CN101158703A - Test method of MOV temperature protecting equipment and MOV temperature protecting equipment tester - Google Patents

Abstract

The present invention relates to a testing method and device for an MOV element temperature protection device of a power transmission line series capacitor compensator. The process of temperature increase of the MOV caused by fault current flowing through the MOV occurred in the short circuit of the power transmission line is a heat insulation process, no heat is dissipated in the process, and the relationship between the energy Exs absorbed by the MOV in the period of the fault and the temperature increase Tws of the MOV can be expressed as a proportional constant Kws, that is, Kws=Tws/Exs. The method of the present invention comprises the following steps: (1) the temperature increase of the MOV is calculated from the energy absorbed by the MOV: Tws=Exs*Kws; (2) the testing square-wave current amplitude is determined by the temperature protective parameters of the MOV; (3) current output of a testing instrument is connected with the current input of the MOV temperature protective device, and the state output of the MOV temperature protective device is connected with state monitoring input of the testing instrument; (4) the square-wave current i(t) is output by the testing instrument to the MOV temperature protective device; (5) the action condition of the MOV temperature protective device is monitored, and correctness of action value of the MOV temperature protective device is determined.

Description

The test method of MOV temperature protective device and MOV temperature protective device test instrument

Technical field:

The present invention is relevant with the test of the MOV temperature protective device of transmission line of electricity compensator with series capaci tance.

Background technology:

On the 500kV transmission line of electricity, install fixed compensator with series capaci tance (being called for short string mends) additional and can effectively shorten the power transmission line electrical distance, reduce the contact impedance between sending end and the receiving end, effectively improve the ability to transmit electricity of passway for transmitting electricity.For series capacitance is not damaged, has MOV (Metal OxideVaristors) element of non-linear volt-ampere characteristic in the parallel connection of series capacitor bank two ends when transmission line of electricity breaks down.Under the transmission line of electricity normal operation, the series capacitor compensation both end voltage is less, only has minimum electric current to flow through MOV, and MOV is in thermal equilibrium state, can not occur the MOV temperature continue increase.When the line failure of string benefit device was housed, MOV can avoid series compensation capacitor to bear too high voltages, thereby avoided the capacitor group to damage, but having very big electric current during transmission line fault flows through MOV.

MOV is stacked in the sealing insulator by the multi-disc zinc oxide valve plate, and the sealing insulator causes the MOV heat radiation extremely slow.When line fault makes MOV flow through big electric current, T0～T1 in the time period MOV absorb ENERGY E can be by formula 1 expression:

$E=\underset{T0}{\overset{T1}{\∫}}u\left(i\right)*i\left(t\right)*\mathrm{dt}$ (joule) (1)

In the formula: i (t) is that T0～T1 flows through the electric current of MOV in the time period, and u (i) is the MOV both end voltage of being determined by the MOV volt-ampere characteristic corresponding with i (t).

Because the line fault electric current may reach tens of kiloamperes, MOV can gather very macro-energy in very short time, cause that the MOV temperature sharply raises, and may cause the MOV blast when serious.For preventing that MOV from damaging because of temperature sharply raises, string is mended device and has been disposed MOV protection and discharging gap.The electric current that flows through MOV is delivered to the MOV protective device by current transformer, and the MOV temperature protection is calculated the MOV temperature according to measuring electric current.Discharging gap is attempted by the MOV two ends.When MOV protection detected the MOV temperature and is elevated to precarious position, the action of MOV temperature protection made discharging gap be in conducting state, and by-pass is crossed the big electric current of MOV.

For guaranteeing discharging gap energy action message, must guarantee the temperature rise of MOV temperature protection energy correct response MOV.But the present domestic testing equipment that does not also have to detect MOV temperature protection action correctness.

Summary of the invention:

The purpose of this invention is to provide a kind of method and test instrument of testing the MOV temperature protective device quickly and accurately at the scene.

The MOV valve block is encapsulated in the heat insulation insulator of airtight insulation, makes the heat radiation time constant of MOV very big, and the process that transmission line malfunction causes the MOV temperature to raise fast is extremely short, therefore can ignore heat radiation to the MOV influence of temperature rise value in short-term.

The object of the present invention is achieved like this:

The test method of MOV temperature protective device of the present invention comprises the steps: that (1) each group MOV has well-determined volt-ampere characteristic, and this curve has been determined the MOV energy absorption characteristics.The ENERGY E xs that is in the MOV absorption of adiabatic condition represents with formula (1):

$\mathrm{Exs}=n*\underset{t0}{\overset{t1}{\∫}}u\left(i\right)*i\left(t\right)*\mathrm{dt}$ (joule) (a)

Wherein: i (t) is the square wave test current that t flows through MOV constantly; U (i) is the MOV both end voltage of being determined by the MOV volt-ampere characteristic corresponding with i (t); T0, t2 be flow through the MOV electric current one-period square wave function the initial moment and stop constantly; T1 is that one-period square wave current amplitude stops constantly, and Esx is the energy that MOV absorbs during test is tested, and n is the periodicity of test current,

(2) ignore the heat radiation influence, the temperature rise that will be in quick energy accumulation process MOV is considered as adiabatic process, is in the temperature rise value of adiabatic condition MOV with formula (b) expression:

Tws＝Kws·Exs (b)

Wherein: Kws is the MOV temperature lift-off value that is caused by the unit energy that MOV structure, material are determined, is a constant to the MOV that determines; Tws is a MOV temperature protection setting valve,

(3) square wave test current i (t) satisfies formula (c) relation:

$\begin{array}{cc}i\left(t\right)=I& t0\&le;t<t1\\ i\left(t\right)=0& \mathrm{<figure-callout\; id="1"\; label="t"\; filenames="S2007100502205E00011.png"\; state="\{\{state\}\}">t</figure-callout>}1\&le;t<t2\\ \mathrm{Kzk}=\frac{t1-t0}{t2-t0}& \end{array}|---\left(c\right)$

In the formula: Kzk is the dutycycle of square wave test current, and I is the amplitude of t0-t1 square wave test current constantly,

In the t1-t2 moment, the amplitude of square wave test current is 0,

Amplitude i according to from small to large select progressively square wave test current i ₁, i ₂... i _k, determine the contact potential series u corresponding with current i by the MOV volt-ampere characteristic ₁, u ₂... u _k, find the one group of current/voltage value i that satisfies formula (d) relation _n, u _n, i _N+1, u _N+1:

i _n*u _n*Kzk*Tset*Kws≤Ttest≤i _n+1*u _n+1*Kzk*Tset*Kws (d)

Wherein: Ttest is the test temperature of check MOV temperature protective device; Tset is a MOV temperature protective device setting time,

Tset＝n(t2-t0) (e)

Utilize formula (f) to calculate to make MOV to produce the square wave current amplitude I of Ttest,

$I*(\frac{(I-i_n)(I-i_{n+1})}{(i_{n-1}-i_n)(i_{n-1}-i_{n+1})}{u}_{n-1}+\frac{(I-i_{n-1})(I-i_{n+1})}{(i_n-i_{n-1})(i_n-i_{n+1})}{u}_n+\frac{(I-i_{n-1})(I-i_n)}{(i_{n+1}-i_{n-1})(i_{n+1}-i_n)}{u}_{n+1})*\mathrm{Kws}*\mathrm{Tset}*\mathrm{Kzk}=\mathrm{Ttest}---\left(f\right)$

(4) when Ttest=0.95*Tws, utilize formula (f) and formula (d) to calculate square wave current amplitude I1, determine square wave test current function i1 (t) in view of the above,

When Ttest=1.05*Tws, utilize formula (f) and formula (d) to calculate square wave current amplitude I2, determine square wave test current function i2 (t) in view of the above,

(5) be the square wave test current of square wave test current function i1 (t) representative of Tset to MOV temperature protective device output duration, the MOV temperature protective device is failure to actuate; To MOV temperature protective device output duration is the square wave test current of square wave test current i2 (t) representative of Tset, the action of MOV temperature protective device, and then the working value of MOV temperature protective device is correct.

MOV temperature protective device test instrument comprises;

Man-machine interface unit: MOV temperature protection test parameters is input to data storage cell;

Data storage cell: store M OV temperature protection definite value Tws, temperature protection time definite value Tset, unit energy temperature rise coefficient Kws, test period are counted n, duty cycle square wave Kzk and the definite many groups current/voltage value I of MOV volt-ampere characteristic ₀, U ₀, I ₁, U ₁, I ₂, U ₂... .I _k, U _k

Calculate and processing unit: utilize T _Ws, T _Set, K _Ws, K _ZkWith many groups current/voltage respective value that the MOV volt-ampere characteristic is determined, calculate and export the square wave test current i (t) that represents with digital signal and change and current amplification unit to D/A;

D/A conversion and current amplification unit: the digital signal i (t) of input is converted to simulating signal, after current amplifier amplifies, exports the MOV temperature protective device to;

Quantity of state detecting unit: detect MOV temperature protective device operating state.

The MOV temperature rise of the present invention during with transmission line malfunction is considered as adiabatic process; the simulation square wave test current input MOV temperature protective device that calculates is thus tested; whether the operating state that can fast, accurately measure the MOV temperature protective device is one correct; method is easy and simple to handle; can on-the-spotly accurately measure; device precision height, cost is low.

Description of drawings:

Fig. 1 is a structured flowchart of the present invention.

Fig. 2 is a process flow diagram of the present invention.

Embodiment:

MOV protection test instrument of the present invention is made up of hardware circuit and software.

Unit that hardware circuit comprises and function:

Man-machine interface unit: MOV temperature protection test parameters is input to data storage cell.

Data storage cell: store M OV temperature protection definite value Tws, temperature protection time definite value Tset, unit energy temperature rise coefficient Kws, test period are counted n, duty cycle square wave Kzk and the definite many groups current/voltage value I of MOV volt-ampere characteristic ₀, U ₀, I ₁, U ₁, I ₂, U ₂... .I _k, U _k

Calculate and processing unit: many groups current/voltage value of utilizing Tws, Tset, Kws, Kzk and MOV volt-ampere characteristic to determine, calculate and export the current i of representing with digital signal (t) and arrive the D/A converting unit.

D/A conversion and current amplification unit: the digital signal i (t) of input is converted to simulating signal, after current amplifier amplifies, exports the MOV protective device to.

Quantity of state detecting unit: detect MOV temperature protection operating state.

MOV temperature protection test instrument software flow is seen Fig. 2.

Implementation process of the present invention is:

Utilize the man-machine interface unit MOV temperature protection definite value Tws, MOV temperature protection time definite value Tset, unit energy temperature rise coefficient Kws, test period to be counted volt-ampere characteristic (the one group of current/voltage numerical value of determining by the MOV characteristic: i of n, square-wave signal dutycycle Kzk and MOV ₁, u ₁i ₂, u ₂... i _k, u _k) be input to storage unit.

Calculating and processing unit calculate test square wave current amplitude I according to Tws, Tset, Kws, Kzk and MOV volt-ampere characteristic, thus confirmed test signal i (t).

The process of calculating i (t) is as follows: according to the amplitude i of ascending select progressively square wave current i ₁, i ₂... i _k, determine the contact potential series u corresponding with current i by the MOV volt-ampere characteristic ₁, u ₂... u _k, utilize every group of i, u to calculate the MOV temperature rise, find the one group of current/voltage value i that satisfies formula d relation _n, u _n, i _N+1, u _N+1, utilize formula f calculating to make MOV produce the square wave current amplitude I of Tws, determine square wave test current i (t).

Calculating and processing unit are delivered to D/A and current amplification unit with i (t) digital quantity.The simulating signal of D/A and current amplification unit output is sent into MOV temperature protective device input end after current amplifier amplifies.The actuating signal of MOV temperature protective device is sent to the quantity of state detecting unit of MOV protection test instrument, and MOV protection test instrument judges according to MOV temperature protective device the result of the action whether the MOV temperature protective device is correct.

I (t) electric current that will be Tset the duration is sent into MOV temperature protection input end, checks MOV temperature protective device action correctness.

Its test method is as follows:

The test method of MOV temperature protective device; comprise the steps: that (1) each group MOV has well-determined volt-ampere characteristic; this curve has been determined the MOV energy absorption characteristics, and the MOV that is in adiabatic condition represents with formula (a) at the ENERGY E xs that duration of test absorbs:

$\mathrm{Exs}=n*\underset{t0}{\overset{t1}{\&Integral;}}u\left(i\right)*i\left(t\right)*\mathrm{dt}$ (joule) (a)

Wherein: i (t) is the square wave test current that t flows through MOV constantly; U (i) is the MOV both end voltage of being determined by the MOV volt-ampere characteristic corresponding with i (t); T0 is initial moment of square wave function of flowing through the one-period of MOV electric current; T1 is that one-period square wave current amplitude stops constantly, and n is the periodicity of test current,

(2) ignore the heat radiation influence, the temperature rise that will be in quick energy accumulation process MOV is considered as adiabatic process, is in the temperature rise value of adiabatic condition MOV with formula (b) expression:

Tws＝Kws·Exs (b)

Wherein: Kws is the MOV temperature lift-off value that is caused by the unit energy that MOV structure, material are determined, is a constant to the MOV that determines; Tws is a MOV temperature protection setting valve,

(3) square wave test current i (t) satisfies formula (c) relation:

$\begin{array}{cc}i\left(t\right)=I& t0\&le;t<t1\\ i\left(t\right)=0& \mathrm{<figure-callout\; id="1"\; label="t"\; filenames="S2007100502205E00011.png"\; state="\{\{state\}\}">t</figure-callout>}1\&le;t<t2\\ \mathrm{Kzk}=\frac{t1-t0}{t2-t0}& \end{array}|---\left(c\right)$

In the formula: Kzk is the dutycycle of square wave test current, and I is the amplitude of t0-t1 square wave test current constantly, t0, t2 be flow through the MOV electric current one-period square wave function the initial moment and stop constantly,

In the t1-t2 moment, the amplitude of square wave test current is 0,

According to the amplitude i of MOV volt-ampere characteristic according to from small to large select progressively square wave test current i ₁, i ₂... i _k, determine the contact potential series u corresponding with current i by the MOV volt-ampere characteristic ₁, u ₂... u _k, find the one group of current/voltage value i that satisfies formula (d) relation _n, u _n, i _N+1, u _N+1:

i _n*u _n*Kzk*Tset*Kws≤Ttest≤i _n+1*u _n+1*Kzk*Tset*Kws (d)

Wherein: Ttest is the test temperature of check MOV temperature protective device; Tset is a MOV temperature protective device setting time,

Tset＝n(t2-t0) (e)

Utilize formula (f) to calculate to make MOV to produce the square wave current amplitude I of Ttest,

$I*(\frac{(I-i_n)(I-i_{n+1})}{(i_{n-1}-i_n)(i_{n-1}-i_{n+1})}{u}_{n-1}+\frac{(I-i_{n-1})(I-i_{n+1})}{(i_n-i_{n-1})(i_n-i_{n+1})}{u}_n+\frac{(I-i_{n-1})(I-i_n)}{(i_{n+1}-i_{n-1})(i_{n+1}-i_n)}{u}_{n+1})*\mathrm{Kws}*\mathrm{Tset}*\mathrm{Kzk}=\mathrm{Ttest}---\left(f\right)$

(4) when Ttest=0.95*Tws, utilize formula (f) and formula (d) to calculate square wave current amplitude I1, determine square wave test current function i1 (t) in view of the above,

When Ttest=1.05*Tws, utilize formula (f) and formula (d) to calculate square wave current amplitude I2, determine square wave test current function i2 (t) in view of the above,

(5) be the square wave test current of square wave test current function i1 (t) representative of Tset to MOV temperature protective device output duration, the MOV temperature protective device is failure to actuate; To MOV temperature protective device output duration is the square wave test current of square wave test current i2 (t) representative of Tset, the action of MOV temperature protective device, and then the working value of MOV temperature protective device is correct.

Claims (2)

1.MOV the test method of temperature protective device; comprise the steps: that (1) each group MOV has well-determined volt-ampere characteristic; this curve has been determined the MOV energy absorption characteristics, and the MOV that is in adiabatic condition represents with formula (a) at the ENERGY E xs that duration of test absorbs:

$\mathrm{Exs}=n*\underset{t0}{\overset{t1}{\&Integral;}}u\left(i\right)*i\left(t\right)*\mathrm{dt}$ (joule) (a)

Wherein: i (t) is the square wave test current that t flows through MOV constantly; U (i) is the MOV both end voltage of being determined by the MOV volt-ampere characteristic corresponding with i (t); T0 is initial moment of square wave function of flowing through the one-period of MOV electric current; T1 is that one-period square wave current amplitude stops constantly, and n is the periodicity of test current,

(2) ignore the heat radiation influence, the temperature rise that will be in quick energy accumulation process MOV is considered as adiabatic process, is in the temperature rise value of adiabatic condition MOV with formula (b) expression:

Tws＝Kws·Exs (b)

Wherein: Kws is the MOV temperature lift-off value that is caused by the unit energy that MOV structure, material are determined, is a constant to the MOV that determines; Tws is a MOV temperature protection setting valve,

(3) square wave test current i (t) satisfies formula (c) relation:

$\begin{array}{cc}i\left(t\right)=I& t0\&le;t<t1\\ i\left(t\right)=0& t1\&le;t<t2\\ \mathrm{Kzk}=\frac{t1-t0}{t2-t0}& \end{array}|---\left(c\right)$

In the formula: Kzk is the dutycycle of square wave test current, and I is the amplitude of t0-t1 square wave test current constantly, t0, t2 be flow through the MOV electric current one-period square wave function the initial moment and stop constantly,

In the t1-t2 moment, the amplitude of square wave test current is 0,

According to the amplitude i of MOV volt-ampere characteristic according to from small to large select progressively square wave test current i ₁, i ₂... i _k, determine the contact potential series u corresponding with current i by the MOV volt-ampere characteristic ₁, u ₂... u _k, find the one group of current/voltage value i that satisfies formula (d) relation _n, u _n, i _N+1, u _N+1:

i _n*u _n*Kzk*Tset*Kws≤Ttest≤i _n+1*u _n+1*Kzk*Tset*Kws (d)

Wherein: Ttest is the test temperature of check MOV temperature protective device; Tset is a MOV temperature protective device setting time,

Tset＝n(t2-t0) (e)

Utilize formula (f) to calculate to make MOV to produce the square wave current amplitude I of Ttest,

$I*(\frac{(I-i_n)(I-i_{n+1})}{(i_{n-1}-i_n)(i_{n-1}-i_{n+1})}{u}_{n-1}+\frac{(I-i_{n-1})(I-i_{n+1})}{(i_n-i_{n-1})(i_n-i_{n+1})}{u}_n+\frac{(I-i_{n-1})(I-i_n)}{(i_{n+1}-i_{n-1})(i_{n+1}-i_n)}{u}_{n+1})*\mathrm{Kws}*\mathrm{Tset}*\mathrm{Kzk}=\mathrm{Ttest}---\left(f\right)$

(4) when Ttest=0.95*Tws, utilize formula (f) and formula (d) to calculate square wave current amplitude I1, determine square wave test current function i1 (t) in view of the above,

When Ttest=1.05*Tws, utilize formula (f) and formula (d) to calculate square wave current amplitude I2, determine square wave test current function i2 (t) in view of the above,

(5) be the square wave test current of square wave test current function i1 (t) representative of Tset to MOV temperature protective device output duration, the MOV temperature protective device is failure to actuate; To MOV temperature protective device output duration is the square wave test current of square wave test current i2 (t) representative of Tset, the action of MOV temperature protective device, and then the working value of MOV temperature protective device is correct.

2.MOV the temperature protective device test instrument is characterized in that comprising;

Man-machine interface unit: MOV temperature protection test parameters is input to data storage cell;

Data storage cell: store M OV temperature protection definite value Tws, temperature protection time definite value Tset, unit energy temperature rise coefficient Kws, test period are counted n, duty cycle square wave Kzk and the definite many groups current/voltage value I of MOV volt-ampere characteristic ₀, U ₀, I ₁, U ₁, I ₂, U ₂... .I _k, U _k

Calculate and processing unit: utilize T _Ws, T _Set, K _Ws, K _ZkWith many groups current/voltage respective value that the MOV volt-ampere characteristic is determined, calculate and export the square wave test current i (t) that represents with digital signal and change and current amplification unit to D/A;

D/A conversion and current amplification unit: the digital signal i (t) of input is converted to simulating signal, after current amplifier amplifies, exports the MOV temperature protective device to;

Quantity of state detecting unit: detect MOV temperature protective device operating state.

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