KR20190061143A - Apparatus for measuring harmonic impedance of electric power system and method for the same - Google Patents

Abstract

The present invention relates to an apparatus and method for measuring a harmonic impedance of a power system, and a method of measuring a harmonic impedance of a power system according to an embodiment of the present invention is a method for measuring a harmonic impedance of a power system, An abbreviated system setting step of setting an abbreviated system; A measurement result collection step of measuring a current and a voltage of busbars included in the reduction system and collecting measurement results; And an arithmetic step of calculating an admittance or impedance of the abatement system using the collected measurement results.

Description

Technical Field [0001] The present invention relates to a harmonic impedance measuring apparatus and a measuring method for a harmonic impedance of a power system,

The present invention relates to a harmonic impedance measurement device and a measurement method for a power system, and more particularly, to a harmonic impedance measurement device and a measurement method of a power system capable of measuring a harmonic impedance of a power system at a point where electric equipment or the like is connected .

An electric power system is a system in which a power plant, a substation, a transmission / distribution line, and a load are integrated to generate and utilize electric power.

When electrical equipment such as a power plant or a load is added to a power system, there is a risk that system disturbance or malfunction of the equipment may occur due to harmonics. In order to prevent this, a filter designed based on the harmonic impedance of the power system can be applied. That is, by using the filter, it is possible to attenuate transient characteristics that may occur when the electric devices are connected.

However, in order to design a filter or the like, it is necessary to accurately measure the characteristics of the power system, in particular, the harmonic impedance of the power system.

Conventionally, a harmonic current source is applied to a target point where an electric device is installed, and a harmonic impedance of a power system is estimated by using a voltage measured corresponding to the input current. The method of applying a harmonic current source is relatively simple in that the power system is made up only of passive elements. However, it can be applied to various active systems such as generators, FACTs (Flexible AC Transmission System), HVDC (High- There is a problem in that accurate measurement can not be performed in a commercial power system 1 including an active facility.

The present application is intended to provide a harmonic impedance measurement device and a measurement method of a power system capable of measuring a harmonic impedance of a power system at a point where electric equipment or the like is connected.

The present application aims to provide a harmonic impedance measurement device and a measurement method of a power system that can utilize a reduction system in which a power system is shortened.

The present application is intended to provide a harmonic impedance measurement device and a measurement method of a power system capable of eliminating measurement errors using a Kalman filter.

A method of measuring a harmonic impedance of a power system according to an embodiment of the present invention includes: setting an abbreviated system by setting a power system connected to a target point on the basis of a target point; A measurement result collection step of measuring a current and a voltage of busbars included in the reduction system and collecting measurement results; And an arithmetic step of calculating an admittance or impedance of the abatement system using the collected measurement results.

In this case, the reduction system may be configured by abbreviating the topology of the power system. At this time, the topology of the reduction system may be similar to the topology of the power system by more than a predetermined degree of similarity.

Here, the reducing system setting step may include: setting a preliminary reducing system by reducing the power system; Comparing the preliminary reduction system with a topology of the power system to extract a preliminary reduction system having a degree of similarity equal to or greater than a predetermined degree of similarity; And setting a preliminary reduction system having the smallest number of buses in the extracted preliminary reduction system as the reduction system.

Here, the setting of the reduction system may include setting a number of buses included in the internal bus according to an input control signal and setting a preliminary reduction system; Comparing the topology of the preliminary reduction system with the topology of the power system and setting the preliminary reduction system as the reduction system if the degree of similarity is greater than a predetermined degree of similarity; And increasing the number of the busbars included in the preliminary reduction system by transmitting the control signal if the predefined similarity is less than the predefined similarity.

Here, the calculating step may apply a Kalman filter to remove noise included in the measurement result, and calculate the admittance.

Wherein the calculating step includes: a state equation setting step of setting a state equation of the reduction system using the admittance as a state variable, for application to the Kalman filter; A time update step of calculating a predicted value of the state variable with respect to the nth measurement result from the state variable value of the (n-1) th measurement result using the state equation; A measurement update process for correcting the predicted value to a Kalman gain and updating the corrected predicted value to a state variable value for an nth measurement result; And an admittance calculation process of repeating the time update process and the measurement update process to extract an admittance corresponding to the measurement result.

Here, the state equation setting process

To the state equation. (N) is the current value of the actual bus line, z (n) is the current value of the measured bus line, and v (n) is the current value of the measured bus line. (n) is the measurement error, and c is the voltage vector at each busbar.

Here,

을 계산할 수 있다. 이때, P(n)은 상기 상태변수의 오차 공분산이고, P^-(n)는 상기 오차 공분산의 예측값일 수 있다. The predicted value of the state variable

Can be calculated. Where P (n) is the error covariance of the state variable, and P ^- (n) is the predicted value of the error covariance.

Wherein the measuring update step

및 P^-(n)을 이용하여,

및 p(n)을 업데이트할 수 있다. (N) by using the Kalman gain k (n) and the estimated value k

And P < ^- > (n)

And p (n).

According to an embodiment of the present invention, there may be a computer-readable recording medium on which a program for executing the above-described method is recorded.

An apparatus for measuring a harmonic impedance of a power system according to an embodiment of the present invention includes an abbreviated system setting unit for setting an abbreviation system by shortening a power system connected to a target point based on a target point; A measurement result collecting unit for collecting measurement results of current and voltage of busbars included in the reduction system; And an operation unit for calculating an admittance or impedance of the reduction system using the collected measurement results.

Here, the reduced system setting unit may set the topology of the reduced system to be equal to or more similar to the predetermined threshold of the power system.

Here, the abridged system setting unit may select an abbreviated system having the smallest number of buses included in the abridged system when there are a plurality of abridged systems having the predetermined degree of similarity or more.

Here, the calculation unit may calculate the admittance by removing a noise included in the measurement result by applying a Kalman filter.

Here, the operation unit may include: a state equation setting module for setting a state equation of the reduction system using the admittance as a state variable, for application to the Kalman filter; A time update module for calculating a predicted value of the state variable for the nth measurement result from the state variable value for the (n-1) th measurement result using the state equation; A measurement update module for correcting the predicted value to a Kalman gain and performing a measurement update to update the corrected predicted value to a state variable value for an nth measurement result; And an admittance calculation module that controls the time update and measurement update to be repeated so as to extract an admittance corresponding to the measurement result.

Here, the state equation setting module

Can be set to the state equation. (N) is the current value of the actual bus line, z (n) is the current value of the measured bus line, and v (n) is the current value of the measured bus line. (n) is the measurement error, and c is the voltage vector at each busbar.

Wherein the time update module

을 계산할 수 있다. 이때, P(n)은 상기 상태변수의 오차 공분산이고, P^-(n)는 상기 오차 공분산의 예측값일 수 있다. The predicted value of the state variable

Can be calculated. Where P (n) is the error covariance of the state variable, and P ^- (n) is the predicted value of the error covariance.

Wherein the measurement update module

및 P^-(n)을 이용하여,

및 p(n)을 업데이트할 수 있다. (N) by using the Kalman gain k (n) and the estimated value k

And P < ^- > (n)

And p (n).

In addition, the means for solving the above-mentioned problems are not all enumerating the features of the present invention. The various features of the present invention and the advantages and effects thereof will be more fully understood by reference to the following specific embodiments.

According to the apparatus and method for measuring a harmonic impedance of a power system according to an embodiment of the present invention, harmonic impedance at a target point to which an electric equipment or the like is connected can be measured.

According to the apparatus and method for measuring a harmonic impedance of a power system according to an embodiment of the present invention, a harmonic impedance can be efficiently measured by using a reduction system in which a power system is shortened. In addition, since it is calculated by applying the Kalman filter, the harmonic impedance can be measured more accurately.

1 is a schematic diagram showing a harmonic impedance measurement system for a power system according to an embodiment of the present invention.
2 is a block diagram illustrating an apparatus for measuring a harmonic impedance of a power system according to an embodiment of the present invention.
3 to 5 are schematic diagrams for explaining the setting of an abbreviated system according to an embodiment of the present invention.
FIG. 6 is a graph illustrating a harmonic impedance measurement result of a power system according to an embodiment of the present invention.
7 to 8 are flowcharts illustrating a harmonic impedance measurement method of a power system according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings, in order that those skilled in the art can easily carry out the present invention. In the following detailed description of the preferred embodiments of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear. In the drawings, like reference numerals are used throughout the drawings.

In addition, in the entire specification, when a part is referred to as being 'connected' to another part, it may be referred to as 'indirectly connected' not only with 'directly connected' . Also, to "include" an element means that it may include other elements, rather than excluding other elements, unless specifically stated otherwise. Also, the terms " module ", " module " and the like described in the specification mean units for processing at least one function or operation, which may be implemented by hardware or software or by a combination of hardware and software.

1 is a schematic diagram showing a harmonic impedance measurement system for a power system according to an embodiment of the present invention.

Referring to FIG. 1, the harmonic impedance measurement system of a power system according to an embodiment of the present invention may include a power system 1, a measurement instrument 10, and a harmonic impedance measurement apparatus 100.

Hereinafter, a harmonic impedance measurement system for a power system according to an embodiment of the present invention will be described with reference to FIG.

An electric power system (1) is a system in which a power plant, a substation, a transmission / distribution line, and a load are integrated to generate and use electric power. The power system 1 may have a topology as shown in FIG. 1, and may include a bus-bar and a line connecting the bus, a power plant, a substation, a load, etc. in the topology have.

 When electrical equipment such as a power plant or a load is added to the power system 1, there is a risk that system disturbance caused by harmonics occurring in a transient state or malfunction of the equipment occurs. In order to prevent this, a filter designed based on the harmonic impedance of the power system 1 may be applied. That is, by using the filter, it is possible to attenuate transient characteristics that may occur when the electric devices are connected. However, in order to design a filter or the like, it is necessary to accurately measure the characteristics of the power system 1 to which the electric apparatus is connected, in particular, the harmonic impedance of the power system 1.

Conventionally, a harmonic current source is applied to a target point A where an electric device is installed, and a harmonic impedance of the power system 1 is estimated by using a voltage measured corresponding to the input current. The method of inputting the harmonic current source allows a relatively accurate measurement when the power system is made up only of passive elements. However, there is a problem that accurate measurement can not be performed in a commercial power system 1 including a variety of active facilities such as a generator, a FACTs (Flexible AC Transmission system), and a HVDC (High-Voltage Direct Current) system.

On the other hand, the influence of the harmonics that can occur in the power system 1 at the time of connection of the electric devices can be analyzed by a simulation method after modeling the entire power system 1. In this case, since the characteristics of the entire power system 1 can be reflected by the modeling, it is possible to accurately confirm the influence of the harmonics that may occur when the electric device or the like is connected to the object point A. However, considering the entire characteristics of the power system 1, modeling is very difficult to be applied in consideration of the amount of data required for modeling, time required, cost, security, and the like.

The harmonic impedance measuring apparatus 100 can reduce the power system 1 for efficient measurement and can estimate the harmonic impedance of the entire power system 1 by analyzing the reduced system.

Specifically, as shown in Fig. 3, the harmonic impedance measurement apparatus 100 can be set to a reduction system of various ranges from the power system 1. Fig. That is, the entire power system 1 can be shortened to one bus line as shown in FIG. 3 (a), and as shown in FIGS. 3 (b) to 3 (g) The system can be set up in a stepwise manner. Finally, it can be extended to the entire power system 1 as shown in Fig. 3 (g).

4 and 5 are graphs illustrating the amplitude and phase of the harmonic impedance corresponding to each abbreviated abbreviated system. That is, the magnitude of the harmonic impedance corresponding to the reduced system of FIG. 3A is shown in FIG. 4A, the phase is shown in FIG. 5A, and the magnitude of the harmonic impedance corresponding to the reduced system of FIG. And phase are shown in Figs. 4 (b) and 5 (b), respectively. The magnitude and phase of the harmonic impedance are displayed in the same manner for the restraining systems.

3 to 5, it can be confirmed that the reduced system shown in FIG. 3 (e) and FIG. 3 (f) shows almost the same result as the case of calculating the harmonic impedance for the entire power system 1. That is, the more abrupt the reduction, the more the harmonic impedance of the reduction system may be different from the harmonic impedance of the actual power system 1. On the other hand, as the topology of the buses included in the reduction system is similar to the overall power system 1, It can be confirmed that the impedances become similar. Therefore, it is possible to obtain the harmonic impedance by using the reduction system instead of the entire power system 1. [

In addition, the harmonic impedance measurement apparatus 100 can receive measurement results of the current and voltage of each bus line included in the reduction system from the measurement equipment 10, in order to perform an analysis on the reduction system. The harmonic impedance measuring apparatus 100 can extract the harmonic impedance in the reduction system.

Here, the measurement apparatus 10 can perform measurement at each measurement point set in the power system 1, and can provide measurement results to the harmonic impedance measurement apparatus 100 via wired or wireless communication. However, since the measurement current and voltage measured by the measuring instrument 1 may include measurement errors, it is necessary to perform correction for the error. Accordingly, the harmonic impedance measuring apparatus 100 can correct the errors included in the measurement results by applying a Kalman filter, and obtain an accurate harmonic impedance.

That is, the harmonic impedance measuring apparatus 100 according to an embodiment of the present invention can accurately and efficiently measure the harmonic impedance of the power system 1, as compared with the conventional methods.

Hereinafter, a specific operation of the harmonic impedance measuring apparatus 100 according to an embodiment of the present invention will be described.

2 is a block diagram illustrating an apparatus for measuring a harmonic impedance of a power system according to an embodiment of the present invention.

Referring to FIG. 2, an apparatus for measuring a harmonic impedance of a power system according to an embodiment of the present invention may include a reduction system setting unit 110, a measurement result collecting unit 120, and a calculating unit 130.

The reduction system setting unit 110 may shorten the power system 1 connected to the target point A based on the target point A and set the reduction system as an abbreviation system. Here, the object point A may be the point where the electric device is connected to the power system.

The reduction system sets the whole power system 1 in an abbreviated form. When setting the reduction system, it is important to reduce the power system 1 to a certain extent.

The harmonic impedance is characterized in that the buses far from the target point (A) are less influential and can be influenced by the buses approaching the target point (A). Therefore, if the topology of the overall power system 1 and the reduction system are the same within a certain range from the target point A, the harmonic impedances measured for each case become very similar.

That is, since the harmonic impedance is influenced by the topology, the reduction system setting unit 110 can select a reduction system that is at least similar to the topology of the entire power system at least by a predetermined degree of similarity. For example, among the plurality of reduction systems shown in FIG. 3, a reduction system similar to the topology of the entire power system more than a preset similarity degree may be selected and used for measuring the harmonic impedance. 3 (e) and 3 (d) are different from the topology of the actual power system 1, and Fig. 3 (e) and Fig. 3 (f) It can be judged that the above is similar.

On the other hand, when there are a plurality of reduction systems having a predetermined degree of similarity or more, the reduction system setting unit 110 can select the reduction system having the smallest number of buses included in the reduction system. As the number of buses increases, the number of factors to be measured and calculated increases. To minimize this, an abbreviation system having the smallest bus line can be selected. Here, there are various ways of calculating the similarity of the topology, and the present invention is not limited by the similarity calculation method. Since the similarity calculation method is known, a detailed description of the calculation method is omitted here.

Specifically, the reduction system setting unit 110 may configure a plurality of preliminary reduction systems by shortening the power system, and may compare the topology of the plurality of preliminary reduction systems with the topology of the power system 1. Thereafter, a preliminary reduction system having a degree of similarity equal to or greater than a predetermined degree of similarity to the topology of the power system 1 can be extracted, and a preliminary reduction system having the smallest number of buses included in the extracted preliminary reduction system can be set as the reduction system .

Also, according to the embodiment, it is possible to set the preliminary reduction system while increasing the number of bus bars included in the reduction system. That is, it is possible to set a preliminary reduction system having the number of bus lines set according to the control signal, and compare the topology of the power system with the predetermined degree of similarity or more. In this case, if the similarity degree is more than the predetermined degree, the reduction system can be set. However, when the degree of similarity is less than the predetermined similarity degree, the control signal may be transmitted to increase the number of buses included in the reduction system to generate the preliminary reduction system.

In addition, according to the embodiment, the bus line directly connected to the bus line including the target point A may be referred to as a first step, the bus lines directly connected to the first bus line may be referred to as the second bus line, Three steps, and so on. In this case, it is also possible to set an abbreviated system by selecting a abbreviated system to which at least n bus lines are connected.

The measurement result collection unit 120 may collect measurement results of the current and voltage of the busbars included in the reduction system. As shown in FIG. 1, the harmonic impedance measuring apparatus 100 can receive measurement results from the measuring instrument 10, and the measuring instrument 10 can measure current and voltage for each bus. Here, the measurement result can be transmitted between the measurement equipment 10 and the measurement result collection unit 120 through wired or wireless communication.

The calculation unit 130 can calculate the admittance or impedance of the reduction system using the collected measurement results. Since the current and voltage measured by the measuring instrument 10 may include measurement errors or the like, the calculating unit 130 may apply a Kalman filter to remove the noise included in the measurement result. Then, the admittance of the reduction system corresponding to the harmonic impedance can be calculated.

Specifically, the operation unit 130 may include a state equation setting module 131, a time update module 132, a measurement update module 133, and an admittance calculation module 134.

The state equation setting module 131 can set the state equation of the reduction system using the admittance as a state variable in order to apply it to the Kalman filter. Specifically, the state equation can be set as follows.

(N) is a state variable, which is the admittance of the reduction system, Φ is a modeling function for the admittance change characteristic, Γ is the process noise coefficient, and w (n) It is a process noise vector. where n (n) is the true value, z (n) is the measured value, v (n) is the measurement error, c is the bais function, 10) < / RTI >

Φ can be replaced with a unit matrix in a simple estimation or the like, and in the case of a generator having a high nonlinearity, a formula corresponding to the generator can be reflected. The state variable x (n) may be the admittance of the reduced system, where the basis function c may be the voltage of the busbars measured in the metrology equipment 10. In this case, y (n) can be a true value for the current of the busbars. Depending on the embodiment, it is also possible to set the basis function c to a function c (t) with respect to time. That is, when the associated electric device is a nonlinear device such as a generator, the base function c is updated every moment, so that it can be calculated by setting c (t).

On the other hand, the process noise vector w (n) can be ignored because it is very small compared to the measurement error due to the error in the prediction process to the next state. In this case, the state equations can be summarized as follows.

The time update module 132 may perform a time update to calculate a predicted value of the state variable for the nth measurement result using the state equation. The time update in the Kalman filter can calculate the predicted value of the state variable for the nth measurement result from the state variable for the n-1th measurement result. In other words,

을 계산할 수 있다. 또한, 상태변수의 오차 공분산(error covariance)인 P(n)에 대하여도 예측값 P^-(n)을 계산할 수 있다. 여기서 윗첨자 T는 전치행렬(Transposed matrix)을 의미할 수 있다. 한편, Q는 공정 노이즈의 공분산 행렬(process noise covariance matrix)이나, 여기서 공정오차와 측정오차는 상호 독립적이므로 0으로 둘 수 있다. The predicted value of the state variable

Can be calculated. Also, the predicted value P ^- (n) can be calculated for the error covariance P (n) of the state variable. The superscript T may refer to a transposed matrix. On the other hand, Q is a process noise covariance matrix of the process noise, wherein the process error and the measurement error are independent of each other and can be set to zero.

Accordingly, the time update module 132 may calculate the predicted values of the state variable and the error covariance using the following equation.

The measurement update module 133 may perform a measurement update that corrects the predicted value to the Kalman gain and updates the corrected predicted value to the state variable value for the nth measurement result. In other words,

및 P^-(n)을 이용하여,

및 p(n)을 업데이트할 수 있다. 여기서, r은 측정오차 ν(n)의 공분산에 해당한다. 즉, 측정 업데이트 모듈(133)은 예측값

에 칼만 게인 k(n)과 측정오차를 적용하는 방식으로,

으로 업데이트할 수 있으며, 이를 통하여, 정확하게

을 계산할 수 있다. 여기서,

을 이용하면

으로 나타낼 수 있다.The Kalman gain k (n) can be calculated using the Kalman gain k (n)

And P < ^- > (n)

And p (n). Here, r corresponds to the covariance of the measurement error v (n). That is, the measurement update module 133 updates the prediction value

(N) and the measurement error,

, Which allows you to accurately

Can be calculated. here,

Using

.

는 축약시스템의 어드미턴스에 대응하므로, 이를 활용하여 전기기기가 연계되는 대상지점의 축약 계통을 구성할 수 있다. 이때, 축약시스템의 어드미턴스 매트릭스는, 전기기기가 대상지점(A)에서 바라보는 전체 전력계통의 하모닉 임피던스를 반영하게 된다. 따라서, 이를 통하여 전력계통의 하모닉 임피던스를 계산하는 것이 가능하다. The admittance calculation module 134 may control to repeat the time update and the measurement update so that the admittance corresponding to the measurement result can be extracted. That is,

Corresponds to the admittance of the reduction system, so that it can be used to configure the reduction system of the target point to which the electric apparatus is connected. At this time, the admittance matrix of the reduction system reflects the harmonic impedance of the entire power system viewed from the target point (A) of the electric device. Hence, it is possible to calculate the harmonic impedance of the power system.

On the other hand, since the admittance extracted by the admittance calculation module 134 is presented in a matrix form, it can be applied to the power flow calculation to confirm its accuracy. 6 (a) is an actual admittance matrix of the reduction system, FIG. 6 (b) is an admittance matrix calculated by the admittance calculation module 134, and FIG. 6 (c) FIG. Referring to FIG. 6, it can be confirmed that the admittance matrix calculated by the admittance calculation module 134 has almost no error with the actual admittance matrix.

7 and 8 are flowcharts illustrating a harmonic impedance estimation method of a power system according to an embodiment of the present invention.

7 and 8, the harmonic impedance estimation method for a power system according to an embodiment of the present invention includes an abstraction system setting step (S10), a measurement result collection step (S20), and an operation step (S30) .

Hereinafter, a harmonic impedance estimation method by a harmonic impedance estimation apparatus according to an embodiment of the present invention will be described with reference to FIGS. 7 and 8. FIG.

In the reduction system setting step S10, the power system connected to the target point can be shortened based on the target point to set the reduction system. Here, the target point may be a point where the electric device is connected to the power system.

An abbreviation system is a set of abbreviated total power systems. When setting abbreviated systems, it is important to reduce the power system to a certain extent.

Harmonic impedances are influenced by the topology, so to get accurate results, you can choose a reduction system that is at least similar to the topology of the entire power system, at least over a predetermined similarity.

On the other hand, when there are a plurality of reduction systems having a predetermined degree of similarity or more, it is possible to select the reduction system having the smallest number of buses included in the reduction system. In other words, as the number of buses increases, the number of factors to be measured and calculated increases. Therefore, in order to minimize the number of buses, an abbreviation system having the least number of buses can be selected.

The reduction system setting step S10 may include setting a plurality of preliminary reduction systems by shrinking the power system and comparing the topology of the preliminary reduction system with the power system to obtain a preliminary reduction system Can be performed. Thereafter, the reduction system can be set up through the step of setting the preliminary reduction system having the smallest number of buses included in the extracted preliminary reduction system as the reduction system.

According to an embodiment, it may include a step of generating a preliminary reduction system by setting the number of buses included in the reduction system according to an input control signal. Thereafter, the topology of the preliminary reduction system is compared with the topology of the power system, and if the preliminary reduction system is equal to or greater than the predetermined degree of similarity, the preliminary reduction system may be set as the reduction system. However, if the degree of similarity is less than the predetermined degree of similarity, a control signal may be transmitted to increase the number of buses included in the reduction system to generate a preliminary reduction system to confirm the degree of similarity.

In addition, according to the embodiment, the bus line directly connected to the bus line including the target point is referred to as a first step, the bus lines directly connected to the first bus line in step 2, the bus lines directly connected to the second bus line in three steps, etc. It is also possible to set an abbreviated system by selecting an abbreviated system having at least n connected topologies.

In the measurement result collection step (S20), the measurement result of measuring the current and voltage of the busbars included in the reduction system can be collected. The harmonic impedance measuring device can receive the measurement results from the measuring equipment, and the measuring equipment can measure the current and voltage for each bus. At this time, the measuring instrument can transmit measurement results through wired and wireless communication.

In the calculating step S30, the admittance or impedance of the reduction system can be calculated using the collected measurement results. In the calculation step S30, a Kalman filter may be applied to remove the noise included in the measurement result, and then the admittance of the reduction system corresponding to the harmonic impedance may be calculated.

Specifically, the calculation step S30 may include a state equation setting step S31, a time updating step S32, a measurement updating step S33, an admittance calculating step S34, and the like as shown in FIG. 8 have.

In the state equation setting process S31, the state equation of the reduction system using the admittance as the state variable can be set to apply the Kalman filter. Specifically, the state equation can be set as follows.

Where y (n) is the true value and z (n) is the modeling function for the admittance change characteristics, where y (n) is the state variable and is the admittance of the reduction system, n is the measurement error, c is the bais function, and n is the nth sample of the measurement results transmitted by the measuring instrument.

Φ can be replaced with a unit matrix in a simple estimation or the like, and in the case of a generator having a high nonlinearity, a formula corresponding to the generator can be reflected. The state variable x (n) may be the admittance of the reduction system, where the basis function c may be the voltage of the measured busbars. In this case, y (n) may be the true value of the current of the bus. Depending on the embodiment, it is also possible to set the basis function c to a function c (t) with respect to time. That is, when the associated electric device is a nonlinear device such as a generator, the base function c is updated every moment, so that it can be calculated by setting c (t).

In the time update process S32, a time update may be performed to calculate a predicted value of the state variable for the nth measurement result using the state equation. The time update in the Kalman filter can calculate the predicted value of the state variable for the nth measurement result from the state variable value for the n-1th measurement result. In other words,

을 계산할 수 있다. 또한, 상태변수의 오차 공분산(error covariance)인 P(n)에 대하여도 예측값 P^-(n)을 계산할 수 있다. The predicted value of the state variable

Can be calculated. Also, the predicted value P ^- (n) can be calculated for the error covariance P (n) of the state variable.

In the measurement update process S33, a measurement update may be performed to correct the predicted value to the Kalman gain and update the corrected predicted value to the state variable value for the n-th measurement result. In other words,

및 P^-(n)을 이용하여,

및 p(n)을 업데이트할 수 있다. 여기서, r은 측정오차 ν(n)의 공분산에 해당한다. 측정 업데이트 과정(S33)에서는 예측값

에 칼만 게인 k(n)과 측정오차를 적용하는 방식으로

으로 업데이트할 수 있으며, 이를 통하여

을 정확하게 계산할 수 있다.The Kalman gain k (n) can be calculated using the Kalman gain k (n)

And P < ^- > (n)

And p (n). Here, r corresponds to the covariance of the measurement error v (n). In the measurement updating process (S33)

(N) and the measurement error by applying the Kalman gain k

Can be updated to

Can be calculated accurately.

는 축약시스템의 어드미턴스에 대응하므로, 이를 활용하여 전기기기가 연계되는 대상지점의 축약 계통을 구성할 수 있다. 이때, 축약시스템의 어드미턴스 매트릭스는, 전기기기가 대상지점(A)에서 바라보는 전체 전력계통의 하모닉 임피던스를 반영하게 된다. 따라서, 이를 통하여 전력계통의 하모닉 임피던스를 계산하는 것이 가능하다. In the admittance calculation process (S34), the time update process (S32) and the measurement update process (S33) are repeated to extract the admittance corresponding to the measurement result. That is,

Corresponds to the admittance of the reduction system, so that it can be used to configure the reduction system of the target point to which the electric apparatus is connected. At this time, the admittance matrix of the reduction system reflects the harmonic impedance of the entire power system viewed from the target point (A) of the electric device. Hence, it is possible to calculate the harmonic impedance of the power system.

The present invention described above can be embodied as computer-readable codes on a medium on which a program is recorded. The computer-readable medium may be a computer-executable program that is continuously stored or temporarily stored for execution or download. In addition, the medium may be a variety of recording means or storage means in the form of a combination of a single hardware or a plurality of hardware, but is not limited to a medium directly connected to a computer system, but may be dispersed on a network. Examples of the medium include a magnetic medium such as a hard disk, a floppy disk and a magnetic tape, an optical recording medium such as CD-ROM and DVD, a magneto-optical medium such as a floptical disk, And program instructions including ROM, RAM, flash memory, and the like. As another example of the medium, a recording medium or a storage medium managed by a site or a server that supplies or distributes an application store or various other software to distribute the application may be mentioned. Accordingly, the above description should not be construed in a limiting sense in all respects and should be considered illustrative. The scope of the present invention should be determined by rational interpretation of the appended claims, and all changes within the scope of equivalents of the present invention are included in the scope of the present invention.

The present invention is not limited to the above-described embodiments and the accompanying drawings. It will be apparent to those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

1: Power system 10: Measuring equipment
100: Harmonic impedance measuring apparatus 110: Abbreviation system setting unit
120: measurement result collecting unit 130:
131: State equation setting module 132: Time update module
133: Measurement update module 134: Admittance calculation module
S10: Abbreviation system setting step S20: Measurement result collecting step
S30: operation step S31: state equation setting process
S32: Type update process S33: Measurement update process
S34: Admittance calculation process

Claims (18)

An abridgement system setting step of abbreviating a power system connected to the target point on the basis of a target point to set an abbreviation system;
A measurement result collection step of measuring a current and a voltage of busbars included in the reduction system and collecting measurement results; And
And calculating an admittance or impedance of the reduction system using the collected measurement results. ≪ Desc / Clms Page number 19 >
The system of claim 1,
Wherein the topology of the power system is abbreviated and the topology of the power summation system is similar to the topology of the power system by more than a predetermined degree of similarity.
2. The method of claim 1,
Setting the preliminary reduction system by shortening the power system;
Comparing the preliminary reduction system with a topology of the power system to extract a preliminary reduction system having a degree of similarity equal to or greater than a predetermined degree of similarity; And
And setting a preliminary reduction system having the smallest number of buses included in the extracted preliminary reduction system as the reduction system.
2. The method of claim 1,
Setting a preliminary reduction system by setting the number of busbars included in the system in accordance with an input control signal;
Comparing the topology of the preliminary reduction system with the topology of the power system and setting the preliminary reduction system as the reduction system if the degree of similarity is greater than a predetermined degree of similarity; And
And increasing the number of busbars included in the preliminary reduction system by transmitting the control signal if the predefined similarity is less than the predefined similarity.
2. The method according to claim 1,
A method for measuring a harmonic impedance of a power system, comprising: applying a Kalman filter to remove noise included in the measurement result; and calculating the admittance.
6. The method according to claim 5,
A state equation setting step of setting a state equation of the reduction system using the admittance as a state variable, for application to the Kalman filter;
A time update step of calculating a predicted value of the state variable with respect to the nth measurement result from the state variable value of the (n-1) th measurement result using the state equation;
A measurement update process for correcting the predicted value to a Kalman gain and updating the corrected predicted value to a state variable value for an nth measurement result; And
And an admittance calculation process of repeating the time update process and the measurement update process to extract an admittance corresponding to the measurement result.
7. The method of claim 6,

(N) is a current value of an actual bus line, and z (n) is a measurement value of the admittance of the system. (N) is a measurement error, and c is a voltage vector at each bus line. A method for measuring a harmonic impedance of a power system, comprising:
7. The method of claim 6,

The predicted value of the state variable

, Wherein P (n) is an error covariance of the state variable and P ^- (n) is a predicted value of the error covariance.
7. The method of claim 6,

(N) by using the Kalman gain k (n) and the estimated value k

And P < ^- > (n)

And p (n). ≪ / RTI >
A computer-readable recording medium on which a program for executing the method according to any one of claims 1 to 9 is recorded.
An abbreviation system setting unit for abbreviating a power system connected to the target point on the basis of a target point to set an abbreviation system;
A measurement result collecting unit for collecting measurement results of current and voltage of busbars included in the reduction system; And
And an operation unit for calculating admittance or impedance of the reduction system using the collected measurement result. 2. The harmonic impedance measurement apparatus of claim 1, further comprising:
12. The apparatus of claim 11, wherein the reduced system setting unit
And sets the topology of the reduction system so that the topology of the reduction system resembles a predetermined similarity or more to the toroid of the power system.
12. The apparatus of claim 11, wherein the reduced system setting unit
And selects an abbreviation system having the least number of busbars included in the abbreviated system when the abbreviated abbreviated system has a plurality of abbreviated abbreviated systems.
12. The image processing apparatus according to claim 11,
And applying the Kalman filter to remove noise included in the measurement result and calculate the admittance.
15. The apparatus of claim 14, wherein the calculating unit
A state equation setting module for setting the state equation of the reduction system using the admittance as a state variable so as to be applied to the Kalman filter;
A time update module for calculating a predicted value of the state variable for the nth measurement result from the state variable value for the (n-1) th measurement result using the state equation;
A measurement update module for correcting the predicted value to a Kalman gain and performing a measurement update to update the corrected predicted value to a state variable value for an nth measurement result; And
And an admittance calculation module that controls the time update and measurement update to be repeated so as to extract an admittance corresponding to the measurement result.
16. The system of claim 15, wherein the state equation setting module

(N) is a current value of an actual bus line, and z (n) is a measurement value of the admittance of the system. (N) is a measurement error, and c is a voltage vector at each bus line.
16. The apparatus of claim 15, wherein the time update module

The predicted value of the state variable

, Wherein P (n) is an error covariance of the state variable and P ^- (n) is a predicted value of the error covariance.
16. The system of claim 15, wherein the measurement update module

(N) by using the Kalman gain k (n) and the estimated value k

And P < ^- > (n)

And p (n) of the harmonic impedance of the power system.

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