CN113267711B - On-line monitoring system and method for insulation state of high-voltage electrical equipment of transformer substation - Google Patents
On-line monitoring system and method for insulation state of high-voltage electrical equipment of transformer substation Download PDFInfo
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Abstract
An on-line monitoring system and a monitoring method for the insulation state of high-voltage electrical equipment of a transformer substation are divided into two layers, wherein one layer is a transformer substation control management unit for carrying out monitoring, management, control and diagnosis tasks on the equipment in the transformer substation; the other layer is an on-site intelligent monitoring device for monitoring information outlets. Based on the insulating characteristics of high-voltage capacitive electrical equipment, the problems of unreasonable design structure, poor sensor performance, unstable operation, poor anti-interference capability, easy data loss, poor data sharing degree, complicated upgrading and maintenance of the current high-voltage electrical equipment insulating on-line monitoring system are solved.
Description
Technical Field
The invention relates to the technical field of online insulation monitoring of high-voltage electric equipment of a transformer substation, in particular to an online insulation state monitoring system and an online insulation state monitoring method for the high-voltage capacitive equipment of the transformer substation.
Background
The safe operation of the high-voltage electric equipment often needs to be tested on the insulation level of the high-voltage electric equipment, and the service life of the high-voltage electric equipment is often determined by the insulation level, that is, the higher the insulation level of the high-voltage electric equipment is, the longer the service life of the high-voltage electric equipment is, and vice versa. In order to maintain the normal operation of high-voltage electrical equipment, we generally perform detection by performing a high-voltage insulation test. A preventive test maintenance regime is created which means that after a certain period of operation of the apparatus, whether the apparatus is defect free or has problems, it is stopped for inspection, testing, repair. One disadvantage of this system is that it has relatively large blindness during inspection, test and repair, and it is not possible to accurately judge a certain position corresponding to the relevant equipment on line. And are not sufficiently detailed to be fully integrated when inspected for certain high capacity devices. Meanwhile, the defects are also existed, and the main manifestation is:
(1) Maintenance and testing requires a power outage of the running equipment. The domestic power supply is still relatively tension, especially in the peak period of electricity consumption, and if the power failure maintenance test is carried out in the period, the production benefit is affected to a certain extent. At the same time, maintenance tests are required for such huge power grids each year with power outage, which would require a lot of personnel and maintenance items to be put in. In addition, the temperature drops after the equipment is powered off, and in some tests, accurate judgment is often not possible. Data studies indicate that the results of the test equipment at low temperatures are difficult to make a correct judgment, and will reach about 58.5%.
(2) The periodic maintenance time is short and the workload is heavy. During the maintenance period, the equipment is highly concentrated, the labor intensity is high, each equipment is not diagnosed very carefully, suspicious data of some equipment cannot be studied and comprehensively judged in time, accidents are easy to occur, and accordingly the accidents cannot be avoided.
(3) The voltage of the overhaul test is usually lower, and the true effectiveness of the test result is not clear enough. Because the voltage tested during power failure is lower, the standard state of various devices is changed, the accuracy of test results is affected to different degrees, at this time, the insulativity of the high-voltage electrical device is not well detected, and the authenticity is not clear enough.
The occurrence of electrical faults is often an insulation accident, and according to statistics, the insulation accident of a high-voltage power system is more than 80%. In order to prevent or even stop the occurrence of insulation accidents, online insulation monitoring which is studied by us changes passive troubleshooting into active troubleshooting. Meanwhile, good insulating materials are needed, an insulating structure is improved, and a manufacturing process is optimized to improve the technical level of equipment insulation defect diagnosis.
According to the insulating structural characteristics of the capacitive device, the dielectric loss tangent tg delta, the capacitance Cx, and the end shield leakage current Ix may increase after insulation degradation. From these characteristics, insulation on-line monitoring research is developed. The insulation defect can be well found by monitoring and researching the capacitance value and dielectric loss of the detection equipment. The preventive maintenance of electrical equipment is gradually evolving into predictive maintenance. Therefore, the development of insulation on-line monitoring is significant in ensuring safe and reliable operation of the power system.
Disclosure of Invention
Aiming at the fact that the existing monitoring device is single in function, complex and multifunctional monitoring cannot be achieved. Besides few online insulation monitoring projects at home and abroad can be produced, most online insulation monitoring projects are imperfect for various reasons and are still in a starting stage. The invention provides an on-line monitoring system for the insulation state of high-voltage electrical equipment in a transformer substation, which is used for classifying the high-voltage electrical equipment in the transformer substation, screening characteristic quantities, sampling a field intelligent monitoring device, transmitting a communication module, summarizing a Lon Works bus, operating a communication module function and controlling and diagnosing a PC (personal computer) of a main control room, and solves the problems of unreasonable design structure, poor sensor performance, unstable operation, poor anti-interference capability, easy data loss, poor data sharing degree and complicated upgrading and maintenance of the current on-line monitoring system for the insulation state of the high-voltage electrical equipment. The system is designed as an on-line monitoring system with the distributed field bus technology as a leading part, and is divided into two layers, wherein one layer is a substation control management unit and is used for carrying out tasks such as monitoring, management, control and diagnosis of equipment in a transformer station; the other layer is an on-site intelligent monitoring device, and is an outlet of monitoring information.
In order to achieve the above object, the technical scheme of the present invention is as follows: the on-line monitoring system for the insulation state of the high-voltage electrical equipment of the transformer substation comprises components and parts including an on-site intelligent monitoring device, a communication module, a Lon Works bus, a communication module and a PC (personal computer) of a main control room, wherein the components and parts have the following specific structures and connection relations:
the on-site intelligent monitoring device is in a modularized design and comprises a sampling sensor, a signal conditioning and microprocessor module and a power management module, wherein the communication module is in a modularized design, an asynchronous serial communication mode is selected and independently operated, the communication module is communicated with each other through a field bus, a Lon Works bus adopts a Lon Talk communication protocol, the protocol conforms to an ISO/OSI reference model, provides all 7 layers of services defined by OSI, the communication rate is 78Kbps/2700m,1.25Mbps/130m, the number of nodes is 32000, the transmission medium can be twisted pair, coaxial cable, optical fiber, power line, wireless, infrared and the like, the communication module adopts a Colon communication module based on the Lon Works bus technology, the modules are connected with an upper computer and a lower computer through standard RS-232 serial ports, the communication medium adopts a shielded twisted pair, and three microprocessors are arranged in a core Neuron chip of the module: one for the control of the link layer, one for the control of the network layer and the other for the application program of the user, the PC of the main control room controls the working state of the intelligent monitoring unit of the management control station, reads the measured data and the abnormal information, stores the measured data, waits for the computer access task of the upper user, installs the data management and fault diagnosis software on the computer, analyzes and judges the monitored data,
the connection relation is as follows: when the monitoring signal is input into the signal conditioning circuit by the sensor, the filtered and amplified analog quantity is converted into digital quantity by the A/D conversion device, and then the digital quantity is transmitted to the PC of the main control room by the Lon Works bus, the CPU in the microprocessor module processes, calculates, analyzes and transforms the input data to complete a series of Works of insulating performance operation, insulating state judgment, data control and problem diagnosis treatment of the high-voltage electric equipment of the transformer substation, and the final data result is stored into the RAM, and meanwhile, the data is transmitted to the data management system of the upper computer by the communication interface of the microprocessor.
The system adopts a bus voltage transformer to acquire voltage signals.
The monitoring object of the system is high-voltage electrical equipment of a transformer substation, and the high-voltage electrical equipment is composed of three types of materials: the transformer high-voltage equipment comprises a main transformer, a factory transformer, an isolating switch, a main breaker, a grounding switch, a voltage transformer, a current transformer, a lightning arrester and a post insulator.
The data management system is authorized by DBMS software and is realized by SQLsErver 7.0.
The monitoring method of the transformer substation high-voltage electrical equipment insulation state on-line monitoring system comprises the following steps:
(1) Sampling: firstly, a sampling subroutine is divided into two paths of sampling signals, one path is a voltage signal, the other path is a current signal, when the sampling signals are input into a signal conditioning circuit by a sensor, the sampling signals are filtered and amplified, the conditioned analog quantity is converted into digital quantity by an A/D conversion device and then is sent into a microprocessor module, in order to avoid measurement errors caused by unequal delay time of the two paths of signals due to the discreteness of channel parameters, the voltage and current signals are alternately sampled, and a CPU (central processing unit) in the microprocessor module processes input data and then sends a final data result to a data management system of an upper computer;
(2) And (3) treatment: and (2) then, the DFT subprogram receives the sampling signals acquired by the acquisition subprogram in the step (1), and carries out DFT operation processing on the acquired signals. The signal monitored by the voltage sensor is extracted from the secondary side of the high voltage PT, the current sensor extracts the current signal insulated by the equipment, and K sampling values U are extracted from a sampling result table after sampling quantization processing k 、I k The current fundamental wave Ai, bi and the voltage fundamental wave Au, bu are calculated by the formulas (2-1) and (2-2). Then, calculating the amplitude Di of the current fundamental wave and the amplitude Du of the voltage fundamental wave according to a formula (2-3); after the DFT operation of the fundamental wave, judging whether K is smaller than 193 after K=K+1, if yes, continuing the operation, otherwise, returning to the step (1);
(3) And (3) calculating: then, after the operation in the step (2), the sampled data can easily enter an algorithm program for calculation, the calculation is performed by adopting a floating point system, the floating point number is composed of four bytes, one byte is a step code, three bytes are mantissas, the mantissa decimal point is positioned at the left end of a high byte, the highest bit represents a sign bit, when the mantissa is positive, the highest bit is 0, and for the normalized number, the highest bit is l; when the mantissa is a negative number, the highest number is "l". Due to 2 3 ×8＝2 24 ≈1.6×10 7 The effective bit number can reach more than 7 bits, and can meet the operation requirement of calculation precision. At this time, the parameters of the sampling subprogram and the DFT subprogram are called and substituted into the formula (3-1) for calculation,
wherein X is 1 、X 2 …, xn are each monitoring parameter, Y 1 、Y 2 …, yn are intermediate results of each monitored parameter,
(4) And (3) judging: if the output k=k-1=0 in the step (3), directly taking the average value of 10 times of measurement according to the formula (3-2); if the output k=k-1 is not equal to 0 in the step (3), returning to the step (3) for continuous calculation, and finally enabling the effective data signals to enter a microprocessor module for finishing signal acquisition, A/D conversion and digital signal processing after conditioning, processing anti-interference and calculating insulation parameters by utilizing software, and then transmitting the calculated insulation information to a network communication module, wherein the network communication module transmits the calculated insulation condition information to a main control room host through a cable;
(5) And (3) displaying: and finally, classifying the user interface according to the insulation condition information of the network communication module, comparing the input data by the CPU, displaying prompt information according to the insulation condition calculated and output in the step (4), and respectively outputting state management, accident early warning, accident handling and emergency state prompt according to suspected, normal and exceeding conditions to complete the online monitoring of the insulation state of the high-voltage electrical equipment of the transformer substation.
In order to ensure the accurate precision of sampling, an automatic compensation type zero-flux active sensor is adopted, permalloy with higher initial magnetic permeability and smaller loss is adopted as an iron core, and a deep negative feedback technology is adopted, so that the exciting magnetic potential of the iron core can be fully and automatically compensated, and the iron core is kept to work in an approximately ideal zero-flux state. The on-site intelligent monitoring device adopts a modularized design, and has the characteristics of strong anti-interference capability, strong interchangeability, convenience in production and on-site maintenance, and the like. The monitoring device is installed nearby the equipment operation site, and the monitoring of the insulation state is completed, so that the device has great advantages that the problem that weak insulation information is interfered and distorted in long-distance transmission can be solved, the time is very long when the information transmission amount is large, and the contradiction that the insulation state is difficult to accurately judge due to the small transmission amount can be solved.
In order to reduce the extra power consumption required by the operation of the sampling device, the online monitoring system for the insulation state of the high-voltage electrical equipment of the transformer substation adopts a bus voltage transformer to acquire a voltage signal, so that the sampling of the medium loss can be improved, and the extra power consumption required by the operation of the sampling device can be successfully replaced. Meanwhile, the electrical equipment running under the busbar voltage is equivalent to the test of insulating property, the data is true and reliable, the precision is ensured during data acquisition, and the condition of burning out and explosion after the preventive test is qualified due to the fact that the overhauling test voltage is low and defects are not easy to occur is avoided.
The user interface design is completed by Visual Basic, and the interface is clear, easy to use, complete in function and high in efficiency. And the modularized program design method is adopted, so that the flexibility, safety and reliability of program design are improved. The background database uses SQLserver7.0, fully applies the function of the Transact SQL language, establishes a very perfect database, and ensures the authenticity, consistency, effectiveness, validity and safety of the data in the database. The programmer can establish the WEB application program by utilizing the Activex document technology provided by the VB and the database server, so that a client can acquire all information provided by the application program by recognizing the WEB browser no matter where he is.
Working principle of an insulation state on-line monitoring system of high-voltage electrical equipment of a transformer substation:
1. each device of the monitoring system needs to acquire two paths of signals, one path is a bus voltage signal, and the other path is a leakage current signal. The method comprises the steps of obtaining voltage signals from a bus voltage transformer of a transformer substation, enabling the voltage signals to enter a field intelligent monitoring device through a voltage sensor, enabling current to enter the field intelligent monitoring device through a current sensor, enabling two paths of signals to enter a multiplexer respectively and simultaneously after isolation and low-pass filtering, and enabling one path of signals to enter a converter through an analog multiplexer to complete acquisition. The discrete signals are sent to the host computer for analysis and diagnosis by a serial communication.
2. The current sensor is a key component of the monitoring system, the sampling precision is determined by the current sensor, and the importance of the precision requirement of the current sensor is self-evident, and the precision requirement directly influences the measurement precision of the dielectric loss of the capacitive equipment. In order to ensure the safety of sampling without changing the original wiring mode of the electrical equipment, an electromagnetic current sensor with a core penetrating structure is adopted, and according to the working principle I 1 W 1 +I 2 W 2 ＝I 0 W 1 The main reason for the sensor error is known as excitation potential I 0 W 1 . If a reduction in core magnetic potential is desired, a high permeability core with a larger cross section and a shorter magnetic path is generally required to increase the number of secondary turns. The method is a method which can be thought before, but is not suitable for the precision requirement of dielectric loss measurement, so that a compensation circuit is required to be designed to reduce external exciting current when the measured value of the sensor is required to be accurately measured, an automatic compensation type zero-magnetic-flux active sensor is adopted, a permalloy with higher initial magnetic permeability and smaller loss is adopted as an iron core, a deep negative feedback technology is adopted, full-automatic compensation can be carried out on the exciting magnetic potential of the iron core, and the iron core is kept to work in a state close to ideal zero magnetic flux.
3. The signal adjusting module is used for generating various signals of + -V, + -mA and + -mV by the received equipment, and the signals are formed into various signals by the module and are isolated and transmitted to a PLC/DCS/display instrument and other receiving equipment of a control room, so that signal interference among various equipment can be effectively restrained, and the potential distinction among various equipment on the ground is solved. The signal conditioning module has two input signals. One is a voltage signal and one is a current signal. Considering devices of different capacitance types such as a sleeve, a current transformer and the like, the leakage current of a capacitor flowing through the tail end is different from hundreds of milliamperes to hundreds of milliamperes, and the extraction method is different due to different current signals of the current transformer, so that the processing of a microprocessor is required to be adjusted through a signal amplifying circuit of the module. With sufficient accuracy, 10-bit a/D samples within an 80C198 chip in the microprocessor module are utilized. In order to avoid measurement errors caused by unequal delay time of two paths of signals due to the discreteness of channel parameters, alternative sampling is adopted for the two paths of signals of voltage and current. For this purpose, the present signal conditioning module uses an 8-by-2 analog switch of AD 7502. The singlechip controls the Al end and the A0 end of the AD7502 through the HSO port, and alternately gates voltage and current signals. Since the a/D converter of the microprocessor module can only input a positive polarity signal, a polarity conversion circuit must be provided to convert the bipolar signal output from the amplifying circuit into a positive polarity signal.
4. The microprocessor adopts an Intel high-performance 80C198 single chip microcomputer as a control chip, adopts a single chip microcomputer bus MCUBUS standard for design, has high integration, low power consumption and small volume, and is particularly suitable for field bus control, instruments and meters and a front-end slave station of a distributed control network. The module completes sampling, A/D conversion and digital signal processing of the conditioned signal, including software anti-interference processing and insulation parameter operation, and then sends the calculated insulation state information to the network communication module, and the information is transmitted to the host computer by the network communication module.
5. The transformer substation insulation on-line monitoring system is based on a control management unit. The working state of the intelligent monitoring unit of the control station is mainly finished, the measurement data and the abnormal information are read, the measurement data are stored, and the task of accessing a computer of an upper user is waited. After the data management and fault diagnosis software is installed on the computer, the monitoring data can be analyzed and judged. The software of the online monitoring information management system comprises foreground application software and database management software.
Compared with the prior art, the invention has the outstanding advantages that:
the method can monitor the insulation state of the high-voltage electric equipment of the transformer substation in real time on line, and output state management, accident early warning, accident handling and emergency state prompt according to the diagnosis result of the insulation state, so that the fault of the high-voltage electric equipment of the transformer substation is prevented in the past, the design principle is reliable, the speed is high, the stability is good, the safety is high, the hardware requirement is low, the insulation weak points and the fault equipment can be foreseen in advance, the method is significant for ensuring the safe and reliable operation of the electric power system, and the method has good economic benefit and broad market prospect.
Drawings
Fig. 1 is a block diagram of a field bus structure of an on-line monitoring system for insulation state of high-voltage electrical equipment of a transformer substation.
Fig. 2 is a schematic diagram of a data acquisition principle of a data acquisition unit of the on-site intelligent device according to embodiment 1.
Fig. 3 is a functional block diagram of a user interface according to the present invention.
Fig. 4 is a block diagram of a DFT procedure in accordance with the present invention.
Fig. 5 is a flowchart of an algorithm program according to the present invention.
Fig. 6 is a schematic block diagram of an on-line monitoring system for insulation state of high-voltage electrical equipment of a transformer substation according to the invention.
Detailed Description
The invention is further described below with reference to the drawings and examples.
Example 1
As shown in fig. 1, the on-line monitoring system for the insulation state of the high-voltage electrical equipment of the transformer substation comprises a high-voltage electrical equipment 1 of the transformer substation, a field intelligent monitoring device 2, a communication module 3, a Lon Works bus 4, a communication module 5 and a PC 6 of a main control room. The specific structure and connection relation of the component are as follows: the monitored high-voltage equipment 1 of the transformer substation is provided with a transformer, a breaker, a lightning arrester and the like, the on-site intelligent monitoring device 2 samples voltage and current characteristic quantities of the high-voltage equipment 1 of the transformer substation through an internal sensor 10, signals are output to the communication module 3 from optical fibers after signal conditioning and microcomputer operation processing, and the communication module 3 adopts a Colon communication module based on Lon Works bus technology and is connected with an upper computer and a lower computer through a standard RS-232 serial port. The result of the signal output of each communication module 3 is directly sent to the Lon Works bus 4. The Lon Works bus 4 is formed by a pair of twisted pair wires with shielding, and can be connected with a plurality of communication module 3 devices in a hanging way. And the communication module 5 is connected with a cable to send the information to the PC 6 of the master control room. The PC 6 is a control management unit, which is composed of a PC and a modem, and mainly completes the working state of the intelligent monitoring unit of the control station, reads the measurement data and the abnormal information, saves the measurement data and waits for the upper user to access the task by the computer. After the data management and fault diagnosis software is installed on the computer, the monitoring data can be analyzed and judged.
The on-site intelligent monitoring device 2 is internally provided with a sampling sensor 10, a pre-signal processing unit 11, a sampling hold 12, a multiplexer 13, an A/D converter 14, a DSP module 15 and a power management module.
The microprocessor adopts an Intel high-performance 80C198 single chip microcomputer as a control chip, adopts a single chip microcomputer bus MCUBUS standard for design, has high integration, low power consumption and small volume, and is particularly suitable for field bus control, instruments and meters and a front-end slave station of a distributed control network. The module completes sampling and AD/conversion of the conditioned signals and digital signal processing, including software anti-interference processing and insulation parameter operation, and then sends the calculated insulation state information to a network communication module, and the information is transmitted to a host by the network communication module. 80C198 single-chip microcomputer module characteristic parameters: (1) The power consumption is low, the template device is fully CMOS, and the working current is less than 150mA. (2) The single chip microcomputer has high operation speed and strong function, high-energy 16-bit quick operation and average instruction execution time of 0.5-1.5 mu s. The function library can be used for complex operations such as floating point operation and the like. (3) The module has 4 channels without external A/D, and the A/D converter can complete one time of A/D conversion by about 28.2 mu s.
The user interface 6 is a 4K ultra-clear display screen, the outline dimension is 424mm multiplied by 709mm multiplied by 64mm, the height adjusting bracket is provided, and the height angle is adjustable.
As shown in fig. 3, the user interface 6 includes real-time monitoring frames, data collection, device pre-warning and alarm management, device information recording, information sharing, diagnostic decisions, history information, reporting systems, and device management function modules. The real-time monitoring picture function module displays the current leakage current value, the phase voltage value, the dielectric loss value, the equivalent capacitance, the environmental temperature and humidity value, the system running time and other parameter measurement values related to the insulation state in real time. The data acquisition module acquires the data information converted from the signal in real time and performs arrangement processing. The equipment early warning and alarming function module mainly gives early warning signals, alarms, dangers and other state prompts according to the operation results of all the insulation parameters. The equipment information recording function module is used for mainly recording site intelligent device information, site tested equipment information and the like. The information sharing function module can provide a plurality of user terminals to obtain monitoring data at the same time, and the data information ranges are different according to different authorities. The diagnosis decision function module is used for intelligently diagnosing the running state of the tested equipment and monitoring the development condition of the insulation defect. The history information inquiry function module inquires the equipment data information of the history record and inquires the characteristic data of the tested equipment. The report system functional module can generate each visually represented data chart according to each data, and is favorable for comparison analysis of staff. The equipment management function module is used for mainly managing information of tested equipment of the transformer substation.
Example 2
The monitoring method of the transformer substation high-voltage electrical equipment insulation state on-line monitoring system comprises the following steps:
(1) Sampling: firstly, the sampling subroutine divides two paths of sampling signals, one path is a voltage signal 8 and the other path is a current signal 9, the sampling signals are input into a pre-signal processing unit 11 by a sensor 10, and the signals are filtered, amplified and converted 13. The conditioned analog quantity is converted into digital quantity of DSP15 by A/D conversion device 14 and then is sent to microprocessor module, CPU in the microprocessor module processes the input data and then sends the final data result to the data management system of the upper computer;
(2) And (3) treatment: as shown in the DFT flow chart of fig. 4, the DFT subroutine receives the sampled signal acquired by the acquisition subroutine of step (1), and performs DFT operation on the acquired signal. Taking K sampling values U from the sampling result table k 、I k The current fundamental wave Ai, bi and the voltage fundamental wave Au, bu are calculated by the formulas (2-1) and (2-2). Then, calculating the amplitude Di of the current fundamental wave and the amplitude Du of the voltage fundamental wave according to a formula (2-3); after the DFT operation of the fundamental wave, judging whether K is smaller than 193 after K=K+1, if yes, continuing the operation, otherwise, returning to the step (1);
(3) And (3) calculating: as shown in the algorithm flow chart of FIG. 5, after the operation processing of step (2), the sampled data can be easily entered into the algorithm for calculation, and the calculation adopts a floating point system for calculation. At this time, parameters of the sampling subprogram and the DFT subprogram are called and substituted into a formula (3-1) for calculation, wherein X1, X2, … and Xn are monitoring parameters, and Y1, Y2, … and Yn are intermediate results of the monitoring parameters.
(4) And (3) judging: if the output k=k-1=0 in the step (3) is directly taken as an average value of 10 measurements (formula (3-2)); if the output k=k-1 not equal to 0 in the step (3), returning to the step (3) to continue calculation. And finally, transmitting the effective data signal information to a master control room host through a cable.
(5) And (3) displaying: and finally, the user interface 6 classifies the input data according to the insulation condition information of the network communication module, the CPU compares the input data, and the prompt information is displayed according to the insulation condition calculated and output in the step (4).
Fig. 6 is a schematic block diagram of the on-line monitoring system for the insulation state of the high-voltage electrical equipment of the transformer substation, wherein the insulation related parameters of the equipment are used as characteristic quantities to acquire signals by a sensor, and then the signals are subjected to amplification operation, analysis filtering, system filtering and then A/D conversion. The processed signals are sent to a microprocessor module, and a CPU in the microprocessor module carries out harmonic analysis algorithm calculation on input data and then sends a final data result to a data management system of an upper computer.
Claims (6)
1. The on-line monitoring method for the insulation state of the high-voltage electrical equipment of the transformer substation is characterized by comprising the following steps of: the method comprises the following steps:
(1) Sampling: firstly, a sampling subroutine is divided into two paths of sampling signals, one path is a voltage signal, the other path is a current signal, when the sampling signals are input into a signal conditioning circuit by a sensor, the sampling signals are filtered and amplified, the conditioned analog quantity is converted into digital quantity by an A/D conversion device and then is sent into a microprocessor module, in order to avoid measurement errors caused by unequal delay time of the two paths of signals due to the discreteness of channel parameters, the voltage and current signals are alternately sampled, and a CPU (central processing unit) in the microprocessor module processes input data and then sends a final data result to a data management system of an upper computer;
(2) And (3) treatment: then the DFT subprogram receives the sampling signal obtained by the acquisition subprogram in the step (1), carries out DFT operation processing on the obtained signal, extracts the signal monitored by the voltage sensor from the secondary side of the high voltage PT, extracts the current signal insulated by the equipment by the current sensor, and carries out sampling quantizationAfter processing, K sampling values U are taken out from the sampling result table k 、I k The Ai and Bi of the current fundamental wave and the Au and Bu of the voltage fundamental wave are calculated respectively according to formulas (2-1) and (2-2), and then the amplitude Di of the current fundamental wave and the amplitude Du of the voltage fundamental wave are calculated according to formula (2-3); after the DFT operation of the fundamental wave, judging whether K is smaller than 193 after K=K+1, if yes, continuing the operation, otherwise, returning to the step (1);
(3) And (3) calculating: after the operation in the step (2), the sampled data can easily enter an algorithm program for calculation, the calculation is performed by adopting a floating point system, the floating point number is composed of four bytes, one byte is a step code, three bytes are mantissas, mantissa decimal places are positioned at the left end of a high byte, the highest digit represents a sign bit, when the mantissas are positive, the highest digit is 0, and for the normalized number, the highest digit is l; when the mantissa is negative, the highest number is "l", since 2 3 ×8＝2 24 ≈1.6×10 7 The effective bit number can reach more than 7 bits, can meet the operation requirement of calculation precision, and at the moment, each parameter of the sampling subprogram and the DFT subprogram is calledSubstituting the formula (3-1) for calculation,
wherein X is 1 、X 2 …, xn are each monitoring parameter, Y 1 、Y 2 …, yn are intermediate results of each monitored parameter,
(4) And (3) judging: if the output k=k-1=0 in the step (3), directly taking the average value of 10 times of measurement according to the formula (3-2); if the output k=k-1 is not equal to 0 in the step (3), returning to the step (3) for continuous calculation, and finally enabling the effective data signals to enter a microprocessor module for finishing signal acquisition, A/D conversion and digital signal processing after conditioning, processing anti-interference and calculating insulation parameters by utilizing software, and then transmitting the calculated insulation information to a network communication module, wherein the network communication module transmits the calculated insulation condition information to a main control room host through a cable;
(5) And (3) displaying: finally, the user interface classifies the input data according to the insulation condition information of the network communication module, the CPU compares the input data, the insulation condition calculated and output in the step (4) displays prompt information, and state management, accident early warning, accident handling and emergency state prompt are respectively output according to suspected, normal and exceeding conditions, so that the online monitoring of the insulation state of the high-voltage electrical equipment of the transformer substation is completed;
the equipment adopted by the method for on-line monitoring the insulation state of the high-voltage electrical equipment of the transformer substation comprises an on-site intelligent monitoring device, a communication module, a Lon Works bus, a communication module and a PC (personal computer) of a main control room, wherein the specific structure and the connection relation of the components are as follows:
the on-site intelligent monitoring device is in modularized design and comprises a sampling sensor, a signal conditioning and microprocessor module and a power management module, wherein the communication module is in modularized design, an asynchronous serial communication mode is selected and independently operated, the communication module and the upper computer are communicated through a field bus, a Lon Works bus adopts a Lon Talk communication protocol, the protocol conforms to an ISO/OSI reference model, provides all 7 layers of services defined by OSI, the communication rate is 78Kbps/2700m,1.25Mbps/130m, the number of nodes is 32000, transmission media are twisted pair, coaxial cable, optical fiber, power line, wireless or infrared rays, the communication module adopts a Colon communication module based on the Lon Works bus technology, the communication module is connected with an upper computer and a lower computer through a standard RS-232 serial port, the communication medium adopts a shielded twisted pair, and three microprocessors are arranged in a core Neuron chip of the module: one for the control of the link layer, one for the control of the network layer and the other for the application program of the user, the PC of the main control room controls the working state of the intelligent monitoring unit of the management control station, reads the measured data and the abnormal information, stores the measured data, waits for the computer access task of the upper user, installs the data management and fault diagnosis software on the computer, analyzes and judges the monitored data,
when the monitoring signal is input into the signal conditioning circuit by the sensor, the filtered and amplified analog quantity is converted into digital quantity by the A/D conversion device, and then the digital quantity is transmitted to the PC of the main control room by the Lon Works bus, the CPU in the microprocessor module processes, calculates, analyzes and transforms the input data to complete a series of Works of insulating performance operation, insulating state judgment, data control and problem diagnosis treatment of the high-voltage electric equipment of the transformer substation, and the final data result is stored into the RAM, and meanwhile, the data is transmitted to the data management system of the upper computer by the communication interface of the microprocessor.
2. The method for on-line monitoring the insulation state of high-voltage electrical equipment of a transformer substation according to claim 1, wherein the method comprises the following steps: the equipment adopts a bus voltage transformer to acquire voltage signals.
3. The method for on-line monitoring the insulation state of high-voltage electrical equipment of a transformer substation according to claim 1, wherein the method comprises the following steps: the monitoring object of the equipment is high-voltage electrical equipment of a transformer substation, and the high-voltage electrical equipment is composed of three types of materials: the transformer high-voltage equipment comprises a main transformer, a factory transformer, an isolating switch, a main breaker, a grounding switch, a voltage transformer, a current transformer, a lightning arrester and a post insulator.
4. The method for on-line monitoring the insulation state of high-voltage electrical equipment of a transformer substation according to claim 1, wherein the method comprises the following steps: the microprocessor adopts an Intel high-performance 80C198 single-chip microcomputer as a control chip, and adopts a single-chip microcomputer bus MCUBUS standard for design.
5. The method for on-line monitoring the insulation state of high-voltage electrical equipment of a transformer substation according to claim 1, wherein the method comprises the following steps: the signal conditioning module adopts an 8-by-2 analog switch of AD 7502.
6. The method for on-line monitoring the insulation state of high-voltage electrical equipment of a transformer substation according to claim 1, wherein the method comprises the following steps: the data management system is authorized by DBMS software and is realized by SQLsErver 7.0.
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