A kind of on-line measurement device of electric power system surge protector insulation resistance
Technical field
The utility model belongs to thunder and lightning science and technology field, particularly a kind of on-line measurement device of electric power system surge protector insulation resistance.
Background technology
Surge protector is arranged in supply line, and for a long time under line voltage distribution or superpotential effect, in surge protector, the phenomenons such as aging and decreasing insulating appear in components and parts.Work as decreasing insulating; surge protector loses the energy of release lightning wave and suppresses the function of lightning surge; insulation resistance diminishes, Leakage Current becomes large, even affects the normal operation of transmission system, is therefore very important to the detection of the insulating property of operating surge protector.
The megger test method of surge protector is tested in laboratory, and the insulation resistance of on-line checkingi surge protector does not also have corresponding checkout equipment at present.The method of high voltage equipment insulation resistance on-line checkingi has: DC component method; low frequency overlay method; dielectric loss angular factor mensuration, shelf depreciation method and ground current method, but experiment shows, and the online insulation resistance that these methods are all not suitable for surge protector detects.
Utility model content
In order to solve the technical matters that above-mentioned background technology is mentioned; the utility model aims to provide a kind of on-line measurement device of electric power system surge protector insulation resistance; for the on-line testing of the insulating property of surge protector in electric power system; by measuring the size of surge protector insulation resistance; judge aging, the deterioration condition of surge protector, thus analyze its working condition.
In order to realize above-mentioned technical purpose, the technical solution of the utility model is:
A kind of on-line measurement device of electric power system surge protector insulation resistance, for measuring the insulating resistance value of surge protector in electric power system, comprise adjustable DC high-voltage power supply, reactor, voltage detection unit and the first ~ three reference resistance, described reactor comprises the first ~ three inductance, the three-phase firewire that one end of described first ~ three inductance connects one to one in electric power system, center line in the other end of the first ~ three inductance and electric power system is all connected through the positive output end of the first reference resistance with adjustable DC high-voltage power supply, positive output end ground connection after the second reference resistance of described adjustable DC high-voltage power supply, negative output terminal ground connection after the 3rd reference resistance of adjustable DC high-voltage power supply, described voltage detection unit just comprises, negative input end, the positive input terminal of voltage detection unit connects the center line in electric power system, the negative input end ground connection of voltage detection unit, be connected with the negative output terminal of adjustable DC high-voltage power supply behind the earth terminal disconnection ground of described surge protector.
Wherein, above-mentioned voltage detection unit comprises the sample resistance, low-pass filter, DC amplification circuit and the D.C. voltmeter that connect successively, and the two ends of described sample resistance are respectively as the positive and negative input end of voltage detection unit.
Wherein, the voltage output range of above-mentioned adjustable DC high-voltage power supply is 0 ~ 5kV.
Wherein, above-mentioned first reference resistance is mega-ohms resistance.
Wherein, second, third reference resistance above-mentioned is a kilo-ohm level resistance.
Adopt the beneficial effect that technique scheme is brought:
(1) the utility model utilizes direct current bridge ratio juris, in the supply line run, apply a certain DC voltage, the insulation resistance value of surge protector is calculated by measuring the size flowing through unbalance voltage between two brachium pontis, the insulation variation tendency of surge protector can be judged according to the size of insulating resistance value, Timeliness coverage insulation fault hidden danger, reduce the loss because insulating property cause, the structure of its test circuit is simple, stable and reliable for performance, have easy to operate, measurement data accurately, precision high;
(2) the utility model adopts the on-line testing technique of reactor isolation, does not produce any impact to power-supply unit, and less by the impact of electric power system power supply.
(3) the utility model measurement range is large, and applied range, the scope of insulation resistance can reach a few begohm, is suitable for the test of the insulation resistance of low pressure and high-tension apparatus.
Accompanying drawing explanation
Fig. 1 is structural representation of the present utility model;
Fig. 2 is the structural representation of adjustable DC high-voltage power supply in the utility model;
Fig. 3 is the structured flowchart of voltage detection unit in the utility model;
Fig. 4 is physical circuit connection layout of the present utility model;
Fig. 5 is the equivalent circuit diagram of Fig. 4.
Label declaration: the R1 ~ R3: the first ~ three reference voltage; Rx: the insulation resistance of surge protector; R: the internal resistance of supply line's internal resistance, reactor and the equivalent resistance of protective wire PE line resistance, L: the equivalent inductance of the distributed inductance of reactor inductance and supply line.
Embodiment
Below with reference to accompanying drawing, the technical solution of the utility model is described in detail.
Structural representation of the present utility model as shown in Figure 1, a kind of on-line measurement device of electric power system surge protector insulation resistance, for measuring the insulating resistance value of surge protector in electric power system, comprise adjustable DC high-voltage power supply, reactor, voltage detection unit and the first ~ three reference resistance R1 ~ R3, described reactor comprises the first ~ three inductance, the three-phase firewire that one end of described first ~ three inductance R1 ~ R3 connects one to one in electric power system, center line in the other end of the first ~ three inductance and electric power system is all connected with the positive output end of adjustable DC high-voltage power supply through the first reference resistance R1, positive output end ground connection after the second reference resistance R2 of described adjustable DC high-voltage power supply, negative output terminal ground connection after the 3rd reference resistance R3 of adjustable DC high-voltage power supply, described voltage detection unit just comprises, negative input end, the positive input terminal of voltage detection unit connects the center line in electric power system, the negative input end ground connection of voltage detection unit.When carrying out on-line measurement, be connected with the negative output terminal of adjustable DC high-voltage power supply after the earth terminal of surge protector is disconnected ground.The function of described reactor is that internal inductance is made up of on the circular ferrite of high magnetic conduction coil, and ferritic relative permeability is 2000, and inductance value is 10H, and DC internal resistance is 200 Ω every alternating current, logical direct current.In the present embodiment, the first reference resistance R1 is mega-ohms resistance, and the second reference resistance R2, the 3rd reference resistance R3 are a kilo-ohm level resistance.
The structural representation of adjustable DC high-voltage power supply in the utility model as shown in Figure 2, the external potentiometer of DC high-voltage source of 0 ~ 5kV and 24V direct supply.After the DC energy of 24V direct supply 24V is added in DC high-voltage source, DC high-voltage source medium-high frequency oscillatory circuit converts DC energy to high-voltage alternating energy, carry out rectifying and wave-filtering again, export high direct voltage, output voltage can be made to change within the scope of 0 ~ 5kV by regulator potentiometer resistance.
The structured flowchart of voltage detection unit in the utility model as shown in Figure 3, it comprises the sample resistance, low-pass filter, DC amplification circuit and the D.C. voltmeter that connect successively.Its principle of work is; the voltage signal obtained by sample resistance is by low-pass filter circuit filter out power Resonance Wave Composition; deliver to circuits of direct current amplifier to amplify, the d. c. voltage signal of amplification is delivered to D.C. voltmeter display, directly can converse the insulating resistance value of surge protector.
Physical circuit connection layout of the present utility model as shown in Figure 4; in the present embodiment; electric power system adopts low-voltage electricity transmission line typical case electric power-feeding structure; L1, L2, L3 are three-phase firewire; N is center line, and PE is ground protection line, and VA, VB, VC are the equivalent voltage source of triple-phase line; Ra, Rb, Rc, RN are the equivalent resistance of power transmission line, and La, Lb, Lc, LN are the equivalent inductance of transmission line of electricity.Load connects triple-phase line and center line, and surge protector is arranged in supply line.
The equivalent circuit diagram of Fig. 4 as shown in Figure 5; Rx is the insulation resistance of surge protector; L is the equivalent inductance of the distributed inductance of reactor inductance and supply line; R is supply line's internal resistance, the internal resistance of reactor and the equivalent resistance of protective wire PE line resistance, and its value size depends primarily on the internal resistance of reactor.R1, R2, R3, Rx form direct current bridge.Voltage detection unit is utilized to measure the voltage U g of the first reference resistance and surge protector insulation resistance common port.When measuring insulation resistance, do not consider the impact of L, when bridge balance, the insulation resistance of surge protector is:
u in formula
r2, U
r3the voltage at resistance R2, R3 two ends respectively.When electric bridge is uneven, and R2, R3 and R1 are far smaller than the value of insulation resistance Rx and R, then the value of surge protector insulation resistance is:
u in formula
0for the output voltage of adjustable DC high-voltage power supply, the value of insulation resistance therefore can be calculated by the value measuring Ug.
Above embodiment is only and technological thought of the present utility model is described; protection domain of the present utility model can not be limited with this; every technological thought according to the utility model proposes, any change that technical scheme basis is done, all falls within the utility model protection domain.