CN102694373B - Intelligent electronic device using transient fault information and relay protection method - Google Patents

Abstract

The invention relates to an intelligent electronic device utilizing transient fault information and a relay protection method. The intelligent electronic device includes a distance measuring and wave recording module respectively connected to the process layer and the station control layer through a process layer communication module and a station control layer communication module, The protection module and the measurement and control module, the protection module and the distance measurement and wave recording module are respectively used for fault identification, line protection, fault distance measurement, and wave recording according to the transient fault information uploaded by the process layer; the communication between each module and the external communication mainly adopts 100Mbps Ethernet realizes high-speed exchange and parallel processing of data. The protection module identifies transient fault information such as fault direction, polarity, and distance within a very short time after the fault occurs, and adopts two-out-of-three logic to form a longitudinal protection. The quick action of the protection function is realized, and the reliability of the action is also improved; the invention realizes the multi-functional integration, is applicable to the existing intelligent substation, improves the protection performance and distance measurement accuracy, and reduces the equipment cost and operation and maintenance cost .

Description

Intelligent electronic equipment and relay protection method using transient fault information

technical field

The invention belongs to the technical field of power system automation, and relates to an intelligent electronic device and a relay protection method utilizing transient fault information.

Background technique

Reducing the action time of relay protection is one of the effective measures to increase the transmission power of transmission lines and enhance the transient stability of the system. Accurate identification, processing and utilization of transient fault information can correctly determine the fault in a very short time after the fault occurs, usually only 1~3ms, so the ultra-high-speed operation of relay protection can be realized. However, the protection principle adopted by the relay protection devices widely used in the field is based on the power frequency electrical quantity, and filtering and other methods are usually used to eliminate the influence of the transient process on the protection, and the transient fault information is often regarded as It is filtered out for harmful interference, which prolongs the action time of the protection. However, the relay protection that only uses transient fault information is still in the stage of principle and algorithm research, and it is difficult to be practical.

With the rise and development of the smart grid, optical electronic transformers, optical fiber Ethernet communications, high-performance hardware platforms, and IEC61850 and IEEE1588 standards have made great progress in the application of smart substations. These not only make the effective use of transient fault information possible, but also realize the multifunctional integration of intelligent electronic devices, reducing equipment costs and operation and maintenance costs. The optical electronic transformer has good transient response characteristics and can accurately record the transient process; it has a wide dynamic range and can meet the dual needs of high-precision measurement and protection at the same time. The application of optical fiber Ethernet communication and IEC61850 provides conditions for the realization of standardized information sharing and integration of multiple functions. The high-performance hardware platform can meet the requirements of fast processing of transient signals and execution of various functions. Using IEEE1588 network time synchronization, the accuracy is up to 1ms.

Contents of the invention

The purpose of the present invention is to provide an intelligent electronic device and a relay protection method using transient fault information, so as to reduce the action time of relay protection, improve the distance measurement accuracy, and realize multi-functional integration.

In order to achieve the above object, the intelligent electronic device utilizing transient fault information of the present invention includes a distance measuring and recording module, a protection module and a measurement and control module respectively connected to the process layer and the station control layer through the process layer communication module and the station control layer communication module. module, the protection module and the distance measurement and wave recording module are respectively used for fault identification, line protection, fault distance measurement and wave recording according to the transient fault information uploaded by the process layer; the station control layer communication module is also connected by serial communication There is a machine interface module.

Further, an FPGA is provided between the protection module and the process layer communication module, and the FPGA is respectively connected to the protection module and the process layer communication module through a parallel bus.

Further, both the process layer communication module and the station control layer communication module are equipped with a network time synchronization module and an Ethernet interface module.

Further, the distance measuring and recording module, the protection module and the measurement and control module are all connected to the station control layer communication module by 100Mbps Ethernet, and the distance measurement and recording module and the measurement and control module are all connected to the process layer communication module by 100Mbps Ethernet.

Further, the external communication of the intelligent electronic device adopts Ethernet, and the sampling value transmission between the merge unit in the process layer adopts point-to-point optical fiber Ethernet, and the transmission protocol conforms to IEC61850-9-2, and the switching value between the intelligent terminal GOOSE point-to-point Ethernet is used for transmission; GOOSE network communication is used for other interval layer devices; MMS network communication is used for station control layer devices; IEEE1588 network time synchronization is used for time synchronization.

The steps of the relay protection method utilizing transient fault information of the present invention are as follows:

(1) The protection module of the intelligent electronic device reads the three-phase voltage and current sampling data uploaded by the process layer;

(2) After the start element action based on the improved gradient algorithm, extract the transient fault component 1~3ms after the start time;

(3) Fault identification is carried out according to the fault direction, polarity, and distance criteria. If two or more of the criteria determine that the fault occurs in the protected line, a trip command is issued; if no fault is identified in the protected line, Then switch to the traditional protection that responds to the power frequency electrical quantity, and carry out corresponding fault discrimination.

Further, the start-up criterion based on the improved gradient algorithm in step (2) is: perform phase-mode transformation on the current fault component, use the improved gradient algorithm for the obtained linear modulus, and the sum of the three data after the current point Subtract the sum of the 3 data before the current point to get the gradient value of the current point. If the value is greater than the start-up fixed value, the moment where the current point is is the start-up time, and the start-up element will act.

Further, in the step (3), the protection module and the intelligent electronic device on the opposite side of the line are connected through a communication channel to form a longitudinal protection, so as to obtain the transient fault information on the opposite side of the line, and the criteria for fault direction, polarity, and distance are respectively for:

a) Use voltage and current transient fault components, and use the ratio of time-domain energy of the modulus forward and reverse traveling waves after median filtering to determine the fault direction: if the ratio of time-domain energy is less than a fixed value, it is a forward fault; otherwise , is a reverse fault; the fault direction information on the opposite side of the line is obtained through the communication channel, and if they are all forward faults, it is judged that the fault occurred on the protected line;

b) Using the current transient fault component, if the initial traveling waves at both ends of the line have the same polarity, it is judged as an internal fault, and if the polarity is different, it is judged as an external fault;

c) Use the current transient fault component to calibrate the time when the initial traveling wave of the current arrives at the installation place of the intelligent electronic device on this side, and obtain the arrival time of the initial traveling wave of the current recorded on the opposite side of the line through the communication channel. If the ratio of the length of the protection line to the wave velocity of the transient current is an external fault, otherwise it is an internal fault.

Further, the distance measurement and wave recording module uses the distance measurement of transient fault information to calculate the fault distance through the absolute time difference between the initial traveling wave generated by the internal fault of the line and reaching the installation place of the intelligent electronic device at both ends of the line; The wave module uses an interpolation fitting method to approximate the real arrival time.

Furthermore, the wave recording of the ranging wave recording module adopts the second-generation wavelet transform algorithm-the lifting algorithm to compress the fault record data without loss, and uses a large-capacity storage device to record the whole process of changes in the power system after various disturbances.

The intelligent electronic device using transient fault information of the present invention follows the IEC61850 standard and adopts a multi-CPU distributed structure, including a process layer communication module, a protection module, a distance measurement and wave recording module, a measurement and control module, a station control layer communication module and a man-machine The interface module integrates various functions such as protection, distance measurement, wave recording and measurement and control. FPGA is used for parallel data exchange between the process layer communication module and the protection module, which can quickly transmit a large amount of data and fully guarantee the real-time performance of protection. The external communication of intelligent electronic equipment adopts Ethernet, and the communication module of the process layer receives the transient signal transmitted by the optical electronic transformer through direct sampling. The internal modules mainly use 100Mbps Ethernet to realize fast data transmission and parallelism. deal with. The invention is applicable to the existing intelligent substation, does not need to add or modify other equipment, improves the protection performance and distance measurement accuracy, realizes multifunctional integration, and reduces equipment cost and operation and maintenance expenses.

The relay protection method using transient fault information of the present invention can accurately identify transient states such as fault direction, current initial traveling wave polarity, and current initial traveling wave arrival time within a very short time (1~3ms) after the fault occurs The fault information adopts two out of three logic to form a longitudinal protection, which not only realizes the rapid action of the protection function, but also improves the reliability of the action; if the fault of the protected line is not judged by using the transient fault information, it will switch to the traditional protection According to the principle, the corresponding fault discrimination is carried out, and the utilization of transient fault information further improves the protection performance.

Description of drawings

Fig. 1 is a schematic structural diagram of an intelligent electronic device IED of the present invention;

Figure 2 is a schematic diagram of the application of IEDs in smart substations;

Fig. 3 is the working flowchart of the protection module of IED.

Detailed ways

Aiming at the problem that the transient fault information is difficult to use in relay protection, it is a practical way to combine the utilization of transient fault information with the mature principles of existing relay protection devices. effective solution.

The structure of the multifunctional integrated intelligent electronic device IED is shown in Figure 1. The intelligent electronic device IED includes a process layer communication module, a protection module, a distance measurement and wave recording module, a measurement and control module, a station control layer communication module and a human-machine interface module. Integrated protection, distance measurement, wave recording, measurement and control and other functions in one.

The application of the intelligent electronic device IED in the smart substation is shown in Figure 2. The IED belongs to the bay layer equipment, follows the IEC61850 standard, and uses Ethernet for external communication:

a) The connection with the process layer equipment (merging unit, intelligent terminal) adopts the "direct sampling and direct jumping" method, that is, the sampling value (SV) transmission with the merging unit adopts point-to-point optical fiber Ethernet, and the transmission protocol conforms to IEC61850-9- 2. GOOSE point-to-point Ethernet is used for the switch transmission between intelligent terminals. In this way, the network transmission delay can be reduced, and the action speed of the IED protection module can be accelerated.

b) Use GOOSE network communication with other bay layer devices.

c) Use MMS network communication with the station control layer equipment (monitoring system).

d) Time synchronization adopts IEEE1588 network time synchronization, with an accuracy of 1ms.

The hardware system of the intelligent electronic device IED adopts a multi-CPU distributed structure. On the one hand, the process layer communication module preprocesses the data received from the process layer, such as sampling values and switch input, and quickly distributes them to the protection module, distance measurement and wave recording module, and measurement and control module for processing their respective functions. Receive data such as switching output from the protection module and the measurement and control module and send it to the process layer. The station control layer communication module aggregates the processing results of the protection module, distance measurement and recording module, and measurement and control module to the station control layer, and receives control commands and fixed values from the station control layer and sends them out; it also receives the man-machine interface module (MMI ) input information, and send the output information to be displayed to the MMI.

The high-speed exchange of data between modules is one of the key technologies for IEDs to realize the utilization of transient fault information and functional integration. In view of the fact that the external communication is Ethernet and the high-speed and reliable Ethernet communication, in order to avoid data conversion when using multiple communication methods, reduce hardware types, and simplify software design, the high-speed data exchange between modules still mainly uses 100Mbps Ethernet . The data exchange method between modules is as follows:

a) FPGA (including dual-port RAM) is used for parallel data exchange between the process layer communication module and the protection module, which can quickly transmit large quantities of data and fully guarantee the real-time performance of protection.

b) The data exchange between the station control layer communication module and the MMI does not require high real-time performance, and the serial RS232 communication method is adopted.

c) Between the process layer communication module and the distance measurement and recording module, between the process layer communication module and the measurement and control module, between the protection module and the station control layer communication module, between the distance measurement and recording wave module and the station control layer communication module, Between the measurement and control module and the station control layer communication module, 100Mbps Ethernet is used to realize high-speed data exchange and parallel processing.

The above method puts forward very high requirements on the communication processing capability of the CPU. Therefore, except the MMI, the other modules of the IED use the MPC8358 processor, which has a frequency of 400MHz, integrates a PowerPC core and a dedicated communication processing module, and can provide up to eight 100M Ethernet interfaces. The MMI module uses a single-chip microcomputer.

In order to obtain transient fault information, the process layer equipment needs to meet the following requirements:

a) Optical electronic transformers are used to provide the three-phase voltage and current of the transmission line, and the frequency response range is at least from DC to the 100th harmonic.

b) The output sampling rate of the merging unit should be 400 points per cycle and above.

The steps of the relay protection method using transient fault information are as follows:

(1) The protection module of the intelligent electronic device reads the three-phase voltage and current sampling data uploaded by the process layer;

(2) After the start element action based on the improved gradient algorithm, extract the transient fault component 1~3ms after the start time;

(3) Fault identification is carried out according to the fault direction, fault polarity and fault distance criteria, and two out of three logic is adopted, that is, two or more criteria determine that the fault occurs in the protected line, and a trip command is issued; if not If the fault of the protected line is judged, it will switch to the traditional protection that reflects the power frequency electrical quantity, and carry out corresponding fault judgment.

Transient fault information is concentrated in the fault initial traveling wave, and the fault can be detected and distanced according to the characteristics of the fault initial traveling wave. The utilization of transient fault information by IED is mainly reflected in the protection module and the distance measurement and wave recording module.

The software flow chart of the protection module of IED is shown in Figure 3. In this figure, the protection using transient fault information is called fast protection, which is different from traditional protection. After the activation element based on the improved gradient algorithm operates, the protection module extracts the transient fault component 1~3ms after the activation time—the length of the data window is related to the length of the protected line, and the initial traveling wave of the fault is included in this data window. Then, fault identification is carried out according to the following three criteria:

a) Use voltage and current transient fault components, and use the ratio of time-domain energy of the modulus forward and reverse traveling waves after median filtering to determine the fault direction: if the ratio of time-domain energy is less than a fixed value, it is a forward fault; otherwise , for a reverse fault. The fault direction information on the opposite side of the line is obtained through the communication channel. If they are all positive faults, it is judged that the fault occurred on the protected line.

b) Using the current transient fault component, if the initial traveling waves at both ends of the line have the same polarity, it is judged as an internal fault, and if the polarity is different, it is judged as an external fault.

c) Use the current transient fault component to accurately calibrate the time for the initial traveling wave of the current to arrive at the IED installation on this side (with an accuracy of 1ms), and obtain the arrival time of the initial traveling wave of the current recorded on the opposite side of the line through the communication channel. If both If the time difference is greater than or equal to the ratio of the length of the protected line to the wave velocity of the transient current, it is an external fault, otherwise it is an internal fault.

In order to ensure the reliability of the action of the protection module, the three criteria adopt a two-out-of-three logic, that is, only when two or more criteria determine that the fault occurs in the protected line, the trip command is issued. The above three criteria all require the transient fault information on the opposite side of the line, so the protection module and the IED on the opposite side of the line are connected through a communication channel to form a longitudinal protection to obtain the transient fault information on the opposite side of the line.

If the protection module does not judge the fault of the protected line by using the transient fault information, it will switch to the traditional protection principle that reflects the power frequency electrical quantity, and carry out corresponding fault judgment. Therefore, the use of transient fault information will only improve the protection performance, and will not reduce the performance of the original protection.

The starting element based on the improved gradient algorithm is: perform phase-to-mode transformation on the current fault component, and use the improved gradient algorithm on the obtained linear modulus, that is, the sum of the three data after the current point minus the sum of the three data before the current point to obtain The gradient value of the current point, if the value is greater than the start-up setting value, then the moment where the current point is located is the start-up time, and the start-up element operates.

The ranging principle of the distance measuring and recording module using transient fault information is as follows: the fault distance is calculated by the absolute time difference between the initial traveling wave generated by the internal fault of the line and arriving at the IED installation at both ends of the line. The key to affecting the distance measurement accuracy is to accurately obtain the time when the fault initial traveling wave arrives at the IED installation. The application of the GPS system and the IEEE1588 standard can make the time synchronization error of the IEDs at both ends of the line not exceed 1 ms. However, due to the limited output sampling rate of the merging unit (400 points per cycle and above), it may not be possible to collect the real arrival time of the initial traveling wave of the fault. Arrival time, improve the accuracy of distance measurement.

The ranging wave recording module also uses the ranging principle based on power frequency to calculate the fault distance. The ranging results of the two methods can be compared with the actual fault distance to further improve the ranging algorithm.

The distance measurement and wave recording module adopts the second generation wavelet transform algorithm - the lifting algorithm to compress the fault record data without loss, and uses a large-capacity storage device (Flash) to completely record the whole process of the power system after various disturbances, which is the dynamic process of the system. The analysis provides basic data.

The function of the measurement and control module is the same as that of the traditional measurement and control device, and will not be repeated here.

Finally, it should be noted that: the above embodiments are only used to illustrate and not limit the technical solutions of the present invention, although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand; the present invention can still be modified Or an equivalent replacement, any modification or partial replacement without departing from the spirit and scope of the present invention shall fall within the scope of the claims of the present invention.

Claims (4)

1. A relay protection method utilizing transient fault information, is characterized in that, the steps of the method are as follows: (1) The protection module of the intelligent electronic device reads the three-phase voltage and current sampling data uploaded by the process layer; (2) After the starting element action based on the improved gradient algorithm, extract the transient fault component 1-3ms after the starting time; (3) Fault identification is carried out according to the fault direction, polarity, and distance criteria. If two or more of the criteria determine that the fault occurs in the protected line, a trip command is issued; if no fault is identified in the protected line, Then switch to the traditional protection that responds to the power frequency electrical quantity, and carry out corresponding fault discrimination; it not only realizes the rapid action of the protection function, but also improves the reliability of the action; In step (3), the protection module and the intelligent electronic device on the opposite side of the line are connected through a communication channel to form a longitudinal protection to obtain the transient fault information on the opposite side of the line. The criteria for fault direction, polarity, and distance are: a) Use voltage and current transient fault components, and use the ratio of time-domain energy of forward and backward modulus after median filtering to determine the fault direction: if the ratio of time-domain energy is less than a fixed value, it is a forward fault; otherwise , is a reverse fault; the fault direction information on the opposite side of the line is obtained through the communication channel, and if they are all forward faults, it is judged that the fault occurred on the protected line; b) Using the current transient fault component, if the initial traveling waves at both ends of the line have the same polarity, it is judged as an internal fault, and if the polarity is different, it is judged as an external fault; c) Use the current transient fault component to calibrate the time when the initial traveling wave of the current arrives at the installation place of the intelligent electronic device on this side, and obtain the arrival time of the initial traveling wave of the current recorded on the opposite side of the line through the communication channel. If the ratio of the length of the protection line to the wave velocity of the transient current is an external fault, otherwise it is an internal fault. 2. the relay protection method utilizing transient fault information according to claim 1, is characterized in that, in the described step (2), the starting criterion based on the starting element of improved gradient algorithm is: carry out phase-mode transformation to current fault component , the improved gradient algorithm is used for the obtained linear modulus, and the sum of the three data after the current point is subtracted from the sum of the three data before the current point to obtain the gradient value of the current point. If the value is greater than the starting value, the current point The moment at which it is located is the starting moment, and the starting element acts. 3. according to the relay protection method utilizing transient fault information according to any one of claims 1-2, it is characterized in that, the distance measuring and recording module utilizes the ranging of transient fault information to be produced by line internal fault The fault distance is calculated by the difference between the absolute time when the initial traveling wave arrives at the installation place of the intelligent electronic device at both ends of the line; the ranging wave recording module uses an interpolation fitting method to approach the real arrival time. 4. The relay protection method utilizing transient fault information according to claim 3, characterized in that, the wave recording of the ranging wave recording module adopts the second-generation wavelet transform algorithm—the lifting algorithm to carry out the lossless compression of fault wave recording data , using large-capacity storage devices to record the whole process of changes in the power system after various disturbances.