KR100735803B1 - System for fault location estimation and arcing fault detection using two terminal numerical algorithm - Google Patents

Abstract

The present invention relates to an accident distance estimation and accident discrimination system using numerical analysis of both terminals. The present invention relates to a first PMU and a second PMU which measure in real time a change in voltage and current of a transmission line in synchronization with a time reference signal of a satellite navigation system. ; And a communicator configured to receive voltage and current signals in association with the first PMU and the second PMU, an accident distance estimator configured to estimate a distance of an accident using the voltage and current signals received by the communicator, and for arc voltage modeling. An arc analyzer which numerically analyzes the arc characteristics, an arc voltage measuring unit that calculates the magnitude of the arc voltage using voltage and current signals measured from the first PMU and the second PMU, and determines the type of accident; A computer comprising a communication unit, an accident distance estimating unit, an arc analyzing unit, and a control unit for controlling the arc voltage measuring unit; It includes.

According to the present invention, by accurately measuring the waveform of the voltage and current distorted at both terminals of the transmission line in the event of an accident by synchronizing the time reference signal and the PMU of the satellite navigation device, it is possible to estimate the exact distance of the accident, the stability of the power system In terms of reliability and reliability, there is an effect that enables quick accident recovery and accurate discrimination.

Transmission line, accident distance, arc voltage, arc current, PMU

Description

System for fault location estimation and accident determination using two terminal numerical analysis

1 is a block diagram of an accident distance estimation and accident determination system according to the present invention.

2A is an overall flowchart of an accident distance estimation and accident determination method according to the present invention;

Figure 2b is a synchronization diagram using a satellite navigation system based PMU according to the present invention.

Figure 2c is an exemplary view showing the voltage measured by the first PMU and the second PMU according to the present invention.

Figure 3a is an exemplary view showing an arc ground fault of the three-phase power transmission line according to the first embodiment of the present invention.

Figure 3b is a circuit diagram showing an arc ground fault of the three-phase power transmission line according to the first embodiment of the present invention.

4 is a graph showing a waveform of an arc voltage according to a second embodiment of the present invention.

The present invention relates to a system for estimating an accident distance and an accident discrimination system of a transmission line, and more particularly, by synchronizing a visual reference signal of a satellite navigation system with a PMU (Phasor Measurement Unit) and an accident at both terminals of the transmission line. By accurately measuring the waveform of the distorted voltage and current, it is possible to estimate the accurate accident distance, and to provide an accident distance estimation and accident determination system capable of rapid accident recovery and accurate identification in terms of stability and reliability of the power system.

In recent years, when the power system has become larger and more complicated, an accident of a line or a line equipment, the ripple effect may not only damage the entire power system, but also cause economic losses. In response to these accidents, accident distance estimation and accident discrimination methods have played an important role in eliminating electrical accidents and reducing the effects of accidents, ensuring safety of the power system and securing reliability of power supply.

As a method of calculating a distance to a failure point when an accident occurs in a conventional transmission line, a method using a traveling wave, a method using a propagation equation, and a characteristic using a fundamental wave component of voltage and current are classified into impedance methods.

However, the method of using only the information of the line once by using the fundamental wave components of voltage and current has difficulty in quickly determining an accident and accurately estimating an accident distance because distortion of voltage and current changes is inevitable.

The present invention is to solve the above problems, by accurately measuring the waveform of the voltage and current distorted at both terminals of the transmission line in the event of an accident by synchronizing the time reference signal and the PMU of the satellite navigation device, it is possible to estimate the exact distance In addition, in terms of stability and reliability of the power system, it provides an accident distance estimation and accident determination system using numerical analysis of both terminals, which enables quick accident recovery and accurate identification.

The present invention for achieving the above object, the first PMU and the second PMU synchronized with the time reference signal of the satellite navigation device; and a communication unit, an accident distance estimation unit, arc analysis unit, arc voltage measurement unit and control unit An accident distance estimation and an error discrimination method using a discrimination system comprising a computer; (a) The first PMU and the second PMU synchronize the voltage and current at both ends of a transmission line by synchronizing with the time reference signal of the satellite navigation apparatus. Measuring process; (b) the computer receives the measured voltage and current signal, extracts the voltage at the transmission line accident through a loop equation, measures the current variation amount di / dt over time, and extracts the extracted accident voltage and Extracting the accident distance x using the amount of change in the current; (c) the computer receiving the voltage and current signals measured in step (a) to extract the arc voltage, and determining the type of accident; Characterized in that it comprises a.

Preferably, before the step (b), the computer determines whether the sum of the respective voltages V _S and V _R measured from the first PMU and the second PMU is 0, and as a result of the determination, the non-zero If, the process of determining that an accident occurred; It characterized in that it further comprises.

Also preferably, before the step (c), the computer numerically analyzes the arc voltage waveform based on the non-linear arc characteristics generated during the accident; It characterized in that it further comprises.

Also preferably, the process (c) may include: (c-1) the computer extracting an arc voltage using a matrix; (c-2) the computer determining whether the extracted arc voltage is less than or equal to a predetermined value; And (c-3) classifying it as a temporary accident when the determination result of step (c-2) is less than or equal to a predetermined value; Characterized in that it comprises a.

Preferably, the predetermined value is a product of the length of the suspension insulator and the length of the average arc voltage.

Hereinafter, with reference to the accompanying drawings will be described in detail the present invention.

Prior to this, Figure 1 is a schematic diagram showing an accident distance estimation and accident determination system using a numerical analysis of the two terminals according to the present invention, the description thereof will be omitted below, but all processing is based on the time reference of the satellite navigation system A first PMU 100 and a second PMU 100 'for real-time measurement of changes in voltage and current of a transmission line in synchronization with a signal; and interworking with the first PMU 100 and a second PMU 100' The communication unit 210 for receiving the voltage and current signals, the accident distance estimator 220 for estimating the distance of the accident using the voltage and current signals received by the communication unit 210, and arc characteristics for arc voltage modeling. Calculate the magnitude of the arc voltage using the arc analysis unit 230 for numerical analysis and the voltage and current signals measured from the first PMU 100 and the second PMU 100 ′, and determine the type of accident. Arc voltage measuring unit 240, and the communication unit 210, Performed by the computer 200 consisting of a control unit 250 for controlling the accident distance estimator 220, the arc analyzer 230 and the arc voltage measurement unit 240, using both terminal numerical analysis according to the present invention It is desirable to understand that the accident determination and the accident distance estimation are performed in the computer 200.

In general, the precision required to compare and examine the physical quantities measured in the power system is specified to be 1 μs or more, and as an alternative to realize the precision, by receiving a signal propagated from a satellite, its own location information and visual information There is a satellite navigation system that can be provided. The same reference time information can be obtained at any point of the power system by using a 1PPS signal (± 1 μs, time synchronization deviation) at the receiver of the satellite navigation system as the reference time of the power system. That is, the first PMU 100 and the second PMU 100 ′ measuring voltage and current changes may simultaneously measure not only the magnitude of the bus voltage but also the phase angle in synchronization with the time reference signal of the satellite navigation apparatus. . Therefore, when a transmission line accident occurs, the type of accident is determined by using the accident voltage and the current value extracted according to the present invention, and the accident distance is estimated.

The overall flow of the accident distance estimation and the accident determination method according to an embodiment of the present invention having the above-described configuration will be described with reference to FIGS. 2A to 4.

As shown in FIG. 2A and FIG. 2B, the first PMU 100 and the second PMU 100 ′ synchronized with the time reference signal of the satellite navigation apparatus measure the change in voltage and current of the transmission line in real time. (S100).

Thereafter, the computer 200 executes a process of determining whether an accident occurs using signals of voltage and current measured from the first PMU 100 and the second PMU 100 ′ (S200).

As shown in FIG. 2C, the first PMU 100 and the second PMU 100 ′ normally measure voltages and currents at both ends of a transmission line, and when an accident does not occur, each measured at each end is measured. The sum of the voltages V _S and V _R has a constant value (0). Accordingly, the computer 200 may measure the voltage V _S measured at the first PMU 100 and the second PMU 100 ′, respectively. It is determined whether the sum of the values of and V _R is 0 (zero). If the sum of the two voltages is not 0, it is determined that an accident occurs.

Hereinafter, the computer 200 performs a process of estimating the accident distance x by assuming the same accident as in the first embodiment (S300).

[First Embodiment]

As a first embodiment, a-phase arc ground fault occurred in a three-phase power transmission line, and a voltage and current phaser synchronized across the power transmission line was induced. As shown in FIG. 3A, when an arc occurs in a transmission line, a new line is vertically formed in the line, and the accident voltage V _F of the line is expressed by the following [First Model Formula] by the voltage law. do.

[First Model]

Where V _a (t): arc voltage, R _F : accident resistance, i _F (t): accident current.

Accident distance estimation using the above-described satellite navigation apparatus and the time synchronization technology of the first PMU 100 and the second PMU 100 ', as shown in FIG. Using (V _S , V _R , i _S , i _R ), make the following assumptions:

1. Accident type: a-phase arc ground fault

2. Line length: Short-range line (ignore line capacitance)

Where V _S And V _R Are the voltages at the transmission and receiving side busbars, x is the accident distance, d is the length of the line, and S and R are the sending and receiving busbars of the line.

Thereafter, the computer 200 performs a step of extracting the voltage at the time of the transmission line accident as shown in FIG. 3B using the loop equation (S310).

In case of an accident, the voltage V _nF is derived through Equations 1 and 2 using the loop equation.

[Equation 1]

[Equation 2]

Where V _nF : fault voltage, V _nS : power stage voltage, V _nR : power stage voltage,

n = a, b, c (phase), p = a, b, c (phase)

r _aa , r _bb , r _cc , l _aa , l _bb , l _cc : Self resistance / inductance

r _ab , r _bc , r _ca , l _ab , l _bc , l _ca : denoted by mutual resistance / inductance. [Equation 1] and [Equation 2] are the following [Equation 3] It can be represented as

[Equation 3]

Here, [Equation 3] can be summarized as the following [Equation 4].

[Equation 4]

Then, the computer 200 performs a step of measuring the amount of change in the current (di / dt) (S320).

Using the above Equation 4, the amount of change in the current in the visual domain can be summarized as shown in Equation 5.

[Equation 5]

I (k): instantaneous current value of the k-th sampling, and? T: sampling interval.

For reference, when processing phase pager data of voltage and current acquired at both ends of a transmission line, a phenomenon occurs in which an electric current rises and a voltage decreases when an accident occurs. In the present invention, the One-Window method is used to process the data. It is assumed that the One-Window method samples and processes 64 sine waves per cycle, but accepts 64 data when the initial power is supplied, and then calculates the difference between only one incoming data and one outgoing data thereafter. To match. That is, processing speed can be increased by processing data quickly.

Thereafter, the computer 200 performs a step of extracting the accident distance x by using the change amounts of the accident voltage and the current measured through steps S310 and S320 (S330).

By substituting [Equation 5] into [Equation 4], it can be arranged as shown in [Equation 6] on the basis of the thinking distance (x).

[Equation 6]

A _n (k)-x B _n (k) = 0

Where A _n (k), B _n (k), n = a, b, c, k = 1,2, ... N.

Where V _nS (k), V _nR (k): instantaneous voltage values (n = a, b, c) of each phase of the kth sampling,

i _nS (k), i _nR (k), instantaneous current value of each phase of the kth sampling (n = a, b, c),

N: total number of sampling,

ΔT: Sampling interval.

Using Equation 6 as described above, the thinking distance x, which is a characteristic aspect of the present invention, may be represented as shown in Equation 7.

[Equation 7]

Then, the computer 200 performs a process of numerically analyzing the characteristics of the arc for arc voltage modeling through the second experimental example (S400).

Arc accidents occurring on transmission lines cause severe distortion of the voltage and current waveforms transmitted across the transmission lines, generate low voltage and high current, and decrease the voltage across the arc as the current increases. . As such, the nonlinear nature of the arc makes it difficult to define the arc property. Therefore, the characteristics of the nonlinear arc are numerically analyzed through the following second embodiment.

Second Embodiment

As a second embodiment, the computer 200 numerically analyzes the arc voltage waveform based on the characteristics of the arc obtained through a separate transient recording device. As shown in FIG. 4, the arc voltage and current have an in-phase, and the arc voltage has a shape close to a square wave. In the present invention, the computer 200 utilizes the numerical approach to arc voltage modeling using the arc voltage close to the square wave as described above.

The computer 200 is represented by a Fourier series including only odd waves as shown in [Equation 8].

[Equation 8]

Here, h is a harmonic component having 1, 3, 5, 7, ..., V _ah (t) is the arc voltage of the h order harmonic, ω is the fundamental radian frequency, and k _h is the coefficient of the h order harmonic. The harmonic coefficients of k _h shown in this example are shown in Table 1 below.

TABLE 1

Hereinafter, the computer 200 measures the arc voltage through the third embodiment using the voltage and current signal measured in the step S100 and the model equation of the arc accident, thereby the accident on the transmission line which is a characteristic aspect of the present invention. A type determination process is executed (S500).

Third Embodiment

As a third embodiment, the computer 200 shows the arc voltage as the following [second model] based on the power transmission stage where the arc accident occurred.

[2nd model formula]

As shown in FIG. 4, the distorted arc voltage has a shape close to a square wave. Here, the computer 200 assumes the arc voltage and the arc current in the form of a pure square wave, but executes the step of representing the arc voltage expressed in Equation 9 as shown in Equation 9 (S510).

[Equation 9]

: 가우시안 노이즈, sgn: 시그넘 함수이다. 시그넘 함수는 값이 0 이 상인 경우, + 1 로 정의하고, 0 이하인 경우, -1 로 정의하되, 싸인파의 +, - 를 정의해 주는 것으로 이해하는 것이 바람직하다. here,

Gaussian noise, sgn: signum function. The signum function is defined as + 1 when the value is 0 or more, and -1 when it is 0 or less, but it is preferable to understand that it defines + and-of a sine wave.

Then, using the above-described [first model] and [Equation 9], the arc voltage (V _nF ) as shown in [Equation 10].

[Equation 10]

Next, the computer 200 performs a step of extracting the accident current (i _F ) (S520).

Here, the fault current i _F is expressed by Equation 11 using Kirchhoff's first law.

[Equation 11]

In addition, by substituting [Equation 11] into [Equation 10], it is expressed as [Equation 12].

[Equation 12]

Then, by substituting [Equation 12] into [Second model equation], it is arranged as in [Equation 13].

[Equation 13]

Since the accident distance (x) has already been calculated through [Equation 7], the computer 200 organizes the equation as shown in [Equation 14] for the unknown variable (V _ks ) of [Equation 13]. In operation S530, the arranged Equation 14 is expressed in the form of a matrix equation for sampling N pieces.

[Equation 14]

Where a _k1 = sgn [i (k) -i _L (k)], a _k2 = {i (k) -i _L (k)},

이다.

to be.

If Equation 14 is expressed as a matrix equation for N sampling, it is as follows.

[Matrix]

Here, the above determinant is defined as V = A.X + B, where V is an N × 1 matrix, A is an N × 2 matrix, X is a 2 × 1 matrix, and B is an N × 1 matrix.

Thereafter, the computer 200 extracts an arc voltage from the determinant using a least square method (S540).

The arc voltage (V) = A · X + B is expressed as [Equation 15] by reducing the sum of squares of the error terms to a minimum.

[Equation 15]

X = (A ^T A) ^-1 A ^T (VB)

Where (A ^T A) ^-1 A ^T Is a pseudo inverse.

So far, the arc voltage can be calculated through step S540. Thereafter, the computer 200 compares the magnitude of the arc voltage extracted in step S540 with a predetermined value to determine whether the arc has occurred (temporary accident) (S550).

As a result of the determination in the step S550, if it is less than the predetermined value, it is determined as an accident with an arc (temporary accident) (S560).

In the present invention, the predetermined value is set as the product of the length of the suspension insulator used in the transmission line at the time of accident and the length of the average arc voltage (gradient of the average arc voltage).

For example, if the length of the suspension insulator is 2m, the average arc voltage is 12V / cm, and the extracted arc voltage is 4.5kV, the product of the length of the suspension insulator and the average arc voltage length is the Since it is smaller than the size, it is defined as a temporary accident. Here, the permanent accident can not be determined only by the change in voltage and current because the accident continues to proceed by trees or short circuits.

In summary, when a transmission line accident occurs, the first PMU 100 and the second PMU 100 'are synchronized using the time reference signal of the satellite navigation apparatus to measure the change of voltage and current at high speed, and the measured voltage and The presence or absence of an accident was determined using the signal value of the current. If it is determined to be an accident, the accident distance is estimated using the first experimental example, the nonlinear arc characteristics generated during the accident are numerically defined through the second experimental example, and the type of the accident is determined by the third experimental example.

 According to the present invention, by accurately measuring the waveform of the voltage and current distorted at both terminals of the transmission line in the event of an accident by synchronizing the time reference signal and the PMU of the satellite navigation device, it is possible to estimate the exact distance of the accident, the stability of the power system In terms of reliability and reliability, there is an effect that enables quick accident recovery and accurate discrimination.

Claims (6)

delete delete delete delete delete In the accident distance estimation and accident discrimination system using numerical analysis of both terminals, A first PMU (100) and a second PMU (100 ') which measure in real time a change in voltage and current of a transmission line in synchronization with a time reference signal of the satellite navigation apparatus; And The distance of the accident is estimated using the communication unit 210 receiving the voltage and current signals in cooperation with the first PMU 100 and the second PMU 100 ′, and the voltage and current signals received by the communication unit 210. The accident distance estimator 220, the arc analyzer 230 for numerically analyzing the arc characteristics for arc voltage modeling, the voltage measured from the first PMU 100 and the second PMU 100 'and The arc voltage measuring unit 240 calculates the magnitude of the arc voltage using the current signal and determines the type of the accident, and the communication unit 210, the accident distance estimating unit 220, the arc analyzing unit 230, and the arc voltage. A computer 200 configured as a control unit 250 for controlling the measurement unit 240; Accident distance estimation and accident determination system using a numerical analysis of both terminals, including.

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