A non-intrusive low voltage circuit breaker condition sensing device

Abstract

The application relates to a non-intrusive low-voltage circuit breaker state sensing device which comprises an Internet of Things communication module, a sampling module and a calculation module; the Internet of Things communication module is responsible for communication with a district side device and uploading a circuit breaker state; the sampling module is responsible for collecting voltage and current data around the circuit breaker through a voltage and current transformer; and the calculation module is responsible for sensing the circuit breaker state according to the data collected by the sampling module, which can not only distinguish the opening and closing states of the circuit breaker, but also distinguish short-circuit tripping and non-short-circuit tripping, and further evaluate the operation life of the circuit breaker.

Description

Technical Field

[0001] This invention relates to a sensing device, specifically a non-intrusive low-voltage circuit breaker status sensing device, belonging to the field of power system automation technology. Background Technology

[0002] Currently, the development of digital grids has driven the digital transformation of low-voltage distribution areas, requiring the ability to monitor the operating status of circuit breakers installed at each node. However, since most of the circuit breakers used in existing distribution areas lack IoT communication capabilities, and some circuit breakers cannot even provide location signals, converting a large number of traditional circuit breakers into smart circuit breakers with IoT communication capabilities would be prohibitively costly.

[0003] Currently, online monitoring of circuit breaker status is mostly focused on circuit breakers with voltage levels above 10kV. The common practice is to use auxiliary nodes provided by the circuit breaker or monitor moving mechanisms to determine the circuit breaker's open / closed status and assess its lifespan. However, due to cost constraints, this is not required in low-voltage power distribution systems; therefore, the application of circuit breaker status monitoring in low-voltage power distribution systems is rarely reported. Summary of the Invention

[0004] This invention addresses the problems existing in the prior art by providing a non-intrusive low-voltage circuit breaker status sensing device. This technical solution aims to solve the problem of many old circuit breakers lacking status sensing and IoT communication capabilities, and to accelerate the construction of digital power grids. To minimize the need for replacing existing circuit breakers, this invention utilizes the differences in electrical quantity characteristics during circuit breaker opening and closing to propose a non-intrusive low-voltage circuit breaker status sensing device. This device can not only distinguish between the opening and closing states of the circuit breaker, but also differentiate between short-circuit tripping and non-short-circuit tripping, thereby assessing the circuit breaker's service life.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows: a non-intrusive low-voltage circuit breaker status sensing device, characterized in that the device comprises an IoT communication module, a sampling module, and a calculation module; the IoT communication module is responsible for communicating with the equipment on the side of the distribution area and uploading the circuit breaker status; the sampling module is responsible for collecting voltage and current data around the circuit breaker through voltage and current transformers; and the calculation module is responsible for sensing the circuit breaker status based on the data collected by the sampling module.

[0006] As an improvement of the present invention, the sensing of the circuit breaker's open / closed state is divided into three cases:

[0007] A. Circuit breakers can be used to establish location nodes;

[0008] If the circuit breaker body supports the output of position signal nodes, the circuit breaker status can be directly determined after passing through electrical quantity error prevention, as shown in Figure (1).

[0009] Commissioning Judgment Logic:

[0010]

[0011] In the formula, DL represents the circuit breaker state, 1 represents the closed position, and I represents the current. set.ty This indicates the set value of the operating current.

[0012] Short-circuit tripping detection logic:

[0013]

[0014] In the formula, DL = 1 → 0 indicates that the circuit breaker changes from closed to open, I set.th Indicates the current determination value after tripping, I max This indicates the maximum current during the period before the circuit breaker switches from closed to open.

[0015] Non-short-circuit tripping detection logic:

[0016]

[0017] Anomaly detection logic:

[0018]

[0019] B. If the position node cannot be obtained, the switch state can be determined by the voltage on both sides and the current on one side. As shown in Figure (2).

[0020] Commissioning Judgment Logic:

[0021]

[0022] or

[0023] I≥I set.ty

[0024] In the formula, ΔU represents the voltage amplitude difference between the incoming and outgoing lines of the switch. set The threshold value for determining voltage stepout amplitude is represented by Δθ, which represents the phase angle difference between the input and output voltages of the switch. set This indicates the threshold for determining voltage out-of-step phase angle.

[0025] Short-circuit tripping detection logic:

[0026]

[0027] In the formula, U1 represents the voltage on the incoming side of the circuit breaker, U2 represents the voltage on the outgoing side of the switch, and U set.ty This indicates the voltage threshold for determining whether the voltage is present.

[0028] Non-short-circuit tripping detection logic:

[0029]

[0030] Anomaly detection logic:

[0031]

[0032] C. The location node cannot be identified; the judgment is based solely on the voltage and current on one side.

[0033] If only current data can be obtained, the switch state is determined by electrical quantities, as shown in Figure (3).

[0034] Commissioning Judgment Logic:

[0035] I≥I set.ty ||P≥P set.ty

[0036] Short-circuit tripping detection logic:

[0037]

[0038] Non-short-circuit tripping detection logic:

[0039]

[0040] In the formula, ΔI represents the change in current. set.qd I represents the threshold value for the current change to trigger the signal. -0.2s This represents the current value 0.2 seconds before startup. In this case, the upstream adjacent switches have the same electrical characteristics, and the side-side equipment needs to make further judgments based on the topology.

[0041] Compared with the prior art, the present invention has the following advantages: the technical solution proposes a criterion for non-intrusive circuit breaker state sensing;

[0042] It offers three operating principles and can automatically adapt to the circuit breaker conditions.

[0043] It is a non-invasive sensing method that can determine the switch status through electrical quantities;

[0044] The judgment is made by combining voltage and current timing sequences, and the criteria are sensitive and reliable.

[0045] This invention provides a non-intrusive low-voltage circuit breaker status sensing device. It is simple and reliable in principle, adaptable to various on-site installation and operation methods; it can distinguish between short-circuit tripping and non-short-circuit tripping, providing a reliable basis for circuit breaker life assessment; it requires no modification to the existing circuit breaker's incoming line, resulting in low-cost transformer substation upgrades; and the device is plug-and-play, making installation and use simple and convenient. Attached Figure Description

[0046] Appendix Figure 1 Installation and data collection illustration for scenario A;

[0047] Appendix Figure 2 Scenario B: Installation and data collection diagram;

[0048] Appendix Figure 3 Scenario C: Installation and data collection illustration. Detailed Implementation

[0049] To enhance understanding of the present invention, the embodiments will be described in detail below with reference to the accompanying drawings.

[0050] Example 1: See Figure 1 A non-intrusive low-voltage circuit breaker status sensing device is characterized in that the device includes an IoT communication module, a sampling module, and a calculation module; the IoT communication module is responsible for communicating with the equipment on the side of the distribution area and uploading the circuit breaker status; the sampling module is responsible for collecting voltage and current data around the circuit breaker through voltage and current transformers; and the calculation module is responsible for sensing the circuit breaker status based on the data collected by the sampling module.

[0051] As an improvement of the present invention, the sensing of the circuit breaker's open / closed state is divided into three cases:

[0052] A. Circuit breakers can be used to establish location nodes;

[0053] If the circuit breaker body supports the output of position signal nodes, the circuit breaker status can be directly determined after passing through electrical quantity error prevention, as shown in Figure (1).

[0054] Commissioning Judgment Logic:

[0055]

[0056] In the formula, DL represents the circuit breaker state, 1 represents the closed position, and I represents the current. set.ty This indicates the set value of the operating current.

[0057] Short-circuit tripping detection logic:

[0058]

[0059] In the formula, DL = 1 → 0 indicates that the circuit breaker changes from closed to open, I set.th Indicates the current determination value after tripping, I max This indicates the maximum current during the period before the circuit breaker switches from closed to open.

[0060] Non-short-circuit tripping detection logic:

[0061]

[0062] Anomaly detection logic:

[0063]

[0064] B. If the position node cannot be obtained, the switch state can be determined by the voltage on both sides and the current on one side. As shown in Figure (2).

[0065] Commissioning Judgment Logic:

[0066]

[0067] or

[0068] I≥I set.ty

[0069] In the formula, ΔU represents the voltage amplitude difference between the incoming and outgoing lines of the switch. set The threshold value for determining voltage stepout amplitude is represented by Δθ, which represents the phase angle difference between the input and output voltages of the switch. set This indicates the threshold for determining voltage out-of-step phase angle.

[0070] Short-circuit tripping detection logic:

[0071]

[0072] In the formula, U1 represents the voltage on the incoming side of the circuit breaker, U2 represents the voltage on the outgoing side of the switch, and U set.ty This indicates the voltage threshold for determining whether the voltage is present.

[0073] Non-short-circuit tripping detection logic:

[0074]

[0075] Anomaly detection logic:

[0076]

[0077] C. The location node cannot be identified; the judgment is based solely on the voltage and current on one side.

[0078] If only current data can be obtained, the switch state is determined by electrical quantities, as shown in Figure (3).

[0079] Commissioning Judgment Logic:

[0080] I≥I set.ty ||P≥P set.ty

[0081] Short-circuit tripping detection logic:

[0082]

[0083] Non-short-circuit tripping detection logic:

[0084]

[0085] In the formula, ΔI represents the change in current. set.qd I represents the threshold value for the current change to trigger the signal. -0.2s This represents the current value 0.2 seconds before startup. In this case, the upstream adjacent switches have the same electrical characteristics, and the side-side equipment needs to make further judgments based on the topology.

[0086] It should be noted that the above embodiments are not intended to limit the scope of protection of the present invention. Equivalent transformations or substitutions made based on the above technical solutions all fall within the scope of protection of the claims of the present invention.

Claims

1. A non-intrusive low voltage circuit breaker condition sensing device, characterized by, The device comprises an Internet of Things communication module, a sampling module and a calculation module; the Internet of Things communication module is responsible for communication with a district side device and uploading a circuit breaker state; the sampling module is responsible for collecting voltage and current data around the circuit breaker through a voltage and current transformer; and the calculation module is responsible for sensing the circuit breaker state according to the data collected by the sampling module; The sensing of the opening and closing state of the circuit breaker is divided into three cases: A, the circuit breaker lead-out position node; If the circuit breaker body supports the lead-out position signal node and the electrical quantity error prevention is passed, the circuit breaker state can be directly determined, Commissioning discrimination logic: wherein DL represents the circuit breaker status, 1 represents the closed position, I represents the current, I set.ty represents the set value of the operating current, Short-circuit tripping discrimination logic: wherein DL=1→0 indicates that the circuit breaker is changing from closed to open, I set.th represents the current determination value after tripping, I max represents the maximum current in the period before the circuit breaker changes from closed to open, Non-short-circuit tripping discrimination logic: Abnormality discrimination logic: B, unable to lead out the position node, judge with double-sided voltage + single-sided current If the switch position signal cannot be directly obtained, the switch state can be judged through double-sided voltage and current, Commissioning discrimination logic: or I≥I set.ty In the formula, ΔU represents the difference of voltage amplitude of the switch input and output, ΔU set represents the voltage step-out amplitude determination threshold, Δθ represents the difference of voltage phase angle of the switch input and output, Δθ set represents the voltage step-out phase angle determination threshold, Short-circuit tripping discrimination logic: In the formula, U1 represents the voltage on the incoming line side of the circuit breaker, U2 represents the voltage on the outgoing line side of the switch, U set.ty represents the operating voltage, i.e., the threshold value for judging the presence of voltage. Non-short-circuit tripping discrimination logic: Abnormality discrimination logic: C, unable to lead out the position node, only single-sided voltage and current are used for judgment; If only current data can be obtained, the switch state is determined through electrical quantity, Commissioning discrimination logic: I ≥ I set.ty ||P ≥ P set.ty Short-circuit tripping discrimination logic: Non-short-circuit tripping discrimination logic: where ΔI represents the current change amount, ΔI set.qd represents the current change amount start threshold, I -0.2s represents the current value 0.2s before starting, in this case, the upstream adjacent switch has the same electrical quantity characteristics, and the side device needs to further judge according to the topology structure.

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