RU2542337C1 - Method of determining of point of shorting of electric power transmission line with two-way observation - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: abnormal components of phase voltages and currents on both sides of the line are fixed, zero sequence components are subtracted from them, forming thereby the first voltages and currents, two-wire models of direct sequence for all phases of a power line are compiled which are used in two modes - passive and active. In the passive mode to inputs of both sides of models the first voltages are supplied, and in the active mode the inputs of both sides of models are shunted, the reactions of passive models in the form of the second input currents are determined, the third currents flowing on the shunted inputs of active models are determined by subtracting the second currents from the respective first currents, the relation of the third currents of the opposite sides of each model are determined and using the named relations the place of short circuit of the power line is determined.

EFFECT: improvement of efficiency and simplicity of the method.

5 cl, 15 dwg

Description

The invention as a technical solution is at the junction of electric power and electrical engineering and relates to relay protection and automation of power lines.

Known methods for determining the location of the closure of the power line using its model [1, 2]. Over the past time, more and more attention has been paid to two-way observation of the line. It gives more accurate results than one-way monitoring, and the transmission of information between substations via fiber optic communication is becoming commonplace. Meanwhile, the damage criteria used in two-way observation do not differ much from the damage criteria in one-way observation. The main energy criterion remains, which says that the closure model is dissipative, i.e. it does not consume and does not generate reactive power [3], and in the more general case, that its instantaneous power is non-negative.

There is the task of radically simplifying and unifying the procedures for protecting and locating a power line during two-way observation compared with one-way observation. The task is due to the fact that the information base of two-way observation is incomparably wider and more powerful than one-way. A solution to this problem is aimed at determining the location of damage to the power line [4]. However, it was still not possible to move away from including a resistive damage model in the line model in this method. As a result, it was not possible to move away from the three-phase network model and the generally three-phase resistive model of damage, which is forced to vary depending on the type of fault. In addition, in the prototype, simplification is achieved by allocating a portion of the power transmission modeled without taking into account the distributed capacity, which narrows the possibilities of the method as applied to feeders - power transmission with insulated neutral, where the processes that occur during an earth fault significantly depend on the capacity of the feeder relative to the ground.

The purpose of the present invention is the development of such a method for determining the location of a power line circuit that is invariant to the type of circuit (single-phase, interphase, two-phase to earth, three-phase, including ground and unbalanced), was limited to the simplest two-wire transmission models, did not require the use of a resistive model damage, was applicable both to networks with a dull earthed neutral, and to feeders, of course, subject to their bilateral observation.

This goal is achieved by the fact that in the known method for determining the location of the closure of the power line during its two-way observation, the simplest two-wire power transmission models are used in a new way, which gives the desired positive effect. Known operations include fixing (recording) phase voltages and currents on both sides of the line, determining their non-zero (centered) components, drawing up a two-wire direct sequence model for the controlled line and replicating it for each phase. The values of both the current and the processes preceding it are fixed. Ultimately, emergency components of phase voltage and currents are required, which require information on successive processes for their determination.

New are operations with a power transmission model. Two different modes — passive and active — are alternately created in the model in order to isolate those parts of the emergency components of the observed currents that are created by their unknown source, operating in an unknown place of power transmission. It is very important that these operations are universal and equally suitable for recognizing any types of closures. In passive mode, non-zero voltages (first voltages) are applied to the inputs of both sides of the two-wire model. The reactions of the model are recorded - second currents, in contrast to the first currents (non-zero). In active mode, the inputs of both sides of the model are bypassed. The third currents that flow through the shunted inputs are defined as the differences of the first and second currents. The ratio between the third currents of the opposite sides of the model of any phase carries information about the location of the closure of the power line, which is used in the proposed method.

In additional claims, a specific expression is given for the coordinates of the fault location for a homogeneous short line (no more than 50 km), as well as the ratio defining the fault coordinate in a homogeneous line of any length and, finally, a similar relationship for an inhomogeneous line, which is the most common case True, in operations with complexes of electrical quantities. In the case of the use of ultra-fast circuit breakers on the line, the observation time may not be enough to confidently distinguish sinusoidal components. In this case, and also taking into account the possibility of using this method to build a high-speed protection of absolute selectivity, an option is proposed to search for the coordinates of the location of damage by the instantaneous values of the third currents on the sides of the line.

Figure 1 presents a diagram of a high voltage power line, on which an arbitrary circuit occurred in an unknown place x _ƒ . The line is observed at both terminal substations. The observed values are voltages u _sv , u _rv and currents i _sv , i _rv , where s and r are the indices of the sides of the line; ν = A, B, C - designation of an arbitrary phase.

,

,

,

. В двухпроводной модели действует неизвестный источник тока

. Место действия x_ƒ также неизвестно.Figure 2 shows a two-wire direct sequence model compiled for an arbitrary phase ν. The model has non-zero emergency components of voltages and currents that are assigned the first number. In addition, non-zero components are marked by strokes:

,

,

,

. Two-wire model uses an unknown current source

. The scene of x _{ƒ is} also unknown.

в месте замыкания. На фиг.5 локальная модель переведена в активный режим. В ней по-прежнему неизвестны ток и напряжение источника в месте замыкания, но известны реакции на него

и

.Figure 3 shows a local two-wire model that can be distinguished from the general structure of figure 2 due to the observation results. 4, the local model is shown in passive mode without an unknown source

in the circuit. In Fig. 5, the local model is put into active mode. It still does not know the current and voltage of the source at the fault location, but the reactions to it are known

and

.

6-12 illustrate operations characterizing the proposed method. Figure 6 shows the formation of the first voltages from the emergency components of the phase voltage of the beginning of the line. In Fig.7 - the same with respect to the first currents. The fourth wire at the output is shown with a dashed line, since the sum of the three non-zero components is identically equal to zero. Fig and 9 refer to the end of the line, and the rest is repeated Fig.6 and 7.

Figure 10 shows a two-wire model of an arbitrary type of power transmission. In Fig. 11, the same model is presented in passive mode, and in Fig. 12 - in active mode. Fig.13-15 illustrate the final operation of determining the coordinates of the location of the damage x _f . The simplest version reflects the model of FIG. 13. More complex, taking into account all distributed parameters, - Fig. The most common example of a heterogeneous model is FIG.

In addition to the actual line 1, the power transmission line includes terminal substations 2 and 3, in which sources 4 and 5 are indicated, in order to emphasize the fact that phase voltages and currents are observed first of the previous mode, and then of the current short circuit mode. Of these, emergency components are determined. If u _pd (t) is the previous voltage, where t <t _kz , au _tk (t) is the current voltage, then the emergency component is the difference

- экстраполяция предшествующего процесса на время после смены режима, выполняемая фильтрами аварийных составляющих [5, 6]. Составляющие нулевой последовательности u_s0, i_s0, u_r0, i_r0 выделяются соответствующими измерительными трансформаторами либо определяются как средние арифметические фазных величин. Безнулевые аварийные составляющие получают, устраняя нулевую последовательность в фазных величинахWhere

- extrapolation of the previous process to the time after the regime change, performed by filters of emergency components [5, 6]. The components of the zero sequence u _s0 , i _s0 , u _r0 , i _r0 are selected by the corresponding measuring transformers or are determined as arithmetic means of phase quantities. Non-zero emergency components are obtained by eliminating the zero sequence in phase quantities

(фиг.2). В моделях подстанций 2, 3 источники 4, 5 устраняются, что отражено закоротками 6, 7. На входе и выходе каждой двухпроводной модели прямой последовательности наблюдаются напряжение и ток

,

,

,

. Как следствие, модель линии 8 приобретает независимость от моделей подстанций (фиг.3), а наблюдаемые напряжения могут быть представлены в виде ЭДС 9 и 10, равных

и

. Индексы 1 в схемах фиг.2 и 3 относятся к наблюдаемым величинам. Модель по фиг.4 выведена в пассивный режим: по сравнению с общей моделью по фиг.3 в ней не предусмотрено повреждение, и источник аварийных составляющих

устранен. Наблюдаемые напряжения, т.е. ЭДС 9, 10, являются в данном случае источниками пассивного режима. Токи

,

по фиг.5 с шунтами 11, 12 на ее входах находится в активном режиме. В нее возвращен отсутствовавший в пассивном режиме неизвестный источник

, и именно в ней осуществляется поиск места повреждения x_f благодаря тому, что известны токи

,

на ее зашунтированных входах - реакции на неизвестный источник тока.In two-wire direct sequence models designed for non-zero emergency components, a single unknown current source operates in an unknown location x _f

(figure 2). In substation models 2, 3, sources 4, 5 are eliminated, which is reflected by shorts 6, 7. At the input and output of each two-wire direct sequence model, voltage and current are observed

,

,

,

. As a result, the model of line 8 becomes independent of the models of substations (Fig. 3), and the observed voltages can be represented as EMFs 9 and 10, equal to

and

. Indexes 1 in the diagrams of figure 2 and 3 relate to the observed values. The model of FIG. 4 is put into passive mode: compared to the general model of FIG. 3, it does not provide for damage, and the source of emergency components

eliminated. Observed stresses, i.e. EMF 9, 10, are in this case the sources of the passive mode. Toki

,

figure 5 with shunts 11, 12 at its inputs is in active mode. An unknown source that was absent in passive mode was returned to it.

, and it is in it that the location of the damage x _f is searched due to the fact that currents are known

,

at its shunted inputs - reactions to an unknown current source.

The proposed method is implemented by the driver 13 non-zero emergency voltage components of the first side of the line, the driver 14 non-zero emergency voltage components of the current side, similar converters 15, 16 voltage and currents of the other side. An arbitrary two-wire direct sequence model 17 of FIG. 10 is shown without any sources. It should be noted that its second wire 18 should not be confused with real earth, since it is a common wire only for non-zero components. 11, model 17 is connected to external EMFs 9, 10, i.e. is in the passive mode, and in Fig. 12 it is in the active mode when the coordinate of the fault location x _{f is} determined.

The proposed method is implemented by operation (1) of determining emergency components of electrical quantities, by operation (2) of forming non-zero components. The latter is done in blocks 13-16. Two-wire models 17 of each phase ν = A, B, C operate autonomously. Models work under zero initial conditions, since all sources connected to it are emergency components.

,

- реакции модели на эти источники (схемы фиг.4, фиг.11) и определения разностных токовOf fundamental importance are the operations of switching on the model on EMF 9, 10 - sources of observed voltages, current fixing

,

- the reaction of the model to these sources (diagrams of Fig. 4, Fig. 11) and the determination of difference currents

и напряжение

Данный способ не предполагает обязательного поиска этого источника. В первую очередь определяется место повреждения. Затем уже может быть определен и ток

, что имеет определенный смысл, если требуется подтвердить результаты предварительно проведенной фазовой селекции, т.е. определения поврежденных проводов. Например, при однофазном замыкании фазы Аwhich in turn are a reaction to a source of emergency components, creating a current in an unknown place x _f

and voltage

This method does not imply a mandatory search for this source. First of all, the place of damage is determined. Then the current can be determined

, which makes sense if you want to confirm the results of a preliminary phase selection, i.e. determination of damaged wires. For example, with a single-phase phase A circuit

и

и искомой координатой места замыкания x_f в моделях различной сложности. В короткой линии электропередачи можно пренебречь влиянием распределенной емкости (фиг.13). В однородной двухпроводной модели при этом выполняется равенствоConsider the relationship between currents

and

and the desired coordinate of the fault location x _f in models of varying complexity. In a short power line, the influence of distributed capacity can be neglected (Fig. 13). In a homogeneous two-wire model, the equality

,

в соответствии с выражениемTo determine the coordinate x _{ƒ it is} enough to perform operations with currents

,

according to the expression

In this case, the proposed method has an extremely high speed and can be used to build the protection of the line of absolute selectivity with the function of location of the circuit.

проще перейти к комплексным напряжениям и токам

,

, выделяя с помощью фильтров ортогональных составляющих [7, 8] синусоидальные компоненты наблюдаемых величин (фиг.14). Комплексы связаны в однородной двухпроводной модели соотношениемIn a line of arbitrary length, when it is necessary to take into account the distributed capacity

easier to switch to complex voltages and currents

,

, highlighting using filters orthogonal components [7, 8] the sinusoidal components of the observed values (Fig.14). The complexes are connected in a homogeneous two-wire model by the relation

и

- характеристическое сопротивление и коэффициент распространения прямой последовательности. Отсюда следует выражение для определения координаты x_f Where

and

- characteristic resistance and direct sequence propagation coefficient. From here follows the expression for determining the coordinate x _f

,

,

.

,

,

.

,

между токами

,

и напряжением

вместе x_f (фиг.15):Finally, in the case of heterogeneous model 17, complex mutual conductivities are used

,

between currents

,

and tension

together x _f (Fig. 15):

In the model of instantaneous values of voltages and currents, taking into account the distributed capacitance, it is also possible to determine the coordinate x _f . The corresponding relation follows from the difference equations of the long line [9]:

Where

- волновое сопротивление прямой последовательности,

- время пробега волны вдоль отрезка модели прямой последовательности длиной x_f,

- то же вдоль отрезка l-x_f.

direct impedance

is the travel time of the wave along the segment of the direct sequence model of length x _f ,

- the same along the interval lx _f .

Equality (7) is specific. The fact is that information on the closure arrives at the beginning and at the end of the line at different times, for example, at times t _0s and t _0r, respectively. Therefore, the left-hand side of the equality is taken at discrete time instants t _{0s +} kΔt, and the right-hand side is taken at instants t 0r ₊ kΔt, where Δt is the sampling interval of the observed process, k is the number of the interval. The closure is fixed in the place x _f where the system of equations resulting from equality (7) gives the smallest discrepancy:

where k _con is the last moment of observation.

Relations (4), (5), (6), (8), despite the difference in approaches, just determine the final operations that highlight information about the location of the power line closure delivered by the currents of the two-wire model in its second, active mode. Final operations have different complexity, but the method itself is simple and versatile.

Information sources

1. RF patent No. 2033622, G01R 31/11, H02H 3/28, 1989.

2. RF patent No. 2033623, G01R 31/11, H02H 3/28, 1989.

3. RF application No. 20111147688/28 (071514), decision on the grant of a patent dated April 23, 2013.

4. RF application No. 2012130712/07 (048210), decision on the grant of a patent dated April 25, 2013.

5. Copyright certificate of the USSR No. 1817153, H01H 83/22, 1991.

6. RF patent No. 2035815, H02H 3/38, H02H 7/26, H01H 83/22, 1992.

7. Copyright certificate of the USSR No. 1744733, H01H 83/22, H02H 3/16, 1989.

8. RF patent No. 2030052, H02H 3/40, H01H 83/22, 1992.

9. Karaev R.I., Lyamets Yu.Ya. On the application of difference equations of a long line. - Electricity, 1972, No. 11, p. 28-36.

Claims (5)

1. A method for determining the location of the closure of a power line during two-way observation using its model, according to which the emergency components of phase voltages and currents on both sides of the line are fixed, the components of the zero sequence are subtracted from them, thereby forming the first voltages and currents, are for all phases of the line power transmission two-wire direct sequence models, characterized in that the two-wire models are used in two modes - passive and active, in passive mode to the inputs of both their sides of the models supply the first voltages, and in the active mode, the inputs of both sides of the models are bypassed, they determine the reactions of passive models in the form of second input currents, determine the third currents flowing at the shunted inputs of the active models, subtracting the second currents from the corresponding first currents, find the ratio between the third currents of opposite sides of each model and according to the specified ratios determine the place of closure of the power line. 2. The method according to claim 1, characterized in that the coordinate of the circuit in a uniform short power line is determined by the formula
$$x_{ƒ}=\frac{l}{\mathrm{one}+\frac{R_{\mathrm{one}}^0{i}_{sv3}^{\text{'}\text{'}}+L_{\mathrm{one}}^0\frac{d{i}_{sv3}^{\text{'}\text{'}}}{dt}}{R_{\mathrm{one}}^0{i}_{rv3}^{\text{'}\text{'}}+L_{\mathrm{one}}^0\frac{d{i}_{rv3}^{\text{'}\text{'}}}{dt}}}$$

where l is the length of the line, s and r are the indices of the sides of the line, ν is the designation of an arbitrary phase (ν = A, B, C) $$R_{\mathrm{one}}^0$$

and $$L_{\mathrm{one}}^0$$

- specific resistance and inductance of the direct sequence, i ₃ - third (differential) current of the damaged phase. 3. The method according to claim 1, characterized in that the coordinate of the circuit in a homogeneous power line, regardless of length, is determined from the ratio
$$\frac{sh\underset{\_}{\gamma }{}_{\mathrm{one}}x{}_{ƒ}}{sh\underset{\_}{\gamma }{}_{\mathrm{one}}\left(l-x_{ƒ}\right)}=\frac{{\underset{\_}{I\text{'}\text{'}}}_{rv3}}{{\underset{\_}{I\text{'}\text{'}}}_{sv3}}$$

,
Where $$\underset{\_}{\gamma }{}_{\mathrm{one}}=\sqrt{{\underset{\_}{Z}}_{\mathrm{one}}^0{\underset{\_}{Y}}_{\mathrm{one}}^0}$$

is the propagation coefficient of a long line, $${\underset{\_}{Z}}_{\mathrm{one}}^0=R_{\mathrm{one}}^0+j\omega L_{\mathrm{one}}^0$$

, $${\underset{\_}{Y}}_{\mathrm{one}}^0=j\omega C_{\mathrm{one}}^0$$

- its primary parameters, $$C_{\mathrm{one}}^0$$

- specific capacity of the direct sequence, $${\underset{\_}{I}}_3$$

- complex of the third current. 4. The method according to claim 1, characterized in that the coordinate of the circuit location of the power line is determined from the ratio $$\frac{{\underset{\_}{Y}}_{ƒs\mathrm{one}}\left(x_{ƒ}\right)}{{\underset{\_}{Y}}_{ƒr\mathrm{one}}\left(l-x_{ƒ}\right)}=\frac{{\underset{\_}{I\text{'}\text{'}}}_{sv3}}{{\underset{\_}{I\text{'}\text{'}}}_r{}_{sv3}},$$

Where $${\underset{\_}{Y}}_{ƒs\mathrm{one}}\left(x_{ƒ}\right)$$

- the mutual conductivity of the direct sequence between the circuit branch in place x _ƒ and the shunted input of the line, $${\underset{\_}{Y}}_{ƒr\mathrm{one}}\left(l-x_{ƒ}\right)$$

- the same between the branch circuit at x _ƒ and the shunted line output. 5. The method according to claim 1, characterized in that the coordinate of the point of closure in the power line is determined from the condition for the minimum discrepancy of the equations taken at different points in time: the left side - at times t _0s + kΔt, and the right side - at times t _0r + kΔt:
$$b_{s\mathrm{one}}^{2}i{\text{'}\text{'}}_{sv3}\left(t-{\tau }_{s\mathrm{one}}\right)-a_{s\mathrm{one}}^{2}i{\text{'}\text{'}}_{sv3}\left(t+{\tau }_{s\mathrm{one}}\right)=b_{r\mathrm{one}}^{2}i{\text{'}\text{'}}_{rv3}\left(t-{\tau }_{r\mathrm{one}}\right)-a_{r\mathrm{one}}^{2}i{\text{'}\text{'}}_{rv3}\left(t+{\tau }_{r\mathrm{one}}\right)$$

,
Where
$$a_{s\mathrm{one}}=R_{\mathrm{at}\mathrm{one}}+R_{\mathrm{one}}^0{x}_{ƒ}/2,b_{s\mathrm{one}}=R_{\mathrm{at}\mathrm{one}}-R_{\mathrm{one}}^0{x}_{ƒ}/2,$$

$$a_{r\mathrm{one}}=R_{\mathrm{at}\mathrm{one}}+R_{\mathrm{one}}^0\left(l-x_{ƒ}\right)/2,b_{r\mathrm{one}}=R_{\mathrm{at}\mathrm{one}}-R_{\mathrm{one}}^0\left(l-x_{ƒ}\right)/2,$$

$$R_{\mathrm{at}\mathrm{one}}=\sqrt{L_{\mathrm{one}}^0/C_{\mathrm{one}}^0}$$

direct impedance $$R_{\mathrm{one}}^0$$

, $$L_{\mathrm{one}}^0$$

, $$C_{\mathrm{one}}^0$$

are the specific resistance, inductance and capacitance of the direct sequence, t _0s and t _0r are the moments of change of the regime of zero-zero emergency components, respectively, at the beginning and at the end of the line, Δt is the sampling interval, k is the number of the interval.

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