JPH0419779B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention uses voltage and current information of the power system to
Regarding distance relays that determine the distance to the accident point,
In particular, the present invention relates to a distance relay suitable for calculating a distance using sampling data and protecting the distance by comparing the distance with a set value.

Conventionally, the product type, area type, and phase comparison type are well known as methods for determining the distance to a fault point from voltage and current information of a power system. However, in all of these methods, two vector waveforms are created by multiplying the voltage or current by a preset value, and in the case of product type and phase comparison types, the phase difference between these two vector waveforms is within 90°. Determine whether or not
In the case of area type, the magnitude relationship between two vector waveforms is determined. Therefore, for example, since the first stage reactance and the second stage reactance have different set values, it is necessary to calculate and determine them separately.

An object of the present invention is to solve the above drawbacks of the conventional method by directly calculating the distance to the accident point, so that, for example, the first stage reactance and the second stage reactance can be determined by the same calculation. This is what I did.

In the present invention, the reactance X, ohm R, or mole U up to the fault point is directly calculated by addition, subtraction, multiplication, and division from data obtained by arbitrarily sampling voltage and current information.

FIG. 1 shows sampling data necessary for the calculation of the present invention.

Data v(t), v(t+Δt), extracted from voltage waveform v and current waveform i at sampling intervals of Δt,
i(t), i(t+Δt), data v(t+T ₁ ), v( _t
+Δt+T ₁ ), and data i(t+T 2 ), i(t+Δt+ _{T 2} ) sampled at an arbitrary time delay T ₂ from the sampling for the current waveform, respectively.
From the following equations, each characteristic of the distance relay is realized.

Prior to deriving each characteristic equation, data a(t), a(t+Δt ), b(t+T), b(
t
+Δt+T), set the following formula.

M(Δt,T)=a(t+Δt)・b(t+T)−a
(t)・b(t+Δt+T)=Asin(ωt−ωΔt)・
Bsin(ωt+ωT−θ)−Asinωt・Bsin(ωt−
ωΔt+ωT−θ)=A・Bsinω・Δtsin(ωT−
θ) ...Equation (1) Each characteristic is derived below.

(1) Moo characteristic of characteristic angle α v(t)=Vsinωt i(t)=Isin(ωt−θ) T ₁ =1/ω・π/2 T ₂ 1/ω(π/2+α), then M (Δt, T ₂ )/Mv(Δt, T ₁ )=v(t+
Δt)・i(t+T ₂ )−v(t)・i(t+Δt+T ₂ )/
v(t+Δt)・v(t+T ₁ )−v(t)・v(t+Δt
+T ₁ ) =V・Isinω・Δtsin(π/2+α−
θ)/V ² sinω・Δt・sinπ/2=I/Vcos(α−θ)
...Equation (2) Equation (2) has a Moh characteristic with α as the characteristic angle, and its characteristic diagram is shown in Figure 2.

(2) Ohmic characteristic of characteristic angle β v(t)=Vsinωt, i(t)=Isin(ωt−θ) T ₁ =1/ω(π/2+β), T ₂ =1/ω・π/2 Then, M(Δt, T ₁ )/Mi(Δt, T ₂ )=i(t+
Δt)・v(t+T ₁ )−i(t)・v(t+Δt+T ₁ )/
i(t+Δt)・i(t+T ₂ )−i(t)・i(t+Δt
+T ₂ ) =V・Isinω・Δtsin(π/2+β−
θ)/I ² sinω・Δtsinπ/2=V/Icos(β−θ)…
...Equation (3) Equation (3) has an ohmic characteristic with β as the characteristic angle,
Its characteristic diagram is shown in FIG.

(3) Reactance characteristics v(t)=Vsinωt, i(t)=Isin(ωt−θ) If T ₂ =1/ω・π/2, then M(Δt, O)/Mi(Δt, T ₂ ) =i(t)
・v(t+Δt)−v(t)・i(t+Δt)/i(t+
Δt)・i(t+T ₂ )−i(t)・i(t+Δt+T ₂ ) =V・Isinω・Δtsinθ/I ² sinω・
Δtsinπ/2=V/Isinθ...Equation (4) Equation (4) represents reactance characteristics, and a diagram of the characteristics is shown in FIG.

The implementation flow of the present invention is shown in FIG.

According to the embodiment of the present invention, as is clear from equations (2) to (4) above, there is an advantage that the mho characteristic, ohmic characteristic, or reactance characteristic up to v stages can be determined by performing the calculation once. be.

[Brief explanation of drawings]

FIG. 1 shows sampling data necessary for the calculation of the present invention, FIG. 2 shows an example of characteristics of a distance relay that can be realized by the present invention, and FIG. 3 shows a processing flow of a digital section that implements the calculation of the invention. 1... Voltage waveform, 2... Current waveform, 3... Moh characteristic, 4... Ohm characteristic, 5... Reactance characteristic.

Claims (1)

[Claims] 1. Taking in the voltage and current amount of the power system,
In a distance relay that calculates the distance from the relay setting point to the fault point, the first data v(t), v(t+Δt), i(t), i are obtained by extracting the voltage waveform and current waveform at a sampling interval of Δt. (t+Δt) and
Second data v(t+T ₁ ), v(t+Δt+T ₁ ) sampled with an arbitrary time delay T ₁ from the sampling for the voltage waveform, and an arbitrary time delay T from the sampling for the current waveform. ₂ Obtain the third data i (t + T _{2 )} , i (t + Δt + T ₂ ) sampled at (T ₁ ≠ T 2 ), and calculate data M corresponding to the product of voltage data and current data, and data M corresponding to the product of current data. Data Mi
Or data Mv equivalent to the product of voltage data
The numerical value M/Mi or M/Mv is calculated using
One input data of the product operation for calculation of is the first
data, the other input data is the second or third data, and the first data of the second or third data is
A distance relay characterized in that a delay time T ₁ or T ₂ from the data of is determined according to a characteristic angle realized by the distance relay. 2 In the distance relay described in item 1, T ₁ = π/2ω, T ₂ = 1/ω (π/2+α), M=v(t+Δt)・i(t+T ₂ )−v(t) ・i(t+Δt+T ₂ ), Mv=v(t+Δt)・v(t+T ₁ )−v(t) ・v(t+Δt+T ₁ ), and by calculating M/Mv, a Moh characteristic distance relay that realizes the Moh characteristic of the characteristic angle α . 3 In the distance relay described in item 1, T ₁ =1/ω(π/2+β), T ₂ =π/2ω M=i(t+Δt)・v(t+ _T1 )−i(t)・v(t+Δt+ _T1 ), Mi=i(t+Δt)・i(t+T ₂ )−i(t) ・i(t+Δt+T ₂ ) An ohmic characteristic distance relay that realizes an ohmic characteristic with a characteristic angle β by calculating M/Mi.