CN106405191B - A zero-sequence current sampling circuit for accurate judgment of AC grounding and its judgment method - Google Patents
A zero-sequence current sampling circuit for accurate judgment of AC grounding and its judgment method Download PDFInfo
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Abstract
本发明公开了一种交流接地精准判断的零序电流取样电路，包含A相取样电路、B相取样电路、C相取样电路、零序电流幅值A/D转换模块、零序电阻相位预处理模块、智能微处理器，A相取样电路、B相取样电路和C相取样电路分别进行三相电源电流取样并将三相电流信号叠加后输送至零序电流幅值A/D转换模块和零序电阻相位预处理模块将零序电流的幅值和相位进行正确的接地故障判断、报警或输出保护信号。本发明结构简单、运行可靠、性价比高，有效保证电网的安全、经济运行。
The invention discloses a zero-sequence current sampling circuit for accurate judgment of AC grounding, which includes an A-phase sampling circuit, a B-phase sampling circuit, a C-phase sampling circuit, a zero-sequence current amplitude A/D conversion module, and a zero-sequence resistance phase preprocessing Module, intelligent microprocessor, A-phase sampling circuit, B-phase sampling circuit and C-phase sampling circuit respectively perform three-phase power supply current sampling and superimpose the three-phase current signals and send them to the zero-sequence current amplitude A/D conversion module and zero-sequence current amplitude A/D conversion module The sequence resistance phase preprocessing module will correctly judge the magnitude and phase of the zero-sequence current for grounding faults, alarm or output protection signals. The invention has the advantages of simple structure, reliable operation and high cost performance, and effectively guarantees the safe and economical operation of the power grid.
Description
技术领域technical field
本发明涉及一种零序电流取样电路及接地判断方法，特别是一种交流接地精准判断的零序电流取样电路及其判断方法。The invention relates to a zero-sequence current sampling circuit and a grounding judgment method, in particular to a zero-sequence current sampling circuit and a judgment method for accurately judging AC grounding.
背景技术Background technique
电网的接地故障是一种常见故障，如果发生要及时进行排除处理，否则会影响电网的安全运行。目前在电网的各个连接关口一般均设置具有接地故障保护装置，在其检测到接地故障时会发出报警信号，并在超过设定时间后发出断开接地故障线路的跳闸信号，以避免事故的扩大。The ground fault of the power grid is a common fault. If it occurs, it must be eliminated in time, otherwise it will affect the safe operation of the power grid. At present, each connection point of the power grid is generally equipped with a ground fault protection device, which will send an alarm signal when it detects a ground fault, and send a trip signal to disconnect the ground fault line after the set time, so as to avoid the expansion of the accident .
由于电网结构和接地方式的多样性，现有的电网接地保护装置类产品普遍存在接地判断不准确的问题，多有误报和漏报接地故障的情况，因此危害电网的安全、经济运行。Due to the diversity of power grid structure and grounding methods, the existing power grid grounding protection devices generally have the problem of inaccurate grounding judgment, and often have false or missed grounding faults, which endanger the safe and economical operation of the power grid.
现有的电网接地保护装置类产品的接地故障判断不准确的主要原因是其对接地故障产生的零序电流的取样不准确造成的，因为接地故障产生的零序电流的取样涉及高压电气隔离等措施及较小的接地故障电流混杂于负载大电流中，要取得在幅值上和相位上与实际接地故障电流成线性比例的可让智能微处理电路读取的信号比较困难。The main reason for the inaccurate judgment of the ground fault of the existing power grid grounding protection device products is the inaccurate sampling of the zero-sequence current generated by the ground fault, because the sampling of the zero-sequence current generated by the ground fault involves high-voltage electrical isolation, etc. Measures and small ground fault currents are mixed in the large load current, and it is difficult to obtain a signal that is linearly proportional to the actual ground fault current in amplitude and phase and can be read by an intelligent microprocessor circuit.
发明内容Contents of the invention
本发明所要解决的技术问题是提供一种交流接地精准判断的零序电流取样电路及其判断方法。The technical problem to be solved by the present invention is to provide a zero-sequence current sampling circuit and its judgment method for accurate judgment of AC grounding.
为解决上述技术问题，本发明所采用的技术方案是：In order to solve the problems of the technologies described above, the technical solution adopted in the present invention is:
一种交流接地精准判断的零序电流取样电路，其特征在于：包含A相取样电路、B相取样电路、C相取样电路、零序电流幅值A/D转换模块、零序电阻相位预处理模块、智能微处理器，A相取样电路、B相取样电路和C相取样电路分别进行三相电源电流取样并将三相电流信号叠加后输送至零序电流幅值A/D转换模块和零序电阻相位预处理模块将零序电流的幅值和相位进行正确的接地故障判断、报警或输出保护信号。A zero-sequence current sampling circuit for accurate judgment of AC grounding, characterized in that it includes an A-phase sampling circuit, a B-phase sampling circuit, a C-phase sampling circuit, a zero-sequence current amplitude A/D conversion module, and a zero-sequence resistance phase preprocessing The module, intelligent microprocessor, A-phase sampling circuit, B-phase sampling circuit and C-phase sampling circuit respectively perform three-phase power supply current sampling and superimpose the three-phase current signals and send them to the zero-sequence current amplitude A/D conversion module and zero-sequence current amplitude A/D conversion module. The sequence resistance phase preprocessing module will correctly judge the magnitude and phase of the zero-sequence current for grounding faults, alarm or output protection signals.
进一步地，所述A相取样电路结构为，电流互感器La1设置在三相电源A相线路上进行电流取样，电流互感器La1一端与转换电阻Ra1和分压调节电位器Ra2的一端连接，电流互感器La1另一端与转换电阻Ra1另一端和分压电阻Ra3的另一端连接，分压调节电位器Ra2和分压电阻Ra3的另一端与限流保护电阻Ra4的一端连接，限流保护电阻Ra4另一端与信号跟随PNP型三极管Da1的基极、相位反馈调节电感La2的一端连接，相位反馈调节电感La2另一端与相位反馈限定电阻Ra5一端连接，相位反馈限定电阻Ra5另一端与信号跟随PNP型三极管Da1集电极、相位反馈比例电阻Ra6一端连接，信号跟随PNP型三极管Da1的发射极与信号限定电阻Ra7和信号跟随分流电阻Ra8的一端连接，信号跟随分流电阻Ra8另一端接地，过电压保护器件Da2正极与电流互感器La1另一端连接，过电压保护器件Da2负极与信号跟随PNP型三极管Da1基极连接；Further, the structure of the A-phase sampling circuit is that the current transformer La1 is arranged on the A-phase line of the three-phase power supply for current sampling, and one end of the current transformer La1 is connected with the switching resistor Ra1 and one end of the voltage dividing adjustment potentiometer Ra2, and the current The other end of the transformer La1 is connected to the other end of the conversion resistor Ra1 and the other end of the voltage dividing resistor Ra3, the other end of the voltage dividing adjustment potentiometer Ra2 and the voltage dividing resistor Ra3 is connected to one end of the current limiting protection resistor Ra4, and the current limiting protection resistor Ra4 The other end is connected to the base of the signal following PNP transistor Da1 and one end of the phase feedback adjusting inductor La2, the other end of the phase feedback adjusting inductor La2 is connected to one end of the phase feedback limiting resistor Ra5, the other end of the phase feedback limiting resistor Ra5 is connected to the signal following PNP type The collector of the triode Da1 is connected to one end of the phase feedback proportional resistor Ra6, and the signal follows the emitter of the PNP transistor Da1. The signal limiting resistor Ra7 and one end of the signal following shunt resistor Ra8 are connected, and the other end of the signal following shunt resistor Ra8 is grounded, and the overvoltage protection device The positive electrode of Da2 is connected to the other end of the current transformer La1, and the negative electrode of the overvoltage protection device Da2 is connected to the base of the signal-following PNP transistor Da1;
所述B相取样电路结构为，电流互感器Lb1设置在三相电源B相线路上进行电流取样，电流互感器Lb1一端与转换电阻Rb1和分压调节电位器Rb2的一端连接，电流互感器Lb1另一端与转换电阻Rb1另一端和分压电阻Rb3的另一端连接，分压调节电位器Rb2和分压电阻Rb3的另一端与限流保护电阻Rb4的一端连接，限流保护电阻Rb4另一端与信号跟随PNP型三极管Db1的基极、相位反馈调节电感Lb2的一端连接，相位反馈调节电感Lb2另一端与相位反馈限定电阻Rb5一端连接，相位反馈限定电阻Rb5另一端与信号跟随PNP型三极管Db1集电极、相位反馈比例电阻Rb6一端连接，信号跟随PNP型三极管Db1的发射极与信号限定电阻Rb7和信号跟随分流电阻Rb8的一端连接，信号跟随分流电阻Rb8另一端接地，过电压保护器件Db2正极与电流互感器Lb1另一端连接，过电压保护器件Db2负极与信号跟随PNP型三极管Db1基极连接；The structure of the B-phase sampling circuit is that the current transformer Lb1 is arranged on the B-phase line of the three-phase power supply to perform current sampling, and one end of the current transformer Lb1 is connected with the switching resistor Rb1 and one end of the voltage dividing adjustment potentiometer Rb2, and the current transformer Lb1 The other end is connected to the other end of the conversion resistor Rb1 and the other end of the voltage dividing resistor Rb3, the other end of the voltage dividing adjustment potentiometer Rb2 and the voltage dividing resistor Rb3 is connected to one end of the current limiting protection resistor Rb4, and the other end of the current limiting protection resistor Rb4 is connected to The signal follows the base of the PNP transistor Db1 and one end of the phase feedback adjustment inductor Lb2 is connected, the other end of the phase feedback adjustment inductor Lb2 is connected to one end of the phase feedback limiting resistor Rb5, the other end of the phase feedback limiting resistor Rb5 is connected to the signal following the PNP transistor Db1 set One end of the electrode and phase feedback proportional resistor Rb6 is connected, the signal follows the emitter of the PNP transistor Db1, the signal limiting resistor Rb7 and one end of the signal following shunt resistor Rb8 are connected, the other end of the signal following shunt resistor Rb8 is grounded, and the positive electrode of the overvoltage protection device Db2 is connected to The other end of the current transformer Lb1 is connected, and the negative electrode of the overvoltage protection device Db2 is connected to the base of the signal-following PNP transistor Db1;
所述C相取样电路结构为，电流互感器Lc1设置在三相电源C线路上进行电流取样，电流互感器Lc1一端与转换电阻Rc1和分压调节电位器Rc2的一端连接，电流互感器Lc1另一端与转换电阻Rc1另一端和分压电阻Rc3的另一端连接，分压调节电位器Rc2和分压电阻Rc3的另一端与限流保护电阻Rc4的一端连接，限流保护电阻Rc4另一端与信号跟随PNP型三极管Dc1的基极、相位反馈调节电感Lc2的一端连接，相位反馈调节电感Lc2另一端与相位反馈限定电阻Rc5一端连接，相位反馈限定电阻Rc5另一端与信号跟随PNP型三极管Dc1集电极、相位反馈比例电阻Rc6一端连接，信号跟随PNP型三极管Dc1的发射极与信号限定电阻Rc7和信号跟随分流电阻Rc8的一端连接，信号跟随分流电阻Rc8另一端接地，过电压保护器件Dc2正极与电流互感器Lc1另一端连接，过电压保护器件Dc2负极与信号跟随PNP型三极管Dc1基极连接。The structure of the C-phase sampling circuit is that the current transformer Lc1 is set on the three-phase power supply C line to perform current sampling, one end of the current transformer Lc1 is connected with the switching resistor Rc1 and one end of the voltage dividing adjustment potentiometer Rc2, and the current transformer Lc1 is connected to another end of the current transformer Lc1. One end is connected to the other end of the conversion resistor Rc1 and the other end of the voltage dividing resistor Rc3, the other end of the voltage dividing adjustment potentiometer Rc2 and the voltage dividing resistor Rc3 is connected to one end of the current limiting protection resistor Rc4, and the other end of the current limiting protection resistor Rc4 is connected to the signal Follow the base of the PNP transistor Dc1, connect one end of the phase feedback adjustment inductor Lc2, the other end of the phase feedback adjustment inductor Lc2 is connected to one end of the phase feedback limiting resistor Rc5, and the other end of the phase feedback limiting resistor Rc5 is connected to the collector of the signal follower PNP transistor Dc1 1. One end of the phase feedback proportional resistor Rc6 is connected, the signal follows the emitter of the PNP transistor Dc1 and the signal limiting resistor Rc7 and one end of the signal follows the shunt resistor Rc8 is connected, the other end of the signal follows the shunt resistor Rc8 is grounded, the positive electrode of the overvoltage protection device Dc2 is connected to the current The other end of the transformer Lc1 is connected, and the negative electrode of the overvoltage protection device Dc2 is connected to the base of the signal follower PNP transistor Dc1.
进一步地，电压偏置电阻R9一端与工作直流电源VDD连接，电压偏置电阻R9另一端与电流互感器La1另一端、电流互感器Lc1另一端和电压偏置电阻R10一端连接，电压偏置电阻R10另一端接地，过电压保护器件Da2正极与过电压保护器件D3负极连接，过电压保护器件D3和过电压保护器件Db2的正极接地，过电压保护器件Dc2的正极连接电流互感器Lc1的另一端。Further, one end of the voltage bias resistor R9 is connected to the working DC power supply VDD, the other end of the voltage bias resistor R9 is connected to the other end of the current transformer La1, the other end of the current transformer Lc1 is connected to one end of the voltage bias resistor R10, and the voltage bias resistor The other end of R10 is grounded, the positive pole of the overvoltage protection device Da2 is connected to the negative pole of the overvoltage protection device D3, the positive poles of the overvoltage protection device D3 and the overvoltage protection device Db2 are grounded, and the positive pole of the overvoltage protection device Dc2 is connected to the other end of the current transformer Lc1 .
进一步地，所述相位反馈比例电阻Ra6、相位反馈比例电阻Rb6和相位反馈比例电阻Rc6的另一端与工作直流电源VDD、过电压保护器件D4负极和零序电流提取PNP型三极管D5集电极连接，过电压保护器件D4正极接地，信号限定电阻Ra7、信号限定电阻Rb7和信号限定电阻Rc7的另一端连接零序电流提取PNP型三极管D5的基极，零序电流提取PNP型三极管D5的发射极与零序电流负载电阻R11一端、零序电流幅值A/D转换模块的输入端和零序电阻相位预处理模块的输入端连接，零序电流幅值A/D转换模块和零序电阻相位预处理模块的输出端与智能微处理器连接。Further, the other end of the phase feedback proportional resistor Ra6, the phase feedback proportional resistor Rb6 and the phase feedback proportional resistor Rc6 is connected to the working DC power supply VDD, the negative pole of the overvoltage protection device D4 and the collector of the zero-sequence current extraction PNP transistor D5, The positive electrode of the overvoltage protection device D4 is grounded, the other end of the signal limiting resistor Ra7, the signal limiting resistor Rb7 and the signal limiting resistor Rc7 are connected to the base of the zero-sequence current extraction PNP transistor D5, and the emitter of the zero-sequence current extraction PNP transistor D5 is connected to One end of the zero-sequence current load resistor R11, the input end of the zero-sequence current amplitude A/D conversion module and the input end of the zero-sequence resistance phase preprocessing module are connected, and the zero-sequence current amplitude A/D conversion module and the zero-sequence resistance phase preprocessing module are connected. The output terminal of the processing module is connected with the intelligent microprocessor.
一种交流接地精准判断方法，其特征在于包含以下步骤：A method for accurately judging AC grounding, characterized in that it comprises the following steps:
A相电流精准取样：A相电流经电流互感器La1电气隔离后由转换电阻Ra1转变为转换电阻Ra1二端的电压信号，经分压调节电位器Ra2和分压电阻Ra3分压及分压调节在分压调节电位器Ra2和分压电阻Ra3连接处输出与A相电流在幅值上精准比例的信号，经限流保护电阻Ra4送至信号跟随PNP型三极管Da1的基极，通过相位反馈调节电感La2、相位反馈限定电阻Ra5、相位反馈比例电阻Ra6的相位比例反馈和调节，在信号跟随PNP型三极管Da1的发射级和信号跟随分流电阻Ra8的连接处输出与A相电流在幅值上精准比例和在相位上精准一致的A相电流取样信号；Accurate sampling of A-phase current: A-phase current is electrically isolated by the current transformer La1, and then converted from the conversion resistor Ra1 to the voltage signal at the two ends of the conversion resistor Ra1, and the voltage is divided and adjusted by the voltage divider adjustment potentiometer Ra2 and the voltage divider Ra3. The connection between the voltage divider adjustment potentiometer Ra2 and the voltage divider resistor Ra3 outputs a signal that is precisely proportional to the amplitude of the phase A current, and is sent to the base of the signal following the PNP transistor Da1 through the current limiting protection resistor Ra4, and the inductance is adjusted through phase feedback The phase ratio feedback and adjustment of La2, phase feedback limiting resistor Ra5, and phase feedback proportional resistor Ra6 are precisely proportional to the amplitude of the A-phase current at the junction of the signal following the transmitter stage of the PNP transistor Da1 and the signal following the shunt resistor Ra8 And the A-phase current sampling signal that is accurate and consistent in phase;
B相电流精准取样：B相电流经电流互感器Lb1电气隔离后由转换电阻Rb1转变为转换电阻Rb1二端的电压信号，经分压调节电位器Rb2和分压电阻Rb3分压及分压调节在分压调节电位器Rb2和分压电阻Rb3连接处输出与B相电流在幅值上精准比例的信号，经限流保护电阻Rb4送至信号跟随PNP型三极管Db1的基极，通过相位反馈调节电感Lb2、相位反馈限定电阻Rb5、相位反馈比例电阻Rb6的相位比例反馈和调节，在信号跟随PNP型三极管Db1的发射级和信号跟随分流电阻Rb8的连接处输出与B相电流在幅值上精准比例和在相位上精准一致的B相电流取样信号；Accurate sampling of B-phase current: After the B-phase current is electrically isolated by the current transformer Lb1, it is converted from the conversion resistor Rb1 to the voltage signal at the two ends of the conversion resistor Rb1, and the voltage is divided and adjusted by the voltage division adjustment potentiometer Rb2 and the voltage division resistor Rb3. The connection between the voltage divider adjustment potentiometer Rb2 and the voltage divider resistor Rb3 outputs a signal that is precisely proportional to the amplitude of the B-phase current, and the signal is sent to the base of the PNP transistor Db1 through the current limiting protection resistor Rb4, and the inductance is adjusted through phase feedback Phase proportional feedback and adjustment of Lb2, phase feedback limiting resistor Rb5, and phase feedback proportional resistor Rb6, at the junction where the signal follows the transmitter stage of the PNP transistor Db1 and the signal follows the shunt resistor Rb8, the output is precisely proportional to the amplitude of the B-phase current And the B-phase current sampling signal that is accurate and consistent in phase;
C相电流精准取样：C相电流经电流互感器Lc1电气隔离后由转换电阻Rc1转变为转换电阻Rc1二端的电压信号，经分压调节电位器Rc2和分压电阻Rc3分压及分压调节在分压调节电位器Rc2和分压电阻Rc3连接处输出与C相电流在幅值上精准比例的信号，经限流保护电阻Rc4送至信号跟随PNP型三极管Dc1的基极，通过相位反馈调节电感Lc2、相位反馈限定电阻Rc5、相位反馈比例电阻Rc6的相位比例反馈和调节，在信号跟随PNP型三极管Dc1的发射级和信号跟随分流电阻Rc8的连接处输出与C相电流在幅值上精准比例和在相位上精准一致的C相电流取样信号；Accurate sampling of C-phase current: After the current transformer Lc1 electrically isolates the C-phase current, it is converted from the conversion resistor Rc1 to the voltage signal at the two ends of the conversion resistor Rc1, and the voltage is divided and adjusted by the voltage division adjustment potentiometer Rc2 and the voltage division resistor Rc3. The connection between the voltage divider adjustment potentiometer Rc2 and the voltage divider resistor Rc3 outputs a signal that is precisely proportional to the amplitude of the C-phase current, and the signal is sent to the base of the PNP transistor Dc1 through the current limiting protection resistor Rc4, and the inductance is adjusted through phase feedback The phase proportional feedback and adjustment of Lc2, phase feedback limiting resistor Rc5, and phase feedback proportional resistor Rc6 are precisely proportional to the amplitude of the C-phase current at the connection between the signal following the transmitter stage of the PNP transistor Dc1 and the signal following the shunt resistor Rc8 And the C-phase current sampling signal that is accurate and consistent in phase;
零序电流精确取样：A、B、C三相电流分别经信号限定电阻Ra7、信号限定电阻Rb7、信号限定电阻Rc7汇集至零序电流提取PNP型三极管D5基极处相加，在零序电流提取PNP型三极管D5发射极与零序电流负载电阻R11连接处输出零序电流信号，其幅值经零序电流幅值A/D转换模块数字化、相位经零序电阻相位预处理模块数字化后送至智能微处理器，智能微处理器根据精准的零序电流的幅值和相位进行正确的接地故障判断、报警或输出保护信号。Accurate sampling of zero-sequence current: The three-phase currents of A, B, and C are respectively collected by the signal-limited resistor Ra7, the signal-limited resistor Rb7, and the signal-limited resistor Rc7 to the base of the zero-sequence current extraction PNP transistor D5. Extract the zero-sequence current signal from the connection between the emitter of the PNP transistor D5 and the zero-sequence current load resistor R11, and its amplitude is digitized by the zero-sequence current amplitude A/D conversion module, and the phase is digitized by the zero-sequence resistor phase preprocessing module and then sent To the intelligent microprocessor, the intelligent microprocessor performs correct ground fault judgment, alarm or output protection signal according to the amplitude and phase of the precise zero-sequence current.
进一步地，电压偏置电阻R9和电压偏置电阻R10提供偏置电压、保证A相交流电流的正常取样，过电压保护器件Da2/过电压保护器件Db2/过电压保护器件Dc2和过电压保护器件D3限止其前面部分过电压避免其后面部分电路损坏。Further, the voltage bias resistor R9 and the voltage bias resistor R10 provide the bias voltage to ensure the normal sampling of the A-phase AC current, and the overvoltage protection device Da2/overvoltage protection device Db2/overvoltage protection device Dc2 and overvoltage protection device D3 limits the overvoltage in the front part to avoid damage to the circuit in the back part.
进一步地，过电压保护器件D4限止通过电源引入的损坏性过电压。Further, the overvoltage protection device D4 limits damaging overvoltages introduced through the power supply.
本发明与现有技术相比，具有以下优点和效果：结构简单、运行可靠、性价比高，通过零序电流取样精确判断电网接地保护装置产品的交流接地情况，使接地保护装置产品能够对接地故障准确发出报警信号或者正确发出断开接地故障线路的跳闸信号，保证电网的安全、经济运行。Compared with the prior art, the present invention has the following advantages and effects: simple structure, reliable operation, high cost performance, accurately judge the AC grounding condition of the power grid grounding protection device product through zero-sequence current sampling, so that the grounding protection device product can protect the grounding fault Accurately send out the alarm signal or correctly send out the trip signal for disconnecting the ground fault line to ensure the safe and economical operation of the power grid.
附图说明Description of drawings
图1是本发明的一种交流接地精准判断的零序电流取样电路的电路图。Fig. 1 is a circuit diagram of a zero-sequence current sampling circuit for accurate judgment of AC grounding according to the present invention.
具体实施方式Detailed ways
下面结合附图并通过实施例对本发明作进一步的详细说明，以下实施例是对本发明的解释而本发明并不局限于以下实施例。The present invention will be further described in detail below in conjunction with the accompanying drawings and examples. The following examples are explanations of the present invention and the present invention is not limited to the following examples.
如图所示，一种交流接地精准判断的零序电流取样电路，包含A相取样电路、B相取样电路、C相取样电路、零序电流幅值A/D转换模块1、零序电阻相位预处理模块2、智能微处理器3，A相取样电路、B相取样电路和C相取样电路分别进行三相电源电流取样并将三相电流信号叠加后输送至零序电流幅值A/D转换模块1和零序电阻相位预处理模块2将零序电流的幅值和相位进行正确的接地故障判断、报警或输出保护信号。As shown in the figure, a zero-sequence current sampling circuit for accurate judgment of AC grounding includes A-phase sampling circuit, B-phase sampling circuit, C-phase sampling circuit, zero-sequence current amplitude A/D conversion module 1, zero-sequence resistance phase Preprocessing module 2, intelligent microprocessor 3, A-phase sampling circuit, B-phase sampling circuit and C-phase sampling circuit respectively perform three-phase power supply current sampling and superimpose the three-phase current signals and send them to the zero-sequence current amplitude A/D The conversion module 1 and the zero-sequence resistance phase pre-processing module 2 make correct ground fault judgments, alarms or output protection signals based on the amplitude and phase of the zero-sequence current.
A相取样电路结构为，电流互感器La1设置在三相电源A相线路上进行电流取样，电流互感器La1一端与转换电阻Ra1和分压调节电位器Ra2的一端连接，电流互感器La1另一端与转换电阻Ra1另一端和分压电阻Ra3的另一端连接，分压调节电位器Ra2和分压电阻Ra3的另一端与限流保护电阻Ra4的一端连接，限流保护电阻Ra4另一端与信号跟随PNP型三极管Da1的基极、相位反馈调节电感La2的一端连接，相位反馈调节电感La2另一端与相位反馈限定电阻Ra5一端连接，相位反馈限定电阻Ra5另一端与信号跟随PNP型三极管Da1集电极、相位反馈比例电阻Ra6一端连接，信号跟随PNP型三极管Da1的发射极与信号限定电阻Ra7和信号跟随分流电阻Ra8的一端连接，信号跟随分流电阻Ra8另一端接地，过电压保护器件Da2正极与电流互感器La1另一端连接，过电压保护器件Da2负极与信号跟随PNP型三极管Da1基极连接；The structure of the A-phase sampling circuit is that the current transformer La1 is set on the A-phase line of the three-phase power supply for current sampling, one end of the current transformer La1 is connected with the conversion resistor Ra1 and one end of the voltage divider adjustment potentiometer Ra2, and the other end of the current transformer La1 Connect with the other end of the conversion resistor Ra1 and the other end of the voltage dividing resistor Ra3, the other end of the voltage dividing adjustment potentiometer Ra2 and the voltage dividing resistor Ra3 is connected with one end of the current limiting protection resistor Ra4, and the other end of the current limiting protection resistor Ra4 is connected to the signal follower The base of the PNP transistor Da1 is connected to one end of the phase feedback adjusting inductor La2, the other end of the phase feedback adjusting inductor La2 is connected to one end of the phase feedback limiting resistor Ra5, and the other end of the phase feedback limiting resistor Ra5 is connected to the signal follower PNP transistor Da1 collector, One end of the phase feedback proportional resistor Ra6 is connected, the signal follows the emitter of the PNP transistor Da1 and one end of the signal limiting resistor Ra7 and the signal follows the shunt resistor Ra8 are connected, the other end of the signal follows the shunt resistor Ra8 is grounded, and the positive electrode of the overvoltage protection device Da2 is connected to the current mutual inductance The other end of the device La1 is connected, and the negative electrode of the overvoltage protection device Da2 is connected to the base of the signal follower PNP transistor Da1;
B相取样电路结构为，电流互感器Lb1设置在三相电源B相线路上进行电流取样，电流互感器Lb1一端与转换电阻Rb1和分压调节电位器Rb2的一端连接，电流互感器Lb1另一端与转换电阻Rb1另一端和分压电阻Rb3的另一端连接，分压调节电位器Rb2和分压电阻Rb3的另一端与限流保护电阻Rb4的一端连接，限流保护电阻Rb4另一端与信号跟随PNP型三极管Db1的基极、相位反馈调节电感Lb2的一端连接，相位反馈调节电感Lb2另一端与相位反馈限定电阻Rb5一端连接，相位反馈限定电阻Rb5另一端与信号跟随PNP型三极管Db1集电极、相位反馈比例电阻Rb6一端连接，信号跟随PNP型三极管Db1的发射极与信号限定电阻Rb7和信号跟随分流电阻Rb8的一端连接，信号跟随分流电阻Rb8另一端接地，过电压保护器件Db2正极与电流互感器Lb1另一端连接，过电压保护器件Db2负极与信号跟随PNP型三极管Db1基极连接；The structure of the B-phase sampling circuit is that the current transformer Lb1 is set on the B-phase line of the three-phase power supply for current sampling, one end of the current transformer Lb1 is connected with the conversion resistor Rb1 and one end of the voltage divider adjustment potentiometer Rb2, and the other end of the current transformer Lb1 Connect with the other end of the conversion resistor Rb1 and the other end of the voltage dividing resistor Rb3, the other end of the voltage dividing adjustment potentiometer Rb2 and the voltage dividing resistor Rb3 is connected with one end of the current limiting protection resistor Rb4, and the other end of the current limiting protection resistor Rb4 is connected to the signal follower The base of the PNP transistor Db1 is connected to one end of the phase feedback adjustment inductor Lb2, the other end of the phase feedback adjustment inductor Lb2 is connected to one end of the phase feedback limiting resistor Rb5, and the other end of the phase feedback limiting resistor Rb5 is connected to the signal follower of the PNP transistor Db1 collector, One end of the phase feedback proportional resistor Rb6 is connected, the signal follows the emitter of the PNP transistor Db1 and one end of the signal limiting resistor Rb7 and the signal follows the shunt resistor Rb8 are connected, the other end of the signal follows the shunt resistor Rb8 is grounded, the positive electrode of the overvoltage protection device Db2 is connected to the current mutual inductance The other end of the device Lb1 is connected, and the negative electrode of the overvoltage protection device Db2 is connected to the base of the signal-following PNP transistor Db1;
C相取样电路结构为，电流互感器Lc1设置在三相电源C线路上进行电流取样，电流互感器Lc1一端与转换电阻Rc1和分压调节电位器Rc2的一端连接，电流互感器Lc1另一端与转换电阻Rc1另一端和分压电阻Rc3的另一端连接，分压调节电位器Rc2和分压电阻Rc3的另一端与限流保护电阻Rc4的一端连接，限流保护电阻Rc4另一端与信号跟随PNP型三极管Dc1的基极、相位反馈调节电感Lc2的一端连接，相位反馈调节电感Lc2另一端与相位反馈限定电阻Rc5一端连接，相位反馈限定电阻Rc5另一端与信号跟随PNP型三极管Dc1集电极、相位反馈比例电阻Rc6一端连接，信号跟随PNP型三极管Dc1的发射极与信号限定电阻Rc7和信号跟随分流电阻Rc8的一端连接，信号跟随分流电阻Rc8另一端接地，过电压保护器件Dc2正极与电流互感器Lc1另一端连接，过电压保护器件Dc2负极与信号跟随PNP型三极管Dc1基极连接。The structure of the C-phase sampling circuit is that the current transformer Lc1 is set on the C line of the three-phase power supply for current sampling, one end of the current transformer Lc1 is connected with the conversion resistor Rc1 and one end of the voltage division adjustment potentiometer Rc2, and the other end of the current transformer Lc1 is connected with the The other end of the conversion resistor Rc1 is connected to the other end of the voltage dividing resistor Rc3, the other end of the voltage dividing adjustment potentiometer Rc2 and the voltage dividing resistor Rc3 is connected to one end of the current limiting protection resistor Rc4, and the other end of the current limiting protection resistor Rc4 is connected to the signal following PNP The base of the phase feedback regulating transistor Dc1 is connected to one end of the phase feedback adjusting inductor Lc2, the other end of the phase feedback adjusting inductor Lc2 is connected to one end of the phase feedback limiting resistor Rc5, and the other end of the phase feedback limiting resistor Rc5 is connected to the signal follower PNP type transistor Dc1 collector, phase One end of the feedback proportional resistor Rc6 is connected, the signal follows the emitter of the PNP transistor Dc1, the signal limiting resistor Rc7 and one end of the signal following shunt resistor Rc8 are connected, the other end of the signal following shunt resistor Rc8 is grounded, the positive pole of the overvoltage protection device Dc2 is connected to the current transformer The other end of Lc1 is connected, and the cathode of the overvoltage protection device Dc2 is connected to the base of the signal follower PNP transistor Dc1.
电压偏置电阻R9一端与工作直流电源VDD连接，电压偏置电阻R9另一端与电流互感器La1另一端、电流互感器Lc1另一端和电压偏置电阻R10一端连接，电压偏置电阻R10另一端接地，过电压保护器件Da2正极与过电压保护器件D3负极连接，过电压保护器件D3和过电压保护器件Db2的正极接地，过电压保护器件Dc2的正极连接电流互感器Lc1的另一端。相位反馈比例电阻Ra6、相位反馈比例电阻Rb6和相位反馈比例电阻Rc6的另一端与工作直流电源VDD、过电压保护器件D4负极和零序电流提取PNP型三极管D5集电极连接，过电压保护器件D4正极接地，信号限定电阻Ra7、信号限定电阻Rb7和信号限定电阻Rc7的另一端连接零序电流提取PNP型三极管D5的基极，零序电流提取PNP型三极管D5的发射极与零序电流负载电阻R11一端、零序电流幅值A/D转换模块的输入端和零序电阻相位预处理模块的输入端连接，零序电流幅值A/D转换模块和零序电阻相位预处理模块的输出端与智能微处理器连接。One end of the voltage bias resistor R9 is connected to the working DC power supply VDD, the other end of the voltage bias resistor R9 is connected to the other end of the current transformer La1, the other end of the current transformer Lc1 is connected to one end of the voltage bias resistor R10, and the other end of the voltage bias resistor R10 Grounding, the positive pole of the overvoltage protection device Da2 is connected to the negative pole of the overvoltage protection device D3, the positive poles of the overvoltage protection device D3 and the overvoltage protection device Db2 are grounded, and the positive pole of the overvoltage protection device Dc2 is connected to the other end of the current transformer Lc1. The phase feedback proportional resistor Ra6, the other end of the phase feedback proportional resistor Rb6 and the phase feedback proportional resistor Rc6 are connected to the working DC power supply VDD, the negative pole of the overvoltage protection device D4 and the collector of the zero-sequence current extraction PNP transistor D5, and the overvoltage protection device D4 The positive pole is grounded, the other end of the signal limiting resistor Ra7, the signal limiting resistor Rb7 and the signal limiting resistor Rc7 are connected to the base of the zero-sequence current extraction PNP transistor D5, the emitter of the zero-sequence current extraction PNP transistor D5 and the zero-sequence current load resistor One end of R11 is connected to the input end of the zero-sequence current amplitude A/D conversion module and the input end of the zero-sequence resistance phase preprocessing module, and the output end of the zero-sequence current amplitude A/D conversion module and the zero-sequence resistance phase preprocessing module Connect with intelligent microprocessor.
一种交流接地精准判断方法，包含以下步骤：A method for accurately judging AC grounding, comprising the following steps:
A相电流精准取样：A相电流经电流互感器La1电气隔离后由转换电阻Ra1转变为转换电阻Ra1二端的电压信号，经分压调节电位器Ra2和分压电阻Ra3分压及分压调节在分压调节电位器Ra2和分压电阻Ra3连接处输出与A相电流在幅值上精准比例的信号，经限流保护电阻Ra4送至信号跟随PNP型三极管Da1的基极，通过相位反馈调节电感La2、相位反馈限定电阻Ra5、相位反馈比例电阻Ra6的相位比例反馈和调节，在信号跟随PNP型三极管Da1的发射级和信号跟随分流电阻Ra8的连接处输出与A相电流在幅值上精准比例和在相位上精准一致的A相电流取样信号；电压偏置电阻R9和电压偏置电阻R10提供偏置电压、保证A相交流电流的正常取样，过电压保护器件Da2和过电压保护器件D3限止其前面部分过电压避免其后面部分电路损坏Accurate sampling of A-phase current: A-phase current is electrically isolated by the current transformer La1, and then converted from the conversion resistor Ra1 to the voltage signal at the two ends of the conversion resistor Ra1, and the voltage is divided and adjusted by the voltage divider adjustment potentiometer Ra2 and the voltage divider Ra3. The connection between the voltage divider adjustment potentiometer Ra2 and the voltage divider resistor Ra3 outputs a signal that is precisely proportional to the amplitude of the phase A current, and is sent to the base of the signal following the PNP transistor Da1 through the current limiting protection resistor Ra4, and the inductance is adjusted through phase feedback The phase ratio feedback and adjustment of La2, phase feedback limiting resistor Ra5, and phase feedback proportional resistor Ra6 are precisely proportional to the amplitude of the A-phase current at the junction of the signal following the transmitter stage of the PNP transistor Da1 and the signal following the shunt resistor Ra8 and A-phase current sampling signal that is accurate and consistent in phase; voltage bias resistor R9 and voltage bias resistor R10 provide bias voltage to ensure normal sampling of A-phase AC current, overvoltage protection device Da2 and overvoltage protection device D3 limit The front part of the overvoltage avoids the damage of the rear part of the circuit
B相电流精准取样：B相电流经电流互感器Lb1电气隔离后由转换电阻Rb1转变为转换电阻Rb1二端的电压信号，经分压调节电位器Rb2和分压电阻Rb3分压及分压调节在分压调节电位器Rb2和分压电阻Rb3连接处输出与B相电流在幅值上精准比例的信号，经限流保护电阻Rb4送至信号跟随PNP型三极管Db1的基极，通过相位反馈调节电感Lb2、相位反馈限定电阻Rb5、相位反馈比例电阻Rb6的相位比例反馈和调节，在信号跟随PNP型三极管Db1的发射级和信号跟随分流电阻Rb8的连接处输出与B相电流在幅值上精准比例和在相位上精准一致的B相电流取样信号；电压偏置电阻R9和电压偏置电阻R10提供偏置电压、保证A相交流电流的正常取样，过电压保护器件Db2和过电压保护器件D3限止其前面部分过电压避免其后面部分电路损坏Accurate sampling of B-phase current: After the B-phase current is electrically isolated by the current transformer Lb1, it is converted from the conversion resistor Rb1 to the voltage signal at the two ends of the conversion resistor Rb1, and the voltage is divided and adjusted by the voltage division adjustment potentiometer Rb2 and the voltage division resistor Rb3. The connection between the voltage divider adjustment potentiometer Rb2 and the voltage divider resistor Rb3 outputs a signal that is precisely proportional to the amplitude of the B-phase current, and the signal is sent to the base of the PNP transistor Db1 through the current limiting protection resistor Rb4, and the inductance is adjusted through phase feedback Phase proportional feedback and adjustment of Lb2, phase feedback limiting resistor Rb5, and phase feedback proportional resistor Rb6, at the junction where the signal follows the transmitter stage of the PNP transistor Db1 and the signal follows the shunt resistor Rb8, the output is precisely proportional to the amplitude of the B-phase current and the B-phase current sampling signal that is accurate and consistent in phase; the voltage bias resistor R9 and the voltage bias resistor R10 provide bias voltage to ensure the normal sampling of the A-phase AC current, and the overvoltage protection device Db2 and overvoltage protection device D3 limit The front part of the overvoltage avoids the damage of the rear part of the circuit
C相电流精准取样：C相电流经电流互感器Lc1电气隔离后由转换电阻Rc1转变为转换电阻Rc1二端的电压信号，经分压调节电位器Rc2和分压电阻Rc3分压及分压调节在分压调节电位器Rc2和分压电阻Rc3连接处输出与C相电流在幅值上精准比例的信号，经限流保护电阻Rc4送至信号跟随PNP型三极管Dc1的基极，通过相位反馈调节电感Lc2、相位反馈限定电阻Rc5、相位反馈比例电阻Rc6的相位比例反馈和调节，在信号跟随PNP型三极管Dc1的发射级和信号跟随分流电阻Rc8的连接处输出与C相电流在幅值上精准比例和在相位上精准一致的C相电流取样信号；电压偏置电阻R9和电压偏置电阻R10提供偏置电压、保证A相交流电流的正常取样，过电压保护器件Dc2和过电压保护器件D3限止其前面部分过电压避免其后面部分电路损坏Accurate sampling of C-phase current: After the current transformer Lc1 electrically isolates the C-phase current, it is converted from the conversion resistor Rc1 to the voltage signal at the two ends of the conversion resistor Rc1, and the voltage is divided and adjusted by the voltage division adjustment potentiometer Rc2 and the voltage division resistor Rc3. The connection between the voltage divider adjustment potentiometer Rc2 and the voltage divider resistor Rc3 outputs a signal that is precisely proportional to the amplitude of the C-phase current, and the signal is sent to the base of the PNP transistor Dc1 through the current limiting protection resistor Rc4, and the inductance is adjusted through phase feedback The phase proportional feedback and adjustment of Lc2, phase feedback limiting resistor Rc5, and phase feedback proportional resistor Rc6 are precisely proportional to the amplitude of the C-phase current at the connection between the signal following the transmitter stage of the PNP transistor Dc1 and the signal following the shunt resistor Rc8 And the phase C current sampling signal that is accurate and consistent in phase; the voltage bias resistor R9 and the voltage bias resistor R10 provide the bias voltage to ensure the normal sampling of the A phase AC current, and the overvoltage protection device Dc2 and the overvoltage protection device D3 limit the The front part of the overvoltage avoids the damage of the rear part of the circuit
零序电流精确取样：A、B、C三相电流分别经信号限定电阻Ra7、信号限定电阻Rb7、信号限定电阻Rc7汇集至零序电流提取PNP型三极管D5基极处相加，在零序电流提取PNP型三极管D5发射极与零序电流负载电阻R11连接处输出零序电流信号，其幅值经零序电流幅值A/D转换模块数字化、相位经零序电阻相位预处理模块数字化后送至智能微处理器，智能微处理器根据精准的零序电流的幅值和相位进行正确的接地故障判断、报警或输出保护信号。Accurate sampling of zero-sequence current: The three-phase currents of A, B, and C are respectively collected by the signal-limited resistor Ra7, the signal-limited resistor Rb7, and the signal-limited resistor Rc7 to the base of the zero-sequence current extraction PNP transistor D5. Extract the zero-sequence current signal from the connection between the emitter of the PNP transistor D5 and the zero-sequence current load resistor R11, and its amplitude is digitized by the zero-sequence current amplitude A/D conversion module, and the phase is digitized by the zero-sequence resistor phase preprocessing module and then sent To the intelligent microprocessor, the intelligent microprocessor performs correct ground fault judgment, alarm or output protection signal according to the amplitude and phase of the precise zero-sequence current.
其中，过电压保护器件D4限止通过电源引入的损坏性过电压。Wherein, the overvoltage protection device D4 limits the destructive overvoltage introduced by the power supply.
本说明书中所描述的以上内容仅仅是对本发明所作的举例说明。本发明所属技术领域的技术人员可以对所描述的具体实施例做各种修改或补充或采用类似的方式替代，只要不偏离本发明说明书的内容或者超越本权利要求书所定义的范围，均应属于本发明的保护范围。The above content described in this specification is only an illustration of the present invention. Those skilled in the technical field to which the present invention belongs can make various modifications or supplements to the described specific embodiments or adopt similar methods to replace them, as long as they do not deviate from the content of the present invention specification or exceed the scope defined in the claims, all should Belong to the protection scope of the present invention.
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