CN2205601Y - Suppressor for distribution network wire breakage resonance - Google Patents

Abstract

The utility model relates to a suppressor for wire breakage resonance in a distribution network. The utility model is composed of a self excitation-external excitation converting element, a rectification energy absorption component, and an operation circuit. In the utility model, the self excitation-external excitation converting element is a three phase capacitor bank which is arranged between the phases of a transformer winding in a bridge connection manner; the energy absorption component is composed of a three phase rectification bridge D, a liquid electrolytic capacitor C, and a shunt resistor R; the three phase rectification bridge D, the liquid electrolytic capacitor C, and the shunt resistor R are connected with a low voltage winding; the operation circuit is composed of a control circuit KD and a breaker J. The utility model has the advantages that resonance caused by the wire breakage of a distribution network is effectively suppressed, volume is small, weight is light, operation is reliable, etc., being widely used in substations and pole transformers with voltage from 6 to 35KV.

Description

Suppressor for distribution network wire breakage resonance

The utility model belongs to the high voltage technique field, relates to a kind of new device of inhibition 6～35kv line interruption line resonance.

In the distribution line of 6～35kv, broken string phenomenon (the general reference lead fractures, the phase-splitting fusing of switch tripping, fuse and suit) generally takes place, its result forms series loop between the magnetizing inductance of lead capacitance and zero load (or underloading) user transformers, producing serious appearance over the ground rises overvoltage and has excited the ferro resonance phenomenon, cause blowing and blasting of grading resistor of an arrester, counter-rotating appears in the low capacity motor of load transformer end, so that smash electric equipment such as load transformer.

In the area that has, for the blast that prevents lightning arrester its grading resistor increased and to be twice, but resonance overvoltage still exists.Up to the present, the domestic and international effective ways of unrestraint wire-break resonance still, thereby the insulation damages accident frequently takes place.

The utility model is a kind of protective device of developing at above-mentioned situation, and the appearance that it can be eliminated behind the broken string rises and self-excitation phenomena, makes it to be converted into the outer state that swashs, and utilizes the method for moment energy-absorbing to be suppressed then.

The utility model is by self-excitation-sharp outward conversion elements, and rectification energy-absorbing assembly and actuating circuit three parts are formed.Self-excitation-sharp outward conversion elements is a three-phase condenser bank, is connected across the alternate of Transformer Winding.The energy-absorbing assembly is made of three-phase commutation bridge D, the liquid electrolytic capacitor C and the parallel resistance R that are connected on the low pressure winding.Actuating circuit is made of control circuit KD and relay J, KD mainly is made up of voltage comparator, low pass filter and OR circuit etc., the door turnover voltage of its OR circuit is 1.5 times of specified phase voltage, frequency division turnover voltage behind its frequency-division filter is 0.5 times of specified phase voltage, and the input of KD is connected on the capacitor voltage divider C of transformer three-phase low pressure winding overhang _Fg～C _FdOn; The common junction n of J ₁Be connected on the end of C, normally closed node n ₂Be connected on the leading-out terminal of D normal opened contact n ₃Be connected on the end of R, the signal of J is taken from the output of KD.

Operation principle of the present utility model is seen accompanying drawing 1-3, and accompanying drawing 1 is an example of the resonance major loop of single-phase wire break and mains side ground connection, C ₀Be the lead direct-to-ground capacitance of broken string phase, L and L ' are the magnetizing inductance of load transformer high-pressure side and low-pressure side.In the distribution short-term road of reality, what mainly take place here is to hold to rise overvoltage and self-excitation industrial frequency resonance.Do not add alternate electric capacity △ C in the high-pressure side ₁₂The time, one phase equivalent circuit inserts △ C as shown in Figure 2 ₁₂After, its equivalent electric circuit becomes shown in the accompanying drawing 3, and wherein equivalent potential E ' significantly descends, i.e. E '=E (C ₀)/(C ₀+ 2 △ C ₁₂), equivalent capacity then increases to C ₀+ 2 △ C ₁₂, as long as drop into enough big △ C ₁₂, appearance rises, self-excitation phenomena just can transfer the outer state that swashs to.As self-excitation～the additional alternate electric capacity of sharp conversion elements can be connected on the high-pressure side of transformer outward, its value is about several microfarads at zero point, also can be connected on the low-pressure side of transformer according to the no-load voltage ratio relation, and its value is about tens microfarads.

Accompanying drawing 4 is a specific embodiment of the present utility model.△ C ₁₂For being connected on the alternate self-excitation of step down side～sharp conversion elements outward.Alternate, the output that the input of three-phase commutation bridge D is connected on the low pressure winding is connected on the normally closed node n of relay J ₂On.The end of resistance R is connected on the normal opened contact n of relay J ₃On.The end of liquid electrolytic capacitor C is connected on the common node n of relay J ₁On.The input of control circuit KD is connected on the voltage divider C of three-phase winding overhang _Fg～C _Fd(being a, b, c 3 points in the accompanying drawing 4), the signal input part of output relay termination.The course of work of present embodiment is: the first-harmonic resonance voltage of any phase winding is above 1.5 times of specified phase voltage in network, perhaps the branch frequency component in the phase voltage is above 0.5 times, control circuit produces corresponding signal by OR circuit, exports relay to, makes the common junction n of relay ₁Break away from normally closed node n ₂Often open node n and put into ₃On, capacitor C is discharged by R, through discharge off behind three times of time constant 3RC, the common node n of relay J ₁Be back to normally closed node n ₂On, capacitor C is put into the winding two ends through D, its moment energy-absorbing function make resonance disappear immediately.For the load transformer of general capacity, the size of C is hundred microfarad ranges.

Accompanying drawing 5, wherein A are seen in the wiring of control circuit KD ₁, A ₂And A ₃Be emitter follower, together with full-wave rectifying circuit G ₁, G ₂, and G ₃And voltage comparator A ₄Form the detection loop of first-harmonic resonance, when first-harmonic resonance, obtain a high level V ₁When Subharmonic Resonance, by low pass filter A ₅, A ₆, A ₇With full-wave rectifying circuit G ₄, G ₅, G ₆And voltage comparator A ₈Obtain another high level V ₂V ₁And V ₂By or the door A ₉Export final resonance high level signal V.Subsequently, singly move trigger A ₁₀Triggered by V, the output positive pulse makes and door A ₁₁Action, its high level is delivered to the input of gated squarewave generator, and square width equals 1.4R ₀C ₀, positive square wave makes triode BG conducting, the relay J action, and its node is from n ₁With n ₂Link to each other and transfer to and n ₃Link to each other, when the losing side ripple, node n ₁Return and harmonic elimination.

The restraining device of the power distribution network interrupt line resonance of making according to the utility model not only can suppress the power distribution network caused resonance phenomena that breaks effectively, reduces the generation of insulation damages accident, and because its additional alternate electric capacity △ C ₁₂Directly be connected on the alternate of three phase windings, other parts then are assembled into case separately, thereby have characteristics such as volume is little, in light weight, reliable in action, and is safe in utilization, can extensive use in the pole transformer of 6～35KV and electric substation.

Accompanying drawing 1～3 is a schematic diagram of the present utility model.Accompanying drawing 4 is a schematic circuit of the present utility model, and wherein I is self-excitation-sharp outward conversion elements.II is a rectification energy-absorbing assembly, and III is an actuating circuit.Accompanying drawing 5 is the winding diagram of control circuit KD.

Claims (2)

1, a kind of restraining device of distribution network interrupt line resonance is made up of self-excitation～sharp outward conversion elements, rectification energy-absorbing assembly and actuating circuit three parts, it is characterized in that:

Described self-excitation～sharp outward conversion elements is a three-phase condenser bank, is connected across the alternate of Transformer Winding;

Described energy-absorbing assembly is made of three-phase commutation bridge D, the liquid electrolytic capacitor C and the parallel resistance R that are connected on the low pressure winding;

Described actuating circuit is made of control circuit KD and relay J, and the input of KD is connected on the capacitor voltage divider C of transformer three-phase low pressure winding overhang _Fg～C _FdOn, the common junction n of J ₁Be connected on the end of C, normally closed node n ₂Be connected on the leading-out terminal of D, often open node n ₃Be connected on the end of R.

2, the restraining device of distribution network interrupt line resonance as claimed in claim 1, it is characterized in that: described control circuit KD's or door upset power-frequency voltage be 1.5 times of specified phase voltage, be 0.5 times of specified phase voltage by the upset frequency division voltage behind the frequency-division filter circuit.

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