WO2015081826A1 - Electrical line protection method - Google Patents
Electrical line protection method Download PDFInfo
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- WO2015081826A1 WO2015081826A1 PCT/CN2014/092679 CN2014092679W WO2015081826A1 WO 2015081826 A1 WO2015081826 A1 WO 2015081826A1 CN 2014092679 W CN2014092679 W CN 2014092679W WO 2015081826 A1 WO2015081826 A1 WO 2015081826A1
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- traveling wave
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
- H02H7/265—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured making use of travelling wave theory
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/22—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for distribution gear, e.g. bus-bar systems; for switching devices
- H02H7/228—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for distribution gear, e.g. bus-bar systems; for switching devices for covered wires or cables
Definitions
- the present invention relates to power system protection and control techniques, and in particular to power line protection.
- the power line is the link between the power system and the load of the power system, and is an important part of the power system. Power lines pass through plain rivers, across alpine forests, and the corridors are complex and prone to failure. The failure of the power line not only damages the power equipment, but also affects the power supply of the user and jeopardizes the normal social and living order. Power line protection is an important topic in power system research.
- Existing power line protection technologies include current protection based on single-ended electrical quantities, voltage protection and distance protection, current differential protection based on double-ended electrical quantities, longitudinal direction protection, and the like.
- the existing power line protection in the field is based on the power frequency steady state electrical quantity.
- the transient traveling wave information after the fault and the steady-state electrical quantity of the power frequency include the fault information such as the fault occurrence and the fault location.
- the power line protection can also be formed based on the transient fault traveling wave information.
- the existing relay protection technology is difficult to protect the single-phase ground fault of the neutral point non-effective grounding system. As the grid interconnects, the system becomes larger and larger, and the stability of the system becomes more and more prominent.
- the fault information based on transient traveling wave has been used to construct traveling wave protection, traveling wave ranging and traveling wave selection, and some progress has been made.
- the existing protection techniques based on traveling wave information also have their own shortcomings, such as it is difficult to distinguish between traveling waves generated by faults and traveling waves generated by system disturbances such as lightning strikes or even switching operations.
- the existing relay protection technology focuses on the fast and selective isolation of faulty equipment after the fault occurs, which is a post-processing strategy, the purpose is to reduce the fault loss, prevent the fault from further worsening, and cause system accidents.
- the existing relay protection technology provides the current safe operation of the power system. Guarantee. However, if the fault development process can be identified, the fault warning is realized, and the problem is prevented, the fault loss can be reduced, and the reliability, safety and economy of the power system operation will be greatly improved.
- Another object of the present invention is to achieve power line protection capable of predicting faults in advance.
- the power line protection method provided by the present invention includes: collecting real-time traveling wave electric quantity and power frequency electric quantity on one end of the protected line in real time; determining whether traveling wave disturbance occurs in the system based on the traveling wave electric quantity; If traveling wave disturbance occurs in the system, the disturbance occurrence time is recorded, and whether the disturbance occurs on the protected line based on the traveling wave electric quantity; if it is determined that the disturbance occurs on the protected line, it is judged based on the power frequency electric quantity whether the occurrence occurs in the system.
- the protection action is output and the trip signal is output; if it is determined that no fault occurs in the system, it is judged whether the continuous traveling wave disturbance criterion is satisfied; if the continuous traveling wave disturbance criterion is satisfied, the output fault is output Early warning signal.
- the basic principle of the invention is that after the power line fails, the power system enters the steady state after the fault after the transient process.
- Transient traveling wave information and steady-state power frequency information after the fault are all part of the fault phenomenon.
- Transient traveling wave information and steady-state power frequency information can also reflect faults.
- Transient traveling wave information reflects the microscopic situation after the failure of the AC system.
- the steady-state power frequency information reflects the macroscopic situation of the system after the AC system fails.
- the system will generate a fault traveling wave that propagates along the system from the point of failure.
- the initial traveling wave of the fault is only affected by the electrical equipment passing through the path, and is not affected by the electrical equipment in the system that has not passed the traveling wave.
- the initial traveling wave is not affected by the neutral grounding method. Whether it is a neutral grounding system or a non-effective grounding system, the measuring point can effectively obtain the initial traveling wave.
- the initial traveling wave of the measuring point when a fault occurs in the protected line (referred to as a fault in the area), the initial traveling wave of the measuring point has both a reverse traveling wave and a forward traveling wave; when a fault occurs outside the protected line (referred to as an out-of-zone fault), the measurement is performed.
- the initial traveling wave of the point has only a forward traveling wave, and there is no reverse traveling wave. After a ground fault occurs in the power line, the steady-state power frequency electrical quantity after the fault changes significantly compared with that before the fault.
- the three-phase voltage is symmetrical, the three-phase voltage is maintained near the rated voltage, the three-phase current is the load current, and there is no zero-sequence voltage and zero-sequence current. Therefore After the barrier, the voltage and current will change significantly.
- the neutral point effective grounding system after the fault, the fault phase power frequency steady-state voltage decreases, and the fault phase power frequency steady-state current increases.
- the negative sequence voltage and zero sequence voltage will also rise.
- the neutral point non-effective earthing system after the single-phase ground fault, the zero-sequence voltage rises, and the short-circuit fault other than single-phase grounding, the fault phase current rises, and the fault phase voltage decreases.
- the fault transient process varies with the time of the fault. Therefore, the steady-state power frequency electrical quantity after the fault is a necessary condition for protection tripping.
- the insulation breakdown before the fault also produces traveling waves, so the traveling wave information can be used for fault prevention.
- the traveling wave information can be used for fault prevention.
- not only the fault, but also the insulation breakdown before the fault will generate traveling waves.
- the lightning strike or the switching operation will also generate traveling waves. Therefore, it is necessary to identify whether the traveling wave is a fault precursor or a disturbance caused by lightning strike or switching operation. .
- the traveling wave For a normally operating power line, it is subjected to the excitation of the AC power source. If the traveling wave is caused by a certain insulation reduction, the traveling wave will be repeated in a short period of time. If the traveling wave is generated due to lightning strikes or switching operations, the traveling wave will be instantaneous and will not be repeated in the short term. Therefore, the frequency of the upstream wave of the protected line can be used to identify the source of the disturbance and constitute a fault prevention criterion.
- the traveling wave in the present invention refers to an electromagnetic wave propagating in an electric power system due to disturbance caused by an electric power device in operation.
- the invention is based on detecting the electrical quantity of one end of the protected line and realizing rapid protection of the power line.
- the present invention is based on detecting the electrical quantity at one end of the protected line to achieve power line fault warning.
- the invention can monitor the running condition of the power line in real time, provide the power line fault early warning information in time, reduce the power line fault, and improve the reliability of the power line operation.
- FIG. 1 is a flow chart showing a power line protection method according to the present invention
- FIG. 2 shows a block diagram of a power line protection flow in accordance with an embodiment of the present invention.
- FIG. 1 is a flow chart showing a power line protection method according to the present invention, including:
- Step 1 Real-time acquisition of traveling wave electrical quantity and power frequency electrical quantity at one end of the protected line
- Step 2 Based on the traveling wave electrical quantity, determine whether a traveling wave disturbance occurs in the system;
- Step 3 If a traveling wave disturbance occurs in the system, record the disturbance occurrence time, and determine whether the disturbance occurs on the protected line based on the traveling wave electrical quantity;
- Step 4 If it is determined that the disturbance occurs on the protected line, it is determined whether a fault has occurred in the system based on the power frequency electrical quantity;
- Step 5 If it is determined that a fault has occurred in the system, the protection action is issued and a trip signal is issued;
- Step 6 If it is determined that no fault has occurred in the system, it is determined whether the continuous traveling wave disturbance criterion is satisfied;
- Step 7 If the continuous traveling wave disturbance criterion is satisfied, a fault warning signal is issued.
- the present invention devises an exemplary embodiment for implementing the method.
- the method is as shown in FIG. 2 and includes the following steps:
- Step S1 synchronously collecting the three-phase voltage traveling wave and the three-phase current traveling wave on the protected line, and the sampling frequency can be set to, for example, 1 MHz, real-time collecting the three-phase voltage and the three-phase current on the protected line, and the sampling frequency is for example Can be set to 1KHz;
- Step S2 Based on the electric quantity of the traveling wave, it is judged whether or not the traveling wave disturbance has occurred in the system. For example, a real-time three-phase voltage traveling wave and a three-phase current traveling wave analog input level comparison circuit are compared with a preset threshold to determine whether a traveling wave disturbance has occurred in the system.
- the voltage threshold can be set to 100-400 mV, preferably 200 mV.
- Step S3 If a traveling wave disturbance occurs in the system, the disturbance occurrence time is recorded, and based on the traveling wave electric quantity, it is judged whether the disturbance occurs on the protected line, that is, whether it is a disturbance in the area. For example, if a traveling wave disturbance occurs in the system, the disturbance occurrence time is recorded, and each predetermined amount of data, such as 32-point data, is stored before and after the three-phase voltage traveling wave and the three-phase current traveling wave disturbance.
- the phase-mode transformation is performed on the three-phase voltage traveling wave, and the phase-mode transformation matrix adopts the Karenbel matrix to obtain the voltage traveling wave line mode component and the zero-mode component.
- phase-to-phase transformation of three-phase current traveling wave transformation matrix adopts Kai The Lumbbell matrix obtains the current traveling wave line mode component and the zero mode component.
- the wavelet function can use the first derivative function of the cubic B-spline function.
- the first derivative of the cubic center B-spline function is shown in Equation 1.
- the wavelet function determined by the first derivative of the cubic central B-spline function is called the cubic center B-spline wavelet function.
- the wavelet transform is implemented by the Mallat algorithm shown in equation (2).
- f(n) is the voltage and current signal obtained by the acquisition.
- the forced component of the wavelet transform result;
- n is the sample number,
- j is the scale of the wavelet transform, and
- h k and g k are wavelet coefficients determined by the wavelet function.
- the modulus maxima are extracted from the wavelet transform result of the traveling wave data.
- the wavelet transform modulus maximum polarity is opposite, then the decision is made.
- the disturbance occurs on the protected line; if none of the above is satisfied, it is determined that the disturbance occurs outside of the protected line.
- Step S4 If a traveling wave disturbance occurs in the system, it is determined whether a fault has occurred in the system based on the power frequency electrical quantity. If a traveling wave disturbance occurs in the system, a predetermined amount of data, such as 20 points of data, is stored after the three-phase power frequency voltage and the three-phase power frequency current are disturbed. The phase sequence transformation is performed on the three-phase power frequency voltage and the three-phase power frequency current respectively, and the power frequency voltage and the power frequency current are obtained.
- a predetermined amount of data such as 20 points of data
- the Fourier transform and the positive sequence current RMS are respectively obtained by using the Fourier transform. Compare the zero sequence voltage rms value with the voltage setting value. If the zero sequence voltage RMS value is greater than the voltage setting value, it is determined that a fault has occurred in the system.
- the voltage setting value can generally be taken as 30V; otherwise, the positive sequence current effective value and the positive sequence current setting value are compared. If the positive sequence current effective value is greater than the positive sequence current setting value, it is determined that a fault has occurred in the system, and if the above is not satisfied, It is determined that no fault has occurred in the system.
- Step S5 If it is determined that a fault has occurred in the system, the protection action is issued and a trip signal is issued.
- Step S6 If it is determined that no fault has occurred in the system, it is determined whether the continuous traveling wave disturbance criterion is satisfied.
- the two disturbance time intervals are calculated based on the time when the recorded protection line has been subjected to the last two traveling wave disturbances.
- the time interval between the last two disturbances of the protected line and the setting time interval are compared. If the calculated time interval is less than the setting time interval, the continuous traveling wave disturbance criterion is satisfied.
- the setting interval of the 60 Hz system is 16 ms
- the setting interval of the 50 Hz system is 20 ms. If normal operation is considered, the positive and negative two and a half weeks may break down, the 60Hz system setting interval is 8ms, and the 50Hz system setting interval is 10ms.
- Step S7 If the continuous traveling wave disturbance criterion is satisfied, a fault early warning signal is issued.
Abstract
An electrical line protection method comprises: collecting a traveling wave electrical quantity and a power frequency electrical quantity at one end of a protected line in real time; determining whether disturbance occurs on the protected line based the traveling wave electrical quantity; if disturbance occurs on the protected line, determining whether the protected line has a fault based on the power frequency electrical quantity; if the protected line has a fault, outputting a trip signal; if the protected line does not have a fault, determining whether the criteria for continuous traveling wave disturbance is satisfied; and if the criteria for continuous traveling wave disturbance is satisfied, outputting a fault warning signal. The method can provide fault information about the protected line in time, especially can provide fault warning information about the protected line in time, and can accurately and rapidly detect an earth fault, reduce and prevent fault, improve power supply reliability of an electrical system, and ensure secure operation of the electrical line.
Description
本发明涉及电力系统保护和控制技术，具体涉及电力线路保护。The present invention relates to power system protection and control techniques, and in particular to power line protection.
电力线路是电力系统电源与负荷的纽带，是电力系统的重要组成部分。电力线路穿过平原河流，跨过高山森林，线路走廊复杂，易于发生故障。电力线路故障，不仅损坏电力设备，还将影响用户供电，危害正常的社会和生活秩序。电力线路保护是电力系统研究的重要课题。The power line is the link between the power system and the load of the power system, and is an important part of the power system. Power lines pass through plain rivers, across alpine forests, and the corridors are complex and prone to failure. The failure of the power line not only damages the power equipment, but also affects the power supply of the user and jeopardizes the normal social and living order. Power line protection is an important topic in power system research.
现有的电力线路保护技术包括基于单端电气量的电流保护、电压保护和距离保护，基于双端电气量的电流差动保护、纵联方向保护等等。现有的在现场的电力线路保护都是基于工频稳态电气量的。但是电力线路发生故障后，故障后的暂态行波信息和工频稳态电气量一样都包括了故障发生、故障地点等故障信息。基于暂态故障行波信息也一样可以构成电力线路保护。而且，现有的继电保护技术难以保护中性点非有效接地系统的单相接地故障。随着电网互联，系统越来越大，系统的稳定性问题越来越突出。众所周知，故障切除的越快，越有利于系统稳定。而基于暂态行波的保护技术比基于工频稳态的保护技术具有先天的快速性。因此，研究基于暂态行波的继电保护能够有利促进继电保护技术的发展。Existing power line protection technologies include current protection based on single-ended electrical quantities, voltage protection and distance protection, current differential protection based on double-ended electrical quantities, longitudinal direction protection, and the like. The existing power line protection in the field is based on the power frequency steady state electrical quantity. However, after the power line fails, the transient traveling wave information after the fault and the steady-state electrical quantity of the power frequency include the fault information such as the fault occurrence and the fault location. The power line protection can also be formed based on the transient fault traveling wave information. Moreover, the existing relay protection technology is difficult to protect the single-phase ground fault of the neutral point non-effective grounding system. As the grid interconnects, the system becomes larger and larger, and the stability of the system becomes more and more prominent. It is well known that the faster the fault is removed, the more favorable the system is. The protection technology based on transient traveling wave is inherently faster than the protection technology based on power frequency steady state. Therefore, the study of relay protection based on transient traveling wave can promote the development of relay protection technology.
基于暂态行波的故障信息已被用于构造行波保护、行波测距和行波选线，已取得了一些进展。但是现有的基于行波信息的保护技术也有其自身的不足，如由于难以区分故障产生的行波和系统扰动如雷击甚至开关操作产生的行波而易于误动。The fault information based on transient traveling wave has been used to construct traveling wave protection, traveling wave ranging and traveling wave selection, and some progress has been made. However, the existing protection techniques based on traveling wave information also have their own shortcomings, such as it is difficult to distinguish between traveling waves generated by faults and traveling waves generated by system disturbances such as lightning strikes or even switching operations.
另外，现有的继电保护技术集中在故障发生后的快速有选择隔离故障设备，是一种事后处理的策略，目的是减少故障损失，防止故障进一步恶化，引起系统事故。现有的继电保护技术为目前电力系统安全运行提供了
保障。但是如果能识别故障发展过程，实现故障预警，防患于未然，则不仅能减少故障损失，而且将大大提高电力系统运行的可靠性、安全性和经济性。In addition, the existing relay protection technology focuses on the fast and selective isolation of faulty equipment after the fault occurs, which is a post-processing strategy, the purpose is to reduce the fault loss, prevent the fault from further worsening, and cause system accidents. The existing relay protection technology provides the current safe operation of the power system.
Guarantee. However, if the fault development process can be identified, the fault warning is realized, and the problem is prevented, the fault loss can be reduced, and the reliability, safety and economy of the power system operation will be greatly improved.
发明内容Summary of the invention
本发明的一个目的是实现能够快速切除故障的电力线路保护。It is an object of the present invention to achieve power line protection that enables rapid removal of faults.
本发明的另一个目的是实现能够提前预报故障的电力线路保护。Another object of the present invention is to achieve power line protection capable of predicting faults in advance.
本发明提出的电力线路保护方法，其特征在于，包括：实时采集被保护线路一端上的行波电气量和工频电气量；基于行波电气量，判断系统中是否发生了行波扰动；如果系统中发生了行波扰动，则记录扰动发生时间，基于行波电气量判断扰动是否发生在被保护线路上；如果判定扰动发生在被保护线路上，则基于工频电气量判断系统中是否发生了故障；如果判定系统中发生了故障，则保护动作，输出跳闸信号；如果判定系统中没有发生故障，则判断连续行波扰动判据是否满足；如果连续行波扰动判据满足，则输出故障预警信号。The power line protection method provided by the present invention includes: collecting real-time traveling wave electric quantity and power frequency electric quantity on one end of the protected line in real time; determining whether traveling wave disturbance occurs in the system based on the traveling wave electric quantity; If traveling wave disturbance occurs in the system, the disturbance occurrence time is recorded, and whether the disturbance occurs on the protected line based on the traveling wave electric quantity; if it is determined that the disturbance occurs on the protected line, it is judged based on the power frequency electric quantity whether the occurrence occurs in the system. If the fault occurs in the system, the protection action is output and the trip signal is output; if it is determined that no fault occurs in the system, it is judged whether the continuous traveling wave disturbance criterion is satisfied; if the continuous traveling wave disturbance criterion is satisfied, the output fault is output Early warning signal.
本发明的基本原理是电力线路发生故障后，电力系统经过暂态过程后进入故障后稳态。故障后的暂态行波信息和稳态工频信息都是故障现象的一部分。暂态行波信息和稳态工频信息也都能反映故障。暂态行波信息反映了交流系统发生故障后的微观情况。稳态工频信息反映了交流系统发生故障后系统的宏观情况。电力线路发生故障后，系统中将产生从故障点出发沿系统传播的故障行波。故障初始行波仅受经过的路径上电气设备的影响，不受系统中行波尚未经过的电气设备的影响。因此，在测量点，初始行波不受中性点接地方式的影响。无论是中性点接地系统，还是非有效接地系统，测量点都能有效获取初始行波。另外，被保护线路内发生故障(简称区内故障)时，测量点初始行波既有反向行波，又有正向行波；被保护线路外发生故障(简称区外故障)时，测量点初始行波只有正向行波，没有反向行波。电力线路发生接地故障后，故障后的稳态工频电气量与故障前相比发生了显著变化。故障前，三相对称，三相电压对称，三相电压维持在额定电压附近，三相电流为负荷电流，无零序电压和零序电流。故
障后，电压电流将出现显著变化。中性点有效接地系统中，故障后，故障相工频稳态电压降低，故障相工频稳态电流升高。不对称故障后，负序电压和零序电压还将升高。中性点非有效接地系统中，单相接地故障后，零序电压升高，除单相接地以外的短路故障，故障相电流升高，故障相电压降低。The basic principle of the invention is that after the power line fails, the power system enters the steady state after the fault after the transient process. Transient traveling wave information and steady-state power frequency information after the fault are all part of the fault phenomenon. Transient traveling wave information and steady-state power frequency information can also reflect faults. Transient traveling wave information reflects the microscopic situation after the failure of the AC system. The steady-state power frequency information reflects the macroscopic situation of the system after the AC system fails. After the power line fails, the system will generate a fault traveling wave that propagates along the system from the point of failure. The initial traveling wave of the fault is only affected by the electrical equipment passing through the path, and is not affected by the electrical equipment in the system that has not passed the traveling wave. Therefore, at the measurement point, the initial traveling wave is not affected by the neutral grounding method. Whether it is a neutral grounding system or a non-effective grounding system, the measuring point can effectively obtain the initial traveling wave. In addition, when a fault occurs in the protected line (referred to as a fault in the area), the initial traveling wave of the measuring point has both a reverse traveling wave and a forward traveling wave; when a fault occurs outside the protected line (referred to as an out-of-zone fault), the measurement is performed. The initial traveling wave of the point has only a forward traveling wave, and there is no reverse traveling wave. After a ground fault occurs in the power line, the steady-state power frequency electrical quantity after the fault changes significantly compared with that before the fault. Before the fault, the three-phase symmetry, the three-phase voltage is symmetrical, the three-phase voltage is maintained near the rated voltage, the three-phase current is the load current, and there is no zero-sequence voltage and zero-sequence current. Therefore
After the barrier, the voltage and current will change significantly. In the neutral point effective grounding system, after the fault, the fault phase power frequency steady-state voltage decreases, and the fault phase power frequency steady-state current increases. After an asymmetrical fault, the negative sequence voltage and zero sequence voltage will also rise. In the neutral point non-effective earthing system, after the single-phase ground fault, the zero-sequence voltage rises, and the short-circuit fault other than single-phase grounding, the fault phase current rises, and the fault phase voltage decreases.
但是，故障暂态过程随故障时刻的不同而不同，因此，故障后的稳态工频电气量是保护跳闸的必要条件。另一方面，故障前的绝缘击穿也会产生行波，因此行波信息可用于故障预防。但是电力系统中不仅故障、故障前的绝缘击穿会产生行波，雷击或者开关操作也会产生行波，因此，有必要识别行波到底是故障前兆，还是由雷击、开关操作等扰动产生的。However, the fault transient process varies with the time of the fault. Therefore, the steady-state power frequency electrical quantity after the fault is a necessary condition for protection tripping. On the other hand, the insulation breakdown before the fault also produces traveling waves, so the traveling wave information can be used for fault prevention. However, in the power system, not only the fault, but also the insulation breakdown before the fault will generate traveling waves. The lightning strike or the switching operation will also generate traveling waves. Therefore, it is necessary to identify whether the traveling wave is a fault precursor or a disturbance caused by lightning strike or switching operation. .
对于正常运行的电力线路，其承受交流电源的激励，如果行波是由某点绝缘降低产生的，则该行波将是短期内重复的。如果行波是由于雷击或者开关操作产生的，则该行波将是瞬时的，短期内不重复的。因此，被保护线路上行波出现的频率，可以用于识别扰动来源，构成故障预防判据。For a normally operating power line, it is subjected to the excitation of the AC power source. If the traveling wave is caused by a certain insulation reduction, the traveling wave will be repeated in a short period of time. If the traveling wave is generated due to lightning strikes or switching operations, the traveling wave will be instantaneous and will not be repeated in the short term. Therefore, the frequency of the upstream wave of the protected line can be used to identify the source of the disturbance and constitute a fault prevention criterion.
本发明中的行波是指运行中的电力设备由于受到扰动引起的在电力系统中传播的电磁波。The traveling wave in the present invention refers to an electromagnetic wave propagating in an electric power system due to disturbance caused by an electric power device in operation.
本发明基于检测被保护线路一端的电气量，实现电力线路快速保护。The invention is based on detecting the electrical quantity of one end of the protected line and realizing rapid protection of the power line.
另外，本发明基于检测被保护线路一端的电气量，实现电力线路故障预警。In addition, the present invention is based on detecting the electrical quantity at one end of the protected line to achieve power line fault warning.
本发明能够实时监测电力线路的运行情况，及时提供电力线路故障预警信息，减少电力线路故障，提高电力线路运行可靠性。The invention can monitor the running condition of the power line in real time, provide the power line fault early warning information in time, reduce the power line fault, and improve the reliability of the power line operation.
图1示出了根据本发明的电力线路保护方法的流程框图；1 is a flow chart showing a power line protection method according to the present invention;
图2示出了根据本发明的实施例的电力线路保护流程框图。2 shows a block diagram of a power line protection flow in accordance with an embodiment of the present invention.
为了能够更清楚地理解本发明的上述目的、特征和优点，下面结合附图和具体实施方式对本发明进行进一步的详细描述。
The present invention will be further described in detail below with reference to the drawings and specific embodiments.
在下面的描述中阐述了很多具体细节以便于充分理解本发明，但是，本发明还可以采用其他不同于在此描述的其他方式来实施，因此，本发明并不局限于下面公开的具体实施例。In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, but the invention may be practiced in other embodiments other than those described herein. .
图1示出了根据本发明的电力线路保护方法的流程框图，包括：1 is a flow chart showing a power line protection method according to the present invention, including:
步骤1：实时采集被保护线路一端的行波电气量和工频电气量；Step 1: Real-time acquisition of traveling wave electrical quantity and power frequency electrical quantity at one end of the protected line;
步骤2：基于行波电气量，判断系统中是否发生了行波扰动；Step 2: Based on the traveling wave electrical quantity, determine whether a traveling wave disturbance occurs in the system;
步骤3：如果系统中发生了行波扰动，记录扰动发生时间，基于行波电气量判断扰动是否发生在被保护线路上；Step 3: If a traveling wave disturbance occurs in the system, record the disturbance occurrence time, and determine whether the disturbance occurs on the protected line based on the traveling wave electrical quantity;
步骤4：如果判定扰动发生在被保护线路上，基于工频电气量判断系统中是否发生了故障；Step 4: If it is determined that the disturbance occurs on the protected line, it is determined whether a fault has occurred in the system based on the power frequency electrical quantity;
步骤5：如果判定系统中发生了故障，保护动作，发出跳闸信号；Step 5: If it is determined that a fault has occurred in the system, the protection action is issued and a trip signal is issued;
步骤6：如果判定系统中没有发生故障，判断连续行波扰动判据是否满足；Step 6: If it is determined that no fault has occurred in the system, it is determined whether the continuous traveling wave disturbance criterion is satisfied;
步骤7：如果连续行波扰动判据满足，发出故障预警信号。Step 7: If the continuous traveling wave disturbance criterion is satisfied, a fault warning signal is issued.
本发明设计了一个实现该方法的典型实施例，该方法如图2所示，包括以下步骤：The present invention devises an exemplary embodiment for implementing the method. The method is as shown in FIG. 2 and includes the following steps:
步骤S1：实时同步采集被保护线路上的三相电压行波和三相电流行波，采样频率例如可设定为1MHz，实时采集被保护线路上的三相电压和三相电流，采样频率例如可设定为1KHz；Step S1: synchronously collecting the three-phase voltage traveling wave and the three-phase current traveling wave on the protected line, and the sampling frequency can be set to, for example, 1 MHz, real-time collecting the three-phase voltage and the three-phase current on the protected line, and the sampling frequency is for example Can be set to 1KHz;
步骤S2：基于行波电气量，判断系统中是否发生了行波扰动。例如，将实时三相电压行波和三相电流行波模拟量输入电平比较电路，与预设阈值比较，判断系统中是否发生了行波扰动。例如电压阈值可以设定为100-400mV，优选为200mV。Step S2: Based on the electric quantity of the traveling wave, it is judged whether or not the traveling wave disturbance has occurred in the system. For example, a real-time three-phase voltage traveling wave and a three-phase current traveling wave analog input level comparison circuit are compared with a preset threshold to determine whether a traveling wave disturbance has occurred in the system. For example, the voltage threshold can be set to 100-400 mV, preferably 200 mV.
步骤S3：如果系统中发生了行波扰动，记录扰动发生时间，并基于行波电气量判断扰动是否发生在被保护线路上，即是否为区内扰动。例如，若监测到系统中发生了行波扰动，记录扰动发生时间，存储三相电压行波和三相电流行波扰动前后各预定量的数据，例如32点数据。对三相电压行波进行相模变换，相模变换矩阵采用凯伦贝尔矩阵，获得电压行波线模分量和零模分量。同理，对三相电流行波进行相模变换，变换矩阵采用凯
伦贝尔矩阵，获得电流行波线模分量和零模分量。Step S3: If a traveling wave disturbance occurs in the system, the disturbance occurrence time is recorded, and based on the traveling wave electric quantity, it is judged whether the disturbance occurs on the protected line, that is, whether it is a disturbance in the area. For example, if a traveling wave disturbance occurs in the system, the disturbance occurrence time is recorded, and each predetermined amount of data, such as 32-point data, is stored before and after the three-phase voltage traveling wave and the three-phase current traveling wave disturbance. The phase-mode transformation is performed on the three-phase voltage traveling wave, and the phase-mode transformation matrix adopts the Karenbel matrix to obtain the voltage traveling wave line mode component and the zero-mode component. Similarly, phase-to-phase transformation of three-phase current traveling wave, transformation matrix adopts Kai
The Lumbbell matrix obtains the current traveling wave line mode component and the zero mode component.
对电压行波线模分量、零模分量、电流行波线模分量和零模分量分别进行四层小波变换。此处的小波函数可选用三次B样条函数的一次导函数。三次中心B样条函数的一阶导数如式1所示。Four-layer wavelet transform is performed on the voltage traveling wave line mode component, the zero mode component, the current traveling wave line mode component and the zero mode component respectively. The wavelet function here can use the first derivative function of the cubic B-spline function. The first derivative of the cubic center B-spline function is shown in Equation 1.
由三次中心B样条函数的一阶导数确定的小波函数称为三次中心B样条小波函数。小波变换由式(2)所示的Mallat算法实现The wavelet function determined by the first derivative of the cubic central B-spline function is called the cubic center B-spline wavelet function. The wavelet transform is implemented by the Mallat algorithm shown in equation (2).
式中，f(n)是采集获得的电压、电流信号，
为小波变换结果的逼进分量；
为变换结果的小波分量，n为采样序号，j为小波变换的尺度，hk和gk是由小波函数决定的小波系数。本技术中，基于三次中心B样条函数的一阶导数确定的小波函数的小波系数：Where f(n) is the voltage and current signal obtained by the acquisition. The forced component of the wavelet transform result; To transform the resulting wavelet component, n is the sample number, j is the scale of the wavelet transform, and h k and g k are wavelet coefficients determined by the wavelet function. In the present technique, the wavelet coefficients of the wavelet function determined based on the first derivative of the cubic center B-spline function:
对行波数据的小波变换结果提取模极大值。The modulus maxima are extracted from the wavelet transform result of the traveling wave data.
比较电压行波线模分量四层小波变换模极大值与对应的电流行波线模分量四层小波变换模极大值的极性，如果有不少于三层的电压行波线模分量和电流行波线模分量的小波变换模极大值极性相反，则判定扰动发生在被保护线路上；否则，比较电压行波零模分量四层小波变换模极大值与对应的电流行波零模分量四层小波变换模极大值的极性，如果有不少于三层的电压行波零模分量和电流行波零模分量的小波变换模极大值极性相反，则判定扰动发生在被保护线路上；如果上述都不满足，判定扰动发生在被保护线路以外。
Comparing the polarity of the four-layer wavelet transform modulus maxima of the voltage traveling wave line mode component and the four-layer wavelet transform modulus maxima of the corresponding current traveling wave line mode component, if there are not less than three layers of voltage traveling wave line mode components And the polarity of the wavelet transform modulus maxima of the current traveling wave line mode component is opposite, then the disturbance is determined to occur on the protected line; otherwise, the four-layer wavelet transform modulus maximum value of the zero-mode component of the voltage traveling wave is compared with the corresponding current row The polarity of the maximum value of the four-layer wavelet transform modulus of the wave zero-module component. If there are not less than three layers of the voltage traveling wave zero-modulus component and the current traveling-wave zero-module component, the wavelet transform modulus maximum polarity is opposite, then the decision is made. The disturbance occurs on the protected line; if none of the above is satisfied, it is determined that the disturbance occurs outside of the protected line.
步骤S4：如果系统中发生了行波扰动，基于工频电气量判断系统中是否发生了故障。若监测到系统中发生了行波扰动，存储三相工频电压和三相工频电流扰动后预定量的数据，例如20点数据。对三相工频电压和三相工频电流分别进行相序变换，获得工频电压和工频电流正负零三序分量。Step S4: If a traveling wave disturbance occurs in the system, it is determined whether a fault has occurred in the system based on the power frequency electrical quantity. If a traveling wave disturbance occurs in the system, a predetermined amount of data, such as 20 points of data, is stored after the three-phase power frequency voltage and the three-phase power frequency current are disturbed. The phase sequence transformation is performed on the three-phase power frequency voltage and the three-phase power frequency current respectively, and the power frequency voltage and the power frequency current are obtained.
利用傅里叶变换分别求取零序电压、正序电流有效值。比较零序电压有效值与电压整定值，如果零序电压有效值大于电压整定值，则判定系统中发生了故障。电压整定值一般可取为30V；否则，比较正序电流有效值与正序电流整定值，如果正序电流有效值大于正序电流整定值，则判定系统中发生了故障，如果上述都不满足，判定系统中没有发生故障。The Fourier transform and the positive sequence current RMS are respectively obtained by using the Fourier transform. Compare the zero sequence voltage rms value with the voltage setting value. If the zero sequence voltage RMS value is greater than the voltage setting value, it is determined that a fault has occurred in the system. The voltage setting value can generally be taken as 30V; otherwise, the positive sequence current effective value and the positive sequence current setting value are compared. If the positive sequence current effective value is greater than the positive sequence current setting value, it is determined that a fault has occurred in the system, and if the above is not satisfied, It is determined that no fault has occurred in the system.
步骤S5：如果判定系统中发生了故障，保护动作，发出跳闸信号。Step S5: If it is determined that a fault has occurred in the system, the protection action is issued and a trip signal is issued.
步骤S6：如果判定系统中没有发生故障，判断连续行波扰动判据是否满足。Step S6: If it is determined that no fault has occurred in the system, it is determined whether the continuous traveling wave disturbance criterion is satisfied.
如果判定扰动发生在被保护线路上，但系统中并没有发生故障，基于记录的被保护线路最近两次发生行波扰动的时间，计算两次扰动时间间隔。If it is determined that the disturbance occurs on the protected line, but there is no fault in the system, the two disturbance time intervals are calculated based on the time when the recorded protection line has been subjected to the last two traveling wave disturbances.
比较计算得到的被保护线路最近两次发生扰动的时间间隔与整定时间间隔，如果计算得到的时间间隔小于整定时间间隔，则连续行波扰动判据满足。考虑系统正常运行的工频周期，60Hz系统整定时间间隔为16ms，50Hz系统整定时间间隔为20ms。如果考虑正常运行时，正负两个半周都可能击穿，则60Hz系统整定时间间隔为8ms，50Hz系统整定时间间隔为10ms。The time interval between the last two disturbances of the protected line and the setting time interval are compared. If the calculated time interval is less than the setting time interval, the continuous traveling wave disturbance criterion is satisfied. Considering the power frequency cycle of the normal operation of the system, the setting interval of the 60 Hz system is 16 ms, and the setting interval of the 50 Hz system is 20 ms. If normal operation is considered, the positive and negative two and a half weeks may break down, the 60Hz system setting interval is 8ms, and the 50Hz system setting interval is 10ms.
步骤S7：如果连续行波扰动判据满足，发出故障预警信号。Step S7: If the continuous traveling wave disturbance criterion is satisfied, a fault early warning signal is issued.
以上所述仅为本发明的优选实施例而已，并不用于限制本发明，对于本领域的技术人员来说，本发明的实施可以有各种更改和变化。凡在本发明的精神和原则之内，所作的任何修改、等同替换、改进等，均应包含在本发明的保护范围之内。
The above description is only the preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes can be made to the embodiments of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and scope of the present invention are intended to be included within the scope of the present invention.
Claims (3)
- 一种电力线路保护方法，其特征在于，包括：A power line protection method, comprising:实时采集被保护线路一端的行波电气量和工频电气量；Real-time acquisition of traveling wave electrical quantity and power frequency electrical quantity at one end of the protected line;基于采集到的行波电气量，判断系统中是否发生了行波扰动；Based on the collected traveling wave electrical quantity, it is determined whether a traveling wave disturbance occurs in the system;如果系统中发生了行波扰动，则记录扰动发生时间，基于行波电气量判断扰动是否发生在被保护线路上；If traveling wave disturbance occurs in the system, record the disturbance occurrence time, and determine whether the disturbance occurs on the protected line based on the traveling wave electric quantity;如果判定扰动发生在被保护线路上，则基于工频电气量判断系统中是否发生了故障；If it is determined that the disturbance occurs on the protected line, it is determined whether a fault has occurred in the system based on the power frequency electrical quantity;如果判定系统中发生了故障，则保护动作，则输出跳闸信号；If it is determined that a fault has occurred in the system, the protection action outputs a trip signal;如果判定系统中没有发生故障，则判断连续行波扰动判据是否满足；If it is determined that no fault has occurred in the system, it is determined whether the continuous traveling wave disturbance criterion is satisfied;如果连续行波扰动判据满足，则输出故障预警信号。If the continuous traveling wave disturbance criterion is satisfied, a failure warning signal is output.
- 如权利要求1所述的电力线路保护方法，其特征在于，A power line protection method according to claim 1, wherein所述行波电气量是三相电压行波和三相电流行波，所述工频电气量是三相电压和三相电流。The traveling wave electrical quantity is a three-phase voltage traveling wave and a three-phase current traveling wave, and the power frequency electrical quantity is a three-phase voltage and a three-phase current.
- 如权利要求1或2所述的电力线路保护方法，其特征在于，A power line protection method according to claim 1 or 2, characterized in that对三相电压行波和三相电流行波依次进行相模变换、四层小波变换来提取电压行波线模分量和零模分量的四层小波变换模极大值、电流行波线模分量和零模分量的四层小波变换模极大值，The three-phase voltage traveling wave and the three-phase current traveling wave are sequentially subjected to phase-modular transformation and four-layer wavelet transform to extract the four-layer wavelet transform modulus maximum value and the current traveling wave line mode component of the voltage traveling wave line mode component and the zero mode component. Four-layer wavelet transform modulus maxima of zero-modulus components,如果有不少于三层的电压行波线模分量与电流行波线模分量的小波变换模极大值极性相反、或者有不少于三层的电压行波零模分量与电流行波零模分量的小波变换模极大值极性相反，则判定扰动发生在所述被保护线路上，则判定扰动发生在所述被保护线路上。 If there are not less than three layers of the voltage traveling wave line mode component and the current traveling wave line mode component of the wavelet transform mode maximum value polarity is opposite, or there are not less than three layers of voltage traveling wave zero mode component and current traveling wave The wavelet transform modulus maxima of the zero mode component has opposite polarities, and it is determined that the disturbance occurs on the protected line, and it is determined that the disturbance occurs on the protected line.
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