CN103176049A - Circuit, device and method used for ground insulation monitoring of earth-free DC (Direct Current) system - Google Patents
Circuit, device and method used for ground insulation monitoring of earth-free DC (Direct Current) system Download PDFInfo
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Abstract
The invention provides a circuit, device and method for monitoring ground insulation of an earth-free C (Direct Current) system to overcome the disadvantage that the ground insulation of the earth-free DC system cannot be detected exactly at the present time. According to the invention, the circuit comprises a resistor R1, a resistor R2, a resistor R0, a resistor Rs, a voltage sensor and a signal generator, wherein a first terminal of the resistor R1 is connected to the positive bus of the earth-free DC system; a first terminal of the resistor R2 is connected to the negative bus of the earth-free DC system; a first input terminal and a second input terminal of the voltage sensor are electrically isolated from an output terminal; a first input terminal is connected to a second terminal of the resistor R1; a second input terminal is connected to a second terminal of the resistor R2; an output terminal outputs a measured voltage between the positive bus and the negative bus; a first terminal of the resistor R0 is connected to the negative bus while a second terminal of the resistor R0 is connected to a first terminal of the resistor Rs; a first terminal of the signal generator is connected to a second terminal of the resistor Rs; a second terminal of the signal generator is earthed; and a third terminal of the signal generator receives a control signal.
Description
Technical field
The present invention relates to the insulating monitoring field, relate in particular to a kind of circuit, apparatus and method of the monitoring of the insulation against ground for earth-free straight-flow system.
Background technology
Current DC power-supply system generally all adopts the method for operation of insulation against ground, when one point earth occurs, can't cause any harm; but must process in time; otherwise, when another ground connection occurs, just likely make relay protection generation mistake action and rejecting action so that damage equipment.Therefore the insulation against ground monitoring of earth-free straight-flow system is very important.
At present, to several technology below main employing of insulativity monitoring of earth-free straight-flow system.
The first technology is that classical bridge method detects, its schematic diagram as shown in Figure 1, wherein, voltage between positive and negative busbar is E, and resistor R1, R2 are that balance resistance and its general value are below 100k Ω, and resistor R+, R-are respectively positive and negative busbar insulation against ground resistance, K is overcurrent relay, Is is for the reometer for detection of the electric current that flows through overcurrent relay K, and when ground current reaches setting valve, the K action makes sends the grounding alarm signal.Certainly, also can adopt the current measurement sampling resistor to replace the voltage that K is ordered to record a.Voltage U ab between 2 of a in Fig. 1, b can be represented by the formula:
U
ab＝E*[R
1/(R
2+R
1)-R
+/(R
++R
-) (1)
Can find out: 1. when the positive and negative busbar insulation against ground is good, bridge balancing, Uab=0; 2. descend while grounding phenomenon occurring when positive bus-bar or negative busbar insulation against ground, " over against ground " or " negative over the ground ", appear in Uab>0 or Uab<0, and reach the threshold value alarm as Uab.But, the function of this detection technique is too dull, it only can be reported to the police to system earth, but usually can not indication fault place branch road and grounding resistance, if R+ and R-equal proportion descend, thereby symmetry earth fault appears, even out-of-limit, also can't report to the police, and when high resistance ground occurring but R+ and R-while differing larger, but can false alarm.
The second technology is the low-frequency signal injection detection method, and it detects schematic diagram as shown in Figure 2, and wherein kx is low frequency generator, and Is is the reometer for detection of electric current.After earth fault appears in straight-flow system, inject the low frequency 30V alternating signal of 5Hz, 10Hz or 20Hz between fault bus and ground, detect the ground connection branch road by detecting the current amplitude variation.Low-frequency current flows out from signal generator kx, via straight-flow system, from earth point, returns, as shown in Figure 2.Detect with the pointwise of pincers type current probe, the low-frequency current trend is followed the trail of, at first find the ground connection branch road, then along this branch road, find earth point, according to the low-frequency current difference before and after earth point, determine the earth point position.This detection technique need to have a power failure and search earth point, and it is very large that the correctness of its detection and sensitivity are affected by the system distributed capacitance.Straight-flow system positive and negative busbar and feed out each duplexure and have over the ground distributed capacitance, the branch road distributed capacitance reaches several μ F when maximum, such as an electric station DC system total capacitance can reach several 10 μ F., because capacitance current flows through, make and be difficult to determine to be capacitance current or stake resistance electric current when certain is put when probe.When there is earth point in a certain branch road of system busbar, if after this branch road, all total equivalence values of distributed capacitance are 1 μ F, as signal frequency is 20Hz, the electric capacity capacitive reactance is about 8k Ω, when branch road resistance is greater than 8k Ω, the electric current that flows to subsequent conditioning circuit will approach with the electric current that flows through fault branch, be difficult to distinguish the ground connection branch road.
The third detection technique is table tennis bridge method detection technique, and it detects schematic diagram as shown in Figure 3, R1=R3 wherein, and R2=R4, the on off state by switch S 1, S2 forms 3 kinds of circuit states, respectively the voltage between 2 of V+ and V-is sampled.When Closing Switch S1, S2, the voltage between 2 of note V+ and V-is U
v+V-1; When Closing Switch S1, cut-off switch S2, the voltage between 2 of note V+ and V-is U
v+V-2; When cut-off switch S1, Closing Switch S2, the voltage between 2 of note V+ and V-is U
v+V-3; According to Ohm law and circuit theory, solve and obtain:
U
+-＝U
V+V-1*(R1+R2+R3+R4)/(R2+R3) (2)
R+＝(R1+R2)*(U
V+V-1-U
V+V-2-U
V+V-3)/U
V+V-3 (3)
R-＝(R4+R3)*(U
V+V-1-U
V+V-2-U
V+V-3)/U
V+V-2 (4)
The third detection technique has overcome the shortcoming existed in the first detection technique substantially, but when busbar voltage exists fluctuation and system under test (SUT) over the ground obvious distributed capacitance to be arranged, can be because sampling makes final result very large deviation occur less than correct voltage.
Summary of the invention
The present invention is directed to the above-mentioned shortcoming existed in prior art, a kind of circuit, apparatus and method that can overcome the monitoring of the insulation against ground for earth-free straight-flow system of above-mentioned shortcoming are provided.
The invention provides a kind of circuit of the monitoring of the insulation against ground for earth-free straight-flow system, the positive bus-bar of this earth-free straight-flow system is Ry with respect to the insulation resistance of the earth, described positive bus-bar is Cy with respect to the distributed capacitance of the earth, the negative busbar of this earth-free straight-flow system is Rx with respect to the insulation resistance of the earth, described negative busbar is Cx with respect to the distributed capacitance of the earth, this circuit comprises resistor R1, resistor R2, resistor R0, resistor Rs, voltage sensor and signal generator, wherein: the first terminal of described resistor R1 is connected to described positive bus-bar, the first terminal of described resistor R2 is connected to described negative busbar, described voltage sensor has first input end, the second input terminal and lead-out terminal, first input end and second input terminal of described voltage sensor are all electrically isolated from one with described lead-out terminal, and the first input end sub-connection of described voltage sensor is to the second terminal of described resistor R1, the second input terminal of described voltage sensor is connected to the second terminal of described resistor R2, the described positive bus-bar that the lead-out terminal of described voltage sensor measures for output and the voltage between described negative busbar, the first terminal of described resistor R0 is connected to described negative busbar, the second connecting terminals of described resistor R0 is received the first terminal of described resistor Rs, the second connecting terminals of described resistor Rs is received the first terminal of described signal generator, the second terminal ground connection of described signal generator, the 3rd terminal of described signal generator controls for receiving the control signal that described signal generator produces signal.
The present invention also provides a kind of device of the monitoring of the insulation against ground for earth-free straight-flow system, and this device comprises above-mentioned circuit, and this device also comprises the first sample circuit and processor, wherein:
Described processor is controlled described signal generator and is produced direct current signal;
Described the first sample circuit is used under the control of described processor, the DC voltage at described resistor Rs two ends being sampled, and sampled result is fed back to described processor;
Described processor is also for receiving described positive bus-bar that described voltage sensor collects and the voltage between described negative busbar, and the sampled result of the voltage between the described positive bus-bar collected based on described voltage sensor and described negative busbar and described the first sample circuit is calculated resistance value and the value in parallel thereof of described insulation resistance Ry and insulation resistance Rx.
The present invention also provides a kind of method that the insulation against ground of earth-free straight-flow system is monitored, the circuit of the method based on above-mentioned, and the method comprises:
Control described signal generator and produce the first direct current signal;
The DC voltage at described resistor Rs two ends is sampled and obtained the first sampled result;
Voltage voltage between positive bus-bar and negative busbar collected between positive bus-bar and negative busbar by described voltage sensor is the first voltage;
Control described signal generator and produce the second direct current signal;
The DC voltage at described resistor Rs two ends is sampled and obtained the second sampled result;
Voltage voltage between positive bus-bar and negative busbar collected between positive bus-bar and negative busbar by described voltage sensor is second voltage;
Calculate resistance value and the value in parallel thereof of described insulation resistance Ry and insulation resistance Rx based on described the first sampled result, the first voltage, the second sampled result and second voltage.
Considered the voltage fluctuation of positive and negative busbar when the insulation against ground resistance R x, the Ry that detect earth-free straight-flow system and the value in parallel thereof due to the circuit of the monitoring of the insulation against ground for earth-free straight-flow system according to the present invention, apparatus and method, and eliminated the impact of distributed capacitance on accuracy of detection, thereby improved accuracy of detection, strengthened antijamming capability.
The accompanying drawing explanation
Fig. 1 is the schematic diagram that in prior art, classical bridge method detects the insulation against ground of earth-free straight-flow system;
Fig. 2 is the schematic diagram that prior art medium and low frequency signal injection method detects the insulation against ground of earth-free straight-flow system;
Fig. 3 detects the schematic diagram of the insulation against ground of earth-free straight-flow system by the table tennis bridge method in prior art;
Fig. 4 is the circuit diagram according to the monitoring of the insulation against ground for earth-free straight-flow system of the present invention;
The reduced graph that Fig. 5 is the circuit diagram in Fig. 4;
The equivalent circuit diagram that Fig. 6 is the circuit diagram in Fig. 5;
Fig. 7 is
three's vector triangle figure;
Fig. 8 is U
aB, U
a, U
bthe triangular graph that the three forms;
Fig. 9 is according to the block diagram of the device detected for the insulation against ground to earth-free straight-flow system of the present invention;
The process flow diagram that Figure 10 is detected the insulation resistance of earth-free straight-flow system for device according to the present invention;
The voltage waveform that Figure 11 is resistor Rs two ends;
The process flow diagram that Figure 12 is adaptively sampled technology;
The circuit diagram that Figure 13 is the second sample circuit.
Embodiment
Below in conjunction with accompanying drawing, describe in detail according to circuit of being monitored for the insulation against ground to earth-free straight-flow system of the present invention, apparatus and method.
Fig. 4 shows the circuit according to the monitoring of the insulation against ground for earth-free straight-flow system of the present invention.Shown in circuit diagram in, earth-free straight-flow system 1 is the system under test (SUT) that will be carried out the insulativity detection, and the positive bus-bar KM+ of earth-free straight-flow system 1 is Ry with respect to the insulation resistance of the earth, this positive bus-bar is Cy with respect to the distributed capacitance of the earth, the negative busbar of earth-free straight-flow system 1 is Rx with respect to the insulation resistance of the earth, this negative busbar is Cx with respect to the distributed capacitance of the earth, the load that resistor RL is earth-free straight-flow system 1.It according to the circuit of the monitoring of the insulation against ground for earth-free straight-flow system of the present invention, is the part shown in the dotted line frame of Fig. 4, this circuit comprises resistor R1, resistor R2, resistor R0, resistor Rs, voltage sensor 2 and signal generator 3, wherein: the first terminal of described resistor R1 is connected to described positive bus-bar KM+, the first terminal of described resistor R2 is connected to described negative busbar KM-, described voltage sensor 2 has first input end, the second input terminal and lead-out terminal, first input end and second input terminal of described voltage sensor are all electrically isolated from one with described lead-out terminal, and the first input end of described voltage sensor 2 is connected to the second terminal of described resistor R1, the second input terminal of described voltage sensor 2 is connected to the second terminal of described resistor R2, the described positive bus-bar that the lead-out terminal of described voltage sensor 2 measures for output and the voltage U between described negative busbar
kM+KM-the first terminal of described resistor R0 is connected to described negative busbar KM-, the second connecting terminals of described resistor R0 is received the first terminal of described resistor Rs, the second connecting terminals of described resistor Rs is received the first terminal of described signal generator 3, the second terminal ground connection of described signal generator 3, the 3rd terminal of described signal generator 3 controls for receiving the control signal that described signal generator 3 produces signal.In addition, in this circuit diagram, EGND means the earth, and the ground GND of signal generator 3 is connected to the earth EGND.
According in a preferred embodiment of the present invention, the resistance value of resistor R0 preferably meets certain standard can not cause the insulation against ground reduction of earth-free straight-flow system 1 to guarantee this circuit according to the present invention when the insulation against ground to earth-free straight-flow system 1 is monitored, but this standard is different because of the difference of application in a circuit according to the invention, usually, when being applied to electric automobiles, the ratio of the resistance value of resistor R0 and bus rated voltage preferably is not less than 100 Ω/V, and in being applied to photo-voltaic power generation station the time, the ratio of the resistance value of resistor R0 and bus rated voltage preferably is not less than 500 Ω/V.
According in a preferred embodiment of the present invention, resistor R1 and R2 can be power resistors, and voltage sensor 2 is preferably the Hall voltage sensor.
According in a preferred embodiment of the present invention, the resistance of resistor Rs is smaller, resistor R0 is the powerful resistor of large resistance, for example the resistance of resistor Rs and resistor R0 can be respectively 2K and 500K, but those skilled in the art are to be understood that, given resistor Rs and the resistance value of R0 are only examples, are not construed as limiting the invention.
When adopting the circuit shown in Fig. 4 to be monitored the insulation against ground of earth-free straight-flow system 1, produce direct current signal under the control of the control signal that signal generator 3 can receive at it, the direct current signal produced successively through resistor Rs and R0, afterwards from the negative busbar KM-of earth-free straight-flow system 1 enter earth-free straight-flow system 1, insulation resistance Ry and the Rx through 1 pair of the earth of earth-free straight-flow system gets back to GND afterwards, thereby form loop.When signal generator 3 produces direct current signal U
1the time, remember that the voltage between the positive and negative busbar of earth-free straight-flow system 1 is U
kM+KM-1, the voltage at note resistor Rs two ends is U
rs1, and obtain equation (5) by Ohm law and superposition theorem; When signal generator 3 produces direct current signal U
2the time, in like manner can obtain equation (6), simultaneous equations (5) and (6) are also solved, and can obtain resistance value and the parallel resistance value thereof of insulation against ground resistance R x and the Ry of earth-free straight-flow system 1.Certainly, in order to simplify calculated amount, one of them direct current signal that can make signal generator 3 produce (U for example
2) equal 0.Wherein, to solve the formula (7), formula (8), the formula (9) that obtain be exactly at U simultaneous equations (5) and (6)
2equal to obtain in 0 situation.In addition, about how obtaining the voltage at resistor Rs two ends, will in conjunction with the device detected for the insulation against ground to earth-free straight-flow system according to the present invention, be described hereinafter.
Can be found out the magnitude of voltage U between the positive and negative busbar that the value Rx//Ry after resistor Rx is in parallel with Ry has comprised twice acquisition by formula (9)
kM+KM-1, U
kM+KM-2thereby played the effect that detects zero point of correcting, that is to say, when there is fluctuation in busbar voltage, while adopting this circuit according to the present invention to carry out the insulation against ground detection to earth-free straight-flow system 1, its testing result can not be subject to the impact of busbar voltage fluctuation, therefore, this circuit according to the present invention is not only simple in structure, and accuracy in detection is high, and antijamming capability is strong.
On the basis of the resistance value of the insulation against ground resistance R x, the Ry that obtain earth-free straight-flow system 1 and value in parallel thereof, just can further obtain the parallel connection value of the capacitance of the Cx of distributed capacitance over the ground of earth-free straight-flow system 1 and distributed capacitance Cy, and, when the parallel connection value of the capacitance of Computation distribution capacitor C x and distributed capacitance Cy, the circuit shown in Fig. 4 can be reduced to the circuit shown in Fig. 5.Below will describe the parallel connection value of the capacitance that how to obtain discrete capacitor Cx and Cy in detail.
At first, produce the AC signal (for example sinusoidal signal) with certain frequency f under the control of the control signal that signal generator 3 receives at it, wherein, the AC signal that signal generator 3 produces is successively through entering earth-free straight-flow system 1 from the negative busbar KM-of earth-free straight-flow system 1 after resistor Rs and R0, isolation resistor Ry, the Rx of the earth-free straight-flow system 1 of process and discrete capacitor Cx and Cy get back to GND afterwards, thereby form loop.In the situation that signal generator 3 produces AC signal, for signal generator 3, earth-free straight-flow system 1 is equivalent to short circuit, so the circuit equivalent shown in Fig. 5 is the circuit shown in Fig. 6.
The AC signal that the signal generator 3 of below take produces illustrates the capacitance that how to obtain distributed capacitance Cx and distributed capacitance Cy as sinusoidal signal as example.The voltage of at first, A being ordered is designated as vector
the voltage that B is ordered is designated as vector
voltage between AB is designated as to vector
by between known their threes of electric circuit knowledge, having vector triangle relation as shown in Figure 7,
and the length of side on three limits of the vector triangle in Fig. 7 has represented respectively the mould that each is vectorial.The AC sine signal that all comes automatic signal generator 3 to produce due to these three vectors, so the effective value U of the ac voltage signal of these three vectorial representatives
aB, U
a, U
bbetween form a triangle similar to the vector triangle shown in Fig. 7, as shown in Figure 8.From the triangular relationship shown in Fig. 8 and in conjunction with the cosine law, can obtain:
Relevant knowledge from circuit: the effective value of singly-terminal pair port voltage and the ratio of port effective value equal the mould of impedance,
and the circuit AB section in Fig. 6 is the pure resistance circuit consisted of resistor R0 and Rs, therefore:
If the impedance over the ground of B point is Z
b, from electric circuit knowledge:
Again by
can obtain:
Simultaneous formula (10), (11), (12), (13) can obtain:
Like this, just obtained the value (being Cx Cy in parallel equivalence value afterwards) of the distributed capacitance of 1 pair of the earth of earth-free straight-flow system.The voltage effective value U of about how obtaining A ordering in addition,
a, the B voltage effective value U of ordering
band the cosine value cos φ of the phase differential between AB two point voltage signals, will in conjunction with the device detected for the insulation against ground to earth-free straight-flow system according to the present invention, be described below.
Below in conjunction with Fig. 9, describe in detail according to the device detected for the insulation against ground to earth-free straight-flow system 90 of the present invention.As shown in Figure 9, the device of being monitored for the insulation against ground of earth-free straight-flow system 90 according to the present invention is except comprising the circuit shown in Fig. 4, also comprise the first sample circuit 902 and processor 901, wherein: described processor 901 is controlled described signal generator 3 and is produced direct current signal; Described the first sample circuit 902 is under the control at described processor 901, the DC voltage at described resistor Rs two ends being sampled, and sampled result is fed back to described processor 901; Described processor 901 is also for receiving positive bus-bar that described voltage sensor 2 collects and the voltage between negative busbar, and the sampled result of the voltage between the positive bus-bar collected based on described voltage sensor 2 and negative busbar and described the first sample circuit 902 is calculated resistance value and the value in parallel thereof of insulation resistance Ry and the insulation resistance Rx of earth-free straight-flow system.
According in a preferred embodiment of the present invention, signal generator 3 can be comprised of digital to analog converter and operational amplifier, wherein, digital to analog converter is from processor 901 receiving digital signals, and convert this digital signal to analog signal output to operational amplifier, this operational amplifier is amplified rear output to the output signal of analog to digital converter, thereby obtains the required signal of insulation against ground detection of earth-free straight-flow system.
According in a preferred embodiment of the present invention, can also there is analog to digital converter between the first sample circuit 902 and processor 901, the digital signal that becomes processor 901 to identify with the analog signal conversion that the first sample circuit 902 is collected.Certainly, the first sample circuit 902 itself also can integrated analog-to-digital function.In addition, the first sample circuit 902 is preferably the difference sample circuit, makes the present invention can be applicable to high-tension earth-free straight-flow system insulativity and detects, and for example the present invention goes for the system under test (SUT) up to 1000V.
Wherein, processor 901 is when the resistance value of calculating insulation resistance Ry and insulation resistance Rx and value in parallel thereof, can with reference to the described algorithm of Fig. 4, realize based on front, the resistance value of its calculating insulation resistance Ry and insulation resistance Rx and the process flow diagram of value in parallel thereof as shown in figure 10, comprise the following steps:
S101, processor 901 are controlled described signal generator 3 and are produced the first direct current signal;
The DC voltage at S102,902 pairs of described resistor Rs two ends of the first sample circuit is sampled and is obtained the first sampled result U
rs1;
S103, the voltage collected between positive bus-bar and negative busbar by the voltage between 2 pairs of positive bus-bars of described voltage sensor and negative busbar are the first voltage U
kM+KM-1;
S104, processor 901 are controlled described signal generator 2 and are produced the second direct current signal;
S105, the first sample circuit 902 are again sampled and are obtained the second sampled result U the DC voltage at described resistor Rs two ends
rs2;
S106, the voltage again voltage between positive bus-bar and negative busbar collected between positive bus-bar and negative busbar by described voltage sensor 2 are second voltage U
kM+KM-2;
S107, processor 901 are based on described the first sampled result U
rs1, the first voltage U
kM+KM-1, the second sampled result U
rs2with second voltage U
kM+KM-2calculate resistance value and the value in parallel thereof of described insulation resistance Ry and insulation resistance Rx.
In order more accurately to obtain insulating resistance value Rx//Ry, Rx, the Ry of earth-free straight-flow system to the earth, the first sampled result U
rs1, the first voltage U
kM+KM-1, the second sampled result U
rs2with second voltage U
kM+KM-2the accurate sampling of these four voltage datas just seems particularly.The present invention is by adopting Hall voltage sensor 2 to realize the voltage U between positive and negative busbar
kM+KM-1, U
kM+KM-2in real time accurately sampling.Electrical isolation between the input terminal of Hall voltage sensor 2 and lead-out terminal, and the first input end of Hall voltage sensor 2 and the second input terminal are connected respectively to the second terminal of resistor R1 and the second terminal of resistor R2, and Hall voltage sensor 2 can not affect earth-free straight-flow system insulativity over the ground, when reality is used, by implement demarcation in the voltage range of its application, with the voltage U of guaranteeing that the application is obtained
kM+KM-1, U
kM+KM-2accuracy.
Next how explanation guarantees the first sampled result U
rs1with the second sampled result U
rs2accuracy.At first the voltage waveform at resistor Rs two ends in analyte detection process, as shown in figure 11.By Figure 11, can be clear that, because (in fact earth-free straight-flow system exists distributed capacitance to the earth, generally all there is distributed capacitance in earth-free straight-flow system to the earth, be either large or small difference), so the voltage at resistor Rs two ends has obvious capacitor charge and discharge characteristic, and in fact the voltage at rear (being CD section or the GH section in Figure 11) the resistor Rs two ends of capacitor charge and discharge process end is only needed actual value.But the length of charge and discharge process duration is different and different because of distributed capacitance and insulating resistance value, therefore can not realize accurately sampling by method such after time delay a period of time simply, for this reason, the application provides a kind of adaptive voltage Sampling techniques to meet this needs, detailed process is as follows: in the AD section in Figure 11 (or EH section), per interval t1 is sampled by the DC voltage at resistor Rs two ends until N the sampled value of sampling, first sampled value and N sampled value are compared, if both equate to show that the voltage sample point is arranged in the CD section shown in Figure 11 (or GH section), thereby show that capacitor charging (or electric discharge) process completes, therefore the voltage obtained from the sampling of resistor Rs two ends is exactly needed real voltage, if both are unequal, continue that per interval t1 is sampled to the DC voltage at resistor Rs two ends until N the sampled value first sampled value and N sampled value are compared of sampling.Sampling flow process by such, improved efficiency to greatest extent, can either automatically adapt to the different distributions electric capacity of different earth-free straight-flow systems, can not affect again the insulation against ground of earth-free straight-flow system, and also do not sacrifice the ageing of monitoring.The process flow diagram of adaptive voltage Sampling techniques as shown in figure 12.
The structure not restriction of the application to the first sample circuit 902, as long as its insulation against ground that can meet earth-free straight-flow system is detected required precision.
As shown in Figure 9, the device detected for the insulation against ground to earth-free straight-flow system according to the present invention also comprises the second sample circuit 903, and wherein: described processor 901 also produces AC signal for controlling described signal generator 3; 903 of described the second sample circuits are sampled and sampled result are fed back to described processor 901 for the alternating voltage to the second terminal place of the first terminal place of described resistor R0 and described resistor Rs under the control at described processor 901; Described processor 901 also calculates the parallel connection value of described distributed capacitance Cy and Cx capacitance for the sampled result of the resistance value based on described insulation resistance Rx and Ry and value in parallel and described the second sample circuit 903.According to device of the present invention can Measurement accuracy up to the distributed capacitance of tens μ F, this also will provide good foundation for field maintemance and the follow-up design improvement of system.
According in a preferred embodiment of the present invention, the circuit diagram of the second sample circuit 903 as shown in figure 13, wherein, by capacitor C120 and resistor R121, AC signal is sampled, the signal sampled carries out computing by chip CS5464 after amplifying by amplifier 1201 again, the cosine value of the voltage phase difference between 2 of A in the voltage effective value of the AC signal that final output samples and Fig. 9, B.Wherein, capacitor C120 high withstand voltage thin-film capacitor preferably.
As shown in Figure 9, the device detected for the insulation against ground to earth-free straight-flow system according to the present invention also comprises the first switch S 1, second switch S2 and the first resistor R10, wherein said the first switch S 1 is connected between the ground GND of the earth EGND and this device 90, described second switch S2 is connected between the first terminal of described negative busbar KM-and described the first resistor R10, the second terminal ground connection of described the first resistor R10, and the break-make of described the first switch S 1 and described second switch S2 is controlled by described processor 901.This partial circuit is mainly used according to the startup self-detection function of device 90 of the present invention and button self-checking function, and whether the function that when start, detects this device 90 is normal.Wherein, the flow process of startup self-detection is as follows: processor 901 is controlled the first switch S 1 and is disconnected, second switch S2 closure, thereby disconnect according to the ground GND of device 90 of the present invention and the earth EGND of earth-free straight-flow system, and the resistor R10 that installs 90 inside with this simulates the insulation resistance of earth-free straight-flow system to the earth, then adopt the flow process of the insulation resistance of the earth-free straight-flow system of above-described detection to be detected, if testing result is correct, processor 901 is controlled the first switch S 1 closure, the insulation resistance that second switch S2 disconnects starting earth-free straight-flow system is detected, otherwise, output fault-signal, and self check again.Certainly, if starting, the user asks to carry out self check according to device of the present invention according to the button on device of the present invention, device according to the present invention just carries out self check after by the signal of key-press input receiving the user, and its flow process is the same with the flow process of startup self-detection.
According in a preferred embodiment of the present invention, as shown in Figure 9, device 90 according to the present invention also comprises display 904, the parallel connection value of the capacitance of the insulation resistance Ry monitored for demonstration and the resistance value of Rx and value in parallel and distributed capacitance Cy and Cx.
According in a preferred embodiment of the present invention, device 90 according to the present invention also comprises the alarm unit 905 be connected with processor 901, and described processor 901 also indicates during lower than threshold value described alarm unit 905 to report to the police for the parallel connection value at described insulation resistance Ry and Rx.Preferably, the two-stage threshold value can be set, first threshold is for reminding, and Second Threshold is for reporting to the police.
Between according to a preferred embodiment of the present invention, device 90 according to the present invention can also comprise the communication unit 906 be connected with processor 901, this communication unit 906 is for the parallel connection value of the capacitance of the resistance value from described processor 901 reception insulation resistance Ry and Rx and value in parallel and distributed capacitance Cy and Cx, and they are delivered to outside (for example, passing to host computer).
Except advantage of the present invention above-mentioned, the present invention also has the following advantages: can be applicable to have over the ground large distributed capacitance or the system that counnter attack fly-wheel diode (photovoltaic system) arranged; No matter be that the one pole insulativity descends or the two-stage insulativity descends simultaneously, can detect accurately in real time.
Below only in conjunction with the preferred embodiment of the present invention, the present invention be have been described in detail, but in the situation that do not deviate from spirit and scope of the invention, can carry out various changes and modifications to the present invention.
Claims (13)
1. the circuit of the monitoring of the insulation against ground for earth-free straight-flow system, the positive bus-bar of this earth-free straight-flow system is Ry with respect to the insulation resistance of the earth, described positive bus-bar is Cy with respect to the distributed capacitance of the earth, the negative busbar of this earth-free straight-flow system is Rx with respect to the insulation resistance of the earth, described negative busbar is Cx with respect to the distributed capacitance of the earth, this circuit comprises resistor R1, resistor R2, resistor R0, resistor Rs, voltage sensor and signal generator, wherein: the first terminal of described resistor R1 is connected to described positive bus-bar, the first terminal of described resistor R2 is connected to described negative busbar, described voltage sensor has first input end, the second input terminal and lead-out terminal, first input end and second input terminal of described voltage sensor are all electrically isolated from one with described lead-out terminal, and the first input end sub-connection of described voltage sensor is to the second terminal of described resistor R1, the second input terminal of described voltage sensor is connected to the second terminal of described resistor R2, the described positive bus-bar that the lead-out terminal of described voltage sensor measures for output and the voltage between described negative busbar, the first terminal of described resistor R0 is connected to described negative busbar, the second connecting terminals of described resistor R0 is received the first terminal of described resistor Rs, the second connecting terminals of described resistor Rs is received the first terminal of described signal generator, the second terminal ground connection of described signal generator, the 3rd terminal of described signal generator controls for receiving the control signal that described signal generator produces signal.
2. circuit according to claim 1, wherein, described voltage sensor is the Hall voltage sensor.
3. circuit according to claim 1, wherein, described resistor R1 and described resistor R2 are power resistor.
4. the device of the monitoring of the insulation against ground for earth-free straight-flow system, this device comprises the described circuit of any one claim in claims 1 to 3, this device also comprises the first sample circuit and processor, wherein:
Described processor is controlled described signal generator and is produced direct current signal;
Described the first sample circuit is used under the control of described processor, the DC voltage at described resistor Rs two ends being sampled, and sampled result is fed back to described processor;
Described processor is also for receiving described positive bus-bar that described voltage sensor collects and the voltage between described negative busbar, and the sampled result of the voltage between the described positive bus-bar collected based on described voltage sensor and described negative busbar and described the first sample circuit is calculated resistance value and the value in parallel thereof of described insulation resistance Ry and described insulation resistance Rx.
5. device according to claim 4, wherein, this device also comprises the second sample circuit, and:
Described processor also produces AC signal for controlling described signal generator;
Described the second sample circuit is sampled and sampled result is fed back to described processor for the alternating voltage to the second terminal place of the first terminal place of described resistor R0 and described resistor Rs under the control of described processor;
Described processor also calculates the parallel connection value of the capacitance of described distributed capacitance Cy and described distributed capacitance Cx for the sampled result of the resistance value based on described insulation resistance Rx and described insulation resistance Ry and value in parallel and described the second sample circuit.
6. according to the described device of claim 4 or 5, wherein, described device also comprises the first switch, second switch and the first resistor, wherein said the first switch is connected between the ground of the earth and this device, described second switch is connected between the first terminal of described negative busbar and described the first resistor, the second terminal of described the first resistor connects the ground of this device, and the break-make of described the first switch and described second switch is controlled by described processor.
7. device according to claim 6, wherein, this device also comprises display, the parallel connection value of the capacitance of the described insulation resistance Ry monitored for demonstration and the resistance value of described insulation resistance Rx and value in parallel and distributed capacitance Cy and distributed capacitance Cx.
8. device according to claim 6, wherein, described device also comprises the alarm unit be connected with described processor, and described processor also indicates during lower than threshold value described alarm unit to report to the police for the parallel connection value at described insulation resistance Ry and described insulation resistance Rx.
9. device according to claim 6, wherein, described device also comprises the communication unit be connected with described processor, and this communication unit is for the parallel connection value of the capacitance of the resistance value that receives and export described insulation resistance Ry and described insulation resistance Rx from described processor and parallel connection value and distributed capacitance Cy and distributed capacitance Cx.
10. the method that the insulation against ground of earth-free straight-flow system is monitored, the method is based on the described circuit of any one claim in claims 1 to 3, and the method comprises:
Control described signal generator and produce the first direct current signal;
The DC voltage at described resistor Rs two ends is sampled and obtained the first sampled result;
Voltage voltage between described positive bus-bar and described negative busbar collected between described positive bus-bar and described negative busbar by described voltage sensor is the first voltage;
Control described signal generator and produce the second direct current signal;
The DC voltage at described resistor Rs two ends is sampled and obtained the second sampled result;
Voltage voltage between described positive bus-bar and described negative busbar collected between described positive bus-bar and described negative busbar by described voltage sensor is second voltage;
Calculate resistance value and the value in parallel thereof of described insulation resistance Ry and described insulation resistance Rx based on described the first sampled result, the first voltage, the second sampled result and second voltage.
11. method according to claim 10 wherein, is sampled and is obtained the first sampled result and the DC voltage at described resistor Rs two ends is sampled and obtained the second sampled result and comprise the DC voltage at described resistor Rs two ends:
(a) per interval t1 is sampled to the DC voltage at described resistor Rs two ends until sample N sampled value;
(b) judge whether first sampled value equates with N sampled value;
(c) if equate, N sampled value is required sampled result, if unequal, returns to step (a).
12. according to the described method of claim 10 or 11, wherein, after the resistance value of calculating described insulation resistance Ry and described insulation resistance Rx based on described the first sampled result, the first voltage, the second sampled result and second voltage and value in parallel thereof, the method also comprises:
Control described signal generator and produce AC signal;
The alternating voltage at the second terminal place of the first terminal place of described resistor R0 and described resistor Rs is sampled and obtained the first AC sampling voltage and the second AC sampling voltage;
Resistance value based on described insulation resistance Rx and described insulation resistance Ry and value in parallel thereof and described the first AC sampling voltage and the second AC sampling voltage calculate the parallel connection value of the capacitance of described distributed capacitance Cy and distributed capacitance Cx.
13. method according to claim 12, wherein, the method also comprises:
When the parallel connection value of described insulation resistance Ry and described insulation resistance Rx, reported to the police during lower than threshold value.
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| CN103487660A (en) * | 2013-10-22 | 2014-01-01 | 上海海事大学 | Low-voltage DC (direct current) busbar ground insulation resistance measurement device |
| CN104076254A (en) * | 2014-06-11 | 2014-10-01 | 惠州市亿能电子有限公司 | Alternating current excitation insulation detection circuit |
| CN105182117B (en) * | 2015-08-27 | 2018-05-11 | 广西电网有限责任公司电力科学研究院 | A kind of direct current comprehensive test platform |
| CN105182117A (en) * | 2015-08-27 | 2015-12-23 | 广西电网有限责任公司电力科学研究院 | DC integrated test platform |
| CN106093586A (en) * | 2016-08-17 | 2016-11-09 | 苏州爱康能源工程技术股份有限公司 | Photovoltaic combiner box insulation resistance of DC system detecting system and detection method thereof |
| CN106093586B (en) * | 2016-08-17 | 2022-10-11 | 苏州爱康能源集团股份有限公司 | Insulation resistance detection system and detection method for photovoltaic combiner box direct current system |
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| CN107727934A (en) * | 2017-10-31 | 2018-02-23 | 中国科学技术大学 | A kind of electric automobile power battery insulation resistance monitoring device based on width phase Cleaning Principle |
| CN110967560A (en) * | 2019-03-01 | 2020-04-07 | 宁德时代新能源科技股份有限公司 | Insulation detection circuit, insulation detection method and battery management system |
| CN110687353A (en) * | 2019-11-15 | 2020-01-14 | 华霆（合肥）动力技术有限公司 | Insulation resistance detection method, device, system and storage medium |
| CN110687353B (en) * | 2019-11-15 | 2022-04-15 | 华霆（合肥）动力技术有限公司 | Insulation resistance detection method, device, system and storage medium |
| CN113315101A (en) * | 2021-05-28 | 2021-08-27 | 国网冀北综合能源服务有限公司 | Short-circuit fault recovery device and method |
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