Fault diagnosis method and device for electric loop

Abstract

The invention discloses a fault diagnosis method and device for an electric loop. The method comprises the steps that current signals and voltage signals of a line interval where a current transformer is located and a plurality of first power signals and a plurality of second power signals of at least two measurement and control devices are obtained; generating a first test power signal and a second test power signal according to the current signal and the voltage signal; generating a third test power signal and a fourth test power signal according to the plurality of first power signals and the plurality of second power signals; and determining the working state of the electric loop of the current transformer according to the relationship between the first test power signal and the third test power signal and the relationship between the second test power signal and the fourth test power signal. The fault diagnosis method provided by the invention can avoid protection maloperation and operation refusal caused by an electric loop fault, and can reduce the cost of manual inspection and improve the inspection efficiency through programmed automatic detection of the current loop.

Description

Technical Field

[0001] The present invention relates to the field of circuit technology, and in particular to a fault diagnosis method and device for an electric circuit. Background Art

[0002] Current loops play an important role in the relay protection, measurement, and fault diagnosis of substations. In daily work, it is often necessary to verify the value and polarity of the current loops of each functional winding, check whether there is an open circuit in the current loop, and check whether the current loop polarity is correct. However, during daily acceptance and inspection, due to the differences in the skill levels of different relay protection personnel, there are problems such as current loop open circuits caused by current loop polarity errors or current continuity failures after inspection. At present, many accidents caused by current loop faults such as current loop polarity errors and current loop open circuits have occurred, seriously affecting the safe and reliable operation of power grid equipment. Summary of the invention

[0003] The present invention provides a fault diagnosis method and device for an electric circuit, which detects the line interval of a substation to avoid false protection failure caused by current circuit faults in the operating interval. By automatically detecting the electric circuit, the cost of manual inspection can be reduced, the efficiency of inspection can be improved, and the number of missed inspections due to skill problems can be reduced.

[0004] According to a first aspect of the present invention, a fault diagnosis method for an electric circuit is provided, which is applied to a current transformer in a substation. The fault diagnosis method comprises:

[0005] Acquire a current signal, a voltage signal, and a plurality of first power signals and a plurality of second power signals of at least two measurement and control devices in the line interval where the current transformer is located;

[0006] generating a first test power signal and a second test power signal according to the current signal and the voltage signal;

[0007] generating a third test power signal and a fourth test power signal according to a plurality of the first power signals and a plurality of the second power signals;

[0008] The working state of the electrical circuit of the current transformer is determined according to the relationship between the first test power signal and the third test power signal and the relationship between the second test power signal and the fourth test power signal; wherein the measurement and control device and the line interval are located on the same bus.

[0009] Optionally, before obtaining the current signal, the voltage signal, and the multiple first power signals and the multiple second power signals of at least two measurement and control devices of the line interval where the current transformer is located, the method further includes:

[0010] Obtain the bus-side disconnector position signal, switch position signal, and line voltage signal of the substation;

[0011] Determine the operating state of the equipment in the line interval according to the bus-side disconnector position signal, the switch position signal, and the line voltage signal.

[0012] Optionally, determining the operating state of the equipment in the line interval according to the bus-side disconnector position signal, the switch position signal, and the line voltage signal includes:

[0013] When the bus-side disconnector position signal, the switch position signal, and the line voltage signal meet the first preset condition, it is determined that the equipment in the line interval is in the operating state;

[0014] When the bus-side disconnector position signal, the switch position signal, and the line voltage signal do not meet the first preset condition, it is determined that the equipment in the line interval is in the non-operating state; wherein, the first preset condition includes that the bus-side disconnector position signal is in the closed state, the switch position signal is in the closed state, and the line voltage exceeds 30% of the phase voltage.

[0015] Optionally, generating a first test power signal and a second test power signal according to the current signal and the voltage signal includes:

[0016] Calculate the first test power signal and the second test power signal through formula (1) and formula (2):

[0017] P 1j = UIcosθ (1)

[0018] Q 1j = UIsinθ (2)

[0019] Wherein, P 1j is the first test power signal of the interval, U is the voltage signal of the interval, I is the current signal of the interval, and θ is the power factor angle.

[0020] Optionally, generating a third test power signal and a fourth test power signal according to multiple first power signals and multiple second power signals includes:

[0021] Record multiple first power signals as P1 to P n and record multiple second power signals as Q1 to Q n ;

[0022] Calculate the third test power signal and the fourth test power signal through formula (3) and formula (4):

[0023] P 1h =-(P2+P3+……+P n ) (three)

[0024] Q 1h =-(Q2+Q3+……+Q n ) (Four)

[0025] Among them, P 1h is the third test power signal of the measurement and control device, Q 1h is the fourth test power signal of the measurement and control device, P2 is the first power signal of the second measurement and control device, P3 is the first power signal of the third measurement and control device, Q2 is the second power signal of the second measurement and control device, and Q3 is the second power signal of the third measurement and control device; wherein n is a positive integer greater than 1.

[0026] Optionally, determining the working state of the electric circuit of the current transformer according to the relationship between the first test power signal and the third test power signal and the relationship between the second test power signal and the fourth test power signal includes:

[0027] When the relationship between the first test power signal and the third test power signal and the relationship between the second test power signal and the fourth test power signal both meet a second preset condition, it is determined that the electrical circuit is in a normal operating state;

[0028] When the relationship between the first test power signal and the third test power signal and the relationship between the second test power signal and the fourth test power signal do not satisfy the second preset condition, it is determined that the electrical circuit is in a fault state; wherein the second preset condition includes that the first test power signal and the third test power signal have the same value and sign, and the second test power signal and the fourth test power signal have the same value and sign.

[0029] Optionally, when the relationship between the first test power signal and the third test power signal and the relationship between the second test power signal and the fourth test power signal do not satisfy a second preset condition, after determining that the electrical circuit is in a fault state, the method further includes:

[0030] Generate alarm information according to the fault status and send it to the user end.

[0031] Optionally, the warning information includes at least one of the following: voice reminder, buzzer reminder and light reminder.

[0032] Optionally, the line interval includes one of a line protection device, a line measurement device, a line metering device and a fault recording device.

[0033] According to a second aspect of the present invention, there is provided a fault diagnosis device for an electric circuit, which is applied to a current transformer of a substation, and the fault diagnosis device is used to perform any of the fault diagnosis methods for the electric circuit described in the first aspect, and the fault diagnosis device comprises:

[0034] An acquisition module, used to acquire a current signal, a voltage signal, and a plurality of first power signals and a plurality of second power signals of at least two measurement and control devices in the line interval where the current transformer is located;

[0035] A calculation module, configured to generate a first test power signal and a second test power signal according to the current signal and the voltage signal; and to generate a third test power signal and a fourth test power signal according to a plurality of the first power signals and a plurality of the second power signals;

[0036] A determination module is used to determine the working state of the electrical circuit of the current transformer based on the relationship between the first test power signal and the third test power signal and the relationship between the second test power signal and the fourth test power signal; wherein the measurement and control device and the line interval are located on the same bus.

[0037] The present invention discloses a method for diagnosing faults in an electric circuit, which is applied to a current transformer in a transformer substation. The method comprises: obtaining a current signal, a voltage signal, and a plurality of first power signals and a plurality of second power signals of at least two measuring and controlling devices in a line interval where the current transformer is located; generating a first test power signal and a second test power signal according to the current signal and the voltage signal; generating a third test power signal and a fourth test power signal according to the plurality of first power signals and the plurality of second power signals; determining the working state of the electric circuit of the current transformer according to the relationship between the first test power signal and the third test power signal and the relationship between the second test power signal and the fourth test power signal; wherein the measuring and controlling device and the line interval are located on the same bus. The present invention provides a method and device for diagnosing faults in an electric circuit, which detects the line interval of the transformer substation to avoid false protection failures caused by current circuit faults in the intervals in operation. By automatically detecting the electric circuit, the cost of manual inspection can be reduced, the efficiency of inspection can be improved, and at the same time, missed inspections due to skill problems can be reduced.

[0038] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0040] Figure 1 It is a flow chart of a fault diagnosis method of an electric circuit provided by an embodiment of the present invention;

[0041] Figure 2 is a flow chart of another method for diagnosing a fault in an electrical circuit provided by an embodiment of the present invention;

[0042] Figure 3 is a flow chart of another method for diagnosing a fault in an electrical circuit provided by an embodiment of the present invention;

[0043] Figure 4 is a power calculation principle diagram provided by an embodiment of the present invention;

[0044] Figure 5 is a flow chart of another method for diagnosing a fault in an electrical circuit provided by an embodiment of the present invention;

[0045] Figure 6 is a flow chart of another method for diagnosing a fault in an electrical circuit provided by an embodiment of the present invention;

[0046] Figure 7 It is a block flow chart of a fault diagnosis device for an electrical circuit provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0047] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0048] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0049] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and this document does not limit this.

[0050] Figure 1 is a flow chart of a fault diagnosis method for an electrical circuit provided by an embodiment of the present invention, with reference to Figure 1 The fault diagnosis method of the electric circuit provided by the embodiment of the present invention is mainly applied to the current transformer in the substation. The fault diagnosis method includes:

[0051] S1. Acquire a current signal, a voltage signal, and a plurality of first power signals and a plurality of second power signals of at least two measurement and control devices in a line interval where a current transformer is located.

[0052] Among them, the current transformer is an electrical device that works on the principle of electromagnetic induction, mainly used to convert large currents into small currents for measurement and protection; the line bay is a specific area or bay in the substation used to connect external power lines and internal distribution equipment; the measurement and control device is a key equipment used to monitor and control the operation of the power system.

[0053] Specifically, the current signal, voltage signal of the line interval where the current transformer is located in the substation and multiple first power signals and multiple second power signals of at least two measurement and control devices are obtained. Exemplarily, the first power signal is active power and the second power signal is reactive power.

[0054] S2. Generate a first test power signal and a second test power signal according to the current signal and the voltage signal.

[0055] Specifically, power flow calculation refers to a method for calculating the distribution of active power, reactive power and voltage in the power grid under given power system network topology, component parameters, and power generation and load parameters. A first test power signal and a second test power signal are generated through power flow calculation according to the current signal and voltage signal obtained in the above step S1. The first test power signal is generated through the current signal and the voltage signal, and the first test power signal can be a test active power. The second test power signal is generated through the current signal and the voltage signal, and the second test power signal can be a test reactive power.

[0056] S3. Generate a third test power signal and a fourth test power signal according to the multiple first power signals and the multiple second power signals.

[0057] Specifically, Kirchhoff's law includes that at any time, the sum of the currents flowing into any node is equal to the sum of the currents flowing out of the node, and in any closed loop, the algebraic sum of the voltages of each segment is always equal to zero. Based on this law, the third test power signal and the fourth test power signal are determined by Kirchhoff's law according to multiple first power signals (i.e., active power) obtained by multiple measurement and control devices and multiple second power signals (i.e., reactive power) obtained by multiple measurement and control devices. Exemplarily, the third test power signal is the test active power signal of the measurement and control device, and the fourth test power signal is the test reactive power signal of the measurement and control device.

[0058] S4. Determine the working state of the electric circuit of the current transformer according to the relationship between the first test power signal and the third test power signal and the relationship between the second test power signal and the fourth test power signal.

[0059] Specifically, the first test power signal is compared with the third test power signal, that is, the first test power signal (test active power signal) on the line interval is compared with the third test power signal (test active power signal) determined on the measurement and control device, and the second test power signal (test reactive power signal) on the line interval is compared with the fourth test power signal (test reactive power signal) determined on the measurement and control device. It can be understood that the active power on the line interval is compared with the active power on the measurement and control device, and the reactive power on the line interval is compared with the reactive power on the measurement and control device to determine the working state of the electrical circuit of the current transformer. For example, if the active power on the line interval is consistent with the value and sign of the active power on the measurement and control device, and the reactive power on the line interval is consistent with the value and sign of the reactive power on the measurement and control device, then the electric circuit of the current transformer is determined to be in a normal operating state; if the active power on the line interval is different from the value or sign of the active power on the measurement and control device, or the reactive power on the line interval is different from the value or sign of the reactive power on the measurement and control device, then the electric circuit of the current transformer is determined to be in a fault state. Wherein, the measurement and control device and the line interval are located on the same busbar.

[0060] The electric circuit fault diagnosis method provided by the embodiment of the present invention determines the electric circuit fault state of the current transformer by comparing the power signal on the line interval and the power signal on the measurement and control device respectively, so as to avoid the protection malfunction caused by the current circuit fault in the operating interval. By automatically detecting the electric circuit, the cost of manual inspection can be reduced, the efficiency of inspection can be improved, and the missed inspection caused by skill problems can be reduced.

[0061] On the basis of the above-mentioned embodiments of the invention, the embodiments of the invention further refine the steps before obtaining the current signal, voltage signal, and multiple first power signals and multiple second power signals of at least two measurement and control devices in the line interval where the current transformer is located. Figure 2 is a flow chart of another method for diagnosing a fault in an electric circuit provided by an embodiment of the present invention, with reference to Figure 2 , the fault diagnosis method of the electric circuit provided by the embodiment of the present invention includes:

[0062] S21. Obtain the busbar side switch position signal, switch position signal and line voltage signal of the substation.

[0063] The main function of the busbar in a substation is to collect, distribute and transmit electrical energy. It achieves effective transmission of electricity by introducing high-voltage power from generators, transformers or other power equipment into low-voltage equipment, or by collecting the power of low-voltage equipment.

[0064] Specifically, the busbar side knife switch position signal, switch position signal and line voltage signal of the substation are obtained, the busbar side knife switch position signal includes the closing and opening states, and the switch position signal includes the closing and opening states.

[0065] S22. Determine the working status of the equipment in the line interval according to the busbar side knife switch position signal, the switch position signal and the line voltage signal.

[0066] Specifically, the operating status of the equipment in the line interval is determined according to the substation bus side knife switch position signal, switch position signal and line voltage signal determined in the above step S21. Only when the equipment in the line interval is in operation, the electrical circuit of the current transformer will be monitored, thereby improving the monitoring efficiency.

[0067] S23, obtaining a current signal, a voltage signal, and a plurality of first power signals and a plurality of second power signals of at least two measurement and control devices in the line interval where the current transformer is located.

[0068] S24. Generate a first test power signal and a second test power signal according to the current signal and the voltage signal.

[0069] S25. Generate a third test power signal and a fourth test power signal according to the multiple first power signals and the multiple second power signals.

[0070] S26. Determine the working state of the electrical circuit of the current transformer according to the relationship between the first test power signal and the third test power signal and the relationship between the second test power signal and the fourth test power signal.

[0071] On the basis of the above-mentioned embodiments of the invention, the embodiments of the invention further refine the working state of the equipment for determining the line interval according to the bus side knife switch position signal, the switch position signal and the line voltage signal. Figure 3 is a flow chart of another method for diagnosing a fault in an electric circuit provided by an embodiment of the present invention, with reference to Figure 3 , the fault diagnosis method of the electric circuit provided by the embodiment of the present invention includes:

[0072] S31. Obtain the busbar side switch position signal, switch position signal and line voltage signal of the substation.

[0073] S32, judging whether the busbar side knife switch position signal, the switch position signal and the line voltage signal meet the first preset condition.

[0074] Compare the bus-side disconnecting switch position signal, switch position signal, and line voltage signal obtained in step S31 with the first preset condition; if the first preset condition is satisfied, execute step S33; if the first preset condition is not satisfied, execute step S38, where the first preset condition includes that the bus-side disconnecting switch position signal is in the closed state, the switch position signal is in the closed state, and the line voltage exceeds 30% of the phase voltage.

[0075] S33. When the bus-side disconnecting switch position signal, switch position signal, and line voltage signal satisfy the first preset condition, it is determined that the equipment in the line interval is in the operating state.

[0076] Specifically, when the bus-side disconnecting switch position signal is in the closed state, the switch position signal is in the closed state, and at the same time the line voltage signal exceeds 30% of the phase voltage, it is determined that the equipment in the line interval is in the operating state; it can be understood that these three conditions must be satisfied simultaneously to be determined to meet the first preset condition.

[0077] S38. When the bus-side disconnecting switch position signal, switch position signal, and line voltage signal do not satisfy the first preset condition, it is determined that the equipment in the line interval is in the non-operating state.

[0078] Specifically, when the bus-side disconnecting switch position signal is in the open state, or the switch position signal is in the open state, or the line voltage signal does not exceed 30% of the phase voltage, it is determined that the equipment in the line interval is not in the operating state, where the equipment not in the operating state may include equipment under power outage for maintenance and hot standby equipment.

[0079] Based on the above invention embodiments, the present invention embodiments further refine the generation of the first test power signal and the second test power signal according to the current signal and the voltage signal. Figure 4 It is the schematic diagram of power calculation provided by the embodiments of the present invention. Refer to Figure 4 , generating the first test power signal and the second test power signal according to the current signal and the voltage signal includes:

[0080] Calculate the first test power signal and the second test power signal through formula (1) and formula (2):

[0081] P 1j =UIcosθ (1)

[0082] Q 1j =UIsinθ (2)

[0083] Among them, P 1j is the first test power signal of the interval, U is the voltage signal of the interval, I is the current signal of the interval, and θ is the power factor angle.

[0084] Specifically, the active power and reactive power of the line interval where the current transformer is located are calculated based on the acquired current signal and voltage signal.

[0085] Optionally, generating a third test power signal and a fourth test power signal according to the plurality of first power signals and the plurality of second power signals includes:

[0086] Record multiple first power signals as P1~P n , record multiple second power signals as Q1~Q n ;

[0087] The third test power signal and the fourth test power signal are calculated by formula (3) and formula (4):

[0088] P 1h =-(P2+P3+……+P n ) (three)

[0089] Q 1h =-(Q2+Q3+……+Q n ) (Four)

[0090] Among them, P 1h is the third test power signal of the measurement and control device, Q 1h is the fourth test power signal of the measurement and control device, P2 is the first power signal of the second measurement and control device, P3 is the first power signal of the third measurement and control device, Q2 is the second power signal of the second measurement and control device, and Q3 is the second power signal of the third measurement and control device; wherein n is a positive integer greater than 1.

[0091] Specifically, the test power signals of multiple measurement and control devices are calculated respectively. For example, there are three measurement and control devices, and the active power and reactive power of each measurement and control device are calculated respectively, and are named P1, P2, P3 and Q1, Q2, Q3 respectively. The third test power signal and the third test power signal are calculated by the above formula (three) and formula (four). The principle of formula (three) and formula (four) is Kirchhoff's law, which is common knowledge and will not be elaborated here.

[0092] On the basis of the above-mentioned embodiments of the invention, the embodiments of the invention further refine the working state of the electric circuit of the current transformer according to the relationship between the first test power signal and the third test power signal and the relationship between the second test power signal and the fourth test power signal. Figure 5 is a flow chart of another method for diagnosing a fault in an electric circuit provided by an embodiment of the present invention, with reference to Figure 5 , the fault diagnosis method of the electric circuit provided by the embodiment of the present invention includes:

[0093] S41, obtaining a current signal, a voltage signal, and a plurality of first power signals and a plurality of second power signals of at least two measurement and control devices in a line interval where a current transformer is located.

[0094] S42. Generate a first test power signal and a second test power signal according to the current signal and the voltage signal.

[0095] S43. Generate a third test power signal and a fourth test power signal according to the multiple first power signals and the multiple second power signals.

[0096] S44. Compare the relationship between the first test power signal and the third test power signal with the second preset condition; compare the relationship between the second test power signal and the fourth test power signal with the second preset condition; if both meet the second preset condition, execute step S45; if the second preset condition is not met, execute step S46, wherein the second preset condition includes that the value and sign of the first test power signal are consistent with those of the third test power signal, and the value and sign of the second test power signal are consistent with those of the fourth test power signal.

[0097] S45. When the relationship between the first test power signal and the third test power signal and the relationship between the second test power signal and the fourth test power signal both meet the second preset condition, it is determined that the electrical circuit is in a normal operating state.

[0098] Specifically, when the relationship between the first test power signal and the third test power signal and the relationship between the second test power signal and the fourth test power signal both meet the second preset condition, it can be understood that when the first test power signal and the third test power signal have the same value and sign, and the second test power signal and the fourth test power signal have the same value and sign, it is determined that the electrical circuit of the current transformer is in a normal operating working state.

[0099] S46: When the relationship between the first test power signal and the third test power signal and the relationship between the second test power signal and the fourth test power signal do not satisfy a second preset condition, it is determined that the electrical circuit is in a fault state.

[0100] Specifically, when the relationship between the first test power signal and the third test power signal and the relationship between the second test power signal and the fourth test power signal do not meet the second preset condition, it can be understood that when one of the values ​​and signs of the first test power signal and the third test power signal is different, or when one of the values ​​and signs of the second test power signal and the fourth test power signal is different, it is determined that the electrical circuit of the current transformer is in a fault state.

[0101] On the basis of the above-mentioned embodiments of the invention, the embodiments of the invention further refine the determination that the electrical circuit is in a fault state when the relationship between the first test power signal and the third test power signal and the relationship between the second test power signal and the fourth test power signal do not satisfy the second preset condition. Figure 6 is a flow chart of another method for diagnosing a fault in an electric circuit provided by an embodiment of the present invention, with reference to Figure 6 , the fault diagnosis method of the electric circuit provided by the embodiment of the present invention includes:

[0102] S51, obtaining a current signal, a voltage signal, and a plurality of first power signals and a plurality of second power signals of at least two measurement and control devices in a line interval where a current transformer is located.

[0103] S52 , generating a first test power signal and a second test power signal according to the current signal and the voltage signal.

[0104] S53. Generate a third test power signal and a fourth test power signal according to the multiple first power signals and the multiple second power signals.

[0105] S54, comparing the relationship between the first test power signal and the third test power signal with the second preset condition; comparing the relationship between the second test power signal and the fourth test power signal with the second preset condition.

[0106] S56: When the relationship between the first test power signal and the third test power signal and the relationship between the second test power signal and the fourth test power signal do not satisfy a second preset condition, it is determined that the electrical circuit is in a fault state.

[0107] S57: Generate alarm information according to the fault status and send it to the user end.

[0108] Specifically, when the above step S56 determines that the electric circuit of the current transformer is in a fault state, an alarm message is generated based on the fault state information and sent to the user end to remind the staff to perform maintenance.

[0109] Optionally, the warning information includes at least one of the following: voice reminder, buzzer reminder and light reminder.

[0110] Specifically, exemplarily, the buzzer reminder may include a buzzer, and the light reminder may include a light emitting diode.

[0111] Optionally, the line interval includes one of a line protection device, a line measurement device, a line metering device and a fault recording device.

[0112] Specifically, the line protection devices, line measuring devices, line metering devices and fault recording devices in the line interval can all perform fault diagnosis of the electrical circuit through the same principle, which will not be elaborated here; the protection devices are mainly used for the protection of the power system. When a short circuit, overload or other fault occurs in the power system, the current signal of the protection group will be transmitted to the protection device (such as a relay), triggering the corresponding protection action, such as tripping, to prevent equipment damage or the expansion of the accident.

[0113] The measuring device is mainly used for real-time monitoring and control of the power system. The current signal of the measuring group will be transmitted to the measuring instrument (such as ammeter, power meter, etc.) to display the current, power and other parameters of the system in real time.

[0114] Metering devices are mainly used for electric energy measurement in power systems. The current signal of the metering group will be transmitted to the electric energy meter to calculate and record the system's electric energy consumption, providing a basis for electricity bill settlement.

[0115] Figure 7 is a block flow chart of a fault diagnosis device for an electric circuit provided by an embodiment of the present invention, with reference to Figure 7 According to the same inventive concept, an embodiment of the present invention provides a fault diagnosis device for an electric circuit, which is applied to a current transformer of a substation. The fault diagnosis device is used to execute the fault diagnosis method for the electric circuit in the above-mentioned embodiment of the invention. The fault diagnosis device includes:

[0116] The acquisition module 1 is used to acquire the current signal, the voltage signal of the line interval where the current transformer is located, and multiple first power signals and multiple second power signals of at least two measurement and control devices.

[0117] The calculation module 2 is used to generate a first test power signal and a second test power signal according to the current signal and the voltage signal; and to generate a third test power signal and a fourth test power signal according to a plurality of first power signals and a plurality of second power signals.

[0118] Determination module 3 is used to determine the working state of the electrical circuit of the current transformer according to the relationship between the first test power signal and the third test power signal and the relationship between the second test power signal and the fourth test power signal; wherein the measurement and control device and the line interval are located on the same bus.

[0119] An electrical circuit fault diagnosis device provided in an embodiment of the present invention can achieve the same technical effect as an electrical circuit fault diagnosis method provided in any of the above-mentioned embodiments of the invention, which will not be described in detail here.

[0120] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for diagnosing a fault in an electrical circuit, characterized in that: For current transformers used in substations, fault diagnosis methods include: Acquire a current signal, a voltage signal, and a plurality of first power signals and a plurality of second power signals of at least two measurement and control devices in the line interval where the current transformer is located; generating a first test power signal and a second test power signal according to the current signal and the voltage signal; generating a third test power signal and a fourth test power signal according to a plurality of the first power signals and a plurality of the second power signals; The working state of the electrical circuit of the current transformer is determined according to the relationship between the first test power signal and the third test power signal and the relationship between the second test power signal and the fourth test power signal; wherein the measurement and control device and the line interval are located on the same bus.

2. The fault diagnosis method of an electrical circuit according to claim 1, characterized in that: Before obtaining the current signal, the voltage signal of the line interval where the current transformer is located, and the multiple first power signals and the multiple second power signals of at least two measurement and control devices, the method further includes: Obtain the busbar side switch position signal, switch position signal and line voltage signal of the substation; The working state of the equipment in the line interval is determined according to the bus-side knife switch position signal, the switch position signal and the line voltage signal.

3. The fault diagnosis method of an electrical circuit according to claim 2, characterized in that: Determining the working state of the equipment in the line interval according to the bus side knife switch position signal, the switch position signal and the line voltage signal includes: When the busbar side knife switch position signal, the switch position signal and the line voltage signal meet a first preset condition, it is determined that the equipment in the line interval is in operation; When the busbar side knife switch position signal, the switch position signal and the line voltage signal do not meet the first preset condition, it is determined that the equipment in the line interval is in a non-operating state; wherein the first preset condition includes that the busbar side knife switch position signal is in a closed state, the switch position signal is in a closed state and the line voltage exceeds 30% of the phase voltage.

4. The fault diagnosis method of an electric circuit according to claim 1, characterized in that: Generating a first test power signal and a second test power signal according to the current signal and the voltage signal, comprising: The first test power signal and the second test power signal are calculated by formula (1) and formula (2): P 1j = UIcosθ (1) Q 1j = UIsinθ (II) Among them, P 1j is the first test power signal of the interval, U is the voltage signal of the interval, I is the current signal of the interval, and θ is the power factor angle.

5. The fault diagnosis method of an electric circuit according to claim 1, characterized in that: Generating a third test power signal and a fourth test power signal according to a plurality of the first power signals and a plurality of the second power signals, comprising: Record multiple first power signals as P1~P n , record multiple second power signals as Q1~Q n ; The third test power signal and the fourth test power signal are calculated by formula (III) and formula (IV): P 1h =-(P2+P3+……+P n )(three) Q 1h =-(Q2+Q3+……+Q n )(four) Among them, P 1h is the third test power signal of the measurement and control device, Q 1h is the fourth test power signal of the measurement and control device, P2 is the first power signal of the second measurement and control device, P3 is the first power signal of the third measurement and control device, Q2 is the second power signal of the second measurement and control device, and Q3 is the second power signal of the third measurement and control device; wherein n is a positive integer greater than 1.

6. The fault diagnosis method of an electric circuit according to claim 1, characterized in that: Determining the working state of the electric circuit of the current transformer according to the relationship between the first test power signal and the third test power signal and the relationship between the second test power signal and the fourth test power signal comprises: When the relationship between the first test power signal and the third test power signal and the relationship between the second test power signal and the fourth test power signal both meet a second preset condition, it is determined that the electrical circuit is in a normal operating state; When the relationship between the first test power signal and the third test power signal and the relationship between the second test power signal and the fourth test power signal do not satisfy the second preset condition, it is determined that the electrical circuit is in a fault state; wherein the second preset condition includes that the first test power signal and the third test power signal have the same value and sign, and the second test power signal and the fourth test power signal have the same value and sign.

7. The fault diagnosis method of an electric circuit according to claim 6, characterized in that: When the relationship between the first test power signal and the third test power signal and the relationship between the second test power signal and the fourth test power signal do not meet a second preset condition, then after determining that the electrical circuit is in a fault state, the method further includes: Generate alarm information according to the fault status and send it to the user end.

8. The fault diagnosis method of an electric circuit according to claim 7, characterized in that: The warning information includes at least one of the following: voice reminder, buzzer reminder and light reminder.

9. The fault diagnosis method of an electric circuit according to claim 1, characterized in that: The line interval includes one of a line protection device, a line measurement device, a line metering device and a fault recording device.

10. A fault diagnosis device for an electrical circuit, characterized in that: A current transformer applied to a substation, wherein the fault diagnosis device is used to perform the fault diagnosis method of an electric circuit according to any one of claims 1 to 9, and the fault diagnosis device comprises: An acquisition module, used to acquire a current signal, a voltage signal, and a plurality of first power signals and a plurality of second power signals of at least two measurement and control devices in the line interval where the current transformer is located; A calculation module, configured to generate a first test power signal and a second test power signal according to the current signal and the voltage signal; and to generate a third test power signal and a fourth test power signal according to a plurality of the first power signals and a plurality of the second power signals; A determination module is used to determine the working state of the electrical circuit of the current transformer based on the relationship between the first test power signal and the third test power signal and the relationship between the second test power signal and the fourth test power signal; wherein the measurement and control device and the line interval are located on the same bus.

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