RU2012086C1 - Device for division constituents of short-circuit current - Google Patents

Abstract

FIELD: electric engineering. SUBSTANCE: device has adaptive filter, oscillator and amplitude-phase corrector. Adaptive filter has setting unit, which output bus is connected to setting inputs of corrector which output bus serves as output bus of device. Spectral analyzer, harmonic components oscillator, subtraction unit, computing unit, solving unit, logarithmic unit are introduced to accomplish the goal of invention. First output bus serves for output of complex amplitudes of all harmonic components from input signal, second and third output buses serve for output of complex frequencies and complex factors. EFFECT: increased functional capabilities. 2 dwg

Description

 The invention relates to electrical engineering, namely to relay protection and automation of electrical systems, and can be used to analyze emergency conditions.

 A device for separating the periodic component of an arbitrary frequency and an arbitrary aperiodic component of a transient electrical quantity, for example, a short circuit current [1]. However, it is not endowed with the ability to determine the parameters of these components.

 A device for separating orthogonal components of electrical quantities. It is correct, that is, without a methodological error, distinguishes the main harmonic against the background of an arbitrary number of unknown exponential and harmonic (both damped and non-damped) components. The device owes such properties to an adaptive filter, which includes a master unit and an adder, and the output of the master unit is made in the form of two buses: the coefficient bus sets the parameters of a non-recursive filter, and the second bus controls the periodic signal generator [2]. But this device has limited capabilities: it is able to suppress arbitrary components, but is not able to emit them, but it only highlights the harmonic of a predetermined frequency.

 The purpose of the invention is to expand the functionality of the device by giving it the ability to isolate from the short circuit current not only the main harmonic, but also all the other components of the transient process.

 The goal is achieved in that in a device for separating components of the short circuit current, containing an adaptive filter made in the form of series-connected master unit, non-recursive filter, adder and threshold element, the output of the latter being connected to the control input of the master unit, the first input of which is an information input device and connected to the parametric input of the non-recursive filter and the second input of the adder, a periodic signal generator and amplitude-phase corrector, output the first bus of which forms the first output bus, a spectral analyzer, series-connected harmonic generator, subtractor and computational unit, series-connected decision block and logarithmic block are introduced, while the parametric input of the periodic signal generator is connected to the second output of the driver block, and the output to the inverse input the adder and the input of the spectral analyzer, the output of which is connected to the control input of the amplitude-phase corrector, the output of which is connected to the input of the generator monic, the second input of the subtractor is connected to the first input of the driver unit, the inputs of the amplitude-phase corrector and the decision unit are connected to the first output of the driver unit, the output of the logarithmic unit forms the second output bus of the device and connected to the second input of the computing unit, the output of which forms the third output bus.

 In FIG. 1 shows a structural diagram of a device; in FIG. 2 is a diagram of a non-recursive filter included in its composition.

 The device consists of an adaptive filter 1, a generator 2 of a periodic signal, an amplitude-phase corrector 3, and additional blocks: a spectral analyzer 4, a harmonic generator 5, a subtractor 6, a logarithmic unit 7, a solving unit 8, and a computing unit 9. The adaptive filter 1 consists of a master block 10, non-recursive filter 11, adder 12 and threshold element 13. The device is made with three output buses 14-16. Information is provided on bus 14 on the parameters of the steady-state periodic term, and on buses 15, 16, on the parameters of the rolling term: on bus 15, on damping coefficients and natural frequencies, and on bus 16, on amplitudes and phases (or orthogonal components) exponential and decaying harmonics. The amplitude-phase corrector 3 is made with an information input 17 and a control input 18. The latter are necessary to set the frequency response of this block. The subtractor 6 is made with two inputs 19 and 20. Its function is to generate a difference between the quantities received at input 20 and input 19. Computing unit 9 is made with the first input 21 and the rest of the inputs combined in the bus 22. The driver unit 10 is made with two outputs 23, 24. The first signals are transmitted to set the parameters of blocks 11, 3 and 8, and the second is the setting of a periodic signal. The master unit 10 has two inputs - information 25 and control 26. Non-recursive filter 11 is made with information input 27 and inputs 28 of the parameters (coefficients). The adder 12 is made with three inputs 29-31. The inputs 20, 25, 27, 29 of various blocks are combined and connected to the input 32 of the device. The non-recursive filter 11 is made on the delay elements 33-35, the multipliers 36-38 and the internal adder 39.

 There is a difference between the generator 2 of the periodic signal and the generator 5 of harmonics. The first reproduces a periodic signal specified by one period, and the second generates a periodic signal specified by its harmonics.

exp

t, (3) где Т_о - период основной частоты ω_o;

= -β_S+jω_S комплексная частота; β_S- коэффициент затухания; ω_S- частота собственных колебаний;

s - комплексный множитель. Экспоненциальной составляющей в выражении (3) соответствуют вещественные параметры

= -β_S и

= I_s. Отсчеты i(l) имеют описание, аналогичное выражениям (1) - (3):
i(l)= i_o(l) +

Ζ $\genfrac{}{}{0ex}{}{\text{l}}{\text{S}}$ ; (4)
i_o (l) = i_o ( l±N ); (5)

= exp

τ (6) где N - число отсчетов на периоде; τ= Т_о/N - интервал дискретизации.The device is a digital system and operates in discrete time l. Samples of the input quantity i (l) proportional to the short-circuit current i (t), which consists of a steady-state (periodic) component and a free (decaying) component, are fed to its input:
i (t) = i _o (t) + i _sv (t); (1)
i _o (t) = i _o (t ± T _o ); (2)
i _sv (t) =

exp

t, (3) where T _o is the period of the fundamental frequency ω _o ;

= -β _S + jω _S complex frequency; β _S - attenuation coefficient; ω _S is the frequency of natural oscillations;

s is the complex factor. The exponential component in expression (3) corresponds to real parameters

= -β _S and

= I _s . Samples i (l) have a description similar to expressions (1) - (3):
i (l) = i _o (l) +

Ζ $\genfrac{}{}{0ex}{}{\text{l}}{\text{S}}$ ; (4)
i _o (l) = i _o (l ± N); (5)

= exp

τ (6) where N is the number of samples per period; τ = T _o / N is the sampling interval.

a_si(l-s)= i

(l), (7) решение которого совпадает с описанием тока короткого замыкания (4). Проблема заключается в том, что в выражении (4) составляющая i_o(l) и параметры

,

, а также число m не известны, следовательно, и у производящего уравнения коэффициенты a_s, правая часть - периодическая функция i_o ^l(l), а также порядок уравнения m.The principle of operation of the device is best illustrated by an approach based on the concept of a generating difference equation
i (l) +

a _s i (ls) = i

(l), (7) the solution of which coincides with the description of the short circuit current (4). The problem is that in the expression (4) the component i _o (l) and the parameters

,

, as well as the number m are not known, therefore, the coefficients a _{s of the} generating equation, the right-hand side is the periodic function i _o ^l (l), as well as the order of the equation m.

The purpose of adaptive filter 1 is to suppress the input quantity i (l). Its output value is the signal ε (l) at the output of the adder 12. The adaptive filter is adjusted according to the condition that the signal ε (l) is small. The main role in the tuning process is played by the master unit 10, which determines the parameters of the non-recursive filter 11 - the coefficients a _s , as well as N samples of the periodic signal i _o ^l (l). The signals a _s are transmitted via bus 23 to the driving inputs 28 of the non-recursive filter 11, and samples i _o ^l (l) are transmitted via bus 24 to the inputs of generator 2, which then reproduces them with a period T _о .

a_si(l-s) .The non-recursive filter 11 (Fig. 2) biases the input quantity i (l) so that at the output of its delay element 33 a value i (l-1) is formed, at the output of the element 34 - i (l-2), and at the output of the last element 35 delays - the value of i (lm _f ), where m _f - the maximum order provided by this filter. In fact, the order of the filter can be anything - from m = 0 to m = m _f , and the function it implements
υ _o (l) =

a _s i (ls).

If all coefficients a _s have a zero level, then filter 11 has a zero order, and if m _f coefficients a _s are nonzero, then the maximum possible.

(l)= -i

(l)+i(l)+

a_si(l-s). (8)
Настройка адаптивного фильтра 1 по условию малости сигналаε(l)(ε(l)_→0) приводит выражение (8) к виду (7), т. е. означает, что фильтр 1 распознал структуру (4) - (6) тока короткого замыкания.The inputs of the adder 12 receives three signals: the input quantity i (l), the input signal of the filter 11 υ (l) and the output signal of the generator 2 i _o ^l (l). Input 31 is made inverting, so the function of the adder
ε (l) = i (l) + ν (l) -i

(l) = -i

(l) + i (l) +

a _s i (ls). (8)
Setting adaptive filter 1 according to the condition of small signal ε (l) (ε (l) _ → 0) leads expression (8) to the form (7), i.e., means that filter 1 recognized the current structure (4) - (6) short circuit.

(l)+

i(l-s)a_s= -i(l), l=

. (9)
Всего в выражении (9) n - m + 1 уравнение. Предполагается, что l = 0 - начальный момент короткого замыкания; n - момент окончания набора данных о коротком замыкании. В выражении (9) N + m неизвестных, а число уравнений в общем случае больше, поэтому задающий блок 10 решает эту систему уравнений в смысле наименьших квадратов. Параметры i_o ¹(l), l =

, a_s, s =

и сам порядок m, определяемые системой (9), отвечают условию малости сигнала ε(l), формируемого сумматором 12 согласно соотношению (8). Необходимо однако учесть, что задающий блок 10 способен скомпановать и решить систему (9) только при фиксированном порядке m, в связи с чем в схеме адаптивного фильтра 1 предусмотрено поэтапное (рекурсивное) наращивание m от нуля до максимально возможного m_ф. Эту функцию осуществляет пороговой элемент 13, реагирующий на уровень сигнала невязки ε(l). Задающий блок 10 наращивает порядок m лишь до тех пор, пока с его управляющего входа 26 не будет снят выходной сигнал порогового элемента 13.The driver unit 10 performs the following operations. From samples of the input quantity i (l) supplied to its information input 25, it forms a system of equations for samples i _o ^l (l) and coefficients a _s :
-i

(l) +

i (ls) a _s = -i (l), l =

. (9)
In total, in the expression (9) n - m + 1 equation. It is assumed that l = 0 is the initial moment of the short circuit; n is the moment of completion of the set of data on the short circuit. In the expression (9), N + m are unknown, and the number of equations in the general case is greater, therefore, the driving unit 10 solves this system of equations in the sense of least squares. Parameters i _o ¹ (l), l =

, a _s , s =

and the order m itself, determined by system (9), corresponds to the condition of small signal ε (l) generated by adder 12 according to relation (8). However, it must be taken into account that the driving unit 10 is able to compose and solve system (9) only with a fixed order m, and therefore, the adaptive filter circuit 1 provides for a phased (recursive) increase of m from zero to the maximum possible m _f . This function is performed by the threshold element 13, which responds to the residual signal level ε (l). The master unit 10 increases the order m only until the output signal of the threshold element 13 is removed from its control input 26.

(kω_o)= (2/N)

i

(l)exp(-jkω_o-τl), k=

. (10)
Назначение амплитудно-фазового корректора 3 - преобразование гармоник

(kω_o) сигнала i₀ ^l(l) в гармоники периодической слагаемой входной величины

(kω_o)=

(kω_o)/H(expjkω_o). (10)
Передаточная функция H(expjkω_o) задается в соответствии с взаимосвязью (7):
H(expjkω_o)= 1+

a_sexp(-jskω_oτ), k=

. (12)
Все необходимые сигналы содержит выходная шина 23, подключенная к управляющему входу 18.Spectral analyzer 4 extracts the harmonics of the periodic signal i ¹ ₀ (l), realizing the function

(kω _o ) = (2 / N)

i

(l) exp (-jkω _o -τl), k =

. (10)
The purpose of the amplitude-phase corrector 3 is the conversion of harmonics

(kω _o ) of the signal i ₀ ^l (l) in the harmonics of the periodic term of the input quantity

(kω _o ) =

(kω _o ) / H (expjkω _o ). (10)
The transfer function H (expjkω _o ) is set in accordance with the relationship (7):
H (expjkω _o ) = 1+

a _s exp (-jskω _o τ), k =

. (12)
All the necessary signals contains the output bus 23 connected to the control input 18.

(kω_o):
i_o(l)=

(kω_o)exp(jkω_oτ). (13)
Вычитатель 6 формирует разностную величину i(l) - i_o(l).The purpose of the 5 harmonic generator is to generate a periodic quantity i _o (l) from its spectrum

(kω _o ):
i _o (l) =

(kω _o ) exp (jkω _o τ). (thirteen)
Subtractor 6 generates the difference value i (l) - i _o (l).

a_sZ^m-s= 0. (14)
Выходные сигналы этого блока совпадают с корнями

, s =

уравнения (14). Логарифмический блок 7 формирует сигналы о комплексных частотах

= (1/τ)ln

= -β_S+jω_S. (15)
Вычислительный блок 9 формирует из сигналов i(l) - i_o(l) и

систему линейных алгебраических уравнений относительно множителей

свободных составляющих тока короткого замыкания:

= i(l)-i_o(l). (16)
Выходными сигналами устройства являются, таким образом, гармоники

(k ω), частоты

и уровни экспонент

, снимаемые соответственно с выходов 14, 15 и 16.The decision block 8 is a processor designed to solve an algebraic equation, which is a characteristic equation of adaptive filter 1:
H (Z) = Z ^m +

a _s Z ^ms = 0. (14)
The output signals of this block coincide with the roots

, s =

equations (14). Logarithmic unit 7 generates signals about complex frequencies

= (1 / τ) ln

= -β _S + jω _S. (fifteen)
The computing unit 9 generates from signals i (l) - i _o (l) and

a system of linear algebraic equations for factors

free components of short circuit current:

= i (l) -i _o (l). (sixteen)
The output signals of the device are thus harmonics

(k ω), frequencies

and exponent levels

removed respectively from outputs 14, 15 and 16.

 The device operates as follows.

(l)+i(l-1)a₁₁= -i(l), l=

и определяет из нее N отсчетов i_о ^′(l) и коэффициент a₁₁. На умножитель 33 нерекурсивного фильтра 11 при этом поступает ненулевой сигнал, а на все прочие умножители 34, 35 - по-прежнему нулевые. Соответственно на выходах сумматоров 39 и 12 появляются сигналы.According to the start signal, indicating a short circuit in the electric network, the driving unit 10 proceeds to configure the adaptive filter 1. The initial order is m = 0. In this case, the signals transmitted via bus 23 have a zero level, i.e., a _so = 0, where the zero index refers to the order of the filter. The signal υ (l) at the output of the non-recursive filter 11 is also of zero level. The bus 24 transmits N samples of the input quantity i (l). Entering the input of generator 2, they are subsequently repeated with a period N, thereby being transformed into a periodic quantity i _oo ¹ (l). The output signal of the adder 12 is the difference ε _o (l) = i (l) - i _oo ¹ (l). The threshold element 13, made according to the scheme of the zero indicator, compares the module | ε (l) | with setting. If the module exceeds the setpoint, which can happen already at the moment l = N, the threshold element 13 is triggered and, acting on the control input 26 of the driver unit 10, causes it to go to the next order m = 1. Unit 10 will form from the samples of the input quantity i (l ) system of equations (9):
-i

(l) + i (l-1) a ₁₁ = -i (l), l =

and determines from it N samples i _o ^′ (l) and the coefficient a ₁₁ . At the same time, a multiplier 33 of the non-recursive filter 11 receives a non-zero signal, and all other multipliers 34, 35 are still zero. Accordingly, the outputs of the adders 39 and 12 appear signals.

(l).ν ₁ (l) = a ₁₁ i (l-1); ε ₁ (l) = i (l) + a ₁₁ i (l-1) -i

(l).

If, in addition to the periodic term i _o (l), only one material exponent, I ₁ exp (-β ₁ t), is present in the composition of the short-circuit current, then the order m = 1 is sufficient to reduce the signal level ε ₁ (l) to zero. If the composition of the free term of the short-circuit current is more complicated, then the signal level ε ₁ (l) remains high, a new triggering of the threshold element 13 and the next launch of the driver unit 10, increasing the order to m = 2. The process of tuning the adaptive filter 1 continues until until the signal ε (l) is reduced to the zero level. Upon completion of the setup, the output signals of the remaining blocks operating according to the algorithms (10) - (16) become reliable.

 The device is free from methodological error, since for a finite number of exponentials and decaying harmonics in the composition of the short circuit current, all their parameters are determined exactly with a strictly defined order of the adaptive filter, and the number of components and their nature are not known in advance. In special cases, when any one group of parameters is required, the device is simplified. So, for relay protection, as a rule, knowledge of only the periodic current component is sufficient. Then there is no need for blocks 5-9. For frequency measuring organs it is enough to have an output 15 and blocks 3-6, 9 can be excluded. In general, the device covers all known applications related to the analysis of the composition of the short circuit current.

Claims (1)

 A DEVICE FOR SEPARATING THE COMPONENTS OF A SHORT CIRCUIT CURRENT, containing an adaptive filter made in the form of series-connected master unit, non-recursive filter, adder and threshold element, the output of the latter connected to the control input of the master unit, the first input of which is the information input of the device and connected to the parametric input filter and the second input of the adder, a periodic signal generator and an amplitude-phase corrector, the output bus of which forms the first output bus, characterized in that, in order to expand functionality by highlighting the fundamental harmonic and all the other components of the transient process, an additional spectral analyzer, series-connected harmonic generator, calculator and computational unit, series-connected decision block and logarithmic block are introduced, while the parametric the input of the periodic signal generator is connected to the second output of the master unit, the output to the inverse input of the adder and the input of spectral analysis jam, the output of which is connected to the control input of the amplitude-phase corrector, the output of which is connected to the input of the harmonic generator, the second input of the subtractor is connected to the first input of the driver unit, the inputs of the amplitude-phase corrector and decision unit are connected to the first output of the driver, the output of the logarithmic block the second output bus and is connected to the second input of the computing unit, the output of which forms the third output bus.

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