CN101071145A - Method for measuring capacitance current of automatic tracking compensating device for arc-extinguishing coil - Google Patents

Abstract

An automatic tracking coil current compensation device capacitance measurement method, the steps are as follows: (1) coil in the second string side in a secondary impedance or resistance components directly and a resistor in series resistance back to a two-way parallel to the road Control silicon modules; (2) use Extinction Coil automatic tracking compensation device controllers, SCR control in the set time breaking and thus control the switching period resistance; (3) coil secondary side resistance from switching Petersen coil a side current and voltage changes, Petersen coil controller according to the state electrical measurement of the two, use of system voltage phase of the unit circle calculation method, the detection system of the capacitive current. This invention is simple, does not affect the normal operation of power grids, and the accuracy is high, suitable for on-line real-time tracking of capacitive current computing systems.

Description

The measuring method of capacitance current of automatic tracking compensating device for arc-extinguishing coil

Technical field

What the present invention relates to is a kind of measuring method of technical field of electricity, specifically is a kind of measuring method of capacitance current of automatic tracking compensating device for arc-extinguishing coil.

Background technology

In arc suppression coil earthing system, measuring the network system capacitance current accurately is the condition precedent that arc suppression coil effectively compensates capacitive earth current, and it is one of major function of automatic tracking compensating device for arc-extinguishing coil.Domestic widely used automatic tracking compensating device for arc-extinguishing coil injects metering system etc. to the mensuration metering system of transferring the files, the harmonic waves of adopting of network system capacitance current more, though these detection modes can be obtained the ground capacitance of system, all exist shortcoming separately.The metering system of transferring the files of system capacitive current: utilize loaded switch to change the gear of arc suppression coil, arc suppression coil neutral point voltage and current status under different gears change, and obtain the capacitance current of system according to the quantity of state under two different conditions.Because automatic tracking compensating device need constantly be transferred the files and just can be finished the system capacitive current tracking measurement, and the used loaded switch of transferring the files is a mechanical organ, reaction velocity is slow, and the noise of transferring the files is big, transfers the files too frequently to break down easily, and reliability is not high.

Find through retrieval the prior art field, Chinese patent application title: " a kind of method for testing single phase grounding current of electric power network ", number of patent application: 02134294, this patent adopts harmonic wave to inject metering system: inject the voltage signal of at least two different frequencies to network system, according to the electric signal frequency of injecting and the electric current of tested electrical network tie point, the capacitance current value that magnitude of voltage calculates electrical network.The required element complexity of this metering system, and injected unnecessary harmonic wave to electrical network, not a kind of ideal system capacitance current measurement mode.

Summary of the invention

The present invention is directed to the deficiency in the existing capacitive earth current measuring technique, a kind of measuring method of simple and reliable capacitance current of automatic tracking compensating device for arc-extinguishing coil is provided, make it in implementation process, not only avoid shortcoming on the existing measuring method, and it is simple, do not influence the normal operation of electrical network, the accuracy rate height is more suitable for the capacitance current of online in real time following calculation system.

The present invention is achieved by the following technical solutions, and step of the present invention is as follows:

1., secondary side string one resistance of arc suppression coil or on the secondary impedance element directly and a resistance, the two-way silicon controlled module in parallel of string on resistance loop;

2., utilize the controller of automatic tracking compensating device for arc-extinguishing coil, constantly control silicon controlled and cut-off setting, thus the switching of controlling resistance;

3., the switching of arc suppression coil secondary resistance causes the variation of arc suppression coil primary side current and voltage, new arc suppression coil control system utilizes the unit circle computing method of system voltage phasor according to the electric parameters of measuring two states, measures the capacitive earth current of system;

Among the present invention,, then draw a winding as the arc suppression coil secondary side from arc suppression coil if arc suppression coil does not have secondary side.

The size of resistance should be selected according to the parameter of arc suppression coil and the degree of accuracy of calculating among the present invention: in order to guarantee resistance switching front and back, the electric current of primary system, voltage have a bigger variation, help the calculating of system capacitive current, choosing of resistance value can not be too big, for make the controllable silicon conducting be flow through the electric current of resistance can not be excessive, it is too little that the choosing of resistance value can not be crossed, and is generally the Secondary Winding reactance value X of 10 times arc suppression coil _L0

Bidirectional triode thyristor of series connection in resistance loop of the present invention, utilize the switching of the controller control silicon controlled conducting controlling resistance of automatic tracking compensating device for arc-extinguishing coil, every conducting of controllable silicon or disconnection once just can be calculated one time capacitive earth current, the silicon controlled ON time is set (as: if per 5 minutes needs of system calculate a capacitance current according to the calculation requirement of fielded system, then controllable silicon conducting in per 5 minutes once, controller has enough sampled values in order to make the controllable silicon conducting time, the retention time of controllable silicon conducting should be greater than 2 seconds), thus reach the purpose of the capacitance current of online in real time following calculation system.

Compared with prior art, the inventive method only needs to draw a secondary side at arc suppression coil, resistance of string on secondary side, controller only needs the switching of controlling resistance can realize the calculating of system capacitive current, and its loaded switch device that do not need simple in structure can not produce harmonic wave yet and bring adverse influence for the electrical network primary system, and through on-the-spot test of many times, error rate is in 2%, and measurement result is more accurate, capacitance current in the energy real-time follow-up arc suppression coil earthing system.

Description of drawings

Fig. 1 arc suppression coil systematic schematic diagram of the present invention;

Fig. 2 is arc suppression coil of the present invention system equivalent circuit diagram;

Fig. 3 is the voltage vector-diagram before and after the resistance switching of the present invention.

Embodiment

Below in conjunction with accompanying drawing embodiments of the invention are elaborated: present embodiment is being to implement under the prerequisite with the technical solution of the present invention, provided detailed embodiment and concrete operating process, but protection scope of the present invention is not limited to following embodiment.

Embodiment:

The turn-adjusting arc suppression coil of putting secondary with damping resistance is an example.

The turn-adjusting arc suppression coil system that damping resistance is put secondary is as shown in Figure 1: L is the arc suppression coil of band secondary, U0 is the unbalance voltage of system, C is the ground capacitance of system, R ' is the resistance of system, R is for eliminating the used damping resistance of system resonance, and r is the used switching resistance of computing system capacitance current, and switching resistance r is in parallel with damping resistance R, bidirectional triode thyristor module K goes here and there on switching resistance r circuit, the switching of controlling resistance r.Silicon controlled module K cut-offs the switching that causes resistance r by new arc suppression coil control system control, controller utilizes the used current transformer CT of measuring system electric current, the used voltage transformer pt of measurement neutral point voltage to record the variation of primary side current voltage, thereby utilize computing formula to solve the capacitance current of system.The resistance of switching resistance r should be chosen according to damping resistance R, guarantees bigger variation of voltage and current of arc suppression coil primary side before and after switching r, can satisfy the needs that calculate capacitance current.

The arc suppression coil system equivalent circuit diagram of computing system capacitance current as shown in Figure 2, wherein XL ' is the equivalent reactance of arc suppression coil primary side, Rb is the equivalent resistance of arc suppression coil primary side.The voltage vector relational expression of system circuit is shown in (formula 1), and the voltage vector relational expression before and after the resistance r switching is shown in (formula 2), and the voltage vector unit's circle diagram before and after the resistance r switching as shown in Figure 3.

U ₀=I[(R '+R _b)+j (X _L ^'-X _c)] (formula 1)

$\left\{\begin{array}{c}{\mathrm{<figure-callout\; id="0"\; label="U"\; filenames="A20071004196300101.png"\; state="\{\{state\}\}">U</figure-callout>}}_0=I_1[(R^{\&prime;}+R_{b1})+j(X_{L1}^{\&prime;}-X_c)]\\ {\mathrm{<figure-callout\; id="0"\; label="U"\; filenames="A20071004196300101.png"\; state="\{\{state\}\}">U</figure-callout>}}_0=I_2[(R^{\&prime;}+R_{b2})+j(X_{L2}^{\&prime;}-X_c)]\end{array}\right.$ (formula 2)

Vector relations according to voltage in the voltage vector-diagram before and after the resistance r switching can get (formula 3), and then tries to achieve the capacitive reactance Xc (formula 4) and the capacitance current Ic (formula 5) of system.

$\left\{\begin{array}{c}{I}_1(R^{\&prime;}+R_{b1})=I_2(R^{\&prime;}+R_{b2})\&CenterDot;\frac{1}{\cos \mathrm{\&theta;}}+I_1(X_{L1}^{\&prime;}-X_C)\mathrm{tg\&theta;}\\ I_2(X_{L2}^{\&prime;}-X_C)=I_2(R^{\&prime;}+R_{b2})\mathrm{tg\&theta;}+I_1(X_{L1}^{\&prime;}-X_C)\&CenterDot;\frac{1}{\cos \mathrm{\&theta;}}\end{array}\right.$ (formula 3)

$X_C=\frac{(R_{b2}-R_{b1})I_1{I}_2\sin \mathrm{\&theta;}+(I_1^2{X}_{L1}^{\&prime;}+I_2^2{X}_{L1}^{\&prime;})-(X_{L1}^{\&prime;}+X_{L2}^{\&prime;})I_1{I}_2\cos \mathrm{\&theta;}}{I_1^2+I_2^2-2I_1{I}_2\cos \mathrm{\&theta;}}$ (formula

4)

$I_c=\frac{U_n}{X_c}$ (formula 5)

Annotate: θ is the difference of the phase angle of a line current of arc suppression coil before and after the resistance r switching:

θ＝θ ₁-θ ₂

θ ₁, θ ₂For flowing through the phase angle of the system power of arc suppression coil before and after the resistance r switching;

I ₁, I ₂Current amplitude for the circuit of arc suppression coil before and after the resistance r switching;

R _B1, R _B2Equivalent series impedance for arc suppression coil primary side before and after the r switching;

X _L1', X _L2' be arc suppression coil primary side equivalent series reactance value before and after the r switching:

$\left\{\begin{array}{c}{R}_{b1}=\frac{U_{N1}}{I_1}\cos {\mathrm{\&beta;}}_1\\ X_{L1}^{\&prime;}=\frac{U_{N1}}{I_1}\sin {\mathrm{\&beta;}}_1\end{array}\right.$ $\left\{\begin{array}{c}{R}_{b2}=\frac{U_{N2}}{I_2}\cos {\mathrm{\&beta;}}_2\\ X_{L2}^{\&prime;}=\frac{U_{N2}}{I_2}\sin {\mathrm{\&beta;}}_2\end{array}\right.$

β ₁, β ₂Be respectively the phase angle difference of r switching front and back neutral point voltage and line current;

U _N1, U _N2Be respectively r switching front and back neutral point voltage amplitude;

U _nPhase voltage for system line.

Carried out simulated experiment in practice according to above condition and computing formula, wherein turn-adjusting arc suppression coil capacity S:300/30KVA, U0=58V, R '=20 Ω, R=11.2 Ω, C=15.14uF, r=10 Ω, neutral point voltage value and primary system current value are calculated by the controller collection of automaton, and be as shown in table 1 in the experimental data of different gears.The capacitive earth current error rate that obtains according to the inventive method is about 1%, and accuracy is than higher.

Table 1

Gear	Voltage magnitude (V)	Current amplitude (A)	Electric current phase angle (radian)	Angle of impedance (degree)	Actual value Ic (A)	Measured value Ic (A)	Error rate
								1	84.91	0.1327	-3.2389	84	28.84	28.66	0.6％
1	84.36	0.1347	-3.0948	78.5
					2	91.516	0.1641	-3.2294	84	28.84	28.49	1.2％
2	90.178	0.1650	-3.0754	78.5
					3	99.64	0.2030	-3.2102	84				28.84	28.34	0.67％
3	97.4	0.2026	-3.0438	78.5
					4	111.34	0.2575	-3.1911	84	28.84	28.41	1.52％
4	107.96	0.2548	-3.0086	78.5
					5	124.63	0.3257	-3.1470	84				28.84	28.88	0.14％
5	119.37	0.3181	-2.9478	78.5
					6	141.3	0.4162	-3.0723	84	28.84	29.16	1.1％
6	132.35	0.3971	-2.8533	78.5
					7	170.29	0.5645	-2.9811	84				28.84	29.24	1.4％
7	154.467	0.5220	-2.7301	78.5
					8	210.70	0.7869	-2.8046	84	28.84	29.05	0.74％
8	177.15	0.6736	-2.5303	78.5
					9	263.757	1.1109	-2.4814	84				28.84	29.06	0.77％
9	197.00	0.8451	-2.2284	78.5
					10	288.09	1.3740	-1.9400	84	28.84	29.11	0.94％
10	195.22	0.9484	-1.8292	78.5
					11	224.33	1.2185	-1.3675	84				28.84	28.60	0.83％
11	164.01	0.9070	-1.4379	78.5
					12	153.91	0.9538	-1.0435	84	28.84	28.85	0.03％
12	124.54	0.7852	-1.1543	78.5
					13	107.16	0.7580	-0.8614	84				28.84	28.21	2.24％

Gear	Voltage magnitude (V)	Current amplitude (A)	Electric current phase angle (radian)	Angle of impedance (degree)	Actual value Ic (A)	Measured value Ic (A)	Error rate
								13	94.17	0.677	-0.9728	78.5
14	78.715	0.6353	-0.7548	84	28.84	29.01	0.62％
								14	70.918	0.5822	-0.8396	78.5

Claims (4)

1. the measuring method of a capacitance current of automatic tracking compensating device for arc-extinguishing coil is characterized in that, step is as follows:

1., secondary side string one resistance of arc suppression coil or on the secondary impedance element directly and a resistance, the two-way silicon controlled module in parallel of string on resistance loop;

2., utilize the controller of automatic tracking compensating device for arc-extinguishing coil, constantly control silicon controlled and cut-off setting, thereby control the switching of described resistance;

3., the switching of arc suppression coil secondary resistance causes the variation of arc suppression coil primary side current and voltage, new arc suppression coil control system utilizes the unit circle computing method of system voltage phasor according to the electric parameters of measuring two states, measures the capacitive earth current of system.

2. the measuring method of capacitance current of automatic tracking compensating device for arc-extinguishing coil according to claim 1 is characterized in that, described 1. in, if arc suppression coil does not have secondary side, then draw a winding as the arc suppression coil secondary side from arc suppression coil.

3. the measuring method of capacitance current of automatic tracking compensating device for arc-extinguishing coil according to claim 1 and 2 is characterized in that, described 1. in, the size of resistance is the Secondary Winding reactance value X of 10 times arc suppression coil _L0

4. the measuring method of capacitance current of automatic tracking compensating device for arc-extinguishing coil according to claim 1 is characterized in that, the described unit circle computing method of utilizing the system voltage phasor are measured the capacitive earth current of system, are specially:

$X_C=\frac{(R_{b2}-R_{b1})I_1{I}_2\sin \mathrm{\&theta;}+(I_1^2{X}_{L1}^{\&prime;}+I_2^2{X}_{L2}^{\&prime;})-(X_{L1}^{\&prime;}+X_{L2}^{\&prime;})I_1{I}_2\cos \mathrm{\&theta;}}{I_1^2+I_2^2-2I_1{I}_2\cos \mathrm{\&theta;}}$

$I_c=\frac{U_n}{X_c}$

Wherein: θ is the difference of the phase angle of a line current of arc suppression coil before and after the resistance r switching:

θ＝θ ₁-θ ₂

I ₁, I ₂Current amplitude for the circuit of arc suppression coil before and after the r switching;

R _B1, R _B2Equivalent series impedance for arc suppression coil primary side before and after the r switching;

X _L1', X _L2' be arc suppression coil primary side equivalent series reactance value before and after the r switching:

$\left\{\begin{array}{c}{R}_{b1}=\frac{U_{N1}}{I_1}\cos {\mathrm{\&beta;}}_1\\ X_{L1}^{\&prime;}=\frac{U_{N1}}{I_1}\sin {\mathrm{\&beta;}}_1\end{array}\right.$ $\left\{\begin{array}{c}{R}_{b2}=\frac{U_{N2}}{I_2}\cos {\mathrm{\&beta;}}_2\\ X_{L2}^{\&prime;}=\frac{U_{N2}}{I_2}\sin {\mathrm{\&beta;}}_2\end{array}\right.$

β ₁, β ₂Be respectively the phase angle difference of r switching front and back neutral point voltage and line current;

U _N1, U _N2Be respectively r switching front and back neutral point voltage amplitude;

U _nPhase voltage for system line.

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