lack the means to detect the DC circuit in advance; therefore, it is very necessary to provide a DC test power supply with a reasonable structure, which can provide DC power supply, monitor AC voltage intrusion, quickly cut off DC power supply, and promptly alarm, and can realize DC circuit AC intrusion monitoring. Summary of the invention

[0003] 1. Technical issues In view of the above-mentioned existing technical status, this application mainly addresses the following technical problems: 1. Due to factors such as wiring errors and cable wear, AC entering the DC system can cause grounding problems that are extremely harmful, such as causing the malfunction of the protection outlet intermediate relay or abnormal melting of the DC fuse, which can cause the protection to refuse to operate. It can also cause the DC-controlled equipment to start automatically, causing great harm to the equipment and personnel. How to monitor the AC voltage? 2. In view of the phenomenon that the DC circuit is not checked after the maintenance work is completed and power is directly supplied to the equipment, which leads to accidents, the substation currently lacks the means to detect the DC circuit in advance. How to effectively detect and cut off the DC power supply in time and alarm at the same time.

[0004] (II) Technical solution The purpose of the present invention is to overcome the shortcomings of the prior art and to provide a DC test power supply with a reasonable structure, which can provide DC power supply, monitor AC voltage intrusion, quickly cut off DC power supply, and promptly alarm, and can realize DC circuit AC intrusion monitoring.

[0005] The object of the present invention is achieved as follows: a DC test power supply that can realize AC intrusion monitoring of a DC circuit, the power supply adopts AC 220V input, and adopts bridge rectification and capacitor filtering to form a voltage-type DC source, and the voltage range is DC280~DC332V; the power supply adopts 4 main power devices Q1~Q4 and anti-parallel diodes and parasitic capacitors to form a full-bridge bridge arm; the power supply is connected to a transformer and a rectifier circuit containing a leakage inductor and an external resonant inductor L to form a full-bridge converter; the upper and lower switch tubes of the two bridge arms of the full-bridge converter are complementary and turned on at 180°, and the output voltage is adjusted between the bridge arms by adjusting the phase shift angle.

[0006] Furthermore, the sampling circuit of the full-bridge converter adopts a DC-blocking capacitor detection technology, connects a capacitor in series in the resistor voltage divider loop, and utilizes the characteristics of the capacitor passing AC and blocking DC, thereby isolating the DC component in the sampled signal and obtaining the AC component.

[0007] Furthermore, the DC test power supply capable of realizing AC intrusion monitoring in a DC circuit also includes a driving hardware control protection circuit, and the driving hardware control protection circuit includes an input sampling circuit, a PWM driving circuit, an output sampling circuit and a hardware protection circuit.

[0008] Furthermore, the control chip of the driving hardware control protection circuit adopts a PPEC-86CA3A phase-shifted full-bridge digital power control chip.

[0009] Furthermore, the DC test power supply that can realize AC intrusion monitoring of the DC circuit also includes an AC intrusion prevention detection circuit, the AC intrusion prevention detection circuit includes a voltage acquisition module, an AC intrusion judgment module, a power supply output status monitoring module, a relay module and a status alarm module, and the voltage acquisition module includes a DC voltage acquisition module and an AC voltage acquisition module.

[0010] Furthermore, the voltage acquisition module uses a differential voltage method to collect the positive and negative bus voltages through a differential circuit composed of dual voltage transformers; the output end of the voltage sampling and conditioning circuit of the voltage acquisition module is connected to an AD converter, and the AD converter converts the analog signal into a digital signal that can be recognized by the control unit MCU, and then calculates and judges through the MCU.

[0011] Furthermore, the AC inrush judgment module adopts AC power detection technology based on DC blocking capacitors to determine whether there is AC inrush; the balancing resistors R1 and R2 of the AC inrush judgment module are arranged between the positive and negative poles of the DC bus; the AC signal extraction circuit composed of a resistor R3, a capacitor C1 and a resistor R4 connected in series in the AC inrush judgment module is arranged between the negative / positive pole of the DC bus and the ground.

[0012] Furthermore, the voltage sampling circuit of the AC intrusion judgment module is connected to both ends of R3, and the output end of the voltage sampling circuit is connected to the AD converter; and the output end of the AD converter is connected to the MCU.

[0013] Furthermore, the DC test power supply that can realize AC intrusion monitoring in the DC circuit also includes a buzzer output interface and an alarm light output interface, and the buzzer output interface and the alarm light output interface are respectively connected to the status alarm module; the power supply also includes at least two relay output interfaces, and the relay output interfaces are connected to the relay module for outputting the normal / abnormal status of the power supply voltage.

[0014] Furthermore, the DC test power supply capable of realizing AC inrush monitoring in a DC circuit also includes a gear selection switch, and the gear selection switch can be used for selecting between 110V and 220V output power supplies.

[0015] (III) Beneficial effects 1. The present invention adopts the DC blocking capacitor detection technology: when designing the sampling circuit, a capacitor is connected in series in the resistor voltage divider loop, and the characteristic of the capacitor passing AC and blocking DC is utilized, thereby isolating the DC component in the sampled signal, so that the AC component can be obtained; 2. The voltage sampling of the present invention: a differential circuit composed of dual voltage transformers is used to collect the positive and negative bus voltages, and a high-precision resistor voltage divider circuit is used to convert the DC220V high voltage into a DC0~3V low voltage signal, which is then connected to the ADC for voltage sampling after low-pass filtering; 3. The present invention determines whether there is AC intrusion by collecting voltage signals. If there is AC intrusion, an alarm is sounded through a buzzer and the output of the DC power supply is cut off at the same time; 4. The power supply of the present invention adopts AC bridge rectification and full-bridge converter to meet the demand of 110V or 220V power supply in the plant, and the power selection switch can switch gears. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The present invention is a power supply topology diagram of a DC test power supply capable of realizing AC intrusion monitoring in a DC circuit.

[0017] Figure 2 The invention discloses a driving hardware protection circuit for a DC test power supply capable of realizing AC intrusion monitoring of a DC circuit.

[0018] Figure 3 The present invention is a diagram of an AC detection module of a DC test power supply capable of monitoring AC intrusion into a DC circuit.

[0019] Figure 4 The present invention is a differential voltage method principle block diagram of a DC test power supply capable of realizing AC intrusion monitoring in a DC circuit.

[0020] Figure 5 The present invention is a block diagram of the principle of AC detection technology based on DC blocking capacitors for a DC test power supply capable of realizing AC intrusion monitoring in a DC circuit. DETAILED DESCRIPTION

[0021] The present invention is further described below in conjunction with embodiments and / or drawings. Example

[0022] like Figure 1 As shown, a DC test power supply capable of realizing monitoring of AC intrusion into a DC circuit, the power supply adopts an AC 220V input, and adopts a bridge rectifier and a capacitor filter to form a voltage-type DC source, and the voltage range is DC280-DC332V; the power supply adopts four main power devices Q1-Q4 and anti-parallel diodes and parasitic capacitors to form a full-bridge bridge arm; the power supply is connected to a transformer and a rectifier circuit containing a leakage inductor and an external resonant inductor L to form a full-bridge converter; the upper and lower switch tubes of the two bridge arms of the full-bridge converter are complementary turned on at 180°, and the output voltage is adjusted between the bridge arms by adjusting the phase shift angle, and the adjustment of the phase shift angle is also the basis for realizing soft switching.

[0023] Specifically, the power supply design of the present invention mainly includes the design of the dual-output power supply topology structure, the implementation of the control protection circuit, the collection, judgment and status monitoring of the voltage signal, etc.

[0024] The sampling circuit of the full-bridge converter adopts DC-blocking capacitor detection technology. A capacitor is connected in series in the resistor voltage divider circuit, and the characteristic of capacitor passing AC and blocking DC is utilized to isolate the DC component in the sampled signal, so as to obtain the AC component.

[0025] like Figure 2 As shown, the driving hardware control protection circuit includes an input sampling circuit, a PWM driving circuit, an output sampling circuit and a hardware protection circuit.

[0026] The control chip of the driving hardware control protection circuit adopts the PPEC-86CA3A phase-shifted full-bridge digital power control chip.

[0027] In the present invention, ① anti-AC intrusion detection circuit: adopts differential voltage method and AC detection method based on DC blocking capacitor to design reliable voltage acquisition circuit; ② DC signal real-time recognition technology: through comparison and analysis of collected data, it can automatically identify whether there is AC intrusion, timely discover power failure, and automatically cut off DC power supply, effectively avoiding protection malfunction or large-scale power outage accidents caused by AC intrusion, and improving the safe operation level of the power grid; ③ multiple alarm mode technology: detection information realizes on-site sound and light alarm, and cuts off the DC power output; ④ At the same time, in order to meet different applications, the DC power supply also has 110V and 220V power output gear switching function.

[0028] The present invention is a DC test power supply capable of realizing monitoring of AC intrusion into a DC circuit. During use, the device of the present invention can not only provide DC power to the circuit, but more importantly, monitor the AC voltage. Once AC intrudes into the circuit, the DC power can be quickly cut off and an alarm can be given in time, thereby discovering the hidden danger of AC intrusion into the DC circuit, thereby eliminating the hidden danger, preventing accidents from occurring, and ensuring safe and reliable operation of the equipment. The present invention can be widely applied to similar equipment to avoid accidents caused by AC intrusion, improve the health level of the equipment, and improve the operational reliability of the power station. The present invention has the advantages of reasonable structure, providing DC power, monitoring AC voltage intrusion, quickly cutting off DC power, and giving an alarm in time. Example

[0029] like Figure 1As shown, a DC test power supply capable of realizing monitoring of AC intrusion into a DC circuit, the power supply adopts an AC 220V input, and adopts a bridge rectifier and a capacitor filter to form a voltage-type DC source, and the voltage range is DC280-DC332V; the power supply adopts four main power devices Q1-Q4 and anti-parallel diodes and parasitic capacitors to form a full-bridge bridge arm; the power supply is connected to a transformer and a rectifier circuit containing a leakage inductor and an external resonant inductor L to form a full-bridge converter; the upper and lower switch tubes of the two bridge arms of the full-bridge converter are complementary turned on at 180°, and the output voltage is adjusted between the bridge arms by adjusting the phase shift angle, and the adjustment of the phase shift angle is also the basis for realizing soft switching.

[0030] like Figure 3 As shown, the present invention also includes an AC intrusion prevention detection circuit, which includes a voltage acquisition module, an AC intrusion judgment module, a power output status monitoring module, a relay module and a status alarm module, and the voltage acquisition module includes a DC voltage acquisition module and an AC voltage acquisition module.

[0031] Specifically: the anti-AC intrusion detection circuit transmits the voltage signal to the voltage sampling and conditioning circuit through the differential voltage method and the AC detection method based on the DC blocking capacitor. The DC or AC voltage is divided and low-pass filtered by high-precision resistors to obtain a low voltage of 0~3V. The output voltage of the conditioning circuit is input into the ADC for sampling. The MCU reads the ADC sampling voltage and performs conversion calculations, and compares in real time to determine whether there is AC intrusion. If it is determined that there is AC intrusion, an indication will be given through the abnormal status relay, and the buzzer will alarm to promptly discover safety hazards, and at the same time cut off the output of the DC power supply to ensure system safety.

[0032] like Figure 4 As shown, the voltage acquisition module uses a differential voltage method to acquire the positive and negative bus voltages through a differential circuit composed of dual voltage transformers; the output end of the voltage sampling and conditioning circuit of the voltage acquisition module is connected to an AD converter, and the AD converter converts the analog signal into a digital signal that can be recognized by the control unit MCU, and then the MCU performs calculation and judgment.

[0033] Specifically: The schematic diagram of the differential voltage method is as follows: Figure 4 As shown, at least one voltage sampling circuit is provided between the DC bus positive pole KM+ and the ground, or between the DC bus negative pole KM- and the ground. The output of the voltage sampling conditioning circuit is connected to the AD converter, and the AD converter converts the analog signal into a digital signal that can be recognized by the control unit MCU, and then the MCU performs calculation and judgment.

[0034] In practical applications, voltage sampling: a differential circuit composed of dual voltage transformers is used to collect the positive and negative bus voltages. At the same time, a high-precision resistor voltage divider circuit is used to convert the DC220V high voltage into a DC0~3V low voltage signal, which is then connected to the ADC for voltage sampling after low-pass filtering.

[0035] like Figure 5 As shown, the AC inrush judgment module adopts the AC power detection technology based on the DC blocking capacitor to judge whether there is AC inrush; the balancing resistors R1 and R2 of the AC inrush judgment module are arranged between the positive and negative poles of the DC bus; the AC signal extraction circuit composed of the resistor R3, the capacitor C1 and the resistor R4 connected in series in the AC inrush judgment module is arranged between the negative / positive pole of the DC bus and the ground.

[0036] The voltage sampling circuit of the AC intrusion judgment module is connected to both ends of R3, and the output end of the voltage sampling circuit is connected to an AD converter; and the output end of the AD converter is connected to the MCU.

[0037] Specifically: The block diagram of the AC detection technology based on DC blocking capacitors is as follows: Figure 5 As shown in the figure, R1 and R2 are balancing resistors in the DC system; an AC signal extraction circuit consisting of a resistor R3, a capacitor C1 and a resistor R4 connected in series is set between the negative pole (or positive pole) of the DC bus and the ground; wherein R3 is set to be less than R4 to achieve the purpose of regulating the voltage, and the voltage sampling circuit is connected from both ends of R3, and its output is connected to the AD converter, which converts the analog signal into a digital signal that can be recognized by the control unit MCU, and then the MCU performs calculation and judgment.

[0038] In practical applications, the present invention determines whether there is AC intrusion by collecting voltage signals. If there is AC intrusion, an alarm is sounded through a buzzer and the output of the DC power supply is cut off at the same time.

[0039] In general, the present invention has the following advantages: ① Two detection technologies based on differential voltage method and DC blocking capacitor method are proposed, which can accurately detect AC intrusion and timely discover abnormal conditions of the DC circuit; ②Multiple output interfaces facilitate access to existing monitoring systems, with good compatibility, and can be connected to existing systems with simple modifications; ③Two power supply gears are optional to meet the different power supply needs of plants and stations; ④ Able to timely discover and handle potential faults caused by AC entering the DC circuit; ⑤ Through real-time online monitoring of the DC circuit, it is possible to detect whether there is AC intrusion, effectively avoiding protection misoperation or large-scale power outages caused by AC intrusion, and improving the safe operation level of the power grid; ⑥ It has good economic and social benefits: The present invention is promoted and applied in substations, which can complete the last power-on monitoring of the DC circuit to be inspected, timely discover the hidden dangers of AC entering the DC circuit, avoid false protection or large-scale power outages, improve the stable operation level of the power grid, improve the operation and maintenance level of substations, provide effective support for the safe and stable operation of the power system, and can generate huge social benefits.

[0040] The present invention is a DC test power supply capable of realizing monitoring of AC intrusion into a DC circuit. During use, the device of the present invention can not only provide DC power to the circuit, but more importantly, monitor the AC voltage. Once AC intrudes into the circuit, the DC power can be quickly cut off and an alarm can be given in time, thereby discovering the hidden danger of AC intrusion into the DC circuit, thereby eliminating the hidden danger, preventing accidents from occurring, and ensuring safe and reliable operation of the equipment. The present invention can be widely applied to similar equipment to avoid accidents caused by AC intrusion, improve the health level of the equipment, and improve the operational reliability of the power station. The present invention has the advantages of reasonable structure, providing DC power, monitoring AC voltage intrusion, quickly cutting off DC power, and giving an alarm in time. Example

[0041] like Figure 1 As shown, a DC test power supply capable of realizing monitoring of AC intrusion into a DC circuit, the power supply adopts an AC 220V input, and adopts a bridge rectifier and a capacitor filter to form a voltage-type DC source, and the voltage range is DC280-DC332V; the power supply adopts four main power devices Q1-Q4 and anti-parallel diodes and parasitic capacitors to form a full-bridge bridge arm; the power supply is connected to a transformer and a rectifier circuit containing a leakage inductor and an external resonant inductor L to form a full-bridge converter; the upper and lower switch tubes of the two bridge arms of the full-bridge converter are complementary turned on at 180°, and the output voltage is adjusted between the bridge arms by adjusting the phase shift angle, and the adjustment of the phase shift angle is also the basis for realizing soft switching.

[0042] The power supply of the present invention also includes a buzzer output interface and an alarm light output interface, and the buzzer output interface and the alarm light output interface are respectively connected to the status alarm module; the power supply also includes at least two relay output interfaces, and the relay output interfaces are connected to the relay module for outputting the normal / abnormal status of the power supply voltage.

[0043] Specifically: Buzzer output interface: when the power supply voltage output is abnormal, the buzzer outputs an alarm sound to remind the operation and maintenance personnel to deal with it in time; at least two relay output interfaces are used to output the normal / abnormal status of the power supply voltage; the power supply of the present invention determines whether there is AC intrusion by collecting the voltage signal. If AC intrusion exists, an alarm is sounded through the buzzer, and the output of the DC power supply is cut off at the same time.

[0044] The power supply of the present invention further comprises a gear selection switch, wherein the gear selection switch can be used for selecting between 110V and 220V output power supplies.

[0045] Specifically: the power supply of the present invention adopts AC bridge rectification and full-bridge converter to meet the demand for 110V or 220V power supply in the plant, and the power selection switch can switch gears.

[0046] The present invention is a DC test power supply capable of realizing monitoring of AC intrusion into a DC circuit. During use, the device of the present invention can not only provide DC power to the circuit, but more importantly, monitor the AC voltage. Once AC intrudes into the circuit, the DC power can be quickly cut off and an alarm can be given in time, thereby discovering the hidden danger of AC intrusion into the DC circuit, thereby eliminating the hidden danger, preventing accidents from occurring, and ensuring safe and reliable operation of the equipment. The present invention can be widely applied to similar equipment to avoid accidents caused by AC intrusion, improve the health level of the equipment, and improve the operational reliability of the power station. The present invention has the advantages of reasonable structure, providing DC power, monitoring AC voltage intrusion, quickly cutting off DC power, and giving an alarm in time.

Claims

1. A DC test power supply capable of realizing AC intrusion monitoring in a DC circuit, characterized in that: The power supply adopts an AC 220V input, and adopts a bridge rectifier and a capacitor filter to form a voltage-type DC source, with a voltage range of DC280 to DC332V; the power supply adopts four main power devices Q1 to Q4 and an anti-parallel diode and a parasitic capacitor to form a full-bridge bridge arm; the power supply is connected to a transformer and a rectifier circuit containing a leakage inductor and an external resonant inductor L to form a full-bridge converter; the upper and lower switch tubes of the two bridge arms of the full-bridge converter are complementary turned on at 180°, and the output voltage is adjusted between the bridge arms by adjusting the phase shift angle.

2. A DC test power supply capable of realizing AC intrusion monitoring in a DC circuit as claimed in claim 1, characterized in that: The sampling circuit of the full-bridge converter adopts a DC-blocking capacitor detection technology, in which a capacitor is connected in series in a resistor voltage-dividing loop, and the DC component in the sampling signal is isolated based on the capacitor passing AC and blocking DC, so that the AC component can be obtained.

3. A DC test power supply capable of realizing AC intrusion monitoring in a DC circuit as claimed in claim 1, further comprising a drive hardware control protection circuit, characterized in that: The driving hardware control protection circuit includes an input sampling circuit, a PWM driving circuit, an output sampling circuit and a hardware protection circuit.

4. A DC test power supply capable of realizing AC intrusion monitoring in a DC circuit as claimed in claim 3, characterized in that: The control chip of the driving hardware control protection circuit adopts the PPEC-86CA3A phase-shifted full-bridge digital power control chip.

5. A DC test power supply capable of realizing AC intrusion monitoring of a DC circuit as claimed in claim 3, further comprising an AC intrusion prevention detection circuit, characterized in that: The anti-AC intrusion detection circuit includes a voltage acquisition module, an AC intrusion judgment module, a power output status monitoring module, a relay module and a status alarm module. The voltage acquisition module includes a DC voltage acquisition module and an AC voltage acquisition module.

6. A DC test power supply capable of realizing AC intrusion monitoring in a DC circuit as claimed in claim 5, characterized in that: The voltage acquisition module uses a differential voltage method to collect positive and negative bus voltages through a differential circuit composed of dual voltage transformers; the output end of the voltage sampling and conditioning circuit of the voltage acquisition module is connected to an AD converter, and the AD converter converts the analog signal into a digital signal that can be recognized by the control unit MCU, and then the MCU performs calculations and judgments.

7. A DC test power supply capable of realizing AC intrusion monitoring in a DC circuit as claimed in claim 5, characterized in that: The AC inrush judgment module adopts AC power detection technology based on DC blocking capacitors to judge whether there is AC inrush; the balancing resistors R1 and R2 of the AC inrush judgment module are arranged between the positive and negative poles of the DC bus; the AC signal extraction circuit composed of a resistor R3, a capacitor C1 and a resistor R4 connected in series in the AC inrush judgment module is arranged between the negative / positive pole of the DC bus and the ground.

8. A DC test power supply capable of realizing AC intrusion monitoring in a DC circuit as claimed in claim 7, characterized in that: The voltage sampling circuit of the AC intrusion judgment module is connected to both ends of R3, and the output end of the voltage sampling circuit is connected to an AD converter; and the output end of the AD converter is connected to the MCU.

9. A DC test power supply capable of realizing AC intrusion monitoring in a DC circuit as claimed in claim 5, further comprising a buzzer output interface and an alarm light output interface, characterized in that: The buzzer output interface and the alarm light output interface are respectively connected to the status alarm module; the power supply also includes at least two relay output interfaces, which are connected to the relay module and are used to output the normal / abnormal status of the power supply voltage.

10. A DC test power supply capable of realizing AC intrusion monitoring in a DC circuit as claimed in claim 1, further comprising a gear selection switch, characterized in that: The gear selection switch can be used to select 110V and 220V output power.

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