WO2013185521A1

WO2013185521A1 - Full component differential coefficient matrix-based method for ultra-high-voltage alternating current electric power transmission line protection

Info

Publication number: WO2013185521A1
Application number: PCT/CN2013/075581
Authority: WO
Inventors: 林富洪; 曾惠敏
Original assignee: 国家电网公司; 福建省电力有限公司; 福建省电力有限公司检修分公司; 福建省电力有限公司莆田电业局
Priority date: 2012-06-11
Filing date: 2013-05-14
Publication date: 2013-12-19
Also published as: CN102694375A; CN102694375B

Abstract

A full component differential coefficient matrix-based method for ultra-high-voltage alternating current electric power transmission line protection, comprising: measuring baseband electrical quantities at two ends of an ultra-high-voltage alternating current electric power transmission line; utilizing a long-term equation, calculating from a positive, negative, and zero sequence current amount of one end the positive, negative, zero current amount of the other end; utilizing the method of symmetrical components to calculate a baseband current amount of the other end; calculating a differential coefficient matrix; utilizing magnitude relations among elements of the differential coefficient matrix to determine the type of a fault, thus protecting a correctly tripped fault phase. The method is applicable in the protection of the ultra-high-voltage alternating current electric power transmission line during the entire process of the fault, particularly when the ultra-high-voltage alternating current electric power transmission line experiences a short-circuit fault in a single-phase-to-earth via high resistance, the method is capable of accurately identifying and correctly tripping the faulted phase, while circuit breakers at the two ends of the remaining two normal phases of the transmission line remain reliably inactive.

Description

UHV AC transmission line protection method based on full component differential coefficient matrix

Technical field

The present invention relates to the field of power system relay protection technologies, and in particular to a method for protecting an UHV AC transmission line based on a full component differential coefficient matrix.

Background technique

At present, China has built the world's first Jindongnan-Nanyang-Jingmen 1000kV UHV AC transmission line that is officially connected to the grid. According to the State Grid Corporation's "Unified Strong Smart Grid Research Report", China will build 39,000 kilometers of UHV AC transmission lines by 2015, and build 47,000 kilometers of UHV AC transmission lines by 2020, basically built with UHV power grids. Backbone grid, the national grid pattern coordinated by all levels of power grids.

UHV AC transmission network can greatly improve the power transmission capacity, alleviate China's tight transportation capacity, help reduce transmission losses, save transmission costs, save energy and reduce emissions, thereby promoting the development of green energy economy, and making China's power grid smarter. Strong, stable and reliable. At the same time, as the grid backbone grid, after the failure of the UHV AC transmission line, if the fault cannot be detected and removed correctly, the stability of the power system will be damaged, and the system may collapse, which will cause social and economic production. Immeasurable loss.

Because it is not affected by the system operation mode and power grid structure, and has a natural phase selection function, current differential protection has always been the main protection of various voltage-level transmission lines. In the transmission line of voltage level of 500kV and below, because the distributed capacitance current along the transmission line is small, the distribution capacitance has little effect on the performance of the current differential protection. However, the voltage and current transmission of UHV AC transmission lines have obvious wave processes, and the distributed capacitance current along the line is very large. The conventional current differential protection using the amplitude of the current vector sum at both ends as the action amount is faced with the current differential protection start. The current is large, and in order to prevent the protection from malfunctioning, raising the starting set value will result in insufficient protection sensitivity, which restricts the application of the conventional current differential protection on the UHV AC transmission line.

In order to overcome the influence of distributed capacitance current on the performance of current differential protection, Guo Zheng and He Jiali published "New Principles of Differential Protection of Transmission Lines" (Power System Automation, Vol. 28, No. 11, 2004) and Xu Song Xiao, He Jiali et al., “Study on phase-phase differential protection of UHV transmission lines” (Power System Protection and Control, Vol. 35, No. 3, 2007) uses the Berrylong model to describe the UHV AC transmission line. Physical characteristics, the amount of current on both sides of the transmission line is calculated from the electrical quantities at both ends, and then the current differential protection is formed by using the conventional ratio braking characteristic at this point, which avoids the distributed capacitance current and current differential protection in principle. The performance of the action, the performance is better than the traditional current differential protection.

However, due to the influence of the load current, in the case of a high-resistance grounding short-circuit fault, whether it is the conventional current differential protection using the amplitude of the current vector sum at both ends as the action amount, or the various characteristics that have been proposed based on the Berrylong model The new principle of current differential protection for high-voltage AC transmission lines cannot correctly trip the fault phase, but the three-phase current differential protection action trips three phases. Since the effect of non-full-phase operation on system stability is much less than that of three-phase tripping, the action strategy of tripping three phases by zero-sequence current differential protection will enhance the stability of the fault to the grid. Shock. Therefore, in the case of single-phase grounding short-circuit fault, if the fault phase can be correctly tripped, the remaining two normal phases will continue to operate, which will help to stabilize the grid and make the grid more robust and reliable.

Summary of the invention

SUMMARY OF THE INVENTION The object of the present invention is to overcome the deficiencies of the prior art and to provide an ultra high voltage AC transmission line protection method based on a full component differential coefficient matrix. The method is applicable to the protection of the entire fault process of the UHV AC transmission line, and can be used as the main protection of the UHV AC transmission line, especially when the UHV AC transmission line has a single-phase high-resistance grounding short-circuit fault, the method of the invention can accurately identify And correctly break the fault phase, the circuit breakers at both ends of the remaining two normal phase lines are not reliable.

In order to accomplish the above object, the present invention adopts the following technical solutions:

(1) Measure the three-phase current ii _mA i _mB , i _mC ) of the UHV AC transmission line at the protection installation of the m substation, and the positive, negative and zero sequence voltages of the A phase (t/ _mA1 U _mA2 U _m0 A phase positive and negative Zero-sequence current (I _mA , I _mn measures the three-phase current of the UHV AC transmission line at the w substation protection installation (/„ _A , /„ _B , I„ _c ) and the A phase positive, negative, zero sequence voltage

U _nA2 , U _n -), A phase positive, negative, zero sequence current (/„ _A1 , /„ _A7 , /„.), as input

(2) _{Calculate the} positive, negative and zero sequence currents of the substation protection installation by using the positive, negative and zero sequence voltages t/ _mA1 U _mA2 t/ _mQ and positive, negative and zero sequence currents / A _{2 mQ} at the m substation protection installation. /„„ _A ,, C i,

UI OSh(^ ^r ₁ / _mH ) sinhO!/

I = sinhO!/

U

I = I COSh(^ ₀ / _mn ) sinh( ₀ /

z where 7 ₁

Ry, Ly, Gy, are the positive sequence resistance, inductance, and

+ j L ₀ )(G ₀ +j )C ₀ ) , L ₀ G ₀ C ₀ are single

G, + j ωθ,

Ro+]0L ₀

Zero-sequence resistance, inductance, conductance and capacitance values of the bit length line; Z _eQ = I is the length of the transmission line between the m substation and the n substation.

(3) Calculate the three-phase currents „ _A , „ _R , I of the substation protection installation using ^, 1 „ _n , Where fl = exp 120. )

(4) Calculate /, dA + /" Calculate the differential coefficient matrix s

(5) Selecting the largest element di in the differential coefficient matrix S, according to the element & di in the differential coefficient matrix S

^L dk and mouth = i, where =ABC ACB BAC BCA CAB CBA phase _c

(6) Set the threshold and use the largest element in the differential coefficient matrix S to select the fault phase:

1) If > n S > is satisfied, the shell ih phase is the fault phase. At the same time, if the positive sequence differential protection is not active, the line fault type is a high-resistance ground short-circuit fault; conversely, if the positive-sequence differential protection action, the line fault type is a medium-to-medium (low) resistance ground short-circuit fault.

2) If > n _l 3⁄4. > is satisfied, the phase is the fault phase. If the zero sequence differential protection action, the line fault type is the phase short circuit and then the ground short circuit fault; if the zero sequence differential protection is not active, the line fault type is the phase short circuit fault.

3) If > > 1, the IJ is ABC three-phase short-circuit fault. Among them, = C, ACB BAC BCA CAB CBA phase.

The characteristics and technical achievements of the invention:

The method of the invention is suitable for the protection of the entire fault process of the UHV AC transmission line, especially when the single-phase high-resistance grounding short-circuit fault occurs in the UHV AC transmission line, the method of the invention can accurately identify and correctly jump the fault phase, and the other two normal phases The circuit breakers at both ends of the line are not reliable. DRAWINGS

1 is a schematic diagram of a fault of an UHV AC transmission line to which the method of the present invention is applied. detailed description

The technical solution of the present invention will be further described in detail below according to the drawings of the specification. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic diagram showing the failure of an UHV AC transmission line to which the method of the present invention is applied. The fundamental substation and the fundamental frequency electrical of the side substation are respectively measured by a phase measurement unit (PMU) installed in the substation. Synchronous phasor measurement unit measures the three-phase current (I mA I mB I _m m _C C ) of the U-voltage substation protection installation and the A-phase positive, negative, zero-sequence voltage iu _mM , u _mA2 u _m0 ), phase A positive, negative, zero sequence current ( _mA1 , i _mA2 , i _m0 ); measure the three-phase current ( „ _A , „B „c ) and phase A of the UHV AC transmission line at the “substation protection installation” , negative, zero-sequence voltage ( _{ϋ ηΑ} , _{ϋ ηΑ2 ϋ} _η0 ), positive, negative, zero-sequence current of phase A (i„ _A1 , „ _A2 , „.), as the input. Use the m substation to protect the installation, Negative, zero-sequence voltage ti _mA1 u _mA2 , ti _mQ and positive, negative, zero-sequence current _mA1 , i _mA2 , m ₀ calculate "positive, negative, zero-sequence current / _m „ _A1 , / _m „ _A2 , i _mn0 : _ϋ

z

U mA2

z

among them,

Positive sequence resistance, inductance, length line

+ j L ₀ )(G ₀ +j )C ₀ ) , L ₀ , G ₀ , Q are single

G, + j ωθ, zero-sequence resistance, inductance, conductance and capacitance value of the bit length line; Z _c0 = ; I is the difference between the m substation and the w substation

Electrical line length. Use I to calculate the three-phase current of the n-substation protection installation I, B C

1 1 1 ' mnA\

a a 1 mnA2

a a I

Mn()

Where a = exp /120°)

Calculate /, dA 1 + I dB B + ^nB I dC C + ^nC Calculate the matrix of differential coefficients

Selecting the largest element = i in the differential coefficient matrix s, then selecting the element = i and the matrix in the differential coefficient matrix S

4i ^l dk

^L dk where =ABC, ACB, BAC, BCA, CAB, CBA phase.

Dj

I,

Set the threshold s _h and select the fault phase using the largest elements S _{ij =} , S _ik = and S = in the differential coefficient matrix S: dj I dk dj

I) If > nS _3⁄4 > is satisfied, the Bayi phase is the fault phase. At the same time, if the positive sequence differential protection does not operate, the line fault type is a high-resistance ground short-circuit fault; on the contrary, if the positive-sequence differential protection action, the line fault type is a medium-to-medium (low) resistance ground short-circuit fault.

II) If >s _h n 3⁄4 > s _h is satisfied, the phase is the fault phase. If the zero sequence differential protection action, the line fault type is the phase short circuit and then the ground short circuit fault; if the zero sequence differential protection is not active, the line fault type is the phase short circuit fault.

III) If > > 1, it is ABC three-phase short-circuit fault. Among them, = C, ACB, BAC, BCA, CAB, CBA phase.

The method of the invention is suitable for the protection of the entire fault process of the UHV AC transmission line, especially when the single-phase high-resistance grounding short-circuit fault occurs in the UHV AC transmission line, the method of the invention can accurately identify and correctly jump the fault phase, and the other two normal phases The circuit breakers at both ends of the line are not reliable.

The above description is only a preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any change or replacement that can be easily conceived by those skilled in the art within the technical scope disclosed by the present invention All should be covered by the scope of the present invention.

Claims

Claim WO 2013/185521 PCT/CN2013/075581

1. A method for protecting an UHV AC transmission line based on a full-component differential coefficient matrix, comprising the following steps:

(1) Measuring the three-phase current of the UHV AC transmission line at the protection installation of the m substation, ii _mA i _mB i _mC ) and the positive, negative, zero sequence voltage (t) _mA1 , u _mA2 , u _m0 ), phase A of the A phase Positive, negative, zero-sequence currents (i _mA1 , i _mA2 i _m0 measure the three-phase current ( „ _A , i _nB , i _nC ) and A phase positive, negative, zero sequence of the UHV AC transmission line at the w substation protection installation Voltage (t) „ _A1 , d ϋ _η0 , A phase positive, negative, zero sequence current (ΐ„ _Α1 „ _Α2 , „.), as input.

(2) Using the m substation to protect the positive, negative, and zero sequence voltages at the installation site t) _mA1 , l) _mA2 , t) _mQ and positive, negative, zero sequence current _mA1 ,

I _mA2 , _mQ calculation "positive, negative, zero sequence current / at the substation protection installation /, Al, I mnNl, ^mnO '

Among them, ^+JO +JO, A, <3⁄4, respectively, the positive sequence resistance of the unit length line, inductance,

+ j L ₀ )(G ₀ +j )C ₀ ) , , L ₀ G ₀ C ₀ are single

G, + j ωθ, zero-sequence resistance, inductance, conductance and capacitance value of the bit length line; I is the input between the m substation and the n substation

Electrical line length.

(3) Calculate the three-phase current of the substation protection installation using ^, 1 „ _n „ _A , „ _R B, I, C

1 1 1 ' mnA\

a a 1 mnA2

a a I

Mn() where fl = exp 120

(4) Calculate /, dA B + I dB B + InB I dC Calculate the differential coefficient matrix S Claim

WO 2013/185521 PCT/CN2013/075581

1 ^ dA ^ dA

I d C

S = 1

1

I d B

(5) Selecting the largest element = i in the differential coefficient matrix S, then selecting the element S _ik = 1 in the differential coefficient matrix S

And ^^. = ^, where =ABC, ACB, BAC, BCA, CAB, CBA phase.

(6) Set the threshold, and use the largest element in the differential coefficient matrix S to select the fault phase:

3) If > > 1, the IJ is ABC three-phase short-circuit fault. Among them, = C, ACB, BAC, BCA, CAB, CBA phase.

2. The method for protecting an UHV AC transmission line based on a full-component differential coefficient matrix according to claim 1, wherein the method is suitable for protection of an entire fault process of an UHV AC transmission line, especially when UHV When a single-phase high-resistance grounding short-circuit fault occurs in an AC transmission line, the method can accurately and reliably trip the circuit breakers at both ends of the faulty phase line, and the circuit breakers at both ends of the remaining two-phase normal lines do not trip.