WO2021147163A1 - 一种基于磁光测量元件的相差保护方法及系统 - Google Patents

一种基于磁光测量元件的相差保护方法及系统 Download PDF

Info

Publication number
WO2021147163A1
WO2021147163A1 PCT/CN2020/080436 CN2020080436W WO2021147163A1 WO 2021147163 A1 WO2021147163 A1 WO 2021147163A1 CN 2020080436 W CN2020080436 W CN 2020080436W WO 2021147163 A1 WO2021147163 A1 WO 2021147163A1
Authority
WO
WIPO (PCT)
Prior art keywords
magneto
optical
phase difference
light intensity
phase
Prior art date
Application number
PCT/CN2020/080436
Other languages
English (en)
French (fr)
Inventor
刘世明
赵永森
王波
南天琦
韩波
Original Assignee
山东大学
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 山东大学 filed Critical 山东大学
Publication of WO2021147163A1 publication Critical patent/WO2021147163A1/zh

Links

Images

Classifications

    • 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
    • H02H7/261—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 involving signal transmission between at least two stations
    • H02H7/263—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 involving signal transmission between at least two stations involving transmissions of measured values
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
    • G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
    • G01R15/24—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using light-modulating devices
    • G01R15/245—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using light-modulating devices using magneto-optical modulators, e.g. based on the Faraday or Cotton-Mouton effect
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
    • H02H3/26—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents
    • H02H3/28—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents involving comparison of the voltage or current values at two spaced portions of a single system, e.g. at opposite ends of one line, at input and output of apparatus
    • H02H3/30—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents involving comparison of the voltage or current values at two spaced portions of a single system, e.g. at opposite ends of one line, at input and output of apparatus using pilot wires or other signalling channel
    • H02H3/302—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents involving comparison of the voltage or current values at two spaced portions of a single system, e.g. at opposite ends of one line, at input and output of apparatus using pilot wires or other signalling channel involving phase comparison

Definitions

  • the invention belongs to the technical field of power system relay protection, and in particular relates to a phase difference protection method and system based on a magneto-optical measuring element.
  • optical current transformers based on Faraday's magneto-optical effect have attracted attention due to their unique advantages such as no magnetic saturation problem and strong anti-electromagnetic interference ability.
  • the measurement accuracy of optical current transformers is susceptible to environmental factors such as temperature changes, external vibrations, and the technological level of internal optical devices and optical circuits, resulting in complex implementation schemes and expensive manufacturing costs for optical current transformers.
  • phase differential protection is abbreviated as phase difference protection. It is a longitudinal protection that uses the phase comparison of the currents at both ends of the line to perform fault judgment. Its principle is simple and it has good performance.
  • phase difference high-frequency protection used analog methods to achieve phase comparison; modern microcomputer protection can use phase calculation comparison technology or digital phase comparison technology.
  • phase difference protection With the popularization of fiber channel, current differential protection has gradually been popularized and applied.
  • the principle of phase difference protection is simple, and the requirements for current transformer performance, communication channels, etc. are not high, and it has advantages in some applications.
  • the distribution network has become a complex and changeable active network, and the traditional three-stage current protection is difficult to meet the requirements.
  • directional current protection and distance protection require voltage, and longitudinal protection requires communication channels. Due to the restrictions of the distribution network, the use of these protections is greatly restricted.
  • the present invention provides a phase difference protection method based on magneto-optical measuring elements.
  • the present invention only needs to measure the phase of light intensity and does not require high amplitude measurement accuracy, thus avoiding magneto-optical elements. Affected by external vibration, temperature changes, etc., the protection performance is reduced.
  • one or more embodiments of the present invention provide the following technical solutions:
  • a phase difference protection method based on magneto-optical measuring element including:
  • the magnetic field generated by the line current rotates the polarization plane of the polarized light, so the light intensity of the output polarized light changes after passing through the analyzer, and the periodic alternating current produces a periodically changing light intensity;
  • Phase difference protection is realized by comparing the waveform phase of the light intensity at both ends.
  • the element with the magneto-optical effect is an optical element based on the Faraday magneto-optical effect.
  • the light intensity waveform of the output polarized light is a periodic waveform formed by subtracting a sine quantity on the basis of a constant value
  • the constant value is determined by the input light intensity, and the fundamental frequency and phase of the sine wave are the same as the fundamental frequency and phase of the line current.
  • the output light intensity is converted into a voltage signal by the detector and filtered, and the fundamental wave component of the output voltage has the same frequency and phase as the fundamental wave frequency and phase of the line current;
  • the phase difference protection criterion is applied to compare the fundamental wave phases of the emitted light intensity on both sides of the protected line to realize the phase difference protection based on the magneto-optical measuring element.
  • the light intensity signal measured by the components with the magneto-optical effect at both ends of the AC line or cable is converted into a digital quantity on the spot, and transmitted to the opposite end through the communication channel to achieve phase comparison;
  • the phase difference protection accepts the phase information of the magneto-optical measuring element measured at the local end and the phase information of the opposite end from the communication channel.
  • the phase difference between the two ends is within the range of [-180°+ ⁇ set ,180°- ⁇ set ], Protection action, where ⁇ set is the setting value of phase difference protection.
  • a further technical solution is to directly transmit the optical signal output by the element with magneto-optical effect to the opposite end through an optical fiber, and convert the light intensity into a digital quantity at the opposite end for phase comparison, omitting the synchronization of the communication channel and the sampling at both ends.
  • the output light intensity of the element with the magneto-optical effect is converted into a voltage signal by the photodiode circuit, the voltage is digitally sampled, and the direct current is filtered out, and the periodic component part is retained;
  • N is the number of sampling points in each fundamental wave period
  • Ps(k) is the comparison result of the k-th sampling point
  • ⁇ set is the set value.
  • One or more embodiments of the present disclosure also provide a phase difference protection system based on a magneto-optical measuring element, including: an optical circuit unit and an electrical circuit unit;
  • the magneto-optical element in the optical circuit unit is placed near the AC line or cable; the magneto-optical element is input with a constant intensity of polarized light through the optical fiber; the magnetic field generated by the line current rotates the polarization plane of the polarized light;
  • the electrical circuit unit converts the light intensity into a voltage, samples the voltage signal to obtain the fundamental wave phase, and realizes phase difference protection by comparing the waveform phases of the light intensity at both ends.
  • the element with magneto-optical effect is an all-fiber optical current transformer.
  • the element with magneto-optical effect adopts a magnetic field measuring element based on a magneto-optical isolator.
  • the invention uses the magneto-optical principle to measure the current phase, avoiding the problems of saturation and insulation of electromagnetic current transformers;
  • the present invention adopts the phase difference principle, only needs to measure the phase of light intensity, and has low requirements for the measurement accuracy of the amplitude. Therefore, the influence of vibration and temperature changes on the amplitude measurement accuracy of the magneto-optical element will not cause the protection performance to decrease;
  • the present invention proposes a scheme of using optical fibers to directly transmit optical signals to the opposite end of the line, omits the need for the communication channel and sampling synchronization at both ends, and greatly reduces the difficulty of realization.
  • phase difference protection scheme proposed by the present invention has low cost, good performance and easy installation, and is beneficial to be popularized and applied to active power distribution networks, factories, mines, oil fields, electric railways, subways, submarine cables and other occasions.
  • Fig. 1 is the phase relationship between the alternating current and the emitted light intensity of the embodiment of the present application
  • FIG. 2 is a schematic diagram of the first protection case of this application.
  • FIG. 3 is a schematic diagram of the phase difference protection phase comparison diagram of the present application.
  • FIG. 4 is a schematic diagram of the second protection case of this application.
  • Fig. 5 is a schematic diagram of the phase difference protection pulse sampling comparison scheme of the present application.
  • the embodiment of the present invention applies the principle of the magneto-optical effect, and uses a magneto-optical measuring element to measure the magnetic field generated by the alternating current.
  • the output light intensity of the magneto-optical measuring element is a periodic signal whose fundamental frequency and phase are the same as the frequency and phase of the alternating current.
  • the invention uses the fundamental wave signal of the output light intensity signal after filtering processing to construct the phase difference protection.
  • the invention uses magneto-optical measuring elements to measure current, avoiding the saturation and insulation problems of electromagnetic current transformers; only the phase of the emitted light intensity needs to be measured, and the interference of external vibration, temperature changes and internal optical circuits on the magneto-optical measuring elements does not affect the magneto-optical measuring element Phase measurement and comparison are easy to implement in engineering, and the performance is stable and reliable.
  • This embodiment discloses a phase difference protection method based on a magneto-optical measuring element.
  • An element with magneto-optical effect is placed near an AC line or cable, and polarized light of constant light intensity is input to the magneto-optical element through an optical fiber; line current
  • the generated magnetic field rotates the polarization plane of the polarized light, so the intensity of the output polarized light changes after passing through the analyzer, and the periodic alternating current produces a periodically changing light intensity.
  • the analyzer is an optical device, which is actually a polarizer with a specific polarization angle, so that the intensity of the polarized light changes after passing through the analyzer, so as to detect the polarization angle of the polarized light.
  • the detector in Figure 2 is a photoelectric conversion device that converts optical signals into electrical signals, and the output electrical signal changes in proportion to the input light intensity.
  • the output light intensity of the magneto-optical measuring element based on the Faraday magneto-optical effect can reflect the phase of the fundamental wave of the grid current, and the phase will not be affected by external vibration, temperature changes, etc. Therefore, it is proposed to measure the light intensity phase to achieve current phase differential protection.
  • Im is the current amplitude
  • ⁇ is the angular frequency
  • ⁇ is the initial phase angle
  • ⁇ 0 4 ⁇ *10 -7 N/A 2
  • i the current through the wire
  • B the magnetic field induction intensity
  • the magneto-optical element is placed at the position r from the center of the wire circle, and polarized light is input to the magneto-optical element.
  • the polarization plane of the polarized light output from the magneto-optical element will be deflected, and the deflection angle is:
  • B is the magnetic field induction intensity
  • L is the length of the magneto-optical material
  • V is the Verdet constant
  • ⁇ is the angle of rotation of the polarization plane of polarized light.
  • the output light of the magneto-optical element is passed through an analyzer, and the angle between the transmission axis of the analyzer and the polarization plane of the incident polarized light is ⁇ .
  • the intensity of the emitted light through the analyzer is:
  • I L I L0 e - ⁇ L cos 2 ( ⁇ + ⁇ ) (4)
  • I L is the output light intensity
  • I L0 is the input light intensity
  • ⁇ is the light absorption coefficient of the magneto-optical medium
  • L is the length of the magneto-optical material
  • ⁇ is the difference between the transmission axis of the analyzer and the polarization plane of the incident polarized light. The angle between the two, ⁇ is the angle of rotation of the polarization plane of the polarized light.
  • the output light intensity is a DC component minus an AC component.
  • the DC component is determined by the input light intensity; and the AC component is a sine function, and the angle of the function is a parameter proportional to the sine current.
  • the fundamental frequency and phase of the sine function are the same as the frequency and phase of the sine current. Therefore, after filtering out the DC component of the output light intensity, the AC component can fully reflect the frequency and phase of the current in the wire, as shown in Figure 1.
  • phase difference protection can be realized.
  • An all-fiber optical current transformer is used as the magneto-optical measuring element, and the output light intensity of the optical current transformer is converted into a voltage signal by the detector.
  • the voltage signal is digitally sampled into a digital signal, and the digital signal is Fourier filtered to obtain the phase of the fundamental wave.
  • the phase information is used for the local phase difference protection, and the other is transmitted to the opposite end phase difference protection through the communication channel.
  • the digital sampling on both sides needs to take measures to synchronize, such as applying a synchronization method based on GPS or Beidou signals.
  • the phase difference protection accepts the phase information of the magneto-optical measuring element measured at the local end and the phase information of the opposite end from the communication channel. As shown in Figure 3, when the phase difference between the two ends is [-180°+ ⁇ set ,180°- ⁇ When set ] is within the range, the protection action;
  • ⁇ set is the phase difference protection setting value.
  • ⁇ set 60°.
  • a signal interaction method based on optical fiber direct transmission of light intensity is disclosed, which eliminates the need for the communication channel and sampling synchronization at both ends.
  • the output light of the measuring elements at both ends of the line is transmitted to the phase difference protection at the same end through the optical fiber, thereby omitting the need for communication channel and sampling synchronization;
  • the output light intensity of the magnetic field measuring element is converted into a voltage signal by the PIN photodiode circuit, the voltage is digitally sampled, and the direct current is filtered out, and the periodic component part is retained;
  • N is the number of sampling points in each fundamental wave period; P s (k) is the comparison result of the k-th sampling point; ⁇ set is the setting value.
  • magneto-optical measuring elements such as optical current transformers based on magneto-optical glass (patent number: ZL200820028254.4), and optical fiber-based optical current transformers (patent number: ZL201510543050.9) , And magnetic field measuring element based on magneto-optical isolator (patent number: ZL201610856075.9) and so on. Specific selections are made according to needs, and will not be listed here.
  • the method of the above-mentioned embodiment of the application does not need to measure the voltage of the line/cable, and the amount of data transmission is small; and if the optical fiber is used to directly transmit the optical signal to the opposite end of the line, the need for the communication channel and sampling synchronization at both ends can also be omitted. Greatly reduce the difficulty of realization.
  • the present invention only needs to measure the phase of light intensity.
  • the output light intensity of the magneto-optical measuring element based on the Faraday magneto-optical effect can reflect the phase of the fundamental wave of the grid current, and the accuracy of the amplitude measurement is not high, thus avoiding the magneto-optical element from being affected by the outside world. Vibration, temperature changes and other influences cause the protection performance to decline.
  • phase difference protection method based on the magneto-optical measuring element of the present invention can also be applied to other applications, such as factories and mines, oil fields, electric railways, subways, submarine cables, etc., when applied, by measuring the magnetic field at both ends of the line or cable Realize phase difference protection.
  • This embodiment example discloses a phase difference protection system based on a magneto-optical measuring element, including: an optical circuit unit and an electrical circuit unit;
  • the magneto-optical element in the optical circuit unit is placed near the AC line or cable; the magneto-optical element is input with a constant intensity of polarized light through the optical fiber; the magnetic field generated by the line current rotates the polarization plane of the polarized light;
  • the electrical circuit unit converts the light intensity into a voltage, samples the voltage signal to obtain the fundamental wave phase, and realizes phase difference protection by comparing the waveform phases of the light intensity at both ends.
  • the basic components of the optical circuit unit mainly include: a laser transmitter, an optical fiber (to transmit laser light), a polarizer (to turn laser light into polarized light), a magneto-optical element, and an analyzer (to detect polarization angle);
  • the content of the measurement system is different.
  • the all-fiber optical current transformer shown in Figure 2 also includes a mirror, a quarter-wavelength plate, a polarization-maintaining fiber, and so on.
  • the basic components of the electrical circuit unit mainly include: photodetector (PIN photodiode), operational amplifier, A/D sampling circuit, digital signal processing device (such as single-chip microcomputer) and so on.
  • modules or steps of the present invention can be implemented by a general-purpose computer device. Alternatively, they can be implemented by program codes executable by the computing device, so that they can be stored in a storage device. The device is executed by a computing device, or they are separately fabricated into individual integrated circuit modules, or multiple modules or steps in them are fabricated into a single integrated circuit module for implementation.
  • the present invention is not limited to any specific combination of hardware and software.

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Measuring Instrument Details And Bridges, And Automatic Balancing Devices (AREA)

Abstract

一种基于磁光测量元件的相差保护方法及系统，包括：将具有磁光效应的元件放置在靠近交流线路或电缆的附近；通过光纤给磁光元件输入恒定光强的偏振光；线路电流产生的磁场使偏振光的偏振面发生旋转，于是输出的偏振光经过检偏器后光强发生变化，周期性的交流电流产生周期性变化的光强；通过比较两端光强的波形相位实现相差保护。采用相差原理，只需要测量光强相位，对于幅值的测量精度要求不高，因此振动、温度变化等对磁光元件幅值测量精度的影响不会造成保护性能下降。

Description

一种基于磁光测量元件的相差保护方法及系统 技术领域
本发明属于电力系统继电保护技术领域，尤其涉及一种基于磁光测量元件的相差保护方法及系统。
背景技术
本部分的陈述仅仅是提供了与本公开相关的背景技术信息，不必然构成在先技术。
随着电力系统的发展，电网的短路容量不断提高。发生短路故障时，传统的电磁式电流互感器容易饱和，二次侧电流发生严重畸变，导致继电保护装置难以正确动作。因此，近年来非传统电流互感器得到了大量关注。其中，基于法拉第磁光效应的光学电流互感器，由于无磁饱和问题、抗电磁干扰能力强等独特的优点而受到重视。但是光学电流互感器的测量精度易受温度变化、外界振动等环境因素以及内部光学器件和光学回路的工艺水平影响，导致光学电流互感器实现方案复杂、造价昂贵。
电流相位差动保护简称相差保护，是利用线路两端电流的相位比较进行故障判断的一种纵联保护，其原理简单，具有良好的性能。
发明人在研究中发现，早期相差高频保护采用模拟量方式实现相位比较；现代微机保护可以采用相位计算比较技术或者数字相位比较技术。随着光纤通道的普及，电流差动保护逐步得到推广应用。但是相差保护原理简单，对电流互感器性能、通信通道等的要求不高，在一些应用场合具有优势。
例如在有源配电网中的应用，随着分布式电源大量接入，配电网变为一个复杂多变的有源网络，传统的三段式电流保护难以满足要求。而方向电流保护、距离保护需要电压量，纵联保护需要通信通道，受配电网条件限制，这些保护的使用都受到极大限制。
发明内容
为克服上述现有技术的不足，本发明提供了一种基于磁光测量元件的相差保护方法，本发明只需要测量光强相位，对于幅值的测量精度要求不高，因而避免了磁光元件受外界振动、温度变化等影响而造成保护性能下降。
为实现上述目的，本发明的一个或多个实施例提供了如下技术方案：
一种基于磁光测量元件的相差保护方法，包括：
将具有磁光效应的元件放置在靠近交流线路或电缆的附近；
通过光纤给磁光元件输入恒定光强的偏振光；
线路电流产生的磁场使偏振光的偏振面发生旋转，于是输出的偏振光经过检偏器后光强发生变化，周期性的交流电流产生周期性变化的光强；
通过比较两端光强的波形相位实现相差保护。
进一步的技术方案，所述具有磁光效应的元件是基于法拉第磁光效应的光学元件。
进一步的技术方案，所述输出的偏振光的光强波形是在一个恒定值的基础上，减去一个正弦量而形成的具有周期性的波形；
其中，该恒定值由输入光强决定，正弦量的基波频率和相位与线路电流的基波频率和相位相同。
进一步的技术方案，输出光强经探测器转变成电压信号后滤波，输出电压的基波分量，其频率与相位与线路电流的基波频率与相位相同；
应用相差保护判据，比较被保护线路两侧出射光强的基波相位，实现基于磁光测量元件的相差保护。
进一步的技术方案，交流线路或电缆两端具有磁光效应的元件测量的光强信号，就地转换成数字量，通过通信通道传递给对端，实现相位比较；
相差保护接受本端测量的磁光测量元件的相位信息，以及通信通道传来的对端的相位信息，当两端相位差在[-180°+φ set,180°-φ set]范围内时，保护动 作，其中φ set是相差保护整定值。
进一步的技术方案，将具有磁光效应的元件输出的光信号，直接通过光纤传输到对端，在对端将光强转换成数字量进行相位比较，省略了对通信通道和两端采样同步的需求；
具有磁光效应的元件的输出光强经光电二极管电路转变成电压信号，对该电压进行数字采样，并滤除直流，保留周期分量部分；
然后对周期分量的采样脉冲进行比相，对两端波形每一次采样值进行极性比较，当它们的极性相同时，比较结果置1，反之则置0。累计半个周波内的比较结果，则保护动作的条件为：
Figure PCTCN2020080436-appb-000001
其中，N是每个基波周期的采样点数；Ps(k)是第k个采样点的比较结果；φ set是整定值。
本公开的一个或多个实施例还提供了一种基于磁光测量元件的相差保护系统，包括：光学回路单元及电气回路单元；
光学回路单元中具有磁光效应的元件放置在靠近交流线路或电缆的附近；通过光纤给磁光效应的元件输入恒定光强的偏振光；线路电流产生的磁场使偏振光的偏振面发生旋转；
电气回路单元，将光强转换成电压，对电压信号进行采样，得到基波相位，通过比较两端光强的波形相位实现相差保护。
进一步的技术方案，具有磁光效应的元件为全光纤光学电流互感器。
进一步的技术方案，具有磁光效应的元件采用基于磁光隔离器的磁场测量元件。
以上一个或多个技术方案存在以下有益效果：
本发明采用磁光学原理测量电流相位，避免了电磁式电流互感器的饱和与绝缘等问题；
本发明采用相差原理，只需要测量光强相位，对于幅值的测量精度要求不高，因此振动、温度变化等对磁光元件幅值测量精度的影响不会造成保护性能下降；
本发明提出了采用光纤直接传输光信号到线路对端的方案，省略了对通信通道和两端采样同步的需求，大大降低了实现难度。
本发明提出的相差保护方案成本低、性能好、易于装设，有利于推广应用到有源配电网、厂矿油田、电铁、地铁、海底电缆等场合。
附图说明
构成本发明的一部分的说明书附图用来提供对本发明的进一步理解，本发明的示意性实施例及其说明用于解释本发明，并不构成对本发明的不当限定。
图1是本申请实施例子的交流电流与出射光强的相位关系；
图2是本申请第一种保护案例示意图；
图3是本申请相差保护相位比较示意图；
图4是本申请第二种保护案例示意图；
图5是本申请相差保护脉冲采样比较方案示意图。
具体实施方式
应该指出，以下详细说明都是示例性的，旨在对本发明提供进一步的说明。除非另有指明，本文使用的所有技术和科学术语具有与本发明所属技术领域的普通技术人员通常理解的相同含义。
需要注意的是，这里所使用的术语仅是为了描述具体实施方式，而非意图限制根据本发明的示例性实施方式。如在这里所使用的，除非上下文另外明确指出，否则单数形式也意图包括复数形式，此外，还应当理解的是，当在本说明书中使用术语“包含”和/或“包括”时，其指明存在特征、步骤、操作、器件、组件和/或它们的组合。
在不冲突的情况下，本发明中的实施例及实施例中的特征可以相互组 合。
本发明实施例子应用磁光效应原理，用磁光测量元件测量交流电流产生的磁场。磁光测量元件的输出光强是一个周期信号，其基波频率和相位与交流电流的频率与相位相同。本发明将输出光强信号经过滤波处理后的基波信号用于构造相差保护。本发明采用磁光测量元件测量电流，避免了电磁式电流互感器饱和与绝缘问题；只需要测量出射光强的相位，外界振动、温度变化及内部光学回路等对磁光测量元件的干扰不影响相位的测量和比较，因而易于工程实现，性能稳定可靠。
实施例一
本实施例公开了一种基于磁光测量元件的相差保护方法，将具有磁光效应的元件放置在靠近交流线路或电缆的附近，通过光纤给磁光元件输入恒定光强的偏振光；线路电流产生的磁场使偏振光的偏振面发生旋转，于是输出的偏振光经过检偏器后光强发生变化，周期性的交流电流产生周期性变化的光强。在交流线路或电缆两端放置磁光元件，通过比较两端光强的波形相位实现相差保护。
上述实施例子中，检偏器是一个光学器件，其实就是一个偏振角为特定设置的偏振片，使得偏振光经过检偏器之后光强发生变化，以此检测偏振光的偏振角。
附图2中的探测器是一个光电转换器件，将光信号转换成电信号，输出的电信号大小随输入光强的大小成比例变化。
基于法拉第磁光效应的磁光测量元件的输出光强可以反映电网电流基波相位,而相位不会受外界振动、温度变化等的影响，因此提出通过测量光强相位实现电流相位差动保护。
下面就理论推导给出具体的说明：
设交流输电线路/电缆流过电流为：
i＝I msin(ωt+Φ)   (1)
其中Im是电流幅值，ω是角频率，Φ是初相角。
由安培定律可知，通电导线周围存在着磁场，其大小为：
Figure PCTCN2020080436-appb-000002
其中r是磁光测量点到导线圆心的距离，μ 0＝4π*10 -7N/A 2，i是通过导线的电流，B是磁场感应强度。
因此，在距导线圆心r的位置放置磁光元件，给磁光元件输入偏振光，根据法拉第磁光效应，从磁光元件输出的偏振光的偏振面将发生偏转，偏转角为：
θ＝VBL   (3)
其中，B是磁场感应强度，L是磁光材料长度，V是费尔德常数，θ是偏振光的偏振面旋转的角度。
将磁光元件的输出光经过一个检偏器，检偏器的透光轴与入射偏振光的偏振面之间的夹角为β。根据马吕斯定律，则经过检偏器的出射光强为：
I L＝I L0e -αLcos 2(β+θ)    (4)
其中，I L是输出光强，I L0是输入光强，α是磁光介质的光吸收系数，L是磁光材料长度，β是检偏器的透光轴与入射偏振光的偏振面之间的夹角，θ是偏振光的偏振面旋转的角度。
由式(1)、(2)、(3)、(4)联立可得到，出射光强与入射光强及导线电流的关系式为：
Figure PCTCN2020080436-appb-000003
如果将检偏器的透光轴与入射偏振光的偏振面之间的夹角为β设为45°，代入公式(5)则可以得到：
Figure PCTCN2020080436-appb-000004
分析公式(6)可以知道，输出光强是一个直流分量减去一个交流分量。其中直流分量由输入光强决定；而交流分量是一个正弦函数，函数的角度是一个与正弦电流成比例的参数。经过理论分析和推导，该正弦函数基波频率和相位，与正弦电流的频率和相位相同。因此，将输出光强滤除直流分量之后，其交流分量完全能够反映导线中电流的频率和相位，如图1所示。
在交流线路/电缆两端放置磁光测量元件，通过比较两端输出光强的波形相位，就能够实现相差保护。
其中，在一实施例子中，本实施案例示意图如图2所示；
采用全光纤光学电流互感器作为磁光测量元件，光学电流互感器的输出光强经探测器转变成电压信号。
电压信号经过数字采样变成数字信号，数字信号经过傅立叶滤波，得到基波相位。该相位信息一则用于本端相差保护，一则通过通信通道传递给对端相差保护。
两侧数字采样需要采取措施进行同步，例如应用基于GPS或北斗信号的同步方法。
相差保护接受本端测量的磁光测量元件的相位信息，以及通信通道传来的对端的相位信息，如图3所示，当两端相位差在[-180°+φ set,180°-φ set]范围内时，保护动作；
其中φ set是相差保护整定值，在本实施案例中，φ set＝60°。
在另一实施例子中，公开了基于光纤直接传输光强的信号交互方法，免除了对通信通道和两端采样同步的需求。
本实施案例示意图如图4所示；
采用基于磁光隔离器的磁场测量元件；
线路两端的测量元件的输出光，分别经过光纤，传输到同一端的相差保护中，从而省略了对通信通道和采样同步的需求；
磁场测量元件的输出光强经PIN光电二极管电路转变成电压信号，对该电压进行数字采样，并滤除直流，保留周期分量部分；
然后对周期分量的采样脉冲进行比相，如图5所示。对两端波形每一次采样值进行极性比较，当它们的极性相同时，比较结果置1，反之则置0。累计半个周波内的比较结果，则保护动作的条件为：
Figure PCTCN2020080436-appb-000005
其中，N是每个基波周期的采样点数；P s(k)是第k个采样点的比较结果；φ set是整定值。在本实施案例中，N＝32，φ set＝60°。
在具体实施例子中，磁光测量元件的选择广泛，例如可以是基于磁光玻璃的光学电流互感器(专利号：ZL200820028254.4)，基于光纤的光学电流互感器(专利号：ZL201510543050.9)，以及基于磁光隔离器的磁场测量元件(专利号:ZL201610856075.9)等等。具体根据需要进行选择，此处不再进行列举。
本申请的上述实施例子的方法无需测量线路/电缆的电压量，数据传输量小；而且如果采用光纤直接传输光信号到线路对端的方案，还可以省略对通信通道和两端采样同步的需求，大大降低了实现难度。此外本发明只需要测量光强相位，基于法拉第磁光效应的磁光测量元件的输出光强可以反映电网电流基波相位，对于幅值的测量精度要求不高，因而避免了磁光元件受外界振动、温度变化等影响而造成保护性能下降。
本发明所述的一种基于磁光测量元件的相差保护方法，还可以应用于其它应用场合，如厂矿油田、电铁、地铁、海底电缆等等，应用时，通过测量线路或者电缆两端的磁场实现相差保护。
实施例子二
该实施例子公开了一种基于磁光测量元件的相差保护系统，包括：光学回路单元及电气回路单元；
光学回路单元中具有磁光效应的元件放置在靠近交流线路或电缆的附近；通过光纤给磁光效应的元件输入恒定光强的偏振光；线路电流产生的磁场使偏振光的偏振面发生旋转；
电气回路单元，将光强转换成电压，对电压信号进行采样，得到基波相位，通过比较两端光强的波形相位实现相差保护。
具体实施例中，光学回路单元的基本元件主要包括：激光发射器，光纤(传输激光)，起偏器(将激光变成偏振光)，磁光元件，检偏器(检测偏振角)；不同的测量系统内容不同。例如图2所示的全光纤光学电流互感器，还包括反光镜、1/4波长波片、保偏光纤等等。
电气回路单元的基本元件主要包括：光电检测器(PIN光电二极管)，运算放大器，A/D采样电路，数字信号处理器件(如单片机)等等。
具体技术的实现可参见上述实施例子一的详细描述，此处不再进行说明。
本领域技术人员应该明白，上述本发明的各模块或各步骤可以用通用的计算机装置来实现，可选地，它们可以用计算装置可执行的程序代码来实现，从而，可以将它们存储在存储装置中由计算装置来执行，或者将它们分别制作成各个集成电路模块，或者将它们中的多个模块或步骤制作成单个集成电路模块来实现。本发明不限制于任何特定的硬件和软件的结合。
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。
上述虽然结合附图对本发明的具体实施方式进行了描述，但并非对本发明保护范围的限制，所属领域技术人员应该明白，在本发明的技术方案的基础上，本领域技术人员不需要付出创造性劳动即可做出的各种修改或变形仍在本发明的保护范围以内。

Claims (9)

  1. 一种基于磁光测量元件的相差保护方法，其特征是，包括：
    将具有磁光效应的元件放置在靠近交流线路或电缆的附近；
    通过光纤给磁光元件输入恒定光强的偏振光；
    线路电流产生的磁场使偏振光的偏振面发生旋转，于是输出的偏振光经过检偏器后光强发生变化，周期性的交流电流产生周期性变化的光强；
    通过比较两端光强的波形相位实现相差保护。
  2. 如权利要求1所述的一种基于磁光测量元件的相差保护方法，其特征是，所述具有磁光效应的元件为是基于法拉第磁光效应的光学元件。
  3. 如权利要求1所述的一种基于磁光测量元件的相差保护方法，其特征是，所述输出的偏振光的光强波形是在一个恒定值的基础上，减去一个正弦量而形成的具有周期性的波形；
    其中，该恒定值由输入光强决定，正弦量的基波频率和相位与线路电流的基波频率和相位相同。
  4. 如权利要求3所述的一种基于磁光测量元件的相差保护方法，其特征是，应用相差保护判据，比较被保护线路两侧出射光强的基波相位，实现基于磁光测量元件的相差保护。
  5. 如权利要求1所述的一种基于磁光测量元件的相差保护方法，其特征是，交流线路或电缆两端具有磁光效应的元件测量的光强信号，就地转换成数字量，通过通信通道传递给对端，实现相位比较。
  6. 如权利要求5所述的一种基于磁光测量元件的相差保护方法，其特征是，相差保护接受本端测量的磁光测量元件的相位信息，以及通信通道传来的对端的相位信息，当两端相位差在[-180°+φ set,180°-φ set]范围内时，保护 动作，其中φ set是相差保护整定值。
  7. 如权利要求1所述的一种基于磁光测量元件的相差保护方法，其特征是，将具有磁光效应的元件输出的光信号，直接通过光纤传输到对端，在对端将光强转换成数字量进行相位比较，省略了对通信通道和两端采样同步的需求。
  8. 如权利要求7所述的一种基于磁光测量元件的相差保护方法，其特征是，具有磁光效应的元件的输出光强经光电二极管电路转变成电压信号，对该电压进行数字采样，并滤除直流，保留周期分量部分；
    然后对周期分量的采样脉冲进行比相，对两端波形每一次采样值进行极性比较，当它们的极性相同时，比较结果置1，反之则置0，累计半个周波内的比较结果，则保护动作的条件为：
    Figure PCTCN2020080436-appb-100001
    其中，N是每个基波周期的采样点数；Ps(k)是第k个采样点的比较结果；φ set是整定值。
  9. 一种基于磁光测量元件的相差保护系统，其特征是，包括：光学回路单元及电气回路单元；
    光学回路单元中具有磁光效应的元件放置在靠近交流线路或电缆的附近；通过光纤给磁光效应的元件输入恒定光强的偏振光；线路电流产生的磁场使偏振光的偏振面发生旋转；
    电气回路单元，将光强转换成电压，对电压信号进行采样，得到基波相位，通过比较两端光强的波形相位实现相差保护。
PCT/CN2020/080436 2020-01-20 2020-03-20 一种基于磁光测量元件的相差保护方法及系统 WO2021147163A1 (zh)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CN202010065338.0 2020-01-20
CN202010065338.0A CN111224387B (zh) 2020-01-20 2020-01-20 一种基于磁光测量元件的相差保护方法及系统

Publications (1)

Publication Number Publication Date
WO2021147163A1 true WO2021147163A1 (zh) 2021-07-29

Family

ID=70806830

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CN2020/080436 WO2021147163A1 (zh) 2020-01-20 2020-03-20 一种基于磁光测量元件的相差保护方法及系统

Country Status (2)

Country Link
CN (1) CN111224387B (zh)
WO (1) WO2021147163A1 (zh)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001050988A (ja) * 1999-08-09 2001-02-23 Takaoka Electric Mfg Co Ltd 光電流センサを用いる電流測定方法およびその装置
CN1623261A (zh) * 2002-02-18 2005-06-01 株式会社高岳制作所 使用光电流传感器的保护继电装置
CN1862903A (zh) * 2006-06-16 2006-11-15 天津大学 特高压输电线分相电流相位差动保护方法
CN103715650A (zh) * 2014-01-20 2014-04-09 哈尔滨工业大学 基于法拉第磁光效应的差动保护装置
CN103730884A (zh) * 2014-01-22 2014-04-16 国家电网公司 一种光子差动保护装置

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107884611A (zh) * 2016-09-30 2018-04-06 南京南瑞继保电气有限公司 一种多环全光纤电流互感器

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001050988A (ja) * 1999-08-09 2001-02-23 Takaoka Electric Mfg Co Ltd 光電流センサを用いる電流測定方法およびその装置
CN1623261A (zh) * 2002-02-18 2005-06-01 株式会社高岳制作所 使用光电流传感器的保护继电装置
CN1862903A (zh) * 2006-06-16 2006-11-15 天津大学 特高压输电线分相电流相位差动保护方法
CN103715650A (zh) * 2014-01-20 2014-04-09 哈尔滨工业大学 基于法拉第磁光效应的差动保护装置
CN103730884A (zh) * 2014-01-22 2014-04-16 国家电网公司 一种光子差动保护装置

Also Published As

Publication number Publication date
CN111224387B (zh) 2021-03-16
CN111224387A (zh) 2020-06-02

Similar Documents

Publication Publication Date Title
CN101957399B (zh) 一种数字闭环型光纤电流传感器
CN106526277B (zh) 一种用于低压光学电流传感器的新型光路传感单元
CN107643438A (zh) 基于法拉第磁光效应的光学电流传感器及其电流测量方法
JPH0224349B2 (zh)
CN103777062B (zh) 一种干涉环式全光纤电流互感器
CN113945744B (zh) 一种全光纤直流电流互感器温度补偿系统及方法
CN101968507A (zh) 光纤电压传感器及其调节方法
CN103163351B (zh) 一种三相共用光源的光学电压传感器
CN112904070B (zh) 全光纤电流互感器及其检测模块、光路状态诊断方法
CN114577245B (zh) 一种同时测量电流和振动的光纤传感系统
CN202330519U (zh) 一种采用干涉闭环检测的磁光玻璃光学电流互感器
CN1540355A (zh) 反射式萨格奈克干涉仪型全光纤电流互感器
WO2021147163A1 (zh) 一种基于磁光测量元件的相差保护方法及系统
Wang et al. Application of electronic transformers in digital substation
CN104049230A (zh) 一种光纤电流互感器频响特性测试系统及方法
CN107422166B (zh) 一种光纤电流互感器用抑制光功率波动调制解调方法
CN110927431A (zh) 闭环解调全光纤电流互感器及其大电流波形跳变问题解决方法
CN203606428U (zh) 一种光纤电流传感器
CN102929323A (zh) 全光纤电流传感器及电流闭环反馈校正方法
CN110045169A (zh) 一种磁光材料多级级联的光学电流传感器及测量系统
CN202330527U (zh) 一种光学电场传感器
Ye et al. Application research on fiber-optic current sensor in large pulse current measurement
CN203299254U (zh) 反馈平衡式光纤电流互感器
CN109946511B (zh) 一种集成光波导电功率传感芯片及其构建的测量系统
CN203606419U (zh) 一种干涉环式全光纤电流互感器

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 20916007

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 20916007

Country of ref document: EP

Kind code of ref document: A1

122 Ep: pct application non-entry in european phase

Ref document number: 20916007

Country of ref document: EP

Kind code of ref document: A1

32PN Ep: public notification in the ep bulletin as address of the adressee cannot be established

Free format text: NOTING OF LOSS OF RIGHTS PURSUANT TO RULE 112(1) EPC (EPO FORM 1205A DATED 24.01.2023)

122 Ep: pct application non-entry in european phase

Ref document number: 20916007

Country of ref document: EP

Kind code of ref document: A1