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 PDFInfo
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- 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
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- 230000004224 protection Effects 0.000 title claims abstract description 75
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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
- H02H7/261—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
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- 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.
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Abstract
Description
Claims (9)
- 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。
- 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。
- 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。
- 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。
- 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。
- 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。
- 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。
- 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。
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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 |
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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 |
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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 |
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Patent Citations (5)
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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 |
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