CN222602040U - A differential protection device - Google Patents
A differential protection device Download PDFInfo
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- CN222602040U CN222602040U CN202420831151.0U CN202420831151U CN222602040U CN 222602040 U CN222602040 U CN 222602040U CN 202420831151 U CN202420831151 U CN 202420831151U CN 222602040 U CN222602040 U CN 222602040U
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Abstract
本实用新型提供一种差动保护装置，用以解决现有技术中瞬时TA断线所引起的差动保护误动作的问题。包括：数据采集模块、微处理器、电源模块以及保护驱动模块；数据采集模块、电源模块和保护驱动模块皆与微处理器电连接，数据采集模块包括第一电流互感器、第二电流互感器以及数模转换模块，第一电流互感器和第二电流互感器并联后与数模转换模块电连接，数模转换模块与微处理器电连接。该装置采用第一电流互感器和第二电流互感器并联后连接数据采集模块，可以在一个电流互感器出现断线情况时，及时分辨是否需要进行差动保护，有效避免了因电流互感器断线导致的误动作。
The utility model provides a differential protection device to solve the problem of differential protection misoperation caused by instantaneous TA disconnection in the prior art. It includes: a data acquisition module, a microprocessor, a power module and a protection drive module; the data acquisition module, the power module and the protection drive module are all electrically connected to the microprocessor, the data acquisition module includes a first current transformer, a second current transformer and a digital-to-analog conversion module, the first current transformer and the second current transformer are connected in parallel and then electrically connected to the digital-to-analog conversion module, and the digital-to-analog conversion module is electrically connected to the microprocessor. The device adopts the first current transformer and the second current transformer connected in parallel and then connected to the data acquisition module, and can timely distinguish whether differential protection is needed when a current transformer is disconnected, effectively avoiding misoperation caused by the current transformer disconnection.
Description
Technical field:
The present utility model relates to the field of electronic information technologies, and in particular, to a differential protection device.
The background technology is as follows:
In an electric power system, a differential protection device is an important protection apparatus for rapidly cutting off a faulty line or equipment to prevent the fault from expanding. The differential protection device realizes the protection function by comparing the magnitude and phase of the current at each side in the power system. However, in practical applications, the differential protection device may face some technical challenges due to the characteristics of the current Transformer (TA). Conventional differential protection devices typically protect based on steady state current. This means that they focus mainly on the long-term average or effective value of the current, not on the instantaneous value of the current. However, an instantaneous TA disconnection (an instantaneous current transformer fault) may cause the differential protection device to be misinterpreted as a fault condition, thereby causing unnecessary actions. The conventional differential protection device has limited capability of suppressing external interference signals. For example, lightning, system short-circuits, etc. events may create strong interference signals that may be mistaken by the differential protection device as fault signals, resulting in incorrect protection actions. In order to solve the above problems, an object of the present invention is to provide a differential protection device, which can overcome the shortcomings of the prior art and improve the accuracy and adaptability of differential protection. Specifically, the invention realizes comprehensive protection and efficient management of the power system by introducing an identification mechanism of the instantaneous TA disconnection, a suppression function of an external interference signal and a self-adaptive parameter adjustment mechanism.
The utility model comprises the following steps:
Based on the background, the invention provides a differential protection device for solving the problem of differential protection misoperation caused by the current instantaneous TA disconnection, which mainly comprises a data acquisition module, a microprocessor, a power supply module and a protection driving module, wherein the data acquisition module 3, the power supply module and the protection driving module are electrically connected with the microprocessor, the data acquisition module comprises a first current transformer, a second current transformer and a digital-to-analog conversion module, the first current transformer and the second current transformer are electrically connected with the digital-to-analog conversion module after being connected in parallel, and the digital-to-analog conversion module is electrically connected with the microprocessor.
Preferably, the protection driving module comprises a current transformer broken line locking module and a protection outlet relay, wherein the current transformer broken line locking module is connected with the microprocessor module and used for determining broken line information of the first current transformer or the second current transformer and sending corresponding protection instructions to the protection outlet relay according to the broken line information, and the protection outlet relay is connected with a breaker of protected equipment.
Preferably, the differential protection device further comprises a broken wire indicating module, wherein the broken wire indicating module comprises a broken wire indicating lamp and an alarm module, and the broken wire indicating lamp and the alarm module are electrically connected with the microprocessor.
Preferably, the differential protection device further comprises an information communication module, wherein the information communication module is electrically connected with the microprocessor, and the information communication module is in communication connection with the wireless transmission module of the upper computer.
Preferably, the differential protection device further comprises an input module and a display module, wherein the input module and the display module are electrically connected with the microprocessor.
Preferably, the data acquisition module comprises a first current transformer and a second current transformer, wherein secondary windings of the first current transformer and the second current transformer are connected to two ends of a first resistor R4, one end of the first resistor R4 is grounded through a first capacitor C4, the other end of the first resistor R4 is connected to a bias voltage circuit and is simultaneously connected with one end of a second resistor R3, the other end of the second resistor R3 and one end of the first resistor R4 are connected with a reverse amplifier circuit, and the output end of the reverse amplifier circuit is connected with a digital-to-analog conversion module.
Preferably, the disconnection information sends out corresponding protection instructions represented by the high and low levels of the switching value output circuit, the switching value output circuit adopts an optocoupler conversion circuit, the input end of the optocoupler conversion circuit is connected with the microprocessor, and the output end of the optocoupler conversion circuit is connected with the protection outlet relay.
The differential protection device has the beneficial effects that the data acquisition module after the first current transformer and the second current transformer are connected in parallel is adopted, so that when a broken line condition occurs in one current transformer, whether differential protection is needed or not can be timely distinguished, misoperation caused by broken line of the current transformer is effectively avoided, the protection accuracy and reliability of a power system are improved, the information communication module can be in wireless communication with an upper computer, remote monitoring and control are realized, the intelligent monitoring capability and the operation convenience of the system are enhanced, and powerful guarantee is provided for safe and stable operation of the power system.
Description of the drawings:
FIG. 1 is a schematic diagram of a differential protection device according to a preferred embodiment;
FIG. 2 is a circuit diagram of a data acquisition module of the preferred embodiment;
FIG. 3 is a circuit diagram of a bias voltage circuit of the preferred embodiment;
Fig. 4 is a circuit diagram of a switching value output circuit according to a preferred embodiment.
The specific embodiment is as follows:
In view of this, the present utility model provides a differential protection device, and preferred embodiments of the present utility model are described below with reference to the accompanying drawings.
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present utility model more apparent, the technical solutions of the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present utility model, and it is apparent that the described embodiments are some embodiments of the present utility model, but not all embodiments of the present utility model. All other embodiments, which can be made by those skilled in the art based on the embodiments of the utility model without making any inventive effort, are intended to be within the scope of the utility model.
In addition, it should be understood that in the description of embodiments of the present utility model, the words "first," "second," and the like are used merely for distinguishing between the descriptions and not be construed as indicating or implying a relative importance or order.
Referring to fig. 1, the differential protection device comprises a data acquisition module 3, a microprocessor 1, a power supply module and a protection driving module 5, wherein the data acquisition module 3, the power supply module and the protection driving module 5 are all electrically connected with the microprocessor 1, the data acquisition module 3 comprises a first current transformer, a second current transformer and a digital-to-analog conversion module, the first current transformer and the second current transformer are connected in parallel and then are electrically connected with the digital-to-analog conversion module, and the digital-to-analog conversion module is electrically connected with the microprocessor 1.
Specifically, the basic principle of the differential protection device is to monitor and compare current signals measured by a Current Transformer (CT) in real time so as to judge whether a fault exists in the power system. The device collects current signals entering and exiting the power equipment through two parallel current transformers, and the signals are converted into digital signals through a digital-to-analog conversion module and then are sent to the microprocessor 1 for analysis.
The microprocessor 1 compares whether the two current signals have unbalance according to a preset differential protection algorithm. If there is a significant difference between the current signals, the set threshold is exceeded, which may indicate a fault inside the power device. In this case, the microprocessor 1 will issue a protection command, and trigger the circuit breaker 6 to act through the protection outlet relay in the protection driving module 5, thereby disconnecting the fault part from the system and preventing the fault from spreading.
Meanwhile, the device further comprises a current transformer broken line locking module used for monitoring the working state of the current transformer. If the CT is detected to be broken, the module can send out a locking signal to prevent the protection device from misoperation. In addition, the device is further provided with a broken line indicating module 2, an information communication module, an input/output module and a display module 401, fault indication, remote monitoring and man-machine interaction functions are provided, and the practicability and the operation convenience of the device are improved.
Referring to fig. 2 and 3, the data acquisition module 3 includes a first current transformer and a second current transformer, the secondary windings of which are connected to two ends of a first resistor R4, one end of the first resistor R4 is grounded through a first capacitor C4, the other end of the first resistor R4 is connected to a bias voltage circuit and is simultaneously connected to one end of a second resistor R3, the other end of the second resistor R3 and one end of the first resistor R4 are connected to a reverse amplifier circuit, and the output end of the reverse amplifier circuit is connected to a digital-to-analog conversion module.
The first current transformer and the second current transformer are arranged on two sides of an inlet line and an outlet line of the protected equipment in parallel and are used for monitoring current information in real time.
The digital-to-analog conversion module is responsible for converting the analog current signal output by the transformer into a digital signal so as to be convenient for the microprocessor 1 to process. In the bias voltage circuit in fig. 3, IC1A is a 2-channel integrated operational amplifier, and after 3.3V voltage is divided by two resistors R1 and R2 with the same resistance, the voltage is input to the same direction end of the first operational amplifier IC1A, so that a 1.65V voltage value without any interference can be output through the first operational amplifier, and the output end is 1v65_ct in the figure. In fig. 2, CT is a current transformer, which converts the current of the primary side to the secondary side through a transformation ratio. P1/P2/P3/P4 is a first current transformer, and P5/P6/P7/P8 is a second current transformer of another alternative type. The secondary-side current value is converted into a voltage value after passing through the resistor R4. Since the voltage value has waveforms at both positive and negative half cycles of the Y axis at this time, the waveform MCU at the positive half cycle can be read, but the waveform MCU at the negative half cycle cannot. The voltage of 1.65V output by the bias voltage circuit is overlapped with the voltage value of the resistor R4, and the waveform of the secondary side voltage is completely displayed in the positive half period of the Y axis at the moment, so that the MCU can correctly read the value of the digital-to-analog conversion module ADC. The second operational amplifier IC1B and the resistor R5/R6 form an operational amplifier inverting amplifier circuit, and the input value is amplified and then is transmitted to the microprocessor 1MCU.
The protection driving module 5 comprises a current transformer broken line locking module 501 and a protection outlet relay 502, wherein the current transformer broken line locking module 501 is connected with the microprocessor 1 module and is used for determining broken line information of a first current transformer or a second current transformer and sending corresponding protection instructions to the protection outlet relay 502 according to the broken line information, and the protection outlet relay 502 is connected with a breaker 6 of protected equipment. The disconnection information sends out corresponding protection instructions to be represented by the high and low levels of a switching value output circuit, the switching value output circuit adopts an optical coupler conversion circuit, the input end of the optical coupler conversion circuit is connected with the microprocessor 1, and the output end of the optical coupler conversion circuit is connected with the protection outlet relay 502. And the first current transformer and the second current transformer form a main and standby system, wherein after any one of the current transformers is disconnected, the disconnection analysis can be performed by taking the situation of the other current transformer as a reference.
Isolation protection of the optocoupler conversion circuit, namely, the switching value output circuit adopts the optocoupler conversion circuit to realize electrical isolation between the microprocessor 1 and the protection outlet relay 502, so that the safety of the system is enhanced.
The current transformer disconnection blocking module 501 monitors the states of the first current transformer and the second current transformer through the microprocessor 1, and immediately sends a signal to the microprocessor 1 once a disconnection condition is detected. The microprocessor 1 sends a protection instruction to the protection outlet relay 502 through the switching value output circuit according to the disconnection information and a preset protection strategy, so as to control the action of the circuit breaker 6.
The microprocessor 1 is used as the core of the whole protection device, receives the digital signals from the data acquisition module 3, and runs a differential protection algorithm for processing. The microprocessor 1 is also responsible for communicating with a power module, a protection driving module 5, a disconnection indicating module 2, an information communication module and an input and display module 401, so as to ensure the coordinated operation of the whole system.
The TA disconnection analysis method comprises the following steps:
When any one of the following conditions is met, the judgment of the instantaneous TA disconnection is skipped, namely 1, the maximum phase current of a certain side before starting is smaller than 0.15 times of rated current of a high-voltage side of the transformer, 2, the current of any side after starting is increased compared with that before starting, and 3, the maximum phase current of the certain side after the differential protection is started is smaller than 20% of the rated current of the side, and the TA disconnection of the side is not considered.
Or when the following conditions are met, the CT disconnection performs locking differential protection, wherein the specific criteria are that 1, when the differential current of any phase is larger than 0.15 times of rated current of the high-voltage side of the transformer, 2, the protection current of only one phase is zero, and the difference value between the current of other two phases and the current before the differential protection is started is smaller than 0.05 times of rated current of the high-voltage side of the transformer.
The broken line indicating module 2 comprises a broken line indicating lamp and an alarm module, and the broken line indicating lamp and the alarm module are electrically connected with the microprocessor 1. When the broken line indicator lamp and the alarm module detect broken lines or other abnormal conditions, visual and audible alarms are sent to operators so as to take corresponding measures in time, and the broken line indicator lamp and the alarm module can be controlled remotely or manually in a near place.
The information communication module 7 is electrically connected with the microprocessor 1, and the information communication module 7 is in communication connection with the wireless transmission module 8 of the upper computer 9, so that remote monitoring and control functions are realized, and the intelligent level of the power system is improved.
The input module 402 and the display module 401, the input module 402 and the display module 401 are electrically connected with the microprocessor 1. The input module 402 allows the operator to set protection parameters and view the system state, and the display module 401 visually displays system information and fault records, so that the operator can monitor and maintain conveniently.
In summary, the design of the whole differential protection device considers reliability, instantaneity and operability, can effectively prevent faults such as overcurrent and short circuit in the power system, and ensures safe and stable operation of the power system. Through these advanced designs and functions, the device can meet the increasing requirements of modern power systems on protection equipment.
Claims (7)
1. The differential protection device is characterized by comprising a data acquisition module, a microprocessor, a power supply module and a protection driving module, wherein the data acquisition module, the power supply module and the protection driving module are electrically connected with the microprocessor, the data acquisition module comprises a first current transformer, a second current transformer and a digital-to-analog conversion module, the first current transformer and the second current transformer are connected in parallel and then are electrically connected with the digital-to-analog conversion module, and the digital-to-analog conversion module is electrically connected with the microprocessor.
2. The differential protection device of claim 1, wherein the protection driving module comprises a current transformer disconnection locking module and a protection outlet relay, the current transformer disconnection locking module is connected with the microprocessor module and used for determining disconnection information of the first current transformer or the second current transformer and sending corresponding protection instructions to the protection outlet relay according to the disconnection information, and the protection outlet relay is connected with a breaker of protected equipment.
3. The differential protection device of claim 1, further comprising a disconnection indication module, wherein the disconnection indication module comprises a disconnection indicator light and an alarm module, wherein the disconnection indicator light and the alarm module are electrically connected with the microprocessor.
4. The differential protection device of claim 1, further comprising an information communication module, wherein the information communication module is electrically connected to the microprocessor, and wherein the information communication module is communicatively connected to a wireless communication module of an upper computer.
5. The differential protection device of claim 1, further comprising an input module and a display module, wherein the input module and the display module are electrically connected to the microprocessor.
6. The differential protection device according to claim 1, wherein the data acquisition module comprises the first current transformer and the secondary winding of the second current transformer both connected to two ends of a first resistor (R4), one end of the first resistor (R4) is grounded through a first capacitor (C4), the other end of the first resistor (R4) is connected to the bias voltage circuit, and simultaneously connected to one end of a second resistor (R3), the other end of the second resistor (R3) and one end of the first resistor (R4) are connected to an inverting amplifier circuit, and the output end of the inverting amplifier circuit is connected to the digital-analog conversion module.
7. The differential protection device according to claim 2, wherein the disconnection information sends out a corresponding protection command represented by a high-low level of a switching value output circuit, the switching value output circuit adopts an optocoupler conversion circuit, an input end of the optocoupler conversion circuit is connected with the microprocessor, and an output end of the optocoupler conversion circuit is connected with the protection outlet relay.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202420831151.0U CN222602040U (en) | 2024-04-22 | 2024-04-22 | A differential protection device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202420831151.0U CN222602040U (en) | 2024-04-22 | 2024-04-22 | A differential protection device |
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| Publication Number | Publication Date |
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| CN222602040U true CN222602040U (en) | 2025-03-11 |
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| CN202420831151.0U Active CN222602040U (en) | 2024-04-22 | 2024-04-22 | A differential protection device |
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| CN (1) | CN222602040U (en) |
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