CN111650546A - Online monitoring system and method for effectively preventing explosion of voltage transformer - Google Patents
Online monitoring system and method for effectively preventing explosion of voltage transformer Download PDFInfo
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- CN111650546A CN111650546A CN202010449876.XA CN202010449876A CN111650546A CN 111650546 A CN111650546 A CN 111650546A CN 202010449876 A CN202010449876 A CN 202010449876A CN 111650546 A CN111650546 A CN 111650546A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R35/00—Testing or calibrating of apparatus covered by the other groups of this subclass
- G01R35/02—Testing or calibrating of apparatus covered by the other groups of this subclass of auxiliary devices, e.g. of instrument transformers according to prescribed transformation ratio, phase angle, or wattage rating
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B19/00—Programme-control systems
- G05B19/02—Programme-control systems electric
- G05B19/04—Programme control other than numerical control, i.e. in sequence controllers or logic controllers
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Abstract
The invention provides an online monitoring system and method for effectively preventing explosion of a voltage transformer, wherein a voltage sensor acquires secondary output voltage of the voltage transformer; the weak current sensor collects leakage current of the voltage transformer; the analysis and calculation unit analyzes and processes the secondary output voltage and the leakage current at the same time, analyzes the correlation between the secondary output voltage and the leakage current, judges whether harmonic waves and direct current components exist or not, and judges that an electromagnetic resonance phenomenon occurs when the direct current components just fall on the resonance point of the monitored voltage transformer; when the analysis and calculation unit judges that the electromagnetic resonance phenomenon occurs, the control unit controls and changes the operation mode of the voltage transformer at the moment, eliminates the environment of the voltage transformer in which the electromagnetic resonance occurs, avoids the ferromagnetic resonance of the voltage transformer, and achieves the purpose of preventing the voltage transformer from exploding.
Description
Technical Field
The invention belongs to the technical field of power grid operation and maintenance, and particularly relates to an online monitoring system and method for effectively preventing explosion of a voltage transformer.
Background
Today, with the rapid development of science and technology, the social production and life have been unable to leave electric energy, and the electric energy is also one of the largest proportion of consumable energy. Along with the rapid development of the modern society, the requirement on electric energy is inevitably increased, and the voltage level of a power grid is higher and higher. The huge power transmission network constructed by a large number of distributed capacitive electrical devices greatly increases factors influencing the safe operation of the power system, and if one device fails or has a problem, a series of adverse reactions can be caused, and the power grid system can be disconnected or even crashed seriously.
In the display production process, accidents such as switch cabinet short circuit, overvoltage protector damage, voltage transformer burnout and fuse fusing of a transformer are often caused by ferromagnetic resonance phenomenon in a power transformation and distribution station. Once the accidents happen, irreparable loss is brought to enterprises. For an electric power system, a voltage transformer is an important element, and due to the inductive property of the voltage transformer, the voltage transformer is extremely easy to generate ferromagnetic resonance with a capacitive load element under the working condition, so that the personal safety is caused, or the system operation is seriously damaged. According to analysis reports after explosion of a large number of voltage transformers, ferromagnetic resonance is caused in 90% of explosion accidents of the voltage transformers, and the ferromagnetic resonance of the voltage transformers is caused by high-order harmonics and direct-current components in a power grid.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: the on-line monitoring system and the method for effectively preventing the explosion of the voltage transformer are provided.
The technical scheme adopted by the invention for solving the technical problems is as follows: the utility model provides an effective online monitoring system who prevents voltage transformer explosion which characterized in that: the system comprises:
the voltage sensor is used for collecting secondary output voltage of the voltage transformer;
the weak current sensor is used for collecting leakage current of the voltage transformer;
the acquisition unit is used for sampling and controlling the voltage sensor and the weak current sensor and receiving secondary output voltage and leakage current;
the analysis and calculation unit is used for sequencing the secondary output voltage and the leakage current according to time respectively, analyzing and processing the secondary output voltage and the leakage current at the same time, analyzing the correlation between the secondary output voltage and the leakage current, finding out a direct current component in the leakage current, bringing the direct current component in the leakage current into the design parameters of the monitored voltage transformer, calculating whether the direct current component can cause the voltage transformer to generate resonance or not, and judging that an electromagnetic resonance phenomenon occurs when the direct current component just falls on the resonance point of the monitored voltage transformer;
and the control unit is used for changing the operation mode of the voltage transformer at the moment and eliminating the environment of electromagnetic resonance of the voltage transformer when the analysis and calculation unit judges that the electromagnetic resonance phenomenon occurs.
According to the system, the control unit controls the breaker to carry out reclosing operation so as to change the operation mode of the voltage transformer at the moment.
According to the system, the analysis and calculation unit is arranged in a transformer substation where the voltage transformer is located; the system also comprises a communication unit which is used for uploading the secondary output voltage and the leakage current collected by the collection unit, and the calculation results and the control results of the analysis calculation unit and the control unit to the background system.
According to the system, the accuracy grade of the voltage sensor is 0.02 grade, and the input voltage is the alternating voltage within the range of 57.7-100V.
According to the system, the weak current sensor is of a through type or open type structure, the accuracy level is 0.05 level, and the input alternating current weak current range is 0.1 uA-10 mA.
According to the system, the number of the voltage transformers is at least one, and each voltage transformer corresponds to one voltage sensor and one weak current sensor; the sampling, analysis, calculation and control of each voltage transformer are independent.
An on-line monitoring method implemented by the system is characterized in that: the method comprises the following steps:
s1, initialization:
initializing a system and setting parameters;
s2, signal acquisition:
the acquisition unit is used for sampling and controlling the voltage sensor and the weak current sensor and acquiring secondary output voltage and leakage current of the voltage transformer;
s3, analyzing and calculating:
respectively sequencing the secondary output voltage and the leakage current according to time, analyzing and processing the secondary output voltage and the leakage current at the same time, analyzing the correlation between the secondary output voltage and the leakage current, finding out a direct current component in the leakage current, bringing the direct current component in the leakage current into the design parameters of the monitored voltage transformer, calculating whether the direct current component can cause the voltage transformer to generate resonance or not, and judging that an electromagnetic resonance phenomenon occurs when the direct current component just falls on the resonance point of the monitored voltage transformer;
s4, relay protection equipment control:
when the electromagnetic resonance phenomenon appears in the judgment, the operation mode of the voltage transformer is changed, and the environment of the voltage transformer with the electromagnetic resonance is eliminated.
According to the method, the method adopts an edge calculation mode, and S1-S4 are all completed locally; meanwhile, the method also comprises S5, data communication: and uploading the secondary output voltage and the leakage current acquired by the acquisition unit, and the calculation results and the control results of the analysis calculation unit and the control unit to a background system.
According to the above method, in S4, the operation mode of the voltage transformer is changed by controlling the circuit breaker to perform a reclosing operation.
The invention has the beneficial effects that: the relation between the leakage current and the secondary output voltage of the voltage transformer is monitored in real time, the change of the inductance of the voltage transformer is analyzed, the insulation performance is predicted, ferromagnetic resonance is prevented from being generated inside the voltage transformer by changing the operation mode of the voltage transformer at the initial stage of the abnormal insulation of the voltage transformer, and the explosion accident of the voltage transformer is prevented fundamentally. In addition, the preventive accident can be uploaded to a background monitoring system through communication, management personnel can conveniently monitor running equipment, and the method has a wide popularization and application prospect.
Drawings
Fig. 1 is a block diagram of a system configuration according to an embodiment of the present invention.
FIG. 2 is a flowchart of a method according to an embodiment of the present invention.
Detailed Description
The invention is further illustrated by the following specific examples and figures.
The invention provides an online monitoring system for effectively preventing explosion of a voltage transformer, which comprises a voltage sensor and a voltage transformer, wherein the voltage sensor is used for collecting secondary output voltage of the voltage transformer, as shown in figure 1; the weak current sensor is used for collecting leakage current of the voltage transformer; the acquisition unit is used for sampling and controlling the voltage sensor and the weak current sensor and receiving secondary output voltage and leakage current; the analysis and calculation unit is used for sequencing the secondary output voltage and the leakage current according to time respectively, analyzing and processing the secondary output voltage and the leakage current at the same time, analyzing the correlation between the secondary output voltage and the leakage current, judging whether a direct current component and a harmonic signal exist or not, finding out the direct current component in the leakage current, bringing the direct current component in the leakage current into the design parameters of the monitored voltage transformer, calculating whether the direct current component can cause the voltage transformer to generate resonance or not, and judging that an electromagnetic resonance phenomenon occurs when the direct current component just falls on the resonance point of the monitored voltage transformer; and the control unit is used for changing the operation mode of the voltage transformer at the moment when the analysis and calculation unit judges that the electromagnetic resonance phenomenon occurs, eliminating the environment of the voltage transformer in which the electromagnetic resonance occurs, avoiding the ferromagnetic resonance of the voltage transformer from occurring and realizing the purpose of preventing the voltage transformer from exploding.
In this embodiment, the control unit changes the operation mode of the voltage transformer by controlling the circuit breaker to perform a reclosing operation. The resonance points of each voltage transformer are not identical, and the search of the resonance points can be calculated according to the design parameters of the voltage transformers. Once the direct current signal which can cause the resonance point is monitored, the analysis and calculation unit rapidly submits the situation of the point to a background, and simultaneously the analysis and calculation unit sends reclosing formulation to the breaker, so that the breaker is immediately reclosed. The direct current component is a weak transient signal in an alternating current system, but when a one-time operation mode is suddenly changed, the transient direct current is changed, the reclosing of the circuit breaker is very short and can be completed within 20ms, and for a voltage transformer which is a steady-state device, the rapid reclosing cannot cause the voltage transformer to stop working.
In this embodiment, the dc component in the leakage current is determined and found out by the windowed FFT variation. Specifically, a windowed FFT calculation mode is adopted to extract a direct current signal, a fundamental wave signal and a harmonic signal in the leakage current respectively. In the embodiment, the FPGA is adopted to read the sensor data, so that the triggering of FFT analysis and communication instructions is realized, including the designated triggering of the circuit breaker and the background system.
Furthermore, the analysis and calculation unit is arranged in a transformer substation where the voltage transformer is located, so that an edge calculation mode is adopted, all sampling and analysis and calculation are completed on site, operation control is performed, the real-time performance of data processing and control can be improved, and the safety is guaranteed. The system also comprises a communication unit which is used for uploading the secondary output voltage and leakage current collected by the collecting unit, and the calculation results and control results of the analysis calculating unit and the control unit to a background system, so that related operation and maintenance personnel can conveniently monitor the state of the voltage transformer.
The main technical parameters of the invention comprise:
(1) the voltage sensor accuracy grade is 0.02 grade, and the input is an alternating voltage range: (57.7-100) 80% -120% of V;
(2) the weak current sensor is of a through structure or an open structure, the accuracy grade is 0.05 grade, the input is an alternating current weak current signal, and the current range is 0.1 uA-10 mA;
(3) more than 256 points/cycle of collection frequency, calculate voltage transformer secondary voltage output signal and leakage current, whole analog electric quantity measurement accuracy: 0.1%, resolution: 0.01 percent;
(4) storing instantaneous values of continuous cycles when field data are abnormal, recording 100 cycles for the longest time, and recording the precision of an event recorder for 1 mu s;
(5) all the collected data are provided with time scales, and the time keeping error of the monitoring device is less than 4 mu s/10 min;
(6) the communication protocol meets the requirements of DL/645-;
(7) monitoring device data output
The device is provided with an RS485 interface;
the optical fiber is used for directly penetrating data to a cloud end and communicating with a remote data center;
(8) the electrical safety and electromagnetic compatibility of the device meet the requirements of relevant standards;
(9) the system software safety is in accordance with the relevant standard requirements, and the remote software upgrading can be realized;
(10) the device has the functions of self-checking, event recording and fault indication.
An on-line monitoring method implemented by the system, as shown in fig. 2, includes the following steps:
s1, initialization: initializing the system and setting parameters.
After the system is powered on, initialization is firstly needed, and related parameters are set.
S2, signal acquisition:
the acquisition unit is used for sampling and controlling the voltage sensor and the weak current sensor and acquiring secondary output voltage and leakage current of the voltage transformer.
S3, analyzing and calculating:
respectively sequencing the secondary output voltage and the leakage current according to time, analyzing and processing the secondary output voltage and the leakage current at the same time, analyzing the correlation between the secondary output voltage and the leakage current, finding out the direct current component in the leakage current, bringing the direct current component in the leakage current into the design parameters of the monitored voltage transformer, calculating whether the direct current component can cause the voltage transformer to generate resonance or not, and judging that the electromagnetic resonance phenomenon occurs when the direct current component just falls on the resonance point of the monitored voltage transformer.
S4, relay protection equipment control:
when the electromagnetic resonance phenomenon appears in the judgment, the operation mode of the voltage transformer is changed, and the environment of the voltage transformer with the electromagnetic resonance is eliminated.
The method adopts an edge calculation mode, and S1-S4 are all completed locally.
Preferably, the method further comprises S5, data communication: and uploading the secondary output voltage and the leakage current acquired by the acquisition unit, and the calculation results and the control results of the analysis calculation unit and the control unit to a background system.
Further preferably, in S4, the operation mode of the voltage transformer is changed by controlling the circuit breaker to perform a reclosing operation.
The invention can monitor a single voltage transformer, can also monitor a plurality of voltage transformers simultaneously, and can sample, analyze, calculate and control the plurality of voltage transformers independently. The voltage sensor realizes the acquisition of secondary output voltage of the voltage transformer and reasonable voltage signal conversion, the converted signal is pushed to the acquisition unit, the weak current sensor realizes the acquisition of leakage current of the voltage transformer and converts the leakage current into reasonable voltage signal, the signal is pushed to the acquisition unit, the acquisition unit realizes the sampling control of the voltage sensor and the weak current sensor through a control line and receives the signals transmitted by the voltage sensor and the weak current sensor, the analysis and calculation unit realizes the analysis and processing of the secondary voltage signal and the leakage current signal of the voltage transformer, draws a relevant curve, evaluates the insulation performance of the operating voltage transformer, monitors whether a direct current component or harmonic enough for the voltage transformer to generate ferromagnetic resonance exists in the power grid at the moment, and immediately sends an instruction to the control unit if the voltage transformer is judged to be dangerous during the operation, after the control unit receives the action instruction of the analysis and calculation unit, the circuit breaker is controlled to carry out reclosing operation, the operation mode of the voltage transformer is changed, the environment of electromagnetic resonance of the voltage transformer is eliminated, the key parameters and the operation conditions of the analysis and calculation unit and the control unit are uploaded to a background system by the communication part, and related operation and maintenance personnel can conveniently carry out equipment safety maintenance.
According to the invention, the secondary output voltage and the leakage current of the voltage transformer are simultaneously acquired, the correlation of the secondary output voltage and the leakage current is analyzed, the direct current component and the harmonic component existing in the power supply are evaluated, and the ferromagnetic resonance probability in the voltage transformer is calculated; when the monitoring quantity shows that the phenomenon of ferromagnetic resonance probably appears in the voltage transformer, the circuit breaker is controlled immediately to carry out reclosing operation, the operation mode of the voltage transformer is changed, ferromagnetic resonance of the voltage transformer is avoided, and the purpose of preventing explosion of the voltage transformer is achieved. According to the invention, an edge calculation mode is adopted, all sampling, analysis and calculation are completed on site, operation control is carried out, key output and operation conditions, and the running state of the voltage transformer can be uploaded to a background system, and related operation and maintenance personnel can conveniently monitor the state of the voltage transformer.
The above embodiments are only used for illustrating the design idea and features of the present invention, and the purpose of the present invention is to enable those skilled in the art to understand the content of the present invention and implement the present invention accordingly, and the protection scope of the present invention is not limited to the above embodiments. Therefore, all equivalent changes and modifications made in accordance with the principles and concepts disclosed herein are intended to be included within the scope of the present invention.
Claims (9)
1. The utility model provides an effective online monitoring system who prevents voltage transformer explosion which characterized in that: the system comprises:
the voltage sensor is used for collecting secondary output voltage of the voltage transformer;
the weak current sensor is used for collecting leakage current of the voltage transformer;
the acquisition unit is used for sampling and controlling the voltage sensor and the weak current sensor and receiving secondary output voltage and leakage current;
the analysis and calculation unit is used for sequencing the secondary output voltage and the leakage current according to time respectively, analyzing and processing the secondary output voltage and the leakage current at the same time, analyzing the correlation between the secondary output voltage and the leakage current, finding out a direct current component in the leakage current, bringing the direct current component in the leakage current into the design parameters of the monitored voltage transformer, calculating whether the direct current component can cause the voltage transformer to generate resonance or not, and judging that an electromagnetic resonance phenomenon occurs when the direct current component just falls on the resonance point of the monitored voltage transformer;
and the control unit is used for changing the operation mode of the voltage transformer at the moment and eliminating the environment of electromagnetic resonance of the voltage transformer when the analysis and calculation unit judges that the electromagnetic resonance phenomenon occurs.
2. The system of claim 1, wherein: the control unit controls the breaker to carry out reclosing operation so as to change the operation mode of the voltage transformer at the moment.
3. The system of claim 1, wherein: the analysis and calculation unit is arranged in a transformer substation where the voltage transformer is located; the system also comprises a communication unit which is used for uploading the secondary output voltage and the leakage current collected by the collection unit, and the calculation results and the control results of the analysis calculation unit and the control unit to the background system.
4. The system of claim 1, wherein: the accuracy grade of the voltage sensor is 0.02 grade, and the input voltage is alternating voltage in the range of 57.7-100V.
5. The system of claim 1, wherein: the weak current sensor is of a through type or open type structure, the accuracy level is 0.05 level, and the input alternating current weak current range is 0.1 uA-10 mA.
6. The system of claim 1, wherein: the number of the voltage transformers is at least one, and each voltage transformer corresponds to one voltage sensor and one weak current sensor; the sampling, analysis, calculation and control of each voltage transformer are independent.
7. An on-line monitoring method implemented by the system of claim 1, characterized in that: the method comprises the following steps:
s1, initialization:
initializing a system and setting parameters;
s2, signal acquisition:
the acquisition unit is used for sampling and controlling the voltage sensor and the weak current sensor and acquiring secondary output voltage and leakage current of the voltage transformer;
s3, analyzing and calculating:
respectively sequencing the secondary output voltage and the leakage current according to time, analyzing and processing the secondary output voltage and the leakage current at the same time, analyzing the correlation between the secondary output voltage and the leakage current, finding out a direct current component in the leakage current, bringing the direct current component in the leakage current into the design parameters of the monitored voltage transformer, calculating whether the direct current component can cause the voltage transformer to generate resonance or not, and judging that an electromagnetic resonance phenomenon occurs when the direct current component just falls on the resonance point of the monitored voltage transformer;
s4, relay protection equipment control:
when the electromagnetic resonance phenomenon appears in the judgment, the operation mode of the voltage transformer is changed, and the environment of the voltage transformer with the electromagnetic resonance is eliminated.
8. The method of claim 7, wherein: the method adopts an edge calculation mode, and S1-S4 are completed locally; meanwhile, the method also comprises S5, data communication: and uploading the secondary output voltage and the leakage current acquired by the acquisition unit, and the calculation results and the control results of the analysis calculation unit and the control unit to a background system.
9. The method of claim 7, wherein: in S4, the operation mode of the voltage transformer is changed by controlling the circuit breaker to perform a reclosing operation.
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