CN105514956A - Ground distance relay and action method and device - Google Patents

Abstract

The invention discloses a ground distance relay action method and device and a ground distance relay reflecting a single-phase ground short circuit. The method comprises the following steps that the action criterion comparative quantity is obtained; theta1, theta2 and theta3 are calculated respectively; whether the conditions that the theta1 is larger than 270 degrees and smaller than 360 degrees, the theta2 is larger than 270 degrees and smaller than 360 degrees and the theta3 is larger than 270 degrees and smaller than 360 degrees are satisfied or not is judged respectively; when the theta1 is larger than 270 degrees and smaller than 360 degrees, the theta2 is larger than 270 degrees and smaller than 360 degrees and the theta3 is larger than 270 degrees and smaller than 360 degrees, a signal for making ground distance relay acted is generated. According to the ground distance relay action method and device and the ground distance relay reflecting the single-phase ground short circuit, a phase comparison criterion is simple, the reliability is high, the ground distance relay has strong transition resistance resistant capacity, and a fault phase can be automatically judged.

Description

Grounding distance relay and action method and device

Technical Field

The invention relates to the field of protection of power transmission lines of power systems, in particular to a grounding distance relay, and an action method and device.

Background

Distance protection is widely used in power system line protection, and a distance relay is a measuring element in distance protection. The impedance (distance) relay reflects the distance of a short-circuit point of the power system, and the short-circuit point is positioned in the protection area and is away from the action of the relay; otherwise, no action is taken. The distance relays are of various types so as to be suitable for different application occasions. According to the type of reaction short circuit, the method can be divided into: a ground distance relay and an interphase distance relay.

When the power system has a short circuit, the ground resistance is relatively large. Therefore, it is desirable to have a relatively large allowable transition resistance capability of the ground distance relay.

Patent application CN200410024016 proposes a grounding distance relay which has good performance and relatively large allowable transition resistance capability. But also has disadvantages: the phase comparison criterion is more complex to calculate and has poor reliability.

Disclosure of Invention

Therefore, the technical problem to be solved by the embodiments of the present invention is that the phase comparison criterion of the ground distance relay in the prior art is complex to calculate.

Therefore, the action method of the grounding distance relay in the embodiment of the invention comprises the following steps:

obtaining action criterion comparison quantity, wherein the action criterion comparison quantity comprises voltage quantity of a phase bus where a grounding distance relay is locatedZero sequence current phasorNegative sequence current phasorAnd compensating the voltage vectorWhereinThe phase of the grounding distance relay is represented as a, b or c;

respectively calculate theta according to the following formula₁、θ₂And theta₃：

Respectively determine 270 degree<θ₁<360°、270°<θ₂<360 DEG and 270 DEG<θ₃<Whether 360 degrees is true or not;

when the temperature is 270 DEG<θ₁<360°、270°<θ₂<360 DEG and 270 DEG<θ₃<At 360 DEG, a signal for operating the ground distance relay is generated.

Preferably, the compensation voltage vectorThe calculation formula of (2) is as follows:

wherein, $K=\frac{Z_0-Z_1}{3Z_1},$ Z₀zero sequence impedance per unit length of line, Z₁In units of length of linePositive sequence impedance, Z_zdIn order to set the impedance,is the phase magnitude of the phase current.

An operating device of a ground distance relay according to an embodiment of the present invention includes:

the acquisition unit is used for acquiring action criterion comparison quantity which comprises the voltage component of a phase bus where the grounding distance relay is locatedZero sequence current phasorNegative sequence current phasorAnd compensating the voltage vectorWhereinThe phase of the grounding distance relay is represented as a, b or c;

a calculation unit for calculating θ according to the following formulas₁、θ₂And theta₃：

A judging unit for judging 270 DEG respectively<θ₁<360°、270°<θ₂<360 DEG and 270 DEG<θ₃<Whether 360 degrees is true or not;

a motion signal generating unit for generating a motion signal at 270 °<θ₁<360°、270°<θ₂<360 DEG and 270 DEG<θ₃<At 360 DEG, a signal for operating the ground distance relay is generated.

Preferably, the compensation voltage vectorThe calculation formula of (2) is as follows:

wherein, $K=\frac{Z_0-Z_1}{3Z_1},$ Z₀zero sequence impedance per unit length of line, Z₁Positive sequence impedance per unit length of line, Z_zdIn order to set the impedance,is the phase magnitude of the phase current.

An earth distance relay according to an embodiment of the present invention includes:

a voltage transformer for receiving three-phase voltageAndapplying the three-phase voltageAndconverting the voltage into a voltage suitable for the A/D converter and outputting the voltage;

current/voltage converter for receiving three-phase currentAndapplying the three-phase current Andconverting the voltage into a voltage suitable for the A/D converter and outputting the voltage;

the A/D converter is used for converting the received voltages output by the voltage transformer and the current/voltage converter into digital quantities and outputting the digital quantities;

a processor comprising a ground distance relay actuation device, the ground distance relay actuation device comprising:

an obtaining unit, configured to obtain an action criterion comparison quantity according to the digital quantity output by the a/D converter, where the action criterion comparison quantity includes a phase bus voltage component where a ground distance relay is locatedZero sequence current phasorNegative sequence current phasorAnd compensating the voltage vectorWhereinThe phase of the grounding distance relay is represented as a, b or c;

a calculation unit for calculating θ according to the following formulas₁、θ₂And theta₃：

A judging unit for judging 270 DEG respectively<θ₁<360°、270°<θ₂<360 DEG and 270 DEG<θ₃<Whether 360 degrees is true or not;

a motion signal generating unit for generating a motion signal at 270 °<θ₁<360°、270°<θ₂<360 DEG and 270 DEG<θ₃<At 360 DEG, a signal for operating the ground distance relay is generated.

Preferably, the compensation voltage vectorThe calculation formula of (2) is as follows:

wherein, $K=\frac{Z_0-Z_1}{3Z_1},$ Z₀zero sequence impedance per unit length of line, Z₁Positive sequence impedance per unit length of line, Z_zdIn order to set the impedance,is the phase magnitude of the phase current.

The technical scheme of the embodiment of the invention has the following advantages:

1. according to the grounding distance relay action method and device provided by the embodiment of the invention, the phase bus voltage component of the grounding distance relay is obtainedZero sequence current phasorNegative sequence current phasorAnd compensating the voltage vectorThe motion criterion of (1) is compared to determine 270 DEG<θ₁<360°、270°<θ₂<360 DEG and 270 DEG<θ₃<Whether 360 degrees is established or not realizes the action or non-action of the grounding distance relay, and the phase comparison criterion is simple and the reliability is high.

2. The grounding distance relay provided by the embodiment of the invention has the advantages of simple phase comparison criterion, high reliability, strong resistance to transition resistance, phase selection function and automatic fault phase judgment function.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.

Fig. 1 is a flowchart of a specific example of a method for operating a ground distance relay according to embodiment 1 of the present invention;

fig. 2 is a schematic block diagram of a specific example of a ground distance relay actuation device in embodiment 2 of the present invention;

fig. 3 is a schematic block diagram of a specific example of a ground distance relay in embodiment 3 of the present invention;

FIG. 4 is a schematic diagram of a power system;

FIG. 5(a) is a reverse direction short circuit voltage phasor relationship diagram;

FIG. 5(b) is a diagram showing a phasor relationship between short-circuit voltages in the forward direction region;

FIG. 5(c) is a diagram showing phasor relationship between short-circuit voltages at the end of a forward direction protection section;

FIG. 5(d) is a diagram showing the phasor relationship between the short-circuit voltages in the forward region;

FIG. 6(a) is a plot of non-fault phase zero sequence current versus negative sequence current;

fig. 6(b) is a plot of non-fault phase zero-sequence current versus negative-sequence current.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings, and it should be understood that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The technical features mentioned in the different embodiments of the invention described below can be combined with each other as long as they do not conflict with each other.

Example 1

The embodiment provides an action method of a ground distance relay, for example, the action method is applied to the ground distance relay, as shown in fig. 1, and includes the following steps:

s1, obtaining action criterion comparison quantity, wherein the action criterion comparison quantity comprises the voltage quantity of a phase bus where the grounding distance relay is locatedZero sequence current phasorNegative sequence current phasorAnd compensating the voltage vectorWhereinThe phase of the grounding distance relay is represented as a, b or c;

s2, calculating theta according to the following formulas₁、θ₂And theta₃：

S3, judging respectively 270 °<θ₁<360°、270°<θ₂<360 DEG and 270 DEG<θ₃<Whether 360 degrees is true or not; when the temperature is 270 DEG<θ₁<360°、270°<θ₂<360 DEG and 270 DEG<θ₃<When 360 °, the process proceeds to step S4; otherwise, the process proceeds to step S5.

And S4, generating a signal for operating the grounding distance relay.

And S5, generating a signal for making the grounding distance relay not work.

Preferably, the voltage vector is compensatedThe calculation formula of (2) is as follows:

wherein, $K=\frac{Z_0-Z_1}{3Z_1},$ Z₀zero sequence impedance per unit length of line, Z₁Positive sequence impedance per unit length of line, Z_zdIn order to set the impedance,is the phase magnitude of the phase current.

The distance relay action method comprises the step of obtaining the voltage component of the phase bus where the grounding distance relay is locatedZero sequence current phasorNegative sequence current phasorAnd compensating the voltage vectorThe motion criterion of (1) is compared to determine 270 DEG<θ₁<360°、270°<θ₂<360 DEG and 270 DEG<θ₃<Whether 360 degrees is established or not realizes the action or non-action of the grounding distance relay, and the phase comparison criterion is simple and the reliability is high.

Example 2

In correspondence to embodiment 1 described above, the present embodiment provides a ground distance relay operating device, as shown in fig. 2, including:

an obtaining unit 41, configured to obtain a comparison quantity of action criteria, where the comparison quantity of action criteria includes a voltage component of a phase bus where the grounding distance relay is locatedZero sequence current phasorNegative sequence current phasorAnd compensating the voltage vectorWhereinThe phase of the grounding distance relay is represented as a, b or c;

a calculation unit 42 for calculating θ according to the following formulas₁、θ₂And theta₃：

A judgment unit 43 for judging 270 DEG respectively<θ₁<360°、270°<θ₂<360 DEG and 270 DEG<θ₃<Whether 360 degrees is true or not;

a motion signal generation unit 44 for generating a motion signal at 270 °<θ₁<360°、270°<θ₂<360 DEG and 270 DEG<θ₃<At 360 DEG, a signal for operating the ground distance relay is generated.

Preferably, the voltage vector is compensatedThe calculation formula of (2) is as follows:

wherein,Z₀zero sequence impedance per unit length of line, Z₁Positive sequence impedance per unit length of line, Z_zdIn order to set the impedance,is the phase magnitude of the phase current.

The distance relay action device obtains the voltage component of the phase bus where the grounding distance relay is locatedZero sequence current phasorNegative sequence current phasorAnd compensating the voltage vectorThe motion criterion of (1) is compared to determine 270 DEG<θ₁<360°、270°<θ₂<360 DEG and 270 DEG<θ₃<Whether 360 degrees is established or not realizes the action or non-action of the grounding distance relay, and the phase comparison criterion is simple and the reliability is high.

Example 3

The present embodiment provides a ground distance relay, as shown in fig. 3, including:

voltage transformer 1 for receiving three-phase voltagesAndwill three-phase voltageAndconverting the voltage into a voltage suitable for the A/D converter 3 and outputting;

a current/voltage converter 2 for receiving three-phase currentAndwill make three-phase currentAndconverting the voltage into a voltage suitable for the A/D converter 3 and outputting;

an a/D converter 3 for converting the received voltages output from the voltage transformer 1 and the current/voltage converter 2 into digital values and outputting the digital values;

processor 4, including ground connection distance relay action device, ground connection distance relay action device includes:

an obtaining unit, configured to obtain an action criterion comparison quantity according to a digital quantity output by the a/D converter 3, where the action criterion comparison quantity includes a phase bus voltage component where the grounding distance relay is locatedZero sequence current phasorNegative sequence current phasorAnd compensating the voltage vectorWhereinThe phase of the grounding distance relay is represented as a, b or c;

a calculation unit for calculating θ according to the following formulas₁、θ₂And theta₃：

A judging unit for judging 270 DEG respectively<θ₁<360°、270°<θ₂<360 DEG and 270 DEG<θ₃<Whether 360 degrees is true or not;

a motion signal generating unit for generating a motion signal at 270 °<θ₁<360°、270°<θ₂<360 DEG and 270 DEG<θ₃<At 360 DEG, a signal for operating the ground distance relay is generated.

Preferably, the voltage vector is compensatedThe calculation formula of (2) is as follows:

wherein, $K=\frac{Z_0-Z_1}{3Z_1},$ Z₀zero sequence impedance per unit length of line, Z₁Positive sequence impedance per unit length of line, Z_zdIn order to set the impedance,is the phase magnitude of the phase current.

As shown in fig. 3, the grounding distance relay inputs three-phase voltageAndthree-phase current Andthree-phase voltageAndconverted into a voltage suitable for an A/D converter 3 through a voltage transformer 1; three-phase currentAndconverted into a voltage suitable for the a/D converter 3 via the current/voltage converter 2; the A/D converter 3 converts analog quantities corresponding to three-phase voltage and three-phase current into digital quantities, then transmits the digital quantities to the processor 4, the processor 4 calculates action criteria of the grounding distance relay, and when the action criteria are met, the grounding distance relay outputs action signals; otherwise, a no action signal is output.

The grounding distance relay is arranged in a split-phase mode, namely, the phase A is grounded and reacts with the phase A to be grounded and short-circuited, the phase B is grounded and reacts with the phase B to be grounded and short-circuited, and the phase C is grounded and reacts with the phase C to be grounded and short-circuited. Each phase grounding distance relay has 4 input quantities respectively, and each phase grounding distance relay is driven by three-phase voltageAndthree-phase currentAnd4 action criterion comparison quantities are formed,the method comprises the following steps:

phase A:

phase B:

and C phase:

the action criterion of the grounding distance relay is as follows: computing θ₁,θ₂,θ₃When the angle is larger than 270 degrees and smaller than 360 degrees, the grounding distance relay acts; otherwise, no action is taken.

The following explains that the grounding distance relay has strong anti-transition resistance capability in the case of single-phase grounding short circuit, and has a phase selection function and a fault phase automatic judgment function.

The power system is shown in fig. 4. Assume that the impedance angles of the impedances of the system are all equal, and take the example of a-phase ground short circuit.

Regardless of whether the system oscillates, the following relationship holds:

${\stackrel{\&CenterDot;}{U}}_{ma}={\stackrel{\&CenterDot;}{U}}_{fa}+({\stackrel{\&CenterDot;}{I}}_a+K{\stackrel{\&CenterDot;}{I}}_0)Z_{f1}$

in the formula:is the voltage at the fault phase short-circuit point; z_f1Is the positive sequence impedance of the line between the bus and the short-circuit point.

Substituting the above equation into the compensation voltage expression yields:

${\stackrel{\&CenterDot;}{U}}_a^{\&prime;}={\stackrel{\&CenterDot;}{U}}_{fa}+({\stackrel{\&CenterDot;}{I}}_a+K{\stackrel{\&CenterDot;}{I}}_0)(Z_{f1}-Z_{zd})={\stackrel{\&CenterDot;}{U}}_{fa}+M({\stackrel{\&CenterDot;}{I}}_a+K{\stackrel{\&CenterDot;}{I}}_0)Z_{f1}$

M＝(Z_f1-Z_zd)/Z_f1

if setting the impedance Z_zdAngle of impedance and Z_f1Is equal, then M is a real number, a phasor Are on the same line. When zone short circuit Z_zd＞Z_f1When M is negative real number, U'_aAndare listed inAs shown in fig. 5 (b). The calculation result of the A-phase grounding distance relay is theta₁,θ₂,θ₃Are both larger than 270 degrees and smaller than 360 degrees, and the phase A is grounded and is away from the action of the relay; the calculation result of the B-phase grounding distance relay and the C-phase grounding distance relay is no action.

When Z is_zd＝Z_f1When the temperature of the water is higher than the set temperature,andthe end points of (a) are overlapped together to be in a critical action state, as shown in fig. 5 (c); the critical action state of the phase A grounding distance relay; the calculation result of the B-phase grounding distance relay and the C-phase grounding distance relay is no action.

When Z is_zd＜Z_f1I.e. short circuit outside the forward region, M is a positive number less than 1,in thatAt the same side of, andfall at an end point ofAndas shown in fig. 5 (d). The calculation results of the phase A grounding distance relay, the phase B grounding distance relay and the phase C grounding distance relay are non-action.

When a short circuit in the opposite direction occurs,andis also atOn the same side as (B), butIn thatAndas shown in fig. 5 (a). The calculation results of the phase A grounding distance relay, the phase B grounding distance relay and the phase C grounding distance relay are non-action.

Short circuit point to ground voltageIs the sum of zero sequence currents on two sides of the systemIn arc resistance R_gPressure drop over:

${\stackrel{\&CenterDot;}{U}}_{fa}=3{\stackrel{\&CenterDot;}{I}}_{0\mathrm{\&Sigma;}}{R}_g=3{\stackrel{\&CenterDot;}{I}}_0{R}_g/C_{S0}$

C_S0＝(Z_l0-Z_f0+Z_R0)/(Z_S0+Z_l0+Z_R0)

in the formula: c_S0Is the S-side zero sequence current distribution coefficient; z_S0、Z_R0And Z_l0Zero sequence impedances of the S side, the R side and the line L are respectively set; z_f0The zero sequence impedance from the measuring point to the fault point is measured. C since it has been assumed that the impedance angles of the system are all equal_S0Is a real number. Therefore, the temperature of the molten metal is controlled,phase ofThe same is true.

By judging separately And phasorThe phase relation of the circuit can accurately judge whether the area is short-circuited or not, and is irrelevant to the size of the arc resistance at the short-circuit position and the size of the potential swing angle at the two sides of the circuit.

If the system impedance angles are equal, single-phase grounding short circuit occurs, and negative sequence current of a fault phaseIs always in phase with the zero-sequence current,andthe included angle between them is zero. Therefore, the fault phase is grounded to the distance relay theta₁Greater than 270 and less than 360.

Negative sequence current of non-fault phase with single-phase earth short circuitAnd zero sequence currentThe included angle therebetween is always 120 °, as shown in fig. 6(a), 6 (b). Non-fault phase grounding distance relay theta₁Less than 270 deg., the non-faulted phase ground distance relay will not act. Therefore, the grounding distance relay has the function of selecting the fault phase.

The above-mentioned ground distance relay is only required to reflect a single-phase ground short circuit. When the two-phase short circuit, the three-phase short circuit and the two-phase short circuit are grounded in the power system, the grounding distance relay is locked. When two-phase short circuit, three-phase short circuit and two-phase short circuit ground connection occur in the power system, the protection function is realized by the interphase distance relay.

It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications therefrom are within the scope of the invention.

Claims (6)

1. A grounding distance relay action method is characterized by comprising the following steps:

obtaining action criterion comparison quantity, wherein the action criterion comparison quantity comprises voltage quantity of a phase bus where a grounding distance relay is locatedZero sequence current phasorNegative sequence current phasorAnd compensating the voltage vectorWhereinThe phase of the grounding distance relay is represented as a, b or c;

respectively calculate theta according to the following formula₁、θ₂And theta₃：

Respectively judging the angle theta of 270 degrees₁<360°、270°<θ₂<360 DEG and 270 DEG<θ₃<Whether 360 degrees is true or not;

when the temperature is 270 DEG<θ₁<360°、270°＜θ₂<360 DEG and 270 DEG<θ₃<At 360 DEG, a signal for operating the ground distance relay is generated.

2. The method of claim 1, wherein the compensation voltage vectorThe calculation formula of (2) is as follows:

wherein, $K=\frac{Z_0-Z_1}{3Z_1},$ Z₀zero sequence impedance per unit length of line, Z₁Positive sequence impedance per unit length of line, Z_zdIn order to set the impedance,is the phase magnitude of the phase current.

3. A ground distance relay actuation device, comprising:

the acquisition unit is used for acquiring action criterion comparison quantity which comprises the voltage component of a phase bus where the grounding distance relay is locatedZero sequence current phasorNegative sequence current phasorAnd compensating the voltage vectorWhereinThe phase of the grounding distance relay is represented as a, b or c;

calculation sheetElements for calculating theta according to the following formulas, respectively₁、θ₂And theta₃：

A judging unit for judging 270 DEG respectively<θ₁<360°、270°<θ₂<360 DEG and 270 DEG<θ₃<Whether 360 degrees is true or not;

a motion signal generating unit for generating a motion signal at 270 °<θ₁<360°、270°<θ₂<360 DEG and 270 DEG<θ₃<At 360 DEG, a signal for operating the ground distance relay is generated.

4. The apparatus of claim 3, wherein the compensation voltage vectorThe calculation formula of (2) is as follows:

wherein, $K=\frac{Z_0-Z_1}{3Z_1},$ Z₀zero sequence impedance per unit length of line, Z₁Positive sequence impedance per unit length of line, Z_zdIn order to set the impedance,is the phase magnitude of the phase current.

5. A ground distance relay, comprising:

a voltage transformer (1) for receiving a three-phase voltageAndapplying the three-phase voltageAndconverting the voltage into a voltage suitable for the A/D converter (3) and outputting the voltage;

a current/voltage converter (2) for receiving three-phase currentAndapplying the three-phase currentAndconverting the voltage into a voltage suitable for the A/D converter (3) and outputting the voltage;

the A/D converter (3) is used for converting the received voltages output by the voltage transformer (1) and the current/voltage converter (2) into digital quantities and outputting the digital quantities;

a processor (4) comprising a ground distance relay actuation device comprising:

the acquisition unit is used for acquiring action criterion comparison quantity according to the digital quantity output by the A/D converter (3), and the action criterion comparison quantity comprises the voltage quantity of a phase bus where the grounding distance relay is positionedZero sequence current phasorNegative sequence current phasorAnd compensating the voltage vectorWhereinThe phase of the grounding distance relay is represented as a, b or c;

a calculation unit for calculating θ according to the following formulas₁、θ₂And theta₃：

A judging unit for judging 270 DEG respectively<θ₁<360°、270°<θ₂<360 DEG and 270 DEG<θ₃<Whether 360 degrees is true or not;

a motion signal generating unit for generating a motion signal at 270 °<θ₁<360°、270°<θ₂<360 DEG and 270 DEG<θ₃<360°Then, a signal for operating the ground distance relay is generated.

6. The ground distance relay of claim 5, wherein said compensation voltage vectorThe calculation formula of (2) is as follows:

wherein, $K=\frac{Z_0-Z_1}{3Z_1},$ Z₀zero sequence impedance per unit length of line, Z₁Positive sequence impedance per unit length of line, Z_zdIn order to set the impedance,is the phase magnitude of the phase current.