JPH11230999A - Instrument for measuring harmonic characteristics - Google Patents

Abstract

PROBLEM TO BE SOLVED: To automatically collect the measured data of the voltage and current of a power system based on injection of each intermediate harmonic current once or repeatedly. SOLUTION: A measuring section 7 having a function for controlling injection at an injecting section 6 and a function for collecting the measured data of the voltage and current of a power system comprises means for determining selection between single time measurement and continuous measurement, means for sequentially varying the output current from the injecting section 6 once or repeatedly to each intermediate harmonic current depending on the selection between single time measurement and continuous measurement, means for injecting the output current into the power system by opening the injection gate at the injecting section 6 during stabilized period of output current, means for collecting the measured data of voltage and current during stabilized period, and means for interrupting the operation at the injecting section 6 upon occurrence of abnormality and performing a protective operation preferentially.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a measurement used for measuring harmonic characteristics by injecting an intermediate harmonic current having a frequency that is a non-integer multiple of the system fundamental frequency into a power system and measuring its harmonic characteristics. More specifically, the present invention relates to a measuring device for measuring harmonic characteristics, which injects an intermediate harmonic current into a power system and collects a measured current and a measured voltage of the power system based on the injection.

[0002]

2. Description of the Related Art Conventionally, in a power system, home electric appliances,
One of the important issues is to suppress harmonic currents generated from OA equipment, industrial equipment, etc., and to reduce voltage distortion in the system. Therefore, it is necessary to measure the momentary harmonic characteristics of the power system. There is.

[0003] The nth harmonic of the power system is a frequency n · fs which is an integral multiple of the frequency (system fundamental frequency) fs synchronized with the system fundamental wave, and is a typical fifth and seventh order high frequency. Are frequencies 5 · fs and 7 · fs.

In order to measure the characteristics (harmonic characteristics) of the power system with respect to these harmonics, the applicant of the present application has already invented a harmonic measurement method described below in Japanese Patent Application No. 8-31092. doing.

According to the harmonic measurement method of this application, a current having a frequency that is a non-integer multiple of the system fundamental frequency above and below the harmonic to be measured in the power system is injected into the power system as an intermediate harmonic current, and this injection is performed. The frequency of the measured current and measured voltage of the power system based on
Voltage is detected, admittance or impedance for the intermediate harmonic of the power system is determined based on the detection, and admittance or impedance of the power system for the harmonic to be measured is determined by interpolation from the admittance or impedance. Then, its harmonic characteristics are measured.

In the case of this measuring method, the current of the intermediate harmonics above and below the harmonic to be measured is a current of a non-integer multiple of the system fundamental frequency fs which is not originally present in the power system, and The admittance or impedance can be accurately determined without being affected by the harmonics existing in the system, and the results are used to determine the harmonic characteristics of the power system, such as the fifth and seventh harmonics, every moment. Can be accurately measured and grasped.

In order to measure the harmonic characteristics of one or more harmonics of the power system by performing the above-described measuring method, the applicant of the present application has filed a Japanese Patent Application No. 9-197809. Intermediate harmonic current sequentially (continuously)
A current injection device having an inverter configuration formed and injected into a power system has already been invented.

Further, the applicant of the present application has filed Japanese Patent Application No. 9-205
According to the application of No. 408, in an ungrounded system such as a distribution system, since it is not necessary to consider the zero-phase component, the current of each intermediate harmonic is set to a single-phase current, and the current of each intermediate harmonic is supplied to the power system. Measurement by single-phase injection has already been invented.

[0009]

When measuring the harmonic characteristics of the power system with respect to one or more harmonics by the previously described harmonic measurement method, the current of each intermediate harmonic is injected into the power system. In addition, it is necessary to collect and process data of measured current and measured voltage of the power system based on this injection, and it is desirable that such processing be automated and performed quickly.

The present invention relates to a measurement for harmonic measurement in which the injection of current of each intermediate harmonic and the collection of measured voltage and measured current data of a power system based on the injection are automatically performed by so-called sequential control. It is an object to provide a device.

At this time, injection and measurement of the transient fluctuation component when changing to the frequency of each intermediate harmonic are prevented,
Injection when an abnormality occurs on the device side and power system side is prohibited, giving priority to protection operation, improving performance and reliability, and performing one injection of the current of each intermediate harmonic from an arbitrary timing. The function can be improved by making it possible to select between repeated injection (continuous injection).

[0012]

In order to solve the above-mentioned problems, in the measuring apparatus for measuring harmonics of the present invention, the output frequency is variably set and the output current of the set frequency is set by opening and closing the injection gate. Injection part for current injection controlled to stop injection into and injection into the power system, a function to control the injection of this injection part, and a function to collect the measured current and voltage of the power system based on this injection The measurement unit is provided with a unit for sequentially injecting the current of each intermediate harmonic by a manual trigger and ending once in a single measurement, and sequentially injecting the current of each intermediate harmonic to the timing control. Therefore, means for judging selection of continuous measurement to be repeated and an injection signal for controlling the output frequency are formed and supplied to the injection section, and the output current is reduced by 1 according to one-time measurement and continuous measurement.
Means for sequentially or repeatedly changing the current of each intermediate harmonic, and an injection gate signal for instructing opening and closing of the injection gate is formed and supplied to the injection section, and the output current is converted to the current of each intermediate harmonic. Means for injecting the output current into the power system by opening the injection gate during a stable period until the injection signal changes to the next intermediate harmonic signal after the change, a measured current and a measured voltage of the power system during the stable period Means for collecting the data of the injection unit and means for forcibly stopping the injection of the injection unit when an abnormality occurs by giving an abnormality notification from the injection unit, detecting an abnormality in the power system, and giving priority to the protection operation. Are provided.

Therefore, the output frequency of the injection unit is measured once based on the injection signal supplied from the measurement unit to the injection unit.
The frequency of each intermediate harmonic is variably set once or repeatedly according to the continuous measurement, and the output current of the injection unit automatically changes once or repeatedly to the current of each intermediate harmonic.

By opening and closing the injection gate based on the injection gate signal supplied from the measurement unit to the injection unit, the injection unit does not inject during the transition period when the output frequency changes to the frequency of each intermediate harmonic. Only a stable current of each intermediate harmonic is injected once or repeatedly into the power system.

[0015] Data of the measured current and measured voltage of the power system based on the stable current injection of each intermediate harmonic without transient fluctuations is automatically collected in the measuring unit.

Further, when an abnormality occurs on the device side or the power system side, the protection operation is prioritized by the measurement unit, and the injection of the injection unit is forcibly stopped, so that unnecessary current injection into the power system is reliably prevented. In addition, protection of the apparatus from system abnormalities and the like is achieved.

When the single measurement is selected, the current of each intermediate harmonic is sequentially injected only once into the power system and automatically measured based on an arbitrary timing based on the manual trigger. By the timing control of the measuring unit, the current of each intermediate harmonic is repeatedly injected into the power system and continuously measured.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a single-line connection diagram in a case where measurement is provided at a distribution substation, and three-phase (3
The power system of (φ) is composed of an upper system 1 of 77 KV and a lower system 4 of 6.6 KV connected to the system 1 via a distribution transformer 3 of a substation 2, and the lower system 4 includes a plurality of feeders. Branch out to 4a, 4b, 4c,... And are drawn out from the substation 2 to supply power to each customer facility (load device).

The measuring device 5 for harmonic measurement provided in the substation 2 includes an injection unit 6 for current injection and a measuring unit 7.

The injection section 6 comprises a power single-phase inverter or the like whose output frequency is variably set by an injection signal described later, and opens and closes an injection gate (not shown) made up of an output-stage semiconductor switch or the like. Is controlled to inject the single-phase (1φ) output current of the set frequency into the power system and stop the injection. For example, a single-phase current of each intermediate harmonic of 210 V and 75 A is supplied to an in-house power transformer having a capacity of 20 to 50 KVA. 8
To sub-system 4 via.

The single-phase injection current is measured by a single-phase instrument current transformer 9 provided between the injection section 6 and the transformer 8, and the current and voltage of each phase of the lower system 4 are 3 The phase is measured by the instrument current transformer 10 and the instrument transformer 11.

The injection unit 6 monitors the current, voltage and the like at various points in the apparatus by computer processing and makes a self-diagnosis. If any abnormality occurs, the injection unit 6 outputs a signal to notify the abnormality to the measurement unit 7.

Next, as shown in FIG. 2, the measuring unit 7 connects an operating unit 13 such as a keyboard and a mouse, a display unit 14 such as a CRT, and a data storage unit 15 such as a hard disk device to a main body 12 of a computer. Formed at the injection part 6
The function of controlling the injection of current and the measured current of the current transformers 9 and 10,
It has a function of collecting data (measurement data) of the measurement voltage of the transformer 11.

The main body 12 is a control processing section 16 comprising a CPU or the like, a RAM forming a so-called work memory or the like.
17, an input / output interface section 18 for exchanging signals with the injection section 6, and an A / D conversion section 19 for converting a measurement current and a measurement voltage into digital measurement data.
6 is executed, and the following (i) is executed.
To (v).

(I) one measurement in which the sequential injection of the current of each intermediate harmonic is started by a manual trigger and is ended once;
Means for discriminating between selection of continuous measurement in which the sequential injection of current of each intermediate harmonic is repeated according to timing control

(Ii) An injection signal for controlling the output frequency is formed and supplied to the injection unit 6, and the output current of the injection unit 6 is changed once or repeatedly according to the selection of one time measurement or continuous measurement. Means for sequentially changing to current

(Iii) An injection gate signal for instructing opening and closing of the injection gate is formed and supplied to the injection unit 6, and after the output current of the injection unit 6 changes to the current of each intermediate harmonic, the injection signal is changed to the next harmonic. Means for injecting the output current into the power system by opening the injection gate during a stable period until the signal changes to an intermediate harmonic signal

(Iv) Means for collecting measured current and measured voltage data (measurement data) of the power system during the stable period.

(V) Means for forcibly stopping the injection of the injection unit 6 when an abnormality occurs and giving priority to the protection operation by an interruption process based on an abnormality notification from the injection unit 6 and detection of an abnormality in the power system.

Based on each of the above (i) to (v), the measuring section 7 operates as shown in the flowchart of FIG.
First, when the control processing unit 16 executes the measurement program based on power-on or the like, for example, the display unit 14 displays a selection screen for one-time measurement (manual measurement) and continuous measurement (automatic measurement).

[0031] Then, when both measured by mouse operation or the like of the operation unit 13 are selected alternatively, the selection determined in step S _1, upon selection of one measurement, the trigger manually operated this selection as, the process proceeds to the initial setting of step S _2.

In this initial setting, the injection unit 6 and the measuring unit 7 are initialized, and the injection frequency is initialized based on each intermediate harmonic set according to the mouse operation, keyboard operation, and the like of the operation unit 13.

Each intermediate harmonic is composed of 5 harmonics to be measured.
Assuming the next order and the seventh order, for example, the following is set.

That is, here, a plurality of intermediate harmonics are set above and below the harmonic to be measured, and measurement is performed.
For the fifth harmonic, the upper 5.375 order (n
= 5.375), 5.5th order (n = 5.5), 5.625
The next (n = 5.625) intermediate harmonic and the lower 4.62
5th order (n = 4.625), 4.5th order (n = 4.5),
An intermediate harmonic of the 4.375th order (n = 4.375) is set. Similarly, for the 7th harmonic, the upper harmonic of the seventh harmonic is set.
The 375th, 7.5th, and 7.625th order intermediate harmonics and the lower 6.625th, 6.5th, and 6.375th order intermediate harmonics are set, and a total of 12 (= 3 × The intermediate harmonic of 4) is set.

The harmonics to be measured and the upper and lower intermediate harmonics may of course be one by one. As the set number of the intermediate harmonics increases, the harmonics are increased by averaging or the like. Measurement accuracy of wave characteristics is improved.

Then, for example, the lowest frequency among the set intermediate harmonics is automatically initialized to the first injection frequency.

[0037] When the initial setting of Step S ₂ is finished, in order to immediately start the measurement, the process proceeds to step S _3, no abnormality in the apparatus by the step S _3, it is determined whether injection are ready .

At this time, the presence or absence of an abnormality on the device side is determined, for example, from the presence or absence of an abnormality notification signal from the injection unit 6 and the result of self-diagnosis (failure diagnosis) of the measurement unit 7 by the control processing unit 16.

[0039] Then, if no injection ready, in order to prevent an abnormal current injection, the process proceeds from step S ₃ to stop the process of step S ₄ is stopped (terminated).

On the other hand, if the injection preparation is completed, the flow shifts from step S ₃ to injection / measurement in step S ₅ , and the current of each intermediate harmonic is injected into the power system to collect measurement data.

[0041] Step S ₅ consists Step Q ₁ to Q _8, as shown in FIG. 4, by forming an inverter driving signal, for example the injection frequency PWM waveform step Q _1, input-output interface unit the signal as an injection signal 18 to the injection section 6.

The injection section 6 performs a switching operation according to the injection signal, and is controlled to a current output state at the injection frequency.

[0043] Furthermore, the output frequency of the injection unit 6 is pulled into the frequency of the injection signal, the injection unit 6 shifts to the stable period from the transient period of the output, for example, by the timer operation from the start of the supply of the injection signal to the step Q ₂ Then, the injection gate signal from the input / output interface unit 18 to the injection unit 6 is
For example, a low-level close command is reversed to a high-level open command.

The inversion of the injection gate signal causes the injection portion 6
Is inverted from closed to open, and the single-phase intermediate harmonic current of the injection section 6 is injected into the lower system 4 via the transformer 8.

At this time, the output current (single-phase injection current) of the injection section 6 is measured by the current transformer 9 for the instrument, and the current and voltage of each phase of the lower system 4 based on the current injection of the intermediate harmonic are measured. The current is measured by a current transformer 10 and an instrument transformer 11.

Further, the signals of the measured currents of the current transformers 9 and 10 and the signals of the measured voltage of the transformer 11 are A / D-converted.
The data is supplied to a conversion unit 19, and is converted into measurement data at an appropriate sampling period.

Then, at steps Q ₃ and Q ₄ , each measurement data of the required wavelength (set cycle) of the A / D converter 19 during the stable period is taken into the RAM 17 and temporarily stored.

[0048] With this uptake is complete, inverts the injection gate signal by injection gate block of Step Q ₅ from the open command to the closing command to stop the injection into the lower line 4 of the intermediate harmonic current to close the injection gate.

[0049] Then, the process proceeds to step Q _6, RAM1
Each measurement data taken in 7 is transferred to the data storage unit 15 and stored.

Next, step by Q _7, and determines whether or not the injection and measurement of all intermediate harmonics set has ended, Step Q ₈ Step Q ₇ If not completed
Then, the setting of the injection frequency is automatically changed to the frequency of the next intermediate harmonic.

[0051] Then, the injection signal returns to step Q ₁ is changed to the signal of the frequency of the intermediate harmonics of the following, variably controls the output current of the injection unit 6 in the middle harmonic current of the next.

Further, in steps Q ₂ to Q ₆ , each measurement data based on the injection of the current of the next intermediate harmonic is stored in the data storage unit 15.

[0053] Then, after changing the signal of the frequency of the injection signal further intermediate harmonics follows the step Q _7, Q _8, repeat the process from step S ₁ returns to step S _1.

Thereafter, by repeating the same operation and processing, the output frequency of the injection section 6 changes in order to the frequency of each intermediate harmonic, and the measurement data for the required wavelengths of all the intermediate harmonics is stored in the data storage section 15. Save and collect automatically.

At this time, due to the opening and closing of the injection gate, the collected measurement data of each intermediate harmonic does not include the data of the transition period until the output frequency of the injection section 6 changes to the next intermediate harmonic, and is stable. Only reliable data for the period.

Then, the output frequency of the injection section 6 changes to the frequency of the last intermediate harmonic, and when the measurement data for this intermediate harmonic is collected, one measurement for all the intermediate harmonics is completed. positive step Q ₇ (YE
Passing at S), the process proceeds from step S ₅ of FIG. 3 in step S _6.

[0057] Based on the determination of the selection of the step S _6,
Upon selection of one measurement, the process proceeds from step S ₆ to Step S _4, the stop process of Step S ₄ by turning off the injection signal injection unit 6 stops, the measurement is ended.

By the way, between the injection and measurement of step S _5, to give priority to protection operation, control processor 16 is in a state to accept preferentially abnormal interrupt (hardware interrupt).

Then, the injection section 6 and the measurement section 7 execute a self-diagnosis program together with this measurement program by interrupt processing or parallel processing, and if an abnormality occurs in the injection section 6, the injection section 6 sends the input / output interface section 18 The signal of the abnormality notification is supplied to the control processing unit 16 as an abnormality interrupt signal via the control unit 16. If an abnormality occurs in the measurement unit 7, the abnormality interruption is generated in the control processing unit 16 based on the detection of the abnormality.

A system monitoring unit (not shown) of the measuring device 5 monitors and detects abnormalities such as a short circuit at an injection point of the power system and an excessive or insufficient voltage using an overcurrent relay, an undervoltage relay, an overvoltage relay, or the like. Then, when an abnormality is detected, an abnormality notification signal (an abnormality interrupt signal) similar to the abnormality notification signal of the injection unit 6 is generated.
Through the input / output interface unit 18
To supply.

When an abnormal interrupt signal is generated,
The control processing unit 16 receives the abnormal interrupt preferentially, immediately interrupts the processing of steps Q _{1 to} Q _{8 being} executed, jumps to step S ₄ , forcibly stops the injection of the injection unit 6, and performs measurement. To end.

Therefore, even if an abnormal current is generated as an intermediate harmonic current due to an abnormality on the measuring device 5 side, this current is not injected into the electric power system and adversely affects customer equipment and the like of the electric power system. I will not give.

In addition, when an abnormality such as a short circuit accident occurs on the power system side, the injection section 6 does not become overloaded when trying to inject the current of the intermediate harmonic, and the safety of the measuring device 5 is also ensured. .

Next, when the continuous measurement selection, the process proceeds from step S ₁ of FIG. 3 in the initial setting of Step S _7, after performing the same initialization step S ₂ This step S _7, step S Move to ₈ .

[0065] The step S ₈ based on the start time and repeat period of the setting of the measurement, determines whether it has reached the injection timing of each one measurement (start timing).

[0066] Then, when it reaches the injection timing, the process proceeds to Step S ₃ executes the processing from step S _3, injected once as in the case of measuring, sequentially power system currents of each intermediate harmonics To perform the first injection and measurement.

Further, when step S ₆ is reached and continuous measurement is determined in step S _6, injection and measurement are automatically repeated until measurement stop is instructed by operating the keyboard or mouse of the operation unit 13. Therefore, step S
_{The flow} shifts to ₉ to determine whether or not a command to stop measurement has been issued.

[0068] Then, if it is not commanded stop the measurement, return back the injected frequency to the first frequency (frequency of the initial setting) from step S ₉ to step S _8, 2 nd injection of each intermediate harmonic, Perform measurement.

Thereafter, the flow returns from step S ₉ to step S ₈ until the stop of the measurement is instructed, and the injection and measurement of each intermediate harmonic are repeated.

[0070] When the stop of the measurement is instructed, shifts to injected from step S ₉ to step S _4, the measurement is ended.

[0071] Also in the continuous measurements, between the injection and measurement of step S _5, it controls processing unit 16 is abnormal interrupt state accepting preferentially, the protection operation is given priority.

Therefore, when the single measurement or the continuous measurement is selected, when the single measurement is selected, the current of each intermediate harmonic is sequentially injected at an arbitrary timing triggered by this selection operation, and the power system in the meantime is injected. Measurement data and measurement voltage data (measurement data) can be automatically collected.

When the continuous measurement is selected, the sequential injection of the current of each intermediate harmonic is repeated at a set cycle, and the data of the measured current and measured voltage of the power system during that period is automatically collected. it can.

Therefore, in any of the single measurement and the continuous measurement, injection and measurement of each intermediate harmonic in a wide frequency range can be efficiently performed in a short time by so-called sequential control.

At this time, after the output frequency of the injection section 6 changes to the frequency of each intermediate harmonic, the injection gate is opened, and the current of each intermediate harmonic is injected and measured. Since the gate is closed and the output frequency of the injection unit 6 changes to the frequency of the next intermediate harmonic, current is not injected during the transient period in which the frequency fluctuates, and erroneous measurement current and measurement voltage during that period are collected. Not even.

Therefore, the admittance or impedance of each intermediate harmonic of the power system can be accurately obtained based on each measurement data of the data storage unit 15 without injecting an abnormal current into the power system. Can be measured with high accuracy every moment.

[0077] Incidentally, for example, by increasing the capacity of the RAM 17, Step Q ₆ in FIG. 4 when provided between the step S ₆ step Q ₇ and 3, the injection of a series of harmonic current of each single measurement And collectively stored data up to that time, so that the processing time is further reduced and measurement can be performed more quickly.

Next, since one-time measurement or continuous measurement can be selected, an appropriate measurement can be performed according to the application and the like, and there is an advantage that the usability is excellent.

Furthermore, even if an abnormality that needs immediate attention occurs on either the device side or the power system side, the protection operation against the abnormality is prioritized, the injection of the intermediate harmonic current is immediately stopped, and the measurement is completed. Thus, safety and the like on the device side and the power system side are reliably achieved.

Incidentally, the current of each intermediate harmonic may be a three-phase current instead of a single-phase current. Further, the injection point of each intermediate harmonic current, the injection and measurement sequence, and the like are not limited to the embodiment.

[0081]

The present invention has the following effects. Based on the injection signal supplied from the measurement unit 7 to the injection unit 6, the output frequency of the injection unit 6 is set once or repeatedly set variably to the frequency of each intermediate harmonic according to the continuous measurement. The output current can be automatically changed to the current of each intermediate harmonic once or repeatedly.

The opening and closing of the injection gate based on the injection gate signal supplied from the measuring unit 7 to the injection unit 6 causes the injection unit 6 to inject during the transition period when the output frequency changes to the frequency of each intermediate harmonic. Without this, only the stable current of each intermediate harmonic can be sequentially and repeatedly injected into the power system once or repeatedly.

Then, the measurement unit 7 can automatically collect data of the measured current and measured voltage of the power system based on the stable current injection of each intermediate harmonic without transient fluctuation.

Further, when an abnormality occurs on the device side or the power system side, the protection operation is prioritized by the measuring unit 7 and the injection of the injection unit is forcibly stopped, so that abnormal current injection into the power system is reliably prevented. In addition, the device can be protected from system abnormalities.

When the one-time measurement is selected, the current of each intermediate harmonic can be sequentially injected only once into the power system with reference to an arbitrary timing based on the manual trigger.
When the continuous measurement is selected, the current of each intermediate harmonic can be repeatedly injected into the power system by the timing control of the measurement unit.

Therefore, in any of the single measurement and the continuous measurement, injection and measurement of each intermediate harmonic in a wide frequency range can be efficiently performed in a short time by so-called sequential control.

In addition, since one-time measurement or continuous measurement can be selected, appropriate measurement can be performed according to the application and the like, and there is an advantage that the functionality is excellent.

In addition, even if an abnormality which must be dealt with immediately takes precedence in the protection operation against the abnormality and occurs on either the device side or the power system side, the injection of the intermediate harmonic current is immediately stopped and the measurement is started. The process is completed, and safety and the like on the device side and the power system side can be reliably ensured.

Therefore, it is possible to provide a novel measuring device suitable for measuring the harmonic characteristics of the power system.

[Brief description of the drawings]

FIG. 1 is a single-line diagram of one embodiment of the present invention.

FIG. 2 is a detailed block diagram of a part of FIG. 1;

FIG. 3 is a flowchart for explaining the operation of FIG. 1;

FIG. 4 is a detailed flowchart of a part of FIG. 3;

[Explanation of symbols]

 4 Lower system 6 Injection unit 7 Measurement unit

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[Procedure amendment]

[Submission date] February 1, 1999

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0004

[Correction method] Change

[Correction contents]

[0004] In order to measure the characteristics of the power system (harmonic characteristics) with respect to these harmonics, the applicant of the present application has filed Japanese Patent Application No.
According to the application of Japanese Patent Application No. 8-310192 , a harmonic measurement method described below has already been invented.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Yasuhiro Fuwa 1 Higashi-Shinmachi, Higashi-ku, Nagoya-shi Inside Chubu Electric Power Company (72) Inventor Shoji Nishimura 47-47 Umezu-Takaune-cho, Ukyo-ku, Kyoto-shi Nissin Electric Co., Ltd. (72 Inventor Yoshifumi Minowa 47 Nishijin Electric Co., Ltd., 47 Umezu Takaune-cho, Ukyo-ku, Kyoto-shi (72) Inventor Ikusen Natsuta 47 Nippon Electric Co., Ltd., Umezu-Takaune-cho, Ukyo-ku, Kyoto-shi

Claims (1)

[Claims] An electric current having a frequency that is a non-integer multiple of a system fundamental frequency above and below one or a plurality of harmonics to be measured in an electric power system is respectively injected into an electric power system as an intermediate harmonic current, and power based on the injection is supplied. Detecting the current and voltage of each of the intermediate harmonics of the power system by analyzing the frequency of the measured current and measured voltage of the system, obtaining the admittance or impedance of each of the intermediate harmonics of the power system from the detected current and voltage; From the admittance or impedance for each intermediate harmonic, determine the admittance or impedance of the power system for each harmonic of the measurement object by interpolation calculation, and determine the harmonic characteristics of the power system upon harmonic measurement. A measuring device for measuring harmonic characteristics, which injects current of each intermediate harmonic and collects data of the measured current and the measured voltage. Te, opening of the injection gate with the output frequency is variably set,
An injection section for current injection controlled to inject an output current of a set frequency into the power system and stop injection when closed, a function of controlling injection of the injection section, and data of the measurement current and the measurement voltage are collected. A measuring unit having a function, wherein the measuring unit starts the sequential injection of the current of each of the intermediate harmonics by a manual trigger and finishes it once, and the measurement of the current of each of the intermediate harmonics Means for determining selection of continuous measurement in which sequential injection is repeated in accordance with timing control; forming an injection signal for controlling the output frequency, supplying the signal to the injection section, and performing the single measurement by the injection signal; Means for changing the output current once or repeatedly to the current of each of the intermediate harmonics in accordance with selection of continuous measurement; and forming an injection gate signal for instructing the injection gate to open and close, and After the output current has changed to the current of each of the intermediate harmonics, the injection gate is opened during the stable period until the injection signal changes to the signal of the next intermediate harmonic, and the output current is reduced. Means for injecting into the power system, means for collecting the measured current and measured voltage data of the power system during the stable period, and interrupt processing based on abnormality notification from the injection unit, power system abnormality detection, and the like, A means for forcibly stopping the injection of the injection section when an abnormality occurs and giving priority to the protection operation.