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CN104345218A - Reactance value measurement system and method for three-phase reactor - Google Patents

Reactance value measurement system and method for three-phase reactor Download PDF

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CN104345218A
CN104345218A CN201410550306.4A CN201410550306A CN104345218A CN 104345218 A CN104345218 A CN 104345218A CN 201410550306 A CN201410550306 A CN 201410550306A CN 104345218 A CN104345218 A CN 104345218A
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output
current
phase reactor
power supply
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CN104345218B (en
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徐林峰
朱东柏
毛启武
欧小波
马志钦
柯春俊
饶章权
林一峰
罗彩仪
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Harbin University of Science and Technology
Electric Power Research Institute of Guangdong Power Grid Co Ltd
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Harbin University of Science and Technology
Electric Power Research Institute of Guangdong Power Grid Co Ltd
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Abstract

一种三相电抗器的电抗值测量系统,包括:三相逆变电源单元的直流侧为系统经整流或用蓄电池为逆变器提供的直流电源、交流侧的输出经RC组成的低通滤波器后分别接被测三相电抗器一端;被测三相电抗器另一端接系统中性点;三相电信号检测单元分别串联在三相逆变电源单元输出至接被测三相电抗器的三相线上、其采集的电流信号分别输出至计算控制单元的第一接线端子;计算控制单元的组成和连接关系为:依次连接的第一接线端子、调理电路、A/D、CPLD、双口RAM和DSP,CPLD还分别外接PWM传输电路和开入开出电路,所述的PWM传输电路和开入开出电路通过第二接线端子外联。本发明具有结构紧凑、功能先进、试验效率高、方便现场使用的特点,且测量准确误差小。

A system for measuring the reactance value of a three-phase reactor, including: the DC side of the three-phase inverter power supply unit is the DC power supply provided by the system through rectification or a battery for the inverter, and the output of the AC side is low-pass filtered by RC connected to one end of the three-phase reactor under test; the other end of the three-phase reactor under test is connected to the neutral point of the system; the three-phase electrical signal detection units are respectively connected in series to the output of the three-phase inverter power supply unit and connected to the three-phase reactor under test The collected current signals are respectively output to the first connection terminal of the calculation control unit; the composition and connection relationship of the calculation control unit are: the first connection terminal, conditioning circuit, A/D, CPLD, The dual-port RAM, DSP, and CPLD are respectively externally connected with a PWM transmission circuit and a binary input and output circuit, and the PWM transmission circuit and binary input and output circuit are externally connected through the second connection terminal. The invention has the characteristics of compact structure, advanced function, high test efficiency, convenient on-site use, and small measurement error.

Description

Three-phase reactor reactance value measuring system and method
Technical field
The present invention relates to a kind of three-phase reactor reactance value measuring system.The invention still further relates to the method adopting described system to carry out the measurement of three-phase reactor reactance value.
Background technology
Reactor is a kind of conventional, important power equipment in electrical network, is widely used in the aspects such as reactive-load compensation, current limliting, current stabilization (flat ripple), filtering, damping, phase shift in circuit.GB/T 1094.6-2011 " power transformer the 6th part: reactor " lists the measurement of reactor reactance value in delivery test project; To the reactor put into operation, its reactance value measurement judges that it normally runs no important indicator, lists preventive trial project in; And according to national Specification, to iron core reactor reactance measurement should to be greater than under 90% rated current just effective.
Traditional three-phase reactor reactance value measurement mechanism, is made up of generator, pressure regulator, compensation condenser group, current transformer, voltage transformer (VT), voltage table, reometer, stube cable and mating fastener.There is the shortcoming large, structure is scattered, cost is high that takes up room in such device, can only for the manufacture of factory or professional test mechanism; At present, to the reactor come into operation, almost reactance measurement cannot be completed.
Further, traditional three-phase reactor reactance value measurement is based on three-phase symmetric voltage source metering system, itself there is following defect: (1) inductance measurement result is relevant with the internal resistance of source, and different inner walkway results is different, therefore there is systematic error; (2) be difficult to accomplish that the value of three-phase current is more close, three-phase current varies in size and affects alternate induced voltage by mutual inductance, thus affects measurement result, about current deviation no standard; (3) even if can accomplish that three-phase electricity flow valuve is equal, but three-phase current may not be symmetrical, still affects alternate induced voltage, causes measuring and forbidden.
Summary of the invention
First technical matters to be solved by this invention, proposes a kind of three-phase reactor reactance value measuring system exactly.
Second technical matters to be solved by this invention, proposes a kind of measuring method adopting described system to carry out three-phase reactor reactance value exactly.
The feature that system of the present invention has compact conformation, function is advanced, test efficiency is high, facilitate onsite application, and the reactance value measuring method adopting described system to carry out three-phase reactor to measure accurate error little.
Solve above-mentioned first technical matters, the technical solution used in the present invention is:
A reactance value measuring system for three-phase reactor, is characterized in that: comprise three phase inverter unit, three-phase electricity detecting signal unit and calculation control unit;
The DC side of described three phase inverter unit connects tested three-phase reactor one end respectively through the output of rectification or the direct supply provided for inverter with accumulator, AC for system after the low-pass filter that RC forms; Tested three-phase reactor other end welding system neutral point;
Described three-phase electricity detecting signal unit be connected on respectively three phase inverter unit export to connect tested three-phase reactor triple-phase line on, its current signal gathered exports the first connection terminal of calculation control unit respectively to;
The composition of described calculation control unit with annexation is: the first connection terminal be connected successively, modulate circuit, A/D, CPLD (Complex Programable Logic Device), dual port RAM and DSP (Digital Signal Processing), described CPLD also distinguishes external PWM transmission circuit and input and output circuit, and described PWM transmission circuit and input and output circuit are outreached by the second connection terminal.
The low-pass filter of described RC composition is resistance and the electric capacity of series connection, and the Hall voltage sensor in parallel at electric capacity two ends, it exports u a, u b, u c.
Described three phase inverter unit adopts 3 single-phase inverters composition, and three phase inverter unit adopts PWM (width modulation) technology, the frequency of PWM at 2 ~ 12kHz, instruction cycle 40us, device sine wave output frequency range is 0.5 ~ 50Hz;
Described three-phase electricity detecting signal unit adopts Hall current sensor to measure three-phase current i a, i b, i c, adopt RC filtering circuit (see Fig. 3 modulate circuit) and Hall voltage sensor measurement three-phase voltage u a, u b, u c;
Described calculation control unit CPU adopts TI company floating point DSP chip TMS320C6713, and core frequency can reach 225MHz.Logic chip adopts CPLD, controls outside 8 passage 14 AD, and sends PWM instruction.Controller inside possesses the On-off signal output module of some, for controlling external communication contactor.
Solve above-mentioned second technical matters, the technical solution used in the present invention is:
Adopt described system to carry out a method for three-phase reactor reactance value measurement, comprise the following steps:
The first step, calculates according to the volumeter of the inductance ratings value of tested three-phase reactor, rated current and native system the maximum frequency that native system can bear;
Second step, calculates according to native system output frequency the sampled voltage phase shift and amplitude coefficient that RC wave filter causes, and instead pushes away voltage over zero;
3rd step, finds voltage over zero according to detection magnitude of voltage, and sets up sin ω t and cos ω t;
In formula, ω is power supply angular frequency; T is the time;
4th step, calculates the meritorious of output current and reactive current according to sin ω t and cos ω t:
I M 1 = 2 N Σ k = 1 N i k sin ( k ) ;
I M 2 = 2 N Σ k = 1 N i k cos ( k ) ;
In formula, I m1, I m2be respectively active current, peak value of idle current; N is a cycle discrete point number; i kit is the electric current discrete signal detected; Sin (k), cos (k) are the discrete magnitude of sin ω t and cos ω t respectively;
5th step, calculates the inductance value of reactor according to voltage and reactive current:
L = U M ω I M 2
Capacity formula due to three-phase reactor is P n=3 ω L ni 2namely the capacity of reactor is directly proportional to the frequency applying electric current, and therefore under same test current, reducing ω can effectively reduce capacity of experiment, also just can reduce required testing equipment capacity.
So thinking of the present invention is that the frequency by reducing to measure power supply reaches reduction measuring equipment capacity problem, meets in-site measurement requirement; The current source of making three-phase controlled frequency, controlled current flow substitutes three-phase voltage source to improve the accuracy of three pole reactor measurement.
The present invention compared with prior art has following advantage:
1, the sine wave freuqency scope that system of the present invention exports is 0.5 ~ 50Hz, and the capacity formula of three-phase reactor is P n=3 ω L ni 2therefore, under same test current, reduce required testing equipment capacity can be effectively reduced.
2, three phase inverter unit of the present invention adopts current tracking PWM technology, the three-phase electricity flow valuve exported is symmetrical and equal, eliminates the adverse effect of current deviation to mutual voltage, improves accuracy of measurement, eliminate the impact of the internal resistance of source, measurement result does not have Systematic Errors.
Accompanying drawing explanation
Fig. 1 a is one of structural representation of the present invention (wiring diagram);
Fig. 1 b is structural representation two (three-phase inverting circuit) of the present invention;
Fig. 2 is the wiring schematic diagram of three-phase electricity detecting signal unit;
Fig. 3 is calculation control unit composition and annexation schematic diagram.
Embodiment
Below in conjunction with accompanying drawing, the invention will be further described.
Participate in 4 years Fig. 1-Fig. 3, the reactance value measuring system embodiment of three-phase reactor of the present invention, comprises three phase inverter unit, three-phase electricity detecting signal unit and calculation control unit.
Three phase inverter unit DC side connects tested three-phase reactor one end respectively, tested three-phase reactor other end welding system neutral point for system after the low-pass filter (the external connecting circuit of A, B, C of Fig. 1 a) that the output of rectification or the direct supply provided for inverter with accumulator, AC forms through RC; Three-phase electricity detecting signal unit be connected on respectively three phase inverter unit export to connect tested three-phase reactor triple-phase line on, its current signal gathered exports the first connection terminal of calculation control unit respectively to; Calculating the composition controlling list with annexation is: the first connection terminal, modulate circuit, A/D, CPLD, dual port RAM and the DSP that are connected successively, CPLD also distinguishes external PWM transmission circuit and input and output circuit, and described PWM transmission circuit and input and output circuit are outreached by the second connection terminal.
Three phase inverter unit adopts 3 single-phase inverters composition, and three phase inverter unit adopts PWM (width modulation) technology, the frequency of PWM at 2 ~ 12kHz, instruction cycle 40us, device sine wave output frequency range is 0.5 ~ 50Hz; Three-phase electricity detecting signal unit adopts Hall current sensor to measure three-phase current i a, i b, i c, adopt RC filtering circuit and Hall voltage sensor measurement three-phase voltage u a, u b, u c; Calculation control unit CPU adopts TI company floating point DSP chip TMS320C6713, and core frequency can reach 225MHz.Logic chip adopts CPLD, controls outside 8 passage 14 AD, and sends PWM instruction.Controller inside possesses the On-off signal output module of some, for controlling external communication contactor.
The current signal of Hall current sensor collection enters A/D converter through the RC filtering of control panel, the CPLD control AD sampling time, by the signal write dual port RAM gathered; DSP calculates amplitude and the frequency of instruction current according to the volumeter of tested three-phase reactor rated current, inductance ratings value and testing equipment, CPLD is write back through dual port RAM, CPLD adopts the pwm signal needed for the generation of stagnant ring comparative approach, delivers to driver through isolating chip; Adopt optical-fibre communications between controller and inverter, improve the interference free performance of testing equipment calculation and control device unit.
Adopt said system to carry out the method for three-phase reactor reactance value measurement, comprise the following steps:
The first step, calculates according to the volumeter of the inductance ratings value of tested three-phase reactor, rated current and native system the maximum frequency that native system can bear;
Second step, calculates according to native system output frequency the sampled voltage phase shift and amplitude coefficient that RC wave filter causes, and instead pushes away voltage over zero;
3rd step, finds voltage over zero according to detectable voltage signals, and sets up sin ω t and cos ω t;
4th step, calculates the meritorious of output current and reactive current according to sin ω t and cos ω t;
5th step, calculates the inductance value of reactor according to voltage and reactive current.

Claims (4)

1.一种三相电抗器的电抗值测量系统,其特征是:包括三相逆变电源单元、三相电信号检测单元和计算控制单元;1. A reactance value measurement system of a three-phase reactor, characterized in that it comprises a three-phase inverter power supply unit, a three-phase electrical signal detection unit and a calculation control unit; 所述的三相逆变电源单元的直流侧为系统经整流或用蓄电池为逆变器提供的直流电源、交流侧的输出经RC组成的低通滤波器后分别接被测三相电抗器一端;被测三相电抗器另一端接系统中性点;The DC side of the three-phase inverter power supply unit is rectified by the system or the DC power provided by the battery for the inverter, and the output of the AC side is connected to one end of the three-phase reactor to be tested after passing through a low-pass filter composed of RC ;The other end of the three-phase reactor under test is connected to the neutral point of the system; 所述的三相电信号检测单元分别串联在三相逆变电源单元输出至接被测三相电抗器的三相线上、其采集的电流信号分别输出至计算控制单元的第一接线端子;The three-phase electrical signal detection units are respectively connected in series with the three-phase inverter power supply unit and output to the three-phase line connected to the three-phase reactor to be tested, and the current signals collected by it are respectively output to the first terminal of the calculation control unit; 所述的计算控制单元的组成和连接关系为:依次连接的第一接线端子、调理电路、A/D、CPLD(Complex Programable Logic Device)、双口RAM和DSP(Digital Signal Processing),所述的CPLD还分别外接PWM传输电路和开入开出电路,所述的PWM传输电路和开入开出电路通过第二接线端子外联。The composition and connection relationship of the calculation control unit are: the first connecting terminal, conditioning circuit, A/D, CPLD (Complex Programable Logic Device), dual-port RAM and DSP (Digital Signal Processing) connected in sequence, the described The CPLD is also externally connected with a PWM transmission circuit and a binary input and output circuit, and the PWM transmission circuit and binary input and output circuit are externally connected through the second connection terminal. 2.根据权利要求1所述的三相电抗器的电抗值测量系统,其特征是:所述的RC组成的低通滤波器为串联的电阻和电容,在电容两端并联霍尔电压传感器,其输出uA、uB、uC2. The reactance value measuring system of the three-phase reactor according to claim 1, characterized in that: the low-pass filter formed by the RC is a resistor and a capacitor connected in series, and a Hall voltage sensor is connected in parallel at both ends of the capacitor, It outputs u A , u B , u C . 3.根据权利要求2所述的三相电抗器的电抗值测量系统,其特征是:所述三相逆变电源单元采用3个单相逆变器组成,三相逆变电源单元采用PWM(脉宽调制)技术,PWM的频率在2~12kHz,指令周期40us,装置输出正弦波频率范围为0.5~50Hz;3. the reactance value measurement system of three-phase reactor according to claim 2, is characterized in that: described three-phase inverter power supply unit adopts 3 single-phase inverters to form, and three-phase inverter power supply unit adopts PWM ( Pulse Width Modulation) technology, the PWM frequency is 2-12kHz, the instruction cycle is 40us, and the frequency range of the device output sine wave is 0.5-50Hz; 所述三相电信号检测单元采用霍尔电流传感器测量三相电流iA、iB、iC,采用RC滤波电路(见图3调理电路)与霍尔电压传感器测量三相电压uA、uB、uCThe three-phase electrical signal detection unit uses a Hall current sensor to measure the three-phase currents i A , i B , and i C , uses an RC filter circuit (see Fig. 3 conditioning circuit) and a Hall voltage sensor to measure the three-phase voltages u A , u B , u C ; 所述计算控制单元CPU采用TI公司高速浮点DSP芯片TMS320C6713,内核频率可达到225MHz;逻辑芯片采用CPLD,控制外部8通道14位AD,并发出PWM指令;控制器内部具备一定数量的开关量输入输出模块,用于控制外部交流接触器。The calculation and control unit CPU adopts TI's high-speed floating-point DSP chip TMS320C6713, and the core frequency can reach 225MHz; the logic chip adopts CPLD, controls the external 8-channel 14-bit AD, and sends out PWM instructions; the controller has a certain number of switch input Output module for controlling external AC contactors. 4.一种采用如权利要求1-3任意一项所述的系统进行三相电抗器电抗值测量的方法,其特征是包括以下步骤:4. A method for measuring the reactance value of a three-phase reactor using the system according to any one of claims 1-3, characterized in that it comprises the following steps: 第一步,根据被测三相电抗器的额定电感值、额定电流与本系统的容量计算出本系统所能承受的最大频率;The first step is to calculate the maximum frequency that the system can withstand according to the rated inductance value, rated current of the three-phase reactor to be tested and the capacity of the system; 第二步,根据本系统输出频率计算RC滤波器引起的采样电压相移与幅值系数,反推电压过零点;The second step is to calculate the phase shift and amplitude coefficient of the sampling voltage caused by the RC filter according to the output frequency of the system, and reverse the voltage zero-crossing point; 第三步,根据检测电压值找到电压过零点,并建立sinωt与cosωt;The third step is to find the voltage zero-crossing point according to the detected voltage value, and establish sinωt and cosωt; 式中,ω为电源角频率;t为时间;In the formula, ω is the angular frequency of the power supply; t is the time; 第四步,根据sinωt与cosωt计算输出电流的有功与无功电流:The fourth step is to calculate the active and reactive currents of the output current according to sinωt and cosωt: II Mm 11 == 22 NN ΣΣ kk == 11 NN ii kk sinsin (( kk )) ;; II Mm 22 == 22 NN ΣΣ kk == 11 NN ii kk coscos (( kk )) ;; 式中,IM1、IM2分别为有功电流、无功电流峰值;N为一个周波离散点数目;ik是检测的电流离散信号;sin(k)、cos(k)分别是sinωt与cosωt的离散量;In the formula, I M1 and I M2 are the peak value of active current and reactive current respectively; N is the number of discrete points of a cycle; i k is the detected current discrete signal; sin(k) and cos(k) are the values of sinωt and cosωt respectively Discrete quantity; 第五步,根据电压与无功电流计算电抗器的电感值:The fifth step is to calculate the inductance value of the reactor according to the voltage and reactive current: LL == Uu Mm ωIω I Mm 22 由于三相电抗器的容量公式为PN=3ωLNI2即电抗器的容量与施加电流的频率成正比,因此在同样的试验电流下,减小ω可以有效减小试验容量,也就可以降低所需试验设备容量。Since the capacity formula of the three-phase reactor is P N =3ωL N I 2 , that is, the capacity of the reactor is proportional to the frequency of the applied current, therefore, under the same test current, reducing ω can effectively reduce the test capacity, which can also Reduce the required test equipment capacity.
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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105548724A (en) * 2015-12-10 2016-05-04 广东新昇电业科技股份有限公司 Test system and method of inductance value of smoothing reactor
CN106646029A (en) * 2016-11-18 2017-05-10 武汉电联电力电气技术有限公司 Capacitor measurement device and reactor characteristic testing method
CN107219415A (en) * 2017-05-08 2017-09-29 中国电力科学研究院 A system and method for testing comprehensive electrical performance parameters of dry-type air-core reactors

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN201425872Y (en) * 2009-04-21 2010-03-17 山东哈大电气有限公司 Inductance-adjusting filter reactor
CN102495328A (en) * 2011-12-23 2012-06-13 古亮 Differential power reactor fault on-line monitoring instrument
CN203414528U (en) * 2013-06-28 2014-01-29 国家电网公司 Apparatus for live-line testing of reactance values of parallel-connected reactors
CN103605015A (en) * 2013-10-24 2014-02-26 西安欣东源电气有限公司 Device and method for high-precision electric parameter measurement dry-type reactor online monitoring
CN203759132U (en) * 2014-01-16 2014-08-06 昆山雷特电机有限公司 Novel reactor tester
US20140292455A1 (en) * 2011-10-31 2014-10-02 Hitachi, Ltd. Reactor, Transformer, and Power Conversion Apparatus Using Same

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN201425872Y (en) * 2009-04-21 2010-03-17 山东哈大电气有限公司 Inductance-adjusting filter reactor
US20140292455A1 (en) * 2011-10-31 2014-10-02 Hitachi, Ltd. Reactor, Transformer, and Power Conversion Apparatus Using Same
CN102495328A (en) * 2011-12-23 2012-06-13 古亮 Differential power reactor fault on-line monitoring instrument
CN203414528U (en) * 2013-06-28 2014-01-29 国家电网公司 Apparatus for live-line testing of reactance values of parallel-connected reactors
CN103605015A (en) * 2013-10-24 2014-02-26 西安欣东源电气有限公司 Device and method for high-precision electric parameter measurement dry-type reactor online monitoring
CN203759132U (en) * 2014-01-16 2014-08-06 昆山雷特电机有限公司 Novel reactor tester

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105548724A (en) * 2015-12-10 2016-05-04 广东新昇电业科技股份有限公司 Test system and method of inductance value of smoothing reactor
CN105548724B (en) * 2015-12-10 2018-08-10 广东新昇电业科技股份有限公司 The test system and method for smoothing reactor sensibility reciprocal
CN106646029A (en) * 2016-11-18 2017-05-10 武汉电联电力电气技术有限公司 Capacitor measurement device and reactor characteristic testing method
CN107219415A (en) * 2017-05-08 2017-09-29 中国电力科学研究院 A system and method for testing comprehensive electrical performance parameters of dry-type air-core reactors

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