CN216526239U - Current conduction detection circuit of magnetic field jumper of synchronous generator - Google Patents
Current conduction detection circuit of magnetic field jumper of synchronous generator Download PDFInfo
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- CN216526239U CN216526239U CN202123004842.9U CN202123004842U CN216526239U CN 216526239 U CN216526239 U CN 216526239U CN 202123004842 U CN202123004842 U CN 202123004842U CN 216526239 U CN216526239 U CN 216526239U
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Abstract
The utility model discloses a current conduction detection circuit of a magnetic field jumper of a synchronous generator, which comprises a Hall current converter, a differential measurement amplifier, a zero drift compensation circuit and a current judgment unit, wherein the Hall current converter is respectively connected with a magnetic field jumper loop and the differential measurement amplifier, and the zero drift compensation circuit is connected with the differential measurement amplifier; the current judging unit comprises a reference voltage regulating circuit, a positive current judging branch and a negative current judging branch consisting of a reverser and the positive current judging branch, the positive current judging branch comprises a hysteresis comparison circuit, a delay circuit and an alarm circuit which are sequentially connected, the reverser in the negative current judging branch is connected with the hysteresis comparison circuit, and the differential measuring amplifier is respectively connected with the hysteresis comparison circuit in the positive current judging branch and the reverser in the negative current judging branch. The utility model overcomes the factors of easy zero drift and interference, and ensures the timeliness and the correctness of the output of the detection signal.
Description
Technical Field
The utility model belongs to the technical field of field suppression and overvoltage protection of large synchronous generators, and particularly relates to a current conduction detection circuit of a magnetic field jumper of a synchronous generator, which is used for detecting the current conduction condition in a loop of the magnetic field jumper of the generator.
Background
The field jumper of the generator is connected across the field winding of the synchronous generator. When a large synchronous generator operates, if the generator is shut down due to an accident, a magnetic field breaker in an excitation device of the generator is started to trip. Because the magnetic field energy storage of the large generator is huge, the magnetic field breaker can not safely extinguish the magnetic field only, and the current in the magnetic field winding must be transferred to the demagnetization resistor loop for follow current while the magnetic field breaker trips, so that the magnetic field energy is consumed on the demagnetization resistor. The field suppression resistor and the electronic switch thereof form a magnetic field jumper of the generator. The magnetic field jumper also has the function of magnetic field overvoltage protection, and once abnormal high voltage appears at two ends of the magnetic field winding due to some reason, the magnetic field jumper is immediately conducted to discharge the energy of the high voltage to the resistor, so that the insulation of the magnetic field winding is protected from being damaged.
Therefore, the current on the loop of the magnetic field jumper needs to be detected to judge whether the magnetic field jumper works normally. Generally speaking, no current should flow through the magnetic field jumper when the generator is in normal operation, but in this case, two conditions may cause current to flow through the magnetic field jumper, and a timely alarm needs to be given to start the generator to stop. One is the electronic switching of the magnetic field jumper which should be blocked, which is misconducted due to degradation of blocking capability or interference. And secondly, protecting the error action of the magnetic field overvoltage in normal operation, and turning on the electronic switch.
When the generator is set to be de-energized by starting the magnetic field breaker to trip due to an accident or a shutdown process, current should flow through the magnetic field jumper. If the electronic switch of the magnetic field jumper is not turned on in time and no current flows, an alarm signal is sent out to inform operators to check the equipment in time. Therefore, when the current value is small at the initial stage of the current generation of the magnetic field jumper, the current conduction detection signal is issued as soon as possible to determine whether the magnetic field jumper is operating normally.
At present, the single-machine capacity of a generator is developed to more than one thousand megawatts, the rated current of a magnetic field of a giant unit is close to ten thousand amperes, the theoretically calculated limit accident field suppression current is as high as more than twenty thousand amperes, and in most cases, the current flowing through a magnetic field jumper is field suppression current in a single direction and is different from the alternating short-circuit current waveform on a public power grid. The property of huge one-way impact current and the requirement of sending out detection signals under small current bring difficulty to the current conduction detection of the magnetic field jumper.
The existing current detection means of the magnetic field jumper at the present stage have limitations. One is to detect the rising edge of a signal by using an electromagnetic current transformer; however, the alarm action value of the rising edge detection method is not easy to adjust and is easy to be interfered and falsely alarmed. In addition, the current transformer is easy to be subjected to magnetic hysteresis saturation and lose the alarm function under the impact action of multiple unidirectional de-excitation currents. The other type adopts a general electromagnetic type overcurrent relay; however, since the current capacity of the electromagnetic overcurrent relay is limited, a shunt measure must be taken, which results in a reduction in alarm sensitivity. The other type of relay is formed by adopting a magnetic gathering iron core and a magnetic reed tube, but due to the magnetic sensitivity characteristic of the magnetic reed tube, contact adhesion can occur after the high-current impact of generator accident de-excitation, and meanwhile, the method is not easy to adjust the alarm action value.
Therefore, it is necessary to develop new technologies to improve them.
SUMMERY OF THE UTILITY MODEL
The utility model aims to solve the problems in the prior art and provides a current conduction detection circuit for a magnetic field jumper of a synchronous generator.
In order to achieve the purpose, the technical scheme adopted by the utility model is as follows:
a synchronous generator magnetic field jumper current conduction detection circuit, characterized by: comprises a Hall current converter, a differential measurement amplifier, a zero drift compensation circuit and a current judgment unit, wherein,
the input end of the Hall current converter is connected with a magnetic field jumper loop, the output end of the Hall current converter is connected with the input end of the differential measurement amplifier, and the null shift compensation circuit is connected with the output reference adjusting end of the differential measurement amplifier;
the current judging unit comprises a reference voltage regulating circuit, a positive current judging branch and a negative current judging branch consisting of a reverser and the positive current judging branch, the positive current judging branch comprises a hysteresis comparison circuit, a delay circuit and an alarm circuit which are sequentially connected, the reverser in the negative current judging branch is connected with the hysteresis comparison circuit, and the reference voltage regulating circuit is respectively connected with the reference end of the hysteresis comparison circuit;
the output end of the differential measurement amplifier is respectively connected with a hysteresis comparison circuit in the positive current judgment branch circuit and an inverter in the negative current judgment branch circuit.
The Hall current converter is used for detecting the current in the loop of the magnetic field jumper of the generator and converting a large-current signal on the loop into a small-voltage signal; the differential measurement amplifier is used for amplifying a large voltage signal and a small voltage signal, and the zero drift compensation circuit is used for inputting a voltage-stabilizing signal to the differential measurement amplifier so as to eliminate the zero drift influence of the Hall current converter; the reference voltage adjusting circuit is used for adjusting reference voltage of the hysteresis comparison circuit, the hysteresis comparison circuit is used for comparing an amplified voltage signal with the reference voltage, the delay circuit is used for delaying to output a comparison result, the alarm circuit is used for determining whether to give an alarm or not according to the comparison result, and the inverter is used for converting negative voltage into positive voltage.
The alarm circuit comprises an action alarm circuit and a locking alarm circuit, and the action alarm circuit and the locking alarm circuit are both connected to the output end of the delay circuit.
The alarm circuit comprises a triode and a miniature relay, and the triode is connected with the output end of the delay circuit and the miniature relay respectively.
The locking alarm circuit comprises a thyristor, a miniature relay and a reset operation loop, the thyristor is respectively connected with the output end of the delay circuit and the miniature relay, and the reset operation loop is connected with the miniature relay and used for resetting the alarm signal.
By adopting the technical scheme, the utility model has the beneficial technical effects that:
the utility model designs a signal detection and processing loop, and realizes the detection of the current conduction condition on the magnetic field jumper loop of the large synchronous generator and timely and accurately sends out signals by combining the carefully selected Hall current converter. The main characteristics are as follows:
1. when the current rises to be more than dozens of amperes, the alarm device acts.
2. When the current drops to be less than dozens of amperes of action value, the alarm signal resets.
3. A special zero drift compensation circuit is designed. When the unit has no-load fault forced excitation and demagnetization and other rare limit working conditions, after ten thousand amperes of accident demagnetization current impacts, the Hall current converter may drift due to hysteresis, and then the bias voltage can be simply adjusted by the zero drift compensation circuit to correct, so that the normal working point of the current detector can be quickly recovered.
4. A special delay circuit is designed. Aiming at the characteristics of uncertain amplitude and obvious time characteristic of an interference signal suffered by a Hall current converter matched with the circuit, the designed delay circuit can avoid the interference of an impact event and can ensure the timeliness of the output of a detection signal.
The utility model simply adopts the current conduction detection of the Hall current converter matched with the hysteresis comparison circuit. The magnetic core of the Hall current converter is made of soft magnetic materials, can bear large overload current and is not easy to generate particularly large hysteresis. However, after the large current impacts, the hall current converter still generates small magnetic hysteresis, so that zero drift of an output signal is caused, and obvious errors are brought to small current measurement. In addition, the hall current transducer is based on the principle of magnetoelectric conversion, and is easy to be interfered by the surrounding environment when being positioned in the de-excitation device of the generator. The null shift and immunity of hall current transducers have made this approach to detecting magnetic field jumper current conduction less widely used in the past. The utility model overcomes the influence of two adverse factors of the Hall current converter, and can send out signals when tens of amperes of current flows in the circuit; when thousands or even tens of thousands of impact currents flow through the circuit, the current detector can still ensure the action accuracy and continue to be used through simple inspection and adjustment.
Drawings
FIG. 1 is a schematic circuit diagram of the present invention;
labeled as: 1. the device comprises a Hall current converter, 2, a differential measurement amplifier, 3, a zero drift compensation circuit, 4, a hysteresis comparison circuit, 5, a delay circuit, 6, an action alarm circuit, 7, a locking alarm circuit, 8 and a reference voltage regulating circuit.
Detailed Description
Example 1
The embodiment discloses a synchronous generator magnetic field jumper current conduction detection circuit, which mainly adopts a Hall current converter matched with a hysteresis comparison circuit to detect the current conduction of the magnetic field jumper, and can overcome factors which are easy to generate null shift and interference in the detection process, thereby effectively ensuring the timeliness and correctness of detecting signal output. Specifically, as shown in fig. 1, the detection circuit includes a hall current converter, a differential measurement amplifier, a null shift compensation circuit, and a current determination unit, and the structure, connection relationship, position relationship, and functional functions of each component are as follows:
the input end of the Hall current converter is connected with the magnetic field jumper loop, the output end of the Hall current converter is connected with the input end of the differential measurement amplifier, and the null shift compensation circuit is connected with the output reference adjusting end of the differential measurement amplifier.
The current judging unit comprises a reference voltage regulating circuit, a positive current judging branch and a negative current judging branch consisting of a reverser and the positive current judging branch, the positive current judging branch comprises a hysteresis comparison circuit, a delay circuit and an alarm circuit which are sequentially connected, the reverser in the negative current judging branch is connected with the hysteresis comparison circuit, and the reference voltage regulating circuit is respectively connected with a reference end of the hysteresis comparison circuit.
The output end of the differential measurement amplifier is respectively connected with a hysteresis comparison circuit in the positive current judgment branch circuit and an inverter in the negative current judgment branch circuit.
The Hall current converter is used for detecting the current in a loop of the magnetic field jumper of the generator and converting a large-current signal on the loop into a small-voltage signal; the differential measurement amplifier is used for amplifying a large voltage signal and a small voltage signal, and the zero drift compensation circuit is used for inputting a voltage-stabilizing signal to the differential measurement amplifier so as to eliminate the zero drift influence of the Hall current converter; the reference voltage adjusting circuit is used for adjusting reference voltage of the hysteresis comparison circuit, the hysteresis comparison circuit is used for comparing an amplified voltage signal with the reference voltage, the delay circuit is used for delaying to output a comparison result, the alarm circuit is used for determining whether to give an alarm or not according to the comparison result, and the inverter is used for converting negative voltage into positive voltage.
The hall current converter, the differential measurement amplifier, the null shift compensation circuit, the hysteresis comparison circuit, the delay circuit and the alarm circuit in the embodiment are all conventional commercially available components, and in order to ensure the correctness and timeliness of current detection, the embodiment further sets the components as follows:
1. the Hall current converter is a commercially available device and is used for detecting the current in the magnetic field jumper loop of the generator and converting the large current on the magnetic field jumper loop into a small voltage signal which can be processed by a weak current loop. When the magnetic field jumper is conducted, the current on the loop is large, the magnitude of the current on the magnetic field jumper changes with the type of the generator and the working condition of the generator, and the maximum possible range of the current is hundreds to nearly twenty-thousand amperes. Whereas a large current signal can be converted into a voltage of a few volts as an initial measuring voltage signal by means of a hall current converter. Aiming at the purpose of current conduction detection, a Hall current converter does not need to be selected according to the full range, and the rated range of the Hall current converter is preferably 2000A/4V.
2. The differential measurement amplifier employs a differential measurement amplification chip for amplifying the signal from the hall current transducer to a millivolt level voltage signal to a few volts level for subsequent processing. This embodiment preferably sets the measurement amplification factor to 100 times, and can amplify the 60mV input (corresponding to a current of about 30A on the primary side of the hall current transducer) to 6V.
3. Because the output of the Hall current converter has zero drift, if the generator is demagnetized due to an accident, thousands of amperes or even tens of thousands of amperes can flow through the magnetic field jumper, and the zero drift of the Hall current converter is aggravated after the accident. The null shift of the hall current converter can affect the correct alarm judgment after amplification. Therefore, the zero drift compensation circuit is an adjustable high-precision voltage stabilizing signal, the voltage stabilizing signal is sent to a reference adjusting end of the differential amplifying chip, and a zero drift part is subtracted from the output of the amplifying circuit, so that the zero drift influence of the Hall current converter is eliminated. The zero drift compensation circuit mainly comprises a voltage stabilizing diode, a potentiometer and a voltage follower.
4. The hysteresis comparison circuit is used for comparing the amplified voltage signal with a reference voltage, and when the amplified voltage signal is greater than a high threshold voltage, the hysteresis comparison circuit outputs a high level to drive a subsequent alarm circuit to alarm. The hysteresis comparison circuit can prevent the pumping phenomenon that the alarm output is frequently and repeatedly operated and reset. In this embodiment, the reference voltage setting is preferably 5V, and the hysteretic comparison circuit is preferably designed to go high, 20A current reset, at approximately field jumper current 35A. The hysteresis comparison circuit is mainly composed of an operational amplifier.
5. The hall current converter is interfered by the space magnetic field brought by the operation of surrounding switches, relays and the like, and is characterized in that the interference amplitude is indefinite, and the method of filtering in the measuring link is not suitable. Therefore, the delay circuit can delay the result of the hysteresis comparison circuit for a period of time to be output, and the false alarm caused by the spatial magnetic field interference can be avoided. In this embodiment, the delay circuit is formed by a 555 timing chip, and the delay time of the delay circuit is preferably designed to be 100 ms-200 ms. Through tests and demonstration, the delay circuit adopts the specific design, so that the interference of surrounding impact events can be avoided, and the timeliness of the output of detection signals can be ensured.
Example 2
On the basis of embodiment 1, this embodiment further defines the alarm circuit, as shown in fig. 1, the alarm circuit includes an action alarm circuit and a lock alarm circuit, and both the action alarm circuit and the lock alarm circuit are connected to the output end of the delay circuit. Wherein the content of the first and second substances,
the action alarm circuit comprises a triode and a miniature relay, and the triode is respectively connected with the output end of the delay circuit and the miniature relay. The action alarm circuit converts the output of the delay circuit into a relay signal to be output, and the output relay is also reset after the output of the delay circuit is reset. The alarm signal indicates that current is currently flowing through the magnetic field jumper and that the current has not dropped below the reset level.
The locking alarm circuit comprises a thyristor, a miniature relay and a reset operation loop, the thyristor is respectively connected with the output end of the delay circuit and the miniature relay, and the reset operation loop is connected with the miniature relay and used for resetting the alarm signal. The locking alarm circuit converts the output of the delay circuit into a relay signal output and locks the relay in an action position. The alarm signal indicates that current is or was flowing through the magnetic field jumper, and is manually reset after the delay circuit output is reset.
The implementation principle of the utility model is as follows:
as shown in fig. 1, a magnetic field jumper loop including a field suppression resistor and an electronic switch in the generator is connected to both ends of the magnetic field winding, and an input end of the hall current converter is connected to the magnetic field jumper loop. When the electronic switch T1 is switched on, the forward current passes through the magnetic field jumper loop, at the moment, the Hall current converter converts a forward large current signal on the loop into a forward small voltage signal and inputs the forward small voltage signal to the differential measurement amplifier, the small voltage signal is compensated by the zero drift compensation circuit in the differential measurement amplifier, the forward large current signal is input to the forward current judgment branch circuit for comparison and judgment after the zero drift influence of the Hall converter is eliminated, if the comparison result is larger than a high threshold voltage, the hysteresis comparison circuit sends out a high level signal, the high level signal inputs an action signal to the alarm circuit after being delayed by the delay circuit, and the alarm circuit sends out an alarm after receiving the action signal. If the comparison result is lower than the low threshold voltage, the hysteresis comparison circuit resets to send out a low level signal, the low level signal is input into the alarm circuit after being delayed by the delay circuit, and the alarm circuit does not send out an alarm after receiving the low level signal.
When the electronic switch T2 is turned on, a negative current passes through the magnetic field jumper loop, at this time, the hall current converter converts a negative large-current signal on the loop into a negative small-voltage signal and inputs the negative small-voltage signal to the differential measurement amplifier, the small-voltage signal is compensated by the null shift compensation circuit in the differential measurement amplifier, the small-voltage signal is input to the inverter for inversion after the null shift influence of the hall converter is eliminated, and then the small-voltage signal is input to the positive current judgment branch for comparison and judgment.
In summary, the utility model adopts the Hall current converter to cooperate with the hysteresis comparison circuit to detect the current conduction of the magnetic field jumper, overcomes the factors of easy zero drift and interference in the detection process, and effectively ensures the timeliness and correctness of the output of the detection signal.
While the utility model has been described with reference to specific embodiments, any feature disclosed in this specification may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise; all of the disclosed features, or all of the method or process steps, may be combined in any combination, except mutually exclusive features and/or steps.
Claims (5)
1. A synchronous generator magnetic field jumper current conduction detection circuit, characterized by: comprises a Hall current converter, a differential measurement amplifier, a zero drift compensation circuit and a current judgment unit, wherein,
the input end of the Hall current converter is connected with a magnetic field jumper loop, the output end of the Hall current converter is connected with the input end of the differential measurement amplifier, and the null shift compensation circuit is connected with the output reference adjusting end of the differential measurement amplifier;
the current judging unit comprises a reference voltage regulating circuit, a positive current judging branch and a negative current judging branch consisting of a reverser and the positive current judging branch, the positive current judging branch comprises a hysteresis comparison circuit, a delay circuit and an alarm circuit which are sequentially connected, the reverser in the negative current judging branch is connected with the hysteresis comparison circuit, and the reference voltage regulating circuit is respectively connected with the reference end of the hysteresis comparison circuit;
the output end of the differential measurement amplifier is respectively connected with a hysteresis comparison circuit in the positive current judgment branch circuit and an inverter in the negative current judgment branch circuit.
2. The synchronous generator field jumper current conduction detection circuit of claim 1, wherein: the Hall current converter is used for detecting the current in the loop of the magnetic field jumper of the generator and converting a large-current signal on the loop into a small-voltage signal; the differential measurement amplifier is used for amplifying a large voltage signal and a small voltage signal, and the zero drift compensation circuit is used for inputting a voltage-stabilizing signal to the differential measurement amplifier so as to eliminate the zero drift influence of the Hall current converter; the reference voltage adjusting circuit is used for adjusting reference voltage of the hysteresis comparison circuit, the hysteresis comparison circuit is used for comparing an amplified voltage signal with the reference voltage, the delay circuit is used for delaying to output a comparison result, the alarm circuit is used for determining whether to give an alarm or not according to the comparison result, and the inverter is used for converting negative voltage into positive voltage.
3. A synchronous generator field jumper current conduction detection circuit as claimed in claim 1 or 2, wherein: the alarm circuit comprises an action alarm circuit and a locking alarm circuit, and the action alarm circuit and the locking alarm circuit are both connected to the output end of the delay circuit.
4. A synchronous generator field jumper current conduction detection circuit as claimed in claim 3, wherein: the alarm circuit comprises a triode and a miniature relay, and the triode is connected with the output end of the delay circuit and the miniature relay respectively.
5. A synchronous generator field jumper current conduction detection circuit as claimed in claim 3, wherein: the locking alarm circuit comprises a thyristor, a miniature relay and a reset operation loop, the thyristor is respectively connected with the output end of the delay circuit and the miniature relay, and the reset operation loop is connected with the miniature relay and used for resetting the alarm signal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202123004842.9U CN216526239U (en) | 2021-12-02 | 2021-12-02 | Current conduction detection circuit of magnetic field jumper of synchronous generator |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202123004842.9U CN216526239U (en) | 2021-12-02 | 2021-12-02 | Current conduction detection circuit of magnetic field jumper of synchronous generator |
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| Publication Number | Publication Date |
|---|---|
| CN216526239U true CN216526239U (en) | 2022-05-13 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202123004842.9U Active CN216526239U (en) | 2021-12-02 | 2021-12-02 | Current conduction detection circuit of magnetic field jumper of synchronous generator |
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| CN (1) | CN216526239U (en) |
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2021
- 2021-12-02 CN CN202123004842.9U patent/CN216526239U/en active Active
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