Electricity safety monitoring system, method and device for dual-circuit power supply system

Abstract

The present invention provides a power safety monitoring system, method and device for a double-circuit power supply system, which can be applied to the technical field of online monitoring of power-consuming equipment. The double-circuit power supply system includes a first power supply circuit and a second power supply circuit that respectively supply power to the power supply area, and the power safety monitoring system includes: a signal injection device, which is configured to be connected in parallel with the neutral point grounding device of the first power supply circuit, and the signal injection device is configured to inject a common-mode signal into the double-circuit power supply system; a target grounding device, which is configured to be connected in series with the neutral point grounding device of the second power supply circuit, and the target grounding device is configured to be in a high-impedance state to the ground in response to the common-mode signal; a monitoring device, which is configured to collect the common-mode leakage current of the double-circuit power supply system when the target grounding device is in a high-impedance state to the ground, and determine the power safety monitoring result of the power supply area based on the common-mode voltage and common-mode leakage current of the common-mode signal.

Description

Technical Field

[0001] The present invention relates to the technical field of online monitoring of cable insulation status, and more specifically, to an electricity safety monitoring system, method and device for a double-circuit power supply system. Background Art

[0002] The online monitoring system for power safety is a system used to monitor the operating status and safety of the power system in real time. Among them, the online monitoring technology of partial discharge is one of the important methods for early warning of potential safety problems of ground-insulated electrical equipment.

[0003] In the prior art, for a single-circuit system, the power safety monitoring of each electrical device in the substation can be achieved by injecting a signal at the neutral point of the distribution transformer. However, for a dual-circuit system, there is a lack of communication between the two distribution transformers, and it is impossible to achieve automatic and coordinated intelligent monitoring; in addition, there is a problem of mutual interference between the two distribution transformers. When a monitoring signal is injected from the neutral point of one distribution transformer, a large leakage current will be generated, and the grounding wire of the other distribution transformer will seriously interfere with the monitoring effect, thereby affecting the monitoring accuracy. Summary of the invention

[0004] In view of this, the present invention provides a power safety monitoring system, method and device for a double-circuit power supply system.

[0005] One aspect of the present invention provides an electricity safety monitoring system for a double-circuit power supply system, wherein the double-circuit power supply system includes a first power supply circuit and a second power supply circuit that respectively supply power to a power supply area, wherein the electricity safety monitoring system includes: a signal injection device, configured to be connected in parallel with a neutral point grounding device of the first power supply circuit, and the signal injection device is configured to inject a common-mode signal into the double-circuit power supply system; a target grounding device, configured to be connected in series with a neutral point grounding device of the second power supply circuit, and the target grounding device is configured to be in a high-impedance state with respect to the ground in response to the common-mode signal; a monitoring device, configured to collect the common-mode leakage current of the double-circuit power supply system when the target grounding device is in a high-impedance state with respect to the ground, and determine the electricity safety monitoring result of the power supply area based on the common-mode voltage of the common-mode signal and the common-mode leakage current.

[0006] According to an embodiment of the present invention, the target grounding device includes a capacitor structure, an inductor structure and a resistor structure; wherein, one end of the capacitor structure is configured to be connected to the first end of the target grounding device, the other end of the capacitor structure is configured to be connected to the second end of the target grounding device, one end of the inductor structure is configured to be connected to the first end of the target grounding device, the other end of the inductor structure is configured to be connected to one end of the resistor structure, and the other end of the resistor structure is configured to be connected to the second end of the target grounding device.

[0007] According to an embodiment of the present invention, the resonant frequency of the target grounding device matches the injection frequency of the common-mode signal, so that when the difference between the injection frequency of the common-mode signal and the resonant frequency of the target grounding device is within a preset range, the target grounding device is in the high-impedance state relative to the ground.

[0008] According to an embodiment of the present invention, the above-mentioned power safety monitoring system also includes: a switch module, which is configured to be connected in parallel with the above-mentioned target grounding device, and the above-mentioned switch module is configured to be disconnected in response to the above-mentioned common mode signal to switch the grounding mode of the above-mentioned second power supply circuit to be grounded in series with the neutral point grounding device of the above-mentioned second power supply circuit and the above-mentioned target grounding device.

[0009] According to an embodiment of the present invention, the switch module is configured to: respond to the common-mode signal, disconnect after waiting for a preset period of time, so as to switch the grounding mode of the second power supply circuit to be grounded in series with the neutral point grounding device of the second power supply circuit and the target grounding device; and respond to the monitoring termination signal, close after waiting for the preset period of time, so as to switch the grounding mode of the second power supply circuit to be grounded through the neutral point grounding device of the second power supply circuit.

[0010] According to an embodiment of the present invention, the power supply area includes a plurality of electrical equipment, the electrical equipment includes a frequency converter and a load, and the dual-circuit power supply system is configured to supply power to the load through the frequency converter; wherein the injection frequency of the common-mode signal is different from the switching frequency and harmonic frequency of each of the plurality of frequency converters.

[0011] According to an embodiment of the present invention, the signal injection device is configured to inject the common-mode signal into the dual-circuit power supply system in response to detecting a change in the start / stop state of the inverter.

[0012] According to an embodiment of the present invention, the above-mentioned monitoring device is configured to determine the common-mode impedance to ground of the above-mentioned power supply area based on the common-mode voltage of the above-mentioned common-mode signal and the above-mentioned common-mode leakage current, and obtain the power safety monitoring result of the above-mentioned power supply area based on the above-mentioned common-mode impedance to ground.

[0013] Another aspect of the present invention provides a power safety monitoring method for a dual-circuit power supply system, which is applied to the above-mentioned power safety monitoring system, and the above-mentioned method includes: in response to triggering a power safety monitoring request, injecting a common-mode signal into the above-mentioned dual-circuit power supply system to control the target grounding device to be in a high-resistance state with respect to the ground; collecting the common-mode leakage current of the above-mentioned dual-circuit power supply system; and determining the power safety monitoring result of the above-mentioned power supply area based on the common-mode voltage of the above-mentioned common-mode signal and the above-mentioned common-mode leakage current.

[0014] Another aspect of the present invention provides a power safety monitoring device for a dual-circuit power supply system, which is applied to the above-mentioned power safety monitoring system and is characterized in that the above-mentioned device includes: a control module, which is used to inject a common-mode signal into the above-mentioned dual-circuit power supply system in response to a triggering power safety monitoring request to control the target grounding device to be in a high-resistance state with respect to the ground; an acquisition module, which is used to acquire the common-mode leakage current of the above-mentioned dual-circuit power supply system; and a determination module, which is used to determine the power safety monitoring result of the above-mentioned power supply area based on the common-mode voltage of the above-mentioned common-mode signal and the above-mentioned common-mode leakage current.

[0015] According to an embodiment of the present invention, a common-mode signal is injected into any power supply circuit of a double-circuit power supply system, and the common-mode impedance to ground of the power supply area is monitored based on a monitoring device, so as to realize online monitoring of the power safety of the double-circuit power supply system. In addition, based on a target grounding device connected in series with a neutral point grounding device of the second power supply circuit, the risk of short-circuit damage of the signal injection device due to direct grounding on the opposite side is avoided, thereby improving the safety of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The above and other objects, features and advantages of the present invention will become more apparent through the following description of the embodiments of the present invention with reference to the accompanying drawings, in which:

[0017] Figure 1 A schematic diagram of a power safety monitoring system for a double-circuit power supply system according to an embodiment of the present invention is shown.

[0018] Figure 2 A schematic diagram of a target grounding device according to an embodiment of the present invention is shown.

[0019] Figure 3 A schematic diagram of an electricity safety monitoring system configured with a switch module according to an embodiment of the present invention is shown.

[0020] Figure 4 A schematic diagram of an electricity safety monitoring system configured with a switch module according to a specific embodiment of the present invention is shown.

[0021] Figure 5 A schematic diagram of an electricity safety monitoring system according to a specific embodiment of the present invention is shown.

[0022] Figure 6 A flow chart of a method for monitoring power safety in a double-circuit power supply system according to an embodiment of the present invention is shown.

[0023] Figure 7 A block diagram of a power safety monitoring device for a double-circuit power supply system according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0024] Below, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present invention. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of embodiments of the present invention. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of concepts of the present invention.

[0025] The terms used herein are only for describing specific embodiments and are not intended to limit the present invention. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0026] All terms (including technical and scientific terms) used herein have the meanings commonly understood by those skilled in the art unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0027] When using expressions such as "at least one of A, B, and C, etc.", they should generally be interpreted according to the meaning of the expression commonly understood by those skilled in the art (for example, "a system having at least one of A, B, and C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.).

[0028] The dual-circuit power supply system can improve the reliability and stability of power supply. It consists of two independent power supply circuits, each of which can independently provide power to power equipment. When one power supply circuit fails, the backup circuit can immediately take over the power supply to ensure that the equipment continues to operate without interruption, thereby improving the reliability of the power supply system.

[0029] The online monitoring system for power safety is a system used to monitor the operating status and safety of the power system in real time. Among them, residual current protection is one of the important protection contents for the safety of power use of important loads. The traditional residual current protection device uses a zero-sequence current sensor to surround the three-phase line and the neutral line at the same time, and obtains the current vector sum of the three-phase conductor and the neutral line, that is, to achieve residual current measurement. When there is no ground fault, the vector sum is very close to zero and is not affected by whether the three-phase load is balanced; when a ground fault occurs, the fault current will flow out from the grounding point, so that the current vector sum of the three-phase conductor and the neutral line will not be zero. By setting an alarm threshold for this vector sum, the power supply can be cut off immediately after the ground fault occurs to avoid further expansion of the fault or causing casualties caused by electric shock. However, this relay protection method is aimed at the problem of fast action protection after the fault occurs, and fault warning cannot be achieved.

[0030] Partial discharge online monitoring technology is one of the important methods for early warning of potential insulation safety problems. However, partial discharge signals overlap with the electromagnetic noise spectrum during the switching process of power electronic devices. For systems containing a large number of power switching devices, the monitoring method based on partial discharge signals will be seriously interfered by the switching signals and easily produce false alarms, thereby reducing the effectiveness of the method.

[0031] In the prior art, for a single-circuit system, the power safety monitoring of each electrical device in the substation can be achieved by injecting a signal at the neutral point of the distribution transformer. However, for a dual-circuit system, there is a lack of communication between the two distribution transformers, and it is impossible to achieve automatic and coordinated intelligent monitoring; in addition, there is a problem of mutual interference between the two distribution transformers. When a monitoring signal is injected from the neutral point of one distribution transformer, a large leakage current will be generated, and the grounding wire of the other distribution transformer will seriously interfere with the monitoring effect, thereby affecting the monitoring accuracy.

[0032] In view of this, the embodiment of the present invention realizes online monitoring of the power safety of the double-circuit power supply system by injecting a common-mode signal into any power supply circuit of the double-circuit power supply system and monitoring the common-mode impedance to ground of the power supply area based on the monitoring device. In addition, based on the target grounding device connected in series with the neutral point grounding device of the second power supply circuit, the risk of short-circuit damage of the signal injection device due to direct grounding on the opposite side is avoided, thereby improving the safety of the system.

[0033] Specifically, an embodiment of the present invention provides a power safety monitoring system, method and device for a double-circuit power supply system, wherein the double-circuit power supply system includes a first power supply circuit and a second power supply circuit that respectively supply power to the power supply area, and the power safety monitoring system includes: a signal injection device, configured to be connected in parallel with the neutral point grounding device of the first power supply circuit, and the signal injection device is configured to inject a common-mode signal into the double-circuit power supply system; a target grounding device, configured to be connected in series with the neutral point grounding device of the second power supply circuit, and the target grounding device is configured to be in a high-resistance state to the ground in response to the common-mode signal; a monitoring device, configured to collect the common-mode leakage current of the double-circuit power supply system when the target grounding device is in a high-resistance state to the ground, and determine the power safety monitoring result of the power supply area based on the common-mode voltage and common-mode leakage current of the common-mode signal.

[0034] It should be noted that the power safety monitoring system, method and device for a dual-circuit power supply system determined in the embodiment of the present invention can be used in the field of online monitoring technology for electrical equipment. The power safety monitoring system, method and device for a dual-circuit power supply system determined in the embodiment of the present invention can also be used in any field other than the field of online monitoring technology for electrical equipment, such as the field of live detection and operation and maintenance technology. The application field of the power safety monitoring system, method and device for a dual-circuit power supply system determined in the embodiment of the present invention is not limited.

[0035] The following is combined Figure 1 The technical solution of the present invention is described in detail.

[0036] Figure 1 A schematic diagram of a power safety monitoring system for a double-circuit power supply system according to an embodiment of the present invention is shown.

[0037] An embodiment of the present invention proposes a power safety monitoring system for a double-circuit power supply system, wherein the power safety monitoring system may include a signal injection device 1, a target grounding device 2, and a monitoring device 3, and the double-circuit power supply system includes a first power supply circuit and a second power supply circuit that respectively supply power to a power supply area 8. The first power supply circuit includes a first neutral point grounding device 4 and a first transformer 5, and the second power supply circuit includes a second neutral point grounding device 6 and a second transformer 7. The power supply area 8 includes at least one electrical device.

[0038] According to an embodiment of the present invention, a signal injection device 1 connected in parallel with the original grounding device may be included in the first power supply circuit. Specifically, the signal injection device 1 is configured to be connected in parallel with the first neutral point grounding device 4 of the first power supply circuit. The first end of the first neutral point grounding device 4 is connected to the neutral point of the first transformer 5, and the second end of the first neutral point grounding device 4 is grounded.

[0039] According to an embodiment of the present invention, the signal injection device 1 can be configured to inject a common-mode signal into the double-circuit power supply system. Specifically, the signal injection device 1 can inject a common-mode signal into the double-circuit power supply system without interfering with the normal function of the first neutral point grounding device 4. The common-mode signal can, for example, include a low-frequency signal of a specific frequency to avoid the existing switching frequency and power frequency in the system.

[0040] According to an embodiment of the present invention, a target grounding device 2 connected in series with an original grounding device may be included in the second power supply circuit. Specifically, the target grounding device 2 is configured to be connected in series with a second neutral point grounding device 6 of the second power supply circuit. The first end of the second neutral point grounding device 6 is connected to the neutral point of the second transformer 7, the second end of the second neutral point grounding device 6 is connected to the first end of the target grounding device 2, and the second end of the target grounding device 2 is grounded.

[0041] According to the embodiment of the present invention, both the first neutral point grounding device 4 and the second neutral point grounding device 6 can limit overvoltage and fault current in the power supply system by providing a low-impedance grounding path.

[0042] According to an embodiment of the present invention, the target grounding device 2 can be configured to be in a high-resistance state relative to the ground in response to a common-mode signal. Specifically, when the system detects a common-mode signal, the target grounding device 2 switches from a low-resistance state to a high-resistance state, and changes the impedance characteristics of the grounding path by adjusting the resistance state.

[0043] According to an embodiment of the present invention, the monitoring device 3 is configured to be signal-connected to the signal injection device 1 and the power supply area 8. The monitoring device 3 is configured to collect the common-mode leakage current of the double-circuit power supply system when the target grounding device 2 is in a high-impedance state to the ground, and determine the power safety monitoring result of the power supply area 8 based on the common-mode voltage and common-mode leakage current of the common-mode signal.

[0044] According to a specific embodiment of the present invention, the monitoring device 3 can determine whether there is leakage current in the power supply system by monitoring and analyzing the specific response of at least one power supply area 8 to the injected common-mode signal. When the target grounding device 2 is in a high-resistance state to the ground, the common-mode leakage current of the double-circuit power supply system is obtained, and the specific position and size of the common-mode voltage and the common-mode leakage current of the common-mode signal are used to determine the power safety monitoring result of the power supply area 8, thereby realizing the leakage current monitoring of each electrical equipment in the power supply area 8. Among them, the power safety monitoring result of the power supply area 8, for example, the abnormal increase of the common-mode leakage current is monitored, which may indicate that there is a grounding fault or insulation problem in the system.

[0045] According to the embodiment of the present invention, the first power supply circuit and the second power supply circuit can operate simultaneously, or when one of the power supply circuits fails, the other power supply circuit can automatically take over the power supply task, thereby ensuring the continuity of power supply.

[0046] The embodiment of the present invention proposes a power safety monitoring system including a signal injection device, a target grounding device and a monitoring device, which injects a common-mode signal into any power supply circuit of the double-circuit power supply system and monitors the common-mode impedance to ground of the power supply area based on the monitoring device to achieve online monitoring of the power safety of the double-circuit power supply system. In addition, based on the target grounding device connected in series with the neutral point grounding device of the second power supply circuit, the risk of short-circuit damage of the signal injection device due to direct grounding on the opposite side is avoided, thereby improving the safety of the system.

[0047] The following is combined Figure 2 The target grounding device 2 proposed in the present invention is described in detail.

[0048] Figure 2 A schematic diagram of a target grounding device according to an embodiment of the present invention is shown.

[0049] like Figure 2 As shown, the target grounding device 2 includes a capacitor structure C, an inductor structure L and a resistor structure R.

[0050] Among them, one end of the capacitor structure C is configured to connect to the first end of the target grounding device 2, and the other end of the capacitor structure C is configured to connect to the second end of the target grounding device 2. One end of the inductor structure L is configured to connect to the first end of the target grounding device 2, and the other end of the inductor structure L is configured to connect to one end of the resistor structure R, and the other end of the resistor structure R is configured to connect to the second end of the target grounding device 2.

[0051] According to an embodiment of the present invention, the resonant frequency of the target grounding device matches the injection frequency of the common-mode signal, so that when the difference between the injection frequency of the common-mode signal and the resonant frequency of the target grounding device is within a preset range, the target grounding device is in a high-impedance state with respect to the ground.

[0052] According to an embodiment of the present invention, in order to achieve matching between the resonant frequency of the target grounding device and the injection frequency of the common mode signal, it is necessary to determine the parameters of the capacitance, inductance and resistance included in the target grounding device.

[0053] According to an embodiment of the present invention, the constraint relationship between the capacitance and inductance of the target grounding device can be determined based on the injection frequency of the common-mode signal. Among them, the injection frequency of the common-mode signal can be determined based on the actual needs of the dual-circuit power supply system to avoid frequency overlap or conflict with other systems or electrical equipment, and to prevent unnecessary interference or noise. By making the resonant frequency of the target grounding device equal to the injection frequency of the common-mode signal, the constraint relationship between the capacitance and inductance in the target grounding device can be expressed as follows:

[0054] (1);

[0055] Where L represents the inductance of the target grounding device, C represents the capacitance of the target grounding device, and f inj Indicates the injection frequency of the common-mode signal.

[0056] According to an embodiment of the present invention, a quality factor can be used to describe a quality indicator of the ratio of the energy stored by the target grounding device at the resonant frequency to the energy lost per cycle. A higher value of the quality factor means that at the resonant frequency, the target grounding device can store energy more efficiently, reduce energy loss, and have better selectivity for signals of the required frequency. For a target grounding device connected in series, the quality factor can be determined based on the constraint relationship between the inductance and capacitance of the target grounding device and the resistance.

[0057] According to a specific embodiment of the present invention, in order to maintain the stability of the system and reduce the overshoot phenomenon during resonance, the resistance parameters of the target grounding device can be adjusted so that the quality factor of the power supply circuit in which the series target grounding device is located is less than the quality factor threshold. The quality factor threshold can be used to ensure that the impedance of the target grounding device maintains a high amplitude when the difference between the injection frequency of the common-mode signal and the resonant frequency of the target grounding device is within a preset range.

[0058] According to a specific embodiment of the present invention, at the resonant frequency, the impedance of the target grounding device is mainly determined by the resistance. Therefore, in order to ensure that the impedance of the target grounding device maintains a high amplitude at the injection frequency of the common-mode signal to suppress the interference of the common-mode signal, a preset impedance threshold can be determined so that the impedance of the target grounding device is greater than the preset impedance threshold. The preset impedance threshold can be determined based on the impedance to ground of the power supply system at the injection frequency of the common-mode signal. For example, the preset impedance threshold can be greater than or equal to the order of magnitude of the impedance to ground of the power supply system at the injection frequency of the common-mode signal.

[0059] Specifically, the impedance and quality factor of the target grounding device are expressed as follows:

[0060] (2);

[0061] (3);

[0062] Where Z represents the impedance of the target grounding device, R represents the resistance of the target grounding device, and Z set represents the preset impedance threshold, Q represents the quality factor, Q set Indicates the quality factor threshold.

[0063] The embodiment of the present invention configures the target grounding device as a circuit structure composed of resistance, inductance and capacitance, connects the target grounding device in series on the grounding path of one of the power supply circuits of the double-circuit power supply system, and matches the resonant frequency of the target grounding device with the injection frequency of the common-mode signal, thereby ensuring that the target grounding device is in a high-impedance state when the common-mode signal is injected. In addition, by adjusting the resistance, the quality factor of the target grounding device will not be too high, the injection frequency of the common-mode signal can be adjusted within a certain range, and the target grounding device is still in a high-impedance state within the frequency range, so as to better suppress the interference of the common-mode signal.

[0064] According to an embodiment of the present invention, the power safety monitoring system also includes: a switch module, configured to be connected in parallel with the target grounding device, and the switch module is configured to disconnect in response to a common mode signal to switch the grounding mode of the second power supply circuit to be grounded in series with the neutral point grounding device of the second power supply circuit and the target grounding device.

[0065] The following is combined Figure 3 The switch module proposed in the present invention is described in detail.

[0066] Figure 3 A schematic diagram of an electricity safety monitoring system configured with a switch module according to an embodiment of the present invention is shown.

[0067] like Figure 3 As shown, the power safety monitoring system further includes a switch module 9, which is configured in the second power supply circuit in parallel with the target grounding device 2 and is signal-connected to the signal injection device 1. The switch module 9 can be opened or closed according to the injection signal.

[0068] Specifically, the switch module 9 can be configured to disconnect in response to the common-mode signal injected by the signal injection device 1 to switch the grounding mode of the second power supply circuit to be grounded in series with the second neutral point grounding device 6 of the second power supply circuit and the target grounding device 2, thereby suppressing the interference of the common-mode signal by changing the impedance characteristics of the power supply circuit.

[0069] According to an embodiment of the present invention, the switch module is configured to: respond to a common mode signal, disconnect after waiting for a preset period of time, so as to switch the grounding mode of the second power supply circuit to be grounded in series with the neutral point grounding device of the second power supply circuit and the target grounding device; and respond to a monitoring termination signal, close after waiting for a preset period of time, so as to switch the grounding mode of the second power supply circuit to be grounded through the neutral point grounding device of the second power supply circuit.

[0070] like Figure 3 As shown, the switch module 9 can be configured to be in a closed state when there is no common-mode signal injection. In response to receiving a common-mode signal injected by the signal injection device 1, the switch module 9 is disconnected after waiting for a preset time to switch the grounding mode of the second power supply circuit to be grounded in series with the second neutral point grounding device 6 of the second power supply circuit and the target grounding device 2. In response to receiving a monitoring termination signal, the switch module 9 is closed after waiting for a preset time to switch the grounding mode of the second power supply circuit to be grounded only through the second neutral point grounding device 6 of the second power supply circuit.

[0071] According to a specific embodiment of the present invention, the generation condition of the monitoring stop signal may include that the common mode signal stops being injected, the common mode signal decreases to a certain level, or the common mode signal injection duration reaches a preset duration.

[0072] According to an embodiment of the present invention, the preset duration can be used to represent the preset dead time. When the switch module 9 is opened and closed again, based on the preset dead time, the power safety monitoring system has enough time to confirm the authenticity and stability of the signal, so as to avoid the influence on the monitoring system caused by the failure of the grounding circuit to switch in time. The preset dead time can be set to 1ms, for example.

[0073] An embodiment of the present invention configures a switch module on the grounding path of the power supply loop on one side of the dual-circuit power supply system. By dynamically changing the grounding mode, the target grounding device can limit the magnitude of the common-mode interference current, further effectively suppressing the common-mode interference signal, so as to avoid mutual interference between the two distribution transformers in the dual-circuit power supply system, thereby improving the stability and reliability of the power supply system and ensuring the normal operation of the system.

[0074] According to a specific embodiment of the present invention, the settings of the first power supply circuit and the second power supply circuit can be the same, that is, each power supply circuit includes a signal injection device connected in parallel with the neutral point grounding device, a target grounding device connected in series with the neutral point grounding device, and a switch module connected in parallel with the target grounding device, so as to perform power safety monitoring for each circuit respectively.

[0075] Figure 4 A schematic diagram of an electricity safety monitoring system configured with a switch module according to a specific embodiment of the present invention is shown.

[0076] like Figure 4 As shown, the first power supply circuit includes a first signal injection device connected in parallel with the first neutral point grounding device, a first target grounding device connected in series with the first neutral point grounding device, a first switch module connected in parallel with the first target grounding device, and a first monitoring device for performing power safety monitoring on the first power supply circuit.

[0077] like Figure 4 As shown, the second power supply circuit includes a second signal injection device connected in parallel with the second neutral point grounding device, a second target grounding device connected in series with the second neutral point grounding device, a second switch module connected in parallel with the second target grounding device, and a second monitoring device for performing power safety monitoring on the second power supply circuit.

[0078] According to a specific embodiment of the present invention, in the two power supply loops, the frequencies of the common mode signals injected by the first signal injection device and the second signal injection device are different. Specifically, the frequency of the injection signal of the first signal injection device matches the second target grounding device of the second power supply loop, and the frequency of the injection signal of the second signal injection device matches the first target grounding device of the first power supply loop.

[0079] According to an embodiment of the present invention, the power supply area includes a plurality of power-consuming devices, the power-consuming devices include frequency converters and loads, and the double-circuit power supply system is configured to supply power to the loads through the frequency converters.

[0080] According to an embodiment of the present invention, the frequency converter can be used to adjust the frequency and voltage of electricity to meet the needs of different loads, so that the dual-circuit power supply system can distribute electricity more flexibly and ensure that each load can obtain a stable power supply.

[0081] According to an embodiment of the present invention, a load may be an actual power-consuming object in a power system, and may include multiple types of electrical equipment, such as motors, lighting equipment, heaters, etc. In a dual-circuit power supply system, these loads may obtain power from the first power supply circuit or the second power supply circuit through a frequency converter, thereby ensuring the normal operation of the load equipment.

[0082] Figure 5 A schematic diagram of an electricity safety monitoring system according to a specific embodiment of the present invention is shown.

[0083] like Figure 3 and Figure 5 As shown, the power supply area 8 includes at least one power-consuming device, each of which includes a frequency converter 81 and a load 82, and the double-circuit power supply system is configured to supply power to the load 82 through the frequency converter 81. The double-circuit power supply system also includes a first intelligent circuit breaker configured between the first transformer 5 and the power supply area 8 and a second intelligent circuit breaker configured between the second transformer 7 and the power supply area 8.

[0084] According to an embodiment of the present invention, the injection frequency of the common-mode signal is different from the switching frequency and harmonic frequency of each of the multiple inverters to ensure that the injected common-mode signal will not interfere with or be confused with the harmonics or switching frequencies generated by the inverter, thereby ensuring the accuracy and effectiveness of the common-mode signal injection.

[0085] According to an embodiment of the present invention, the signal injection device is configured to inject a common-mode signal into the dual-circuit power supply system in response to detecting a change in the start / stop state of the frequency converter.

[0086] For example, when the start / stop state of the inverter changes, the signal injection device responds to the start / stop state change signal of the inverter detected by the monitoring device, and injects a common-mode signal of a specific frequency into the dual-circuit power supply system. The common-mode signal will flow through each load device in the power supply system and form a specific current or voltage distribution between each load device. If a load device in the power supply system has leakage current, then this load device will respond to the injected common-mode signal, thereby facilitating the monitoring of leakage current of multiple load devices in the power supply area.

[0087] According to an embodiment of the present invention, in a dual-circuit power supply system, the monitoring device can be configured to determine the common-mode impedance to ground of the power supply area based on the common-mode voltage and common-mode leakage current of the common-mode signal, and obtain the power safety monitoring result of the power supply area based on the common-mode impedance to ground.

[0088] According to an embodiment of the present invention, the magnitude of the common-mode impedance to ground can be used to reflect the isolation capability of the power supply system for common-mode interference signals. The larger the impedance value, the stronger the isolation capability of the system for common-mode interference and the higher the power safety performance.

[0089] According to a specific embodiment of the present invention, the monitoring device can be configured to obtain one or more preset safety thresholds of the common-mode impedance to ground. When the monitoring device collects the common-mode voltage and common-mode leakage current of the common-mode signal, the common-mode impedance to ground of the power supply area is determined based on the common-mode voltage and the common-mode leakage current. If the calculated common-mode impedance to ground is lower than the preset safety threshold, it means that the system may face a greater common-mode interference risk. Therefore, the monitoring device can promptly deal with the potential safety hazards in the power supply system through alarms or other corresponding measures.

[0090] Among them, the common-mode impedance to ground of the power supply area can be calculated by the following method:

[0091] (4);

[0092] In the formula, Z CM Indicates the common-mode equivalent impedance of the corresponding frequency, U inj represents the injected common-mode voltage, I CMIndicates the common-mode leakage current at the corresponding frequency.

[0093] The embodiment of the present invention utilizes the monitoring device to calculate the common-mode impedance to ground based on the common-mode voltage and common-mode leakage current of the common-mode signal, so as to realize real-time monitoring and evaluation of the power safety in the power supply area, which is of great significance for ensuring the stable operation of the power system.

[0094] Figure 6 A flow chart of a method for monitoring power safety in a double-circuit power supply system according to an embodiment of the present invention is shown.

[0095] like Figure 6 As shown, the method includes operations S601 to S603.

[0096] In operation S601 , in response to triggering a power safety monitoring request, a common mode signal is injected into a double-circuit power supply system to control a target grounding device to be in a high-impedance state with respect to the ground.

[0097] According to an embodiment of the present invention, the power safety monitoring request may come from an automatic detection mechanism of the power safety monitoring system, for example, in response to monitoring changes in the start / stop status of the frequency converter included in the power supply area, to trigger the power safety monitoring request.

[0098] According to an embodiment of the present invention, in order to make the target grounding device in a high-impedance state with respect to the ground so as to obtain common-mode leakage current and common-mode voltage, a common-mode signal can be injected into the double-circuit power supply system by a signal injection device arranged in one of the power supply loops. The common-mode signal can be used to characterize signals having the same phase and amplitude on two or more phase lines.

[0099] According to an embodiment of the present invention, a signal is sent to a switch module in parallel with the target grounding device in the power supply circuit on the other side, so that the switch module responds to the signal and disconnects after waiting for a preset dead time, so as to switch the grounding mode of the power supply circuit on the other side to series grounding by the neutral point grounding device of the power supply circuit on the other side and the target grounding device, so as to control the target grounding device to be in a high-resistance state with respect to the ground.

[0100] In operation S602 , a common-mode leakage current of the dual-circuit power supply system is collected.

[0101] According to the embodiment of the present invention, the common-mode voltage and common-mode leakage current of the common-mode signal in the dual-circuit power supply system can be acquired by the monitoring device in the system.

[0102] In operation S603 , a power safety monitoring result of the power supply area is determined based on the common mode voltage and the common mode leakage current of the common mode signal.

[0103] According to an embodiment of the present invention, based on the common-mode voltage and common-mode leakage current of the common-mode signal, the common-mode impedance to ground of the power supply area can be determined. After the common-mode impedance to ground of the power supply area is determined, the injection of the common-mode signal into the double-circuit power supply system is stopped, and a monitoring termination signal is sent to the switch module, so that the switch module is closed after waiting for a preset time, so as to switch the grounding mode of the second power supply circuit to grounding through the neutral point grounding device of the second power supply circuit. Based on the common-mode impedance to ground, the power safety monitoring result of the power supply area is obtained.

[0104] An embodiment of the present invention proposes a method for monitoring power safety in a double-circuit power supply system, which realizes online monitoring of power safety in a double-circuit power supply system by injecting a common-mode signal into any power supply circuit of the double-circuit power supply system and detecting common-mode leakage current by a monitoring device. In addition, a switch module on the grounding path of one side of the power supply circuit is controlled by a signal to dynamically change the grounding mode of the power supply circuit on that side, so that the power safety monitoring system can effectively manage and suppress common-mode interference signals to avoid mutual interference between the two distribution transformers in the double-circuit power supply system, thereby improving the stability and reliability of the power supply system and ensuring the normal operation of the system.

[0105] Figure 7 A block diagram of a power safety monitoring device for a double-circuit power supply system according to an embodiment of the present invention is shown.

[0106] like Figure 7 As shown, the power safety monitoring device for a double-circuit power supply system includes a control module 710 , a collection module 720 , and a determination module 730 .

[0107] The control module 710 is used to inject a common mode signal into the dual-circuit power supply system in response to triggering a power safety monitoring request, so as to control the target grounding device to be in a high-impedance state with respect to the ground.

[0108] The acquisition module 720 is used to acquire the common-mode leakage current of the dual-circuit power supply system.

[0109] The determination module 730 is used to determine the power safety monitoring result of the power supply area based on the common mode voltage and the common mode leakage current of the common mode signal.

[0110] According to the embodiments of the present invention, any one or more of the modules, submodules, units, and subunits, or at least part of the functions of any one of them can be implemented in one module. According to the embodiments of the present invention, any one or more of the modules, submodules, units, and subunits can be split into multiple modules for implementation. According to the embodiments of the present invention, any one or more of the modules, submodules, units, and subunits can be at least partially implemented as hardware circuits, such as field programmable gate arrays (FPGAs), programmable logic arrays (PLAs), systems on chips, systems on substrates, systems on packages, application specific integrated circuits (ASICs), or can be implemented by hardware or firmware in any other reasonable way of integrating or packaging the circuit, or by any one of the three implementation methods of software, hardware, and firmware, or by a proper combination of any of them. Alternatively, according to the embodiments of the present invention, one or more of the modules, submodules, units, and subunits can be at least partially implemented as computer program modules, and when the computer program modules are run, the corresponding functions can be executed.

[0111] For example, any multiple of the control module 710, the acquisition module 720, and the determination module 730 can be combined in one module / unit / sub-unit for implementation, or any one of the modules / units / sub-units can be split into multiple modules / units / sub-units. Alternatively, at least part of the functions of one or more of these modules / units / sub-units can be combined with at least part of the functions of other modules / units / sub-units and implemented in one module / unit / sub-unit. According to an embodiment of the present invention, at least one of the control module 710, the acquisition module 720, and the determination module 730 can be at least partially implemented as a hardware circuit, such as a field programmable gate array (FPGA), a programmable logic array (PLA), a system on a chip, a system on a substrate, a system on a package, an application specific integrated circuit (ASIC), or can be implemented by hardware or firmware such as any other reasonable way of integrating or packaging the circuit, or implemented in any one of the three implementation methods of software, hardware, and firmware, or in any appropriate combination of any of them. Alternatively, at least one of the control module 710 , the acquisition module 720 , and the determination module 730 may be at least partially implemented as a computer program module, and when the computer program module is executed, a corresponding function may be executed.

[0112] It should be noted that the part of the power safety monitoring device for a double-circuit power supply system in the embodiment of the present invention corresponds to the part of the power safety monitoring method for a double-circuit power supply system in the embodiment of the present invention. The description of the part of the power safety monitoring device for a double-circuit power supply system specifically refers to the part of the power safety monitoring method for a double-circuit power supply system, which will not be repeated here.

[0113] According to an embodiment of the present invention, the program code for executing the computer program provided by the embodiment of the present invention can be written in any combination of one or more programming languages. Specifically, these computing programs can be implemented using high-level process and / or object-oriented programming languages, and / or assembly / machine languages. Programming languages ​​include, but are not limited to, Java, C++, python, "C" language or similar programming languages. The program code can be executed entirely on the user computing device, partially on the user device, partially on the remote computing device, or entirely on the remote computing device or server. In the case of a remote computing device, the remote computing device can be connected to the user computing device through any type of network, including a local area network (LAN) or a wide area network (WAN), or can be connected to an external computing device (e.g., using an Internet service provider to connect through the Internet).

[0114] The flowcharts and block diagrams in the accompanying drawings illustrate the possible architecture, functions and operations of the systems, methods and computer program products according to various embodiments of the present invention. In this regard, each box in the flowchart or block diagram may represent a module, a program segment, or a part of a code, and the above-mentioned module, program segment, or a part of the code contains one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box may also occur in an order different from the order marked in the accompanying drawings. For example, two boxes represented in succession can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram or flowchart, and the combination of boxes in the block diagram or flowchart, can be implemented with a dedicated hardware-based system that performs the specified function or operation, or can be implemented with a combination of dedicated hardware and computer instructions. It can be understood by those skilled in the art that the features recorded in the various embodiments of the present invention can be combined and / or combined in various ways, even if such a combination or combination is not explicitly recorded in the present invention. In particular, without departing from the spirit and teachings of the present invention, the features recorded in the various embodiments of the present invention can be combined and / or combined in various ways. All these combinations and / or combinations fall within the scope of the present invention.

[0115] The embodiments of the present invention are described above. However, these embodiments are only for the purpose of illustration, and are not intended to limit the scope of the present invention. Although each embodiment is described above, it does not mean that the measures in each embodiment cannot be used in combination advantageously. Without departing from the scope of the present invention, those skilled in the art may make various substitutions and modifications, which should all fall within the scope of the present invention.

Claims

1. A power safety monitoring system for a double-circuit power supply system, characterized in that: The dual-circuit power supply system includes a first power supply circuit and a second power supply circuit that respectively supply power to the power supply area, and the power safety monitoring system includes: A signal injection device, configured to be connected in parallel with the neutral point grounding device of the first power supply circuit, and the signal injection device is configured to inject a common mode signal into the double-circuit power supply system; a target grounding device, configured to be connected in series with the neutral point grounding device of the second power supply circuit, wherein the target grounding device is configured to be in a high impedance state with respect to the ground in response to the common mode signal; The monitoring device is configured to collect the common-mode leakage current of the dual-circuit power supply system when the target grounding device is in a high-resistance state to the ground, and determine the power safety monitoring result of the power supply area based on the common-mode voltage of the common-mode signal and the common-mode leakage current.

2. The power safety monitoring system according to claim 1, characterized in that: The target grounding device includes a capacitor structure, an inductor structure and a resistor structure; Among them, one end of the capacitor structure is configured to be connected to the first end of the target grounding device, and the other end of the capacitor structure is configured to be connected to the second end of the target grounding device, one end of the inductor structure is configured to be connected to the first end of the target grounding device, and the other end of the inductor structure is configured to be connected to one end of the resistor structure, and the other end of the resistor structure is configured to be connected to the second end of the target grounding device.

3. The power safety monitoring system according to claim 1, characterized in that: The resonant frequency of the target grounding device matches the injection frequency of the common mode signal, so that when the difference between the injection frequency of the common mode signal and the resonant frequency of the target grounding device is within a preset range, the target grounding device is in the high impedance state relative to the ground.

4. The power safety monitoring system according to claim 1, characterized in that: The electricity safety monitoring system also includes: A switch module is configured to be connected in parallel with the target grounding device, and the switch module is configured to be disconnected in response to the common mode signal to switch the grounding mode of the second power supply circuit to be grounded in series with the neutral point grounding device of the second power supply circuit and the target grounding device.

5. The power safety monitoring system according to claim 4, characterized in that: The switch module is configured as follows: In response to the common mode signal, disconnect after waiting for a preset time, so as to switch the grounding mode of the second power supply circuit to a neutral point grounding device of the second power supply circuit and the target grounding device being connected in series to ground; and In response to the monitoring suspension signal, the circuit is closed after waiting for the preset time period to switch the grounding mode of the second power supply circuit to grounding through the neutral point grounding device of the second power supply circuit.

6. The power safety monitoring system according to claim 1, characterized in that: The power supply area includes a plurality of power-consuming devices, the power-consuming devices include frequency converters and loads, and the double-circuit power supply system is configured to supply power to the loads through the frequency converters; The injection frequency of the common mode signal is different from the switching frequency and harmonic frequency of each of the plurality of frequency converters.

7. The power safety monitoring system according to claim 6, characterized in that: The signal injection device is configured to inject the common mode signal into the dual-circuit power supply system in response to detecting a change in the start / stop state of the inverter.

8. The power safety monitoring system according to claim 1, characterized in that: The monitoring device is configured to determine the common-mode impedance to ground of the power supply area based on the common-mode voltage of the common-mode signal and the common-mode leakage current, and obtain a power safety monitoring result of the power supply area based on the common-mode impedance to ground.

9. A method for monitoring power safety in a dual-circuit power supply system, applied to the power safety monitoring system as claimed in any one of claims 1 to 8, characterized in that: The method comprises: In response to triggering a power safety monitoring request, injecting a common mode signal into the dual-circuit power supply system to control the target grounding device to be in a high-impedance state relative to the ground; collecting the common-mode leakage current of the dual-circuit power supply system; and Based on the common-mode voltage of the common-mode signal and the common-mode leakage current, a power safety monitoring result of the power supply area is determined.

10. An electric power safety monitoring device for a double-circuit power supply system, applied to the electric power safety monitoring system as claimed in any one of claims 1 to 8, characterized in that: The device comprises: A control module, configured to, in response to triggering a power safety monitoring request, inject a common mode signal into the dual-circuit power supply system to control the target grounding device to be in a high-impedance state relative to the ground; A collection module, used for collecting the common mode leakage current of the dual-circuit power supply system; and A determination module is used to determine the power safety monitoring result of the power supply area based on the common mode voltage of the common mode signal and the common mode leakage current.

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