CN103490404A - Tuning method of following-setting-type arc suppression coil of power distribution network system and fault line selection method - Google Patents

Abstract

The invention provides a tuning method of a following-setting-type arc suppression coil of a power distribution network system and a fault line selection method. When the system normally operates, the following-setting-type arc suppression coil tracks changes of a power distribution network in real time, capacitive currents of the system are accurately measured, the capacity of the arc suppression coil is adjusted to be in the off-tuning degree of 40% according to the capacitive currents, and the arc suppression coil is under an under-compensation state. When a single-phase earth fault is detected, after time window delay for 100 ms, namely five power frequency cyclic waves, the capacity of the arc suppression coil is adjusted to an overcompensation state so as to control grounded residual currents to be under 5A. In a time window undergoing 100 ms delay adjustment, by means of arc suppression coil under-compensation characteristics, firstly four outgoing lines with the largest fundamental wave zero-sequence current amplitude are selected, then phases of the fundamental wave zero-sequence currents of the four outgoing lines are compared, and the outgoing line opposite to the other three outgoing lines is a grounded fault line. The tuning method can effectively overcome the defects that an existing following-setting-type arc suppression coil is slow in response time, high in overvoltage level and low in accuracy of fault line selection.

Description

The tuning methods of the post-set arc suppression coils of distribution network system and fault-line selecting method

Technical field

The present invention relates to electric power system distribution technique field, relate more specifically to a kind of tuning methods and fault-line selecting method of post-set arc suppression coils, be applicable to power network neutral point through the post-set arc suppression coils grounding system.

Background technology

At present, post-set arc suppression coils obtains applying more and more widely in power distribution network.But post-set arc suppression coils real-time monitoring system capacitance current, and the setting compensation parameter, when system is normally moved, arc suppression coil is in the operation of the position away from resonance point, when system generation single-phase earthing, rapidly reactor is adjusted to the parameter of setting before fault, capacitance current is compensated.When system is normally moved, the impedance of post-set arc suppression coils is a very large value, and the neutral point connect is substantially in earth-free state; When ground connection occurs in system, device is just regulated arc suppression coil to overcompensation after earth fault being detected, therefore must there is certain device response time, this type of arc suppression coil device response time is all slow (generally being greater than 40ms) generally, can not play the effect of over-voltage suppression, to the insulation weakness formation potential threat of system equipment.

The selection method of post-set arc suppression coils mainly adopts linear perturbation theory.Linear perturbation theory is to utilize before and after the change of automatic tuning arc depression coil compensativity, and fault point is selected in the variation of each outlet zero-sequence current, and wherein the faulty line variable quantity is maximum, judges accordingly faulty line.Although the method in the system for distribution network of power extensive use, is subject to the impact on current increment of intermittence arc grounding fault and high resistance earthing fault, the failure line selection reliability further improves comparatively difficulty.

Summary of the invention

Shortcoming for existing post-set arc suppression coils, a kind of tuning methods and fault-line selecting method of post-set arc suppression coils of novel distribution network system have been proposed, both solved traditional post-set arc suppression coils slow because of the device response time, the problem that overvoltage level is high, overcome again the existing low deficiency of fault-line selecting method accuracy rate.

Technical problem of the present invention can solve by the following technical programs: when system is normally moved, post-set arc suppression coils real-time tracking power distribution network changes, the Measurement accuracy system capacitive current, and regulate the de-humorous degree of arc suppression coil capacity to 40% according to this capacitance current, arc suppression coil is in the undercompensation state.When detecting when single phase ground fault occurs, through 100ms (5 cycles) time delay, then regulate the arc suppression coil capacity to overcompensation to control the ground connection residual flow below 5A.Time window at delay adjusted 100ms, utilize the under-compensated characteristics of arc suppression coil, at first select four outlets of fundamental wave zero sequence current amplitude maximum, then compare the fundamental wave zero sequence current phase of these four outlets, the outlet contrary with other three outlets is ground path.

The tuning manner of aforesaid post-set arc suppression coils is characterized in that: while normally moving, and the undercompensation state of arc suppression coil in 40% de-humorous degree.Like this when normal operation; can not cause the neutral point overvoltage because of arc suppression coil inductance and the improper system caused of system capacitance parameter configuration; can guarantee that neutral point voltage skew can not surpass the scope of stipulating in China's overvoltage protection rules, 15% of phase voltage.

The inductance value system of selection of post-set arc suppression coils is as follows:

The de-humorous degree of arc suppression coil during normal operation:

$v=\frac{I_C-I_L}{I_c}=40\%$

Wherein: v is de-humorous degree;

I _cfor system capacitive current;

I _l=U _Φthe offset current that/ω L provides for post-set arc suppression coils;

U _Φfor the system phase voltage;

ω=100 π rad/s are the system angle frequency;

L is the post-set arc suppression coils inductance.

Above I _c, U _Φ, ω is and measures, and can obtain the arc suppression coil inductance value to be:

$L=\frac{U_{\mathrm{\Φ}}}{{0.6\mathrm{\ωI}}_C}$

The tuning manner of aforesaid post-set arc suppression coils, it is characterized in that: when single phase ground fault occurs, post-set arc suppression coils is action immediately not, its device response time generally is greater than 40ms, add the time window of 100ms, occur to the arc suppression coil action from single phase ground fault, in about 140ms, arc suppression coil is still in the 40% undercompensation state taken off under humorous degree situation.During this period of time, arc suppression coil has had certain compensating action, can the restriction system overvoltage in the reasonable scope.

Aforesaid fault-line selecting method is characterized in that: single phase ground fault according to each outlet zero-sequence current waveform in the 100ms time window, is selected faulty line after occurring.Its route selection criterion is:

If in every outlet, zero-sequence current temporal evolution function in the 100ms time window is I _j=g _j(t _k), I wherein _jbe the zero-sequence current of j bar outlet, t _kmean k the time that sampled point is corresponding, g _j(t _k) mean the sampled value of k sampled point.Sampling period is T, and N data of per cycle sampling, to I _jcarry out Fourier transform and obtain the fundametal compoment amplitude I of every outlet zero-sequence current _j1, the fundametal compoment phase place

$a_{j1}=\frac{2}{N}\underset{i=0}{\overset{N-1}{\mathrm{\Σ}}}g\left(t_k\right)\cos (\frac{2\mathrm{\π}}{N}\·k),$ $b_{j1}=\frac{2}{N}\underset{i=0}{\overset{N-1}{\mathrm{\Σ}}}g\left(t_k\right)\sin (\frac{2\mathrm{\π}}{N}\·k)$

$I_{j1}=\sqrt{a_{j1}^2+b_{j1}^2},$

Select fundamental voltage amplitude I _j1four maximum outlets, relatively the fundametal compoment phase place of these four outlets if certain circuit and other three-line fundametal compoment single spin-echos, selecting this circuit is faulty line; If four circuit fundametal compoment phase place is identical, faulty line is elected bus as.

Aforesaid fault line selection method for single-phase-to-ground fault, it is characterized in that: route selection under the undercompensation state of post-set arc suppression coils 40% de-humorous degree, eliminated the overcompensation effect of arc suppression coil to capacitance current in traditional fault-line selecting method, because de-humorous degree is larger, no matter be that busbar grounding or high resistance ground all can accurately be judged, can greatly improve the route selection accuracy rate.

The tuning manner of aforesaid post-set arc suppression coils is characterized in that: after judging the generation single phase ground fault, through the 100ms time delays, post-set arc suppression coils is adjusted to rapidly the overcompensation state, so that the ground connection residual flow is down to below 5A.

Advantage of the present invention is:

1. with respect to traditional post-set arc suppression coils operational mode, the present invention does not need to increase any new hardware device, only needs to revise software section, just can greatly improve the route selection accuracy rate.Route selection under the undercompensation state of 40% de-humorous degree, eliminated the overcompensation effect of arc suppression coil to capacitance current under traditional line selection mode, no matter is that busbar grounding or high resistance ground all can accurately be judged.And traditional linear perturbation theory is limited by the impact of high resistance ground on current increment, easily erroneous judgement under high resistive fault.

2. presetting 40% de-humorous degree when post-set arc suppression coils normally moves; both effectively suppressed the intermittent arcing ground over-voltage that traditional post-set arc suppression coils device response time causes excessively slowly; effectively protected power equipment, in the time of guaranteeing normally to move again, the neutral point displacement voltage skew is in overvoltage rules prescribed limit.

The accompanying drawing explanation

Circuit system schematic diagram when Fig. 1 is the single phase ground fault generation;

Fig. 2 is arc grounding overvoltage comparison diagram before and after certain transformer station's post-set arc suppression coils operational mode changes;

Each outlet zero-sequence current comparison diagram in the 100ms window after post-set arc suppression coils action when Fig. 3 is certain substation bus fault;

Each outlet zero-sequence current comparison diagram in the 100ms window after post-set arc suppression coils action when Fig. 4 is certain transformer station single-phase high resistance earthing fault of outlet.

Embodiment

Now the present invention is described further by reference to the accompanying drawings.

Referring to Fig. 1,

for the capacitance current of every outlet,

the zero-sequence current recorded for the current transformer of every outlet,

for system total capacitance electric current,

the offset current provided for post-set arc suppression coils,

fault current during for single-phase earthing.

When system is normally moved, the de-humorous degree of the capacitance current of device real-time monitoring system preset post-set arc suppression coils is 40%, and device detects each outlet zero-sequence current in real time

when the generation single phase ground fault being detected, relatively in the 100ms window before the post-set arc suppression coils action

fundametal compoment amplitude phase place, concrete grammar is: select four outlets of fundametal compoment amplitude maximum, certain outlet and other three-line fundametal compoment reverse-phases, selecting this circuit is faulty line; If circuit fundametal compoment phase place homophase four, faulty line is elected bus as.After the 100ms time window, regulate rapidly arc suppression coil to overcompensation, so that the ground connection residual flow is down to below 5A.

Fig. 2 is under certain transformer station's post-set arc suppression coils different running method, over-voltage condition comparison diagram when intermittent arc-earth fault occurs.Under former operational mode, overvoltage approximately has 38kV (4.4 times of overvoltage); And, under the de-humorous degree operational mode of post-set arc suppression coils presetting 40%, overvoltage is down to about 24kV (2.8 times of overvoltage), the de-humorous degree operational mode of visible post-set arc suppression coils presetting 40% has obvious inhibitory action to intermittent arcing ground over-voltage.

Each outlet zero-sequence current comparison diagram in the 100ms window after post-set arc suppression coils action when Fig. 3 is certain substation bus fault.At first choose four outlets of zero-sequence current first-harmonic content maximum, then compare its phase place, can correctly be chosen to be busbar fault.

Each outlet zero-sequence current comparison diagram in the 100ms window after post-set arc suppression coils action when Fig. 4 is certain transformer station single-phase high resistance earthing fault of outlet.The outlet that earth fault occurs is outlet 5.At first choose four outlets of zero-sequence current first-harmonic content maximum, more relatively phase place, outlet 5 and all the other outlet zero-sequence current fundametal compoment single spin-echos, correctly judgement as seen.

Claims (9)

1. the tuning methods of the post-set arc suppression coils of a distribution network system, wherein, the neutral point of described distribution network system is through post-set arc suppression coils ground connection, it is characterized in that: when distribution network system normally moves, post-set arc suppression coils real-time tracking power distribution network changes, the Measurement accuracy system capacitive current, and regulate the de-humorous degree of arc suppression coil capacity to 40% according to described capacitance current, make arc suppression coil in the undercompensation state; When the generation single phase ground fault being detected, after elapsed time window time delay is regulated, then regulate the arc suppression coil capacity to the overcompensation state, to control the ground connection residual flow.

2. tuning methods as claimed in claim 1, is characterized in that, preferred, time window is 100ms, and the ground connection residual flow is controlled at below 5A.

3. tuning methods as claimed in claim 1, it is characterized in that: when single phase ground fault occurs, post-set arc suppression coils can not move immediately, it has certain response time, simultaneously due to the also time delay of life period window, thereby occur to arc suppression coil action from single phase ground fault, the arc suppression coil undercompensation state in 40% de-humorous degree still in the time limit jointly formed by response time and time window.

4. tuning methods as claimed in claim 3, it is characterized in that: in the time limit jointly consisted of response time and time window, arc suppression coil is exported certain offset current, with the restriction system overvoltage in zone of reasonableness.

5. tuning methods as claimed in claim 3 is characterized in that: preferred, the response time is greater than 40ms.

6. the fault-line selecting method of a distribution network system, wherein, the neutral point of described distribution network system is through post-set arc suppression coils ground connection, it is characterized in that: when system is normally moved, post-set arc suppression coils real-time tracking power distribution network changes, the Measurement accuracy system capacitive current, and regulate the de-humorous degree of arc suppression coil capacity to 40% according to described capacitance current, make arc suppression coil in the undercompensation state; When the generation single phase ground fault being detected, after elapsed time window time delay is regulated, then regulate the arc suppression coil capacity to the overcompensation state, to control the ground connection residual flow; During delay adjusted time window, based on the under-compensated characteristics of arc suppression coil, at first select four outlets of fundamental wave zero sequence current amplitude maximum, then the fundamental wave zero sequence current phase of more described four outlets, therefrom find faulty line.

7. fault-line selecting method as claimed in claim 6 is characterized in that:

After single phase ground fault occurs, according to each outlet fundamental wave zero sequence current waveform interior during time window, can select faulty line, its route selection criterion is:

Select four outlets of fundamental wave zero sequence current amplitude maximum, compare the fundamental wave zero sequence current phase of these four outlets, if certain circuit is contrary with other three-line fundamental wave zero sequence current phases, selecting this circuit is faulty line; If four circuit fundamental wave zero sequence current phase is identical, faulty line is elected bus as.

8. fault-line selecting method as described as any one in claim 6,7 is characterized in that:

After judging the generation single phase ground fault, after the time window time delay, post-set arc suppression coils is adjusted to rapidly the overcompensation state, and the ground connection residual flow is down to below 5A.

9. fault-line selecting method as described as any one in claim 6,7 is characterized in that: preferred, time window is 100ms.

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