JP3347995B2 - Harmonic measurement device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a harmonic measuring device, and more particularly, to a harmonic measuring device capable of easily calculating and specifying a harmonic generation source.

[0002]

2. Description of the Related Art Japanese Unexamined Patent Publication No.
A method for identifying a source of harmonics in a phase three-wire circuit is described. This method is called a power flow method, and its search principle is that, as shown in FIG. 7, the current Ian and the voltage Vabn of the n-th harmonic to be measured are measured by the first harmonic analyzer and the n-th harmonic. The second harmonic current Icn and the voltage Vcbn are measured by the second harmonic analyzer, respectively.
From the measurement result, the active power of the harmonic Pn = Vabn · I
An · cos θn + Vcbn · Icn · cosφn is calculated, and if the active power Pn is a positive value, the first and second
It is specified that there is an n-th harmonic generation source on the power supply side from the harmonic analyzer of the above. If the active power Pn is a negative value, the first
And to specify that the n-th harmonic source is located on the load side of the second harmonic analyzer. Here, θn is a phase difference between the line voltage Vabn and the current Ian, and φn is a phase difference between the line voltage Vcbn and the current Icn.

[0003]

However, the power flow method described above is a good method that can easily search for a power generation source in a power system having a single harmonic generation source, but there are a plurality of harmonic generation sources. In such a case, the harmonics generated by the target customer and the harmonics generated by other customers are superimposed on the measured harmonics. It is difficult to identify the harmonic source.

For example, as shown in FIG. 8, an external customer 101 having a plurality of external customers, ie, an external customer 101 having an impedance Zan and a harmonic source Ian, and an external customer 102 having an impedance Zbn and a harmonic source Ibn. Is present, the harmonic current measured at the evaluation target customer 103 having the impedance Zcn and the harmonic generation source Icn is equal to the external customers 101 and 1
02 is affected by the absolute value of the harmonic current generated and its generation phase. The measured harmonic voltage is also superimposed on the harmonic voltage generated by the external customers 101 and 102. Therefore, the harmonic current and the harmonic voltage measured by the evaluation target customer 103 are significantly different from the true harmonic voltage and the harmonic current generated by the evaluation target customer 103.

As described above, in a power system having a large number of harmonic generation sources, the power flow method for determining the direction of the flow of the active power of the harmonics and searching for the generation source involves the harmonics actually measured. However, there is a problem in that it is not possible to take into account the fact that it is affected by other harmonic sources connected to the power system, and it is not possible to exactly evaluate the true harmonics to be measured.

In view of the above problems, the present invention separates the amount of harmonics of the customer to be evaluated from the amount of harmonics generated by other customers, and obtains the true amount of harmonics of the customer to be evaluated. It is intended to contribute to the harmonic management of the power distribution system and the like, and to clearly identify the harmonic generation source to contribute to the harmonic reduction suppression measure.

[0007]

In order to achieve the above object, the present invention employs the following means.

A detecting means for detecting a harmonic current flowing into and out of the harmonic generation source from the power system and a harmonic voltage of the harmonic generation source; calculating a harmonic current by calculating the detected harmonic current and the harmonic voltage; A measuring means for calculating a wave generation source, and a variable means for changing the detected harmonic current and harmonic voltage, wherein the measuring means varies the variable means. It is characterized in that a plurality of detected harmonic currents and harmonic voltages obtained are calculated to calculate a harmonic generation source.

Further, in the harmonic measuring device according to the present invention, the variable means inserts and removes an impedance in parallel with the harmonic generation source.

Further, in the harmonic measuring device according to claim 2, the impedance is low with respect to a harmonic of a harmonic order of the harmonic generation source, and high with respect to a fundamental wave of the power system. It is characterized by being.

Further, in the harmonic measuring device according to any one of claims 1 to 3, a harmonic of a harmonic order of the harmonic generating source is provided between the harmonic generating source and the power system. An impedance that is high with respect to the wave and low with respect to the fundamental wave of the power system is provided.

Further, in the harmonic measuring apparatus according to the first aspect, the variable means is configured to insert and remove the harmonic generating means in parallel with the harmonic generating source.

Further, in the harmonic measuring device according to the fifth aspect, the harmonic generating means is an active filter.

Further, a harmonic current flowing into and out of a harmonic generation source connected to the power system and a harmonic voltage of the harmonic generation source are detected, and the detected harmonic current and harmonic voltage are calculated. A first step of detecting the harmonic current and the harmonic voltage, and changing the harmonic current and the harmonic voltage, and A second step of detecting a harmonic current and a harmonic voltage, and calculating the harmonic current and the harmonic voltage detected in at least the first step and the second step, respectively. Is calculated.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS. 1, 2 and 3.

FIG. 1 is a block diagram showing a state in which a harmonic measuring device according to the present embodiment and second to fourth embodiments to be described later is applied to an object to be measured.

1 is a harmonic measurement device, 11 is a harmonic sensor unit for detecting a harmonic current or a harmonic voltage, and 12 is a true measurement object to be described later based on the detected harmonic current or the harmonic voltage. A harmonic measuring unit 13 for calculating a harmonic current and an impedance is detected by the harmonic sensor by adding or deleting a known circuit element such as an impedance or a harmonic generation source in parallel or in series with the measurement object. Harmonic variable section that changes harmonic current and harmonic voltage, 2 is a measurement object as an evaluation object customer having a harmonic current source consisting of a harmonic current source and an impedance to be evaluated, 3 is an evaluation object This is a power system to which a power supply source of a fundamental component other than the customer and other customers are connected.

Here, the true harmonic current and the harmonic voltage generated by the measurement target 2 itself vary the harmonic variable unit 13 and the harmonic current and the harmonic voltage before and after the variation are measured by the harmonic sensor. And calculated by the harmonic measurement unit 12 based on the respective detection results.

Next, in a state where a large number of customers having harmonic generation sources are connected to the power system, a method of calculating the true harmonic current and the harmonic voltage generated by the evaluation target customer itself will be described. This will be described with reference to FIGS.

FIG. 2A is a circuit diagram showing a state in which a customer to be evaluated and a large number of external customers are connected to the power system, and FIG. 2B is equivalent to the circuit diagram shown in FIG. FIG.

In these figures, reference numeral 10 denotes a customer to be evaluated having an impedance and a harmonic generation source;
Reference numerals 12 and 13 denote external consumers having respective impedance and harmonic generation sources, and reference numeral 14 denotes a plurality of external consumers 11.
External customers, representing ~ 13 as one equivalent external customer,
Ian is the harmonic current as the n-th harmonic generation source of the customer to be evaluated 10, Zan is the impedance of the customer to be evaluated 10 with respect to the n-th harmonic component, and Ibn is the n-th harmonic of the equivalent external customer 14. A harmonic current as a harmonic generation source, Zbn, is an equivalent impedance of the external elephant consumer 14 to the nth harmonic component.

As shown in FIGS. 2A and 2B,
The plurality of external customers 11 to 13 can be represented as one equivalent external customer 14 when the line impedance connecting the consumers is sufficiently smaller than the impedance of each customer. For example, when there are two external customers, the impedance and the n-th harmonic current of each external customer with respect to the n-th harmonic component are Zbn 'and Zb, respectively.
Assuming that n ″ and Ibn′Ibn ″, the impedance Zan and the n-th harmonic current Ibn of the equivalent external customer with respect to the n-th harmonic component are collectively expressed by the following equations.

Ibn = Ibn ′ + Ibn ″ Zbn = (Zbn ′ × Zbn ″) / (Zbn ′ + Zbn ″) FIG. 3 shows the true harmonic current of the customer to be evaluated 10 itself and the equivalent of the external customer 14. FIG. 3 is a circuit diagram for calculating a true harmonic current.

In this figure, 15 is a switch, Zsn
Is a switch 15 in parallel with the measurement object of the evaluation target customer 10
A known impedance provided so as to be added or removed by the above, Ix is a harmonic current flowing into and out of the measurement target of the evaluation target customer 10 and measured, and Vx is a evaluation target customer 10
Are the harmonic voltages measured between the measurement targets.

In order to calculate the true harmonic current and the harmonic voltage of the customer 10 to be evaluated, the circuit diagram shown in FIG. Zsn is provided so as to be added or removed.

First, in this circuit diagram, when the switch 15 is opened and the impedance Zsn is not connected to the measurement target, the measured value of the harmonic current Ix is expressed as Ix
o, and the measured value of the harmonic voltage Vx is Vxo,
The following equation is obtained.

Ixo = (Zb × Ibn−Zan × Ian) / (Zbn + Zan) (1) Vxo = {Zbn × Zan × (Ian + Idn)} / (Zbn + Zan) (2) Next, the switch 15 is closed to set the impedance Zsn. Is connected to the measurement target, the measured value of the harmonic current Ix is Ixs, and the measured value of the harmonic voltage Vx is Vxs.
Then, the following equation is obtained.

Ixs = {(1 / Zsn + 1 / Zan) × Ibn− (1 / Zdn) × Ian} / (1 / Zbn + 1 / Zan + 1 / Zsn) (3) Vxs = (Ian + Ibn) / (1 / Zbn + 1 / Zan + 1 / Zsn) (4) where the unknowns in the above equation are Ian, Ibn, Zan, Z
bn, there are four equations (1) to (4). Therefore, by solving the equations (1) to (4) simultaneously, the true , And the true harmonic current Ibn generated by the external consumer 14 can be calculated.

Although the calculation on the way is omitted, the harmonic current Ia
n and the harmonic current Ibn are obtained as follows.

Ian = (Vxo × Vxs / Zsn−Ixo × Ixs + Vxs × Ixo + Vxs × Ixo) / (Vxo−Vxs) Ibn = (Vxo × Ixs−Vxs × Ixo) / (Vxo−Vxs) According to the embodiment, as shown in FIG. 1 and FIG. 3, each time a known impedance Zsn is added or removed in parallel to the measurement target 2 as the harmonic variable unit 13, the harmonic sensor unit 11 performs Current Ixo, Ixs and harmonic harmonic voltage V
xo and Vxs are detected and calculated by the harmonic measurement unit 12 based on the detection results, whereby the evaluation target customer 1 is calculated.
The true harmonic current Ian generated by 0 and the true harmonic current Ibn generated by the external customer 14 can be obtained.

Next, a second embodiment of the present invention will be described with reference to FIG.

FIG. 4 is a circuit diagram for calculating the harmonic current of the customer 10 to be evaluated and the harmonic current of the external customer 14 according to the present embodiment.

This embodiment is different from the first embodiment in that
The known impedance Zsn for the nth harmonic is
The impedance is low with respect to the n-th harmonic (the n-th harmonic current is short-circuited), and the impedance is high with respect to the fundamental wave of the power system. ) The difference is that the filter is configured as a filter.

Other configurations are the same as those of the circuit diagram shown in FIG. 3 of the first embodiment. Also, a true harmonic current Ian generated by ten consumers to be evaluated and a true harmonic current Ian generated by an external customer 14 are generated. The principle of obtaining the higher harmonic current Ibn is also the same as that of the first embodiment, and the description is omitted.

In this embodiment, the use of the nth harmonic short-circuit (absorption) filter as the impedance Zsn prevents the flow of the fundamental wave component from the power system into the impedance Zsn. The loss to the components can be reduced.

Next, a third embodiment of the present invention will be described with reference to FIG.

FIG. 5 is a circuit diagram for measuring the harmonic current of the customer 10 to be evaluated according to the present embodiment.

This embodiment is different from the second embodiment in that
When measuring the harmonic current of the customer to be evaluated 10 itself, the n-th power supply is connected to the power system to which the customer to be evaluated 10 is connected.
The difference is that a second harmonic blocking (blocking) filter 16 is interposed.

Reference numeral 17 denotes the nth harmonic blocking (blocking).
A switch 18 for inserting and removing the filter 16 is a switch which is opened when the n-th harmonic blocking (blocking) filter 16 is inserted.

The other structure is the same as the circuit diagram of the second embodiment shown in FIG.

The true harmonic current Ia of the customer 10 to be evaluated
For the measurement of n, first, the switch 18 is opened, the switch 17 is closed, and the nth harmonic blocking (blocking) filter 16 is inserted. Next, the switch 15 is closed and the nth harmonic short circuit (absorption) filter Zsn is inserted, and the harmonic current Ix is measured.

According to the present embodiment, since the n-th harmonic blocking (blocking) filter 16 is interposed between the evaluation target customer 10 and the external customer 14, the evaluation target customer 10 and the external demand The nth harmonic component between the home 14 and the house 14 can be electrically separated, and the evaluation target customer 10
, The harmonic current from the external customer 14 does not flow in, and the harmonic current does not flow out from the evaluation target customer 10 to the external customer 14, so that the true harmonic current Ibn of the external customer must be calculated. However, the true harmonic current Ian of the customer to be evaluated can be directly measured from the detected harmonic current Ix.

As described above, according to this embodiment, the harmonic current Ian of the customer 10 to be evaluated can be easily obtained directly from the detected harmonic current Ix without performing any calculation.

Next, a fourth embodiment of the present invention will be described with reference to FIG.

FIG. 6 is a circuit diagram for calculating the harmonic current of the customer 10 to be evaluated and the harmonic current of the external customer 14 according to the present embodiment.

This embodiment is different from the first embodiment in that
The difference is that a harmonic injection source Isn is used as harmonic variable means instead of the known impedance Zsn for the nth harmonic.

The other configuration is the same as the circuit diagram shown in FIG. 3 of the first embodiment, and the description is omitted.

The true harmonic current Ian generated by the customer 10 to be evaluated and the true harmonic current Ibn generated by the external customer 14 are obtained as follows.

First, when the switch 15 is opened and the harmonic injection source Isn is not connected to the measurement target, the measured value of the harmonic current Ix is represented by Ixo and the harmonic voltage Vx
Let Vxo be the measured value of .times.

Ixo = (Zb × Ibn−Zan × Ian) / (Zbn + Zan) (5) Vxo = {Zbn × Zan × (Ian + Idn)} / (Zbn + Zan) (6) Next, the switch 15 is closed and harmonics Assuming that the measured value of the harmonic current Ix is Ixs and the measured value of the harmonic voltage Vx is Vxs in a state where the injection source Isn is connected to the measurement target, the following equation is obtained.

Ixs = {Ibn / Zan- (Ian + Ixs) / Zbn} / (1 / Zbn + 1 / Zan) (7) Vxs = (Ian + Ixs + Ibn) / (1 / Zbn + 1 / Zan +) (8) Are Ian, Ibn, Zan, Z
bn, by solving the equations (5) to (8) simultaneously, the true harmonic current Ian generated by the evaluation target customer 10 and the true harmonic current generated by the external customer 14 The current Ibn can be calculated.

As a result of the calculation, the harmonic current Ian and the harmonic current Ibn are obtained by the following equations.

Ian = (− Vxo × Ixs + Vxs × Ixo + Vxs × Ixo) / (Vxo−Vxs) −Isn Ibn = (Vxo × Ixs−Vxs × Ixo) / (Vxo−Vxs) As described above, according to the present embodiment. For example, as shown in FIG. 1 and FIG.
Is added or removed in parallel to the measurement target 2 by the harmonic sensor unit 11, the respective harmonic currents Ixo and Ixs and the harmonic harmonic voltages Vxo and Vx at that time.
s, and the harmonic measurement unit 12 calculates the true harmonic current Ian generated by the measurement target 2 of the evaluation target consumer 10 based on the detection result, and the external consumer 14
Can be obtained.

In this embodiment, by using an active filter for power as the harmonic injection source Isn, it can be used as a harmonic injection source for harmonic measurement and at the same time as a harmonic reduction device. it can.

As described above, according to the above embodiments,
It is possible to easily calculate the harmonic generation source of the evaluation customer, and to clearly identify the harmonic generation source of the evaluation target customer and the harmonic generation source of the external customer, so that a more accurate harmonic generation source can be obtained. Therefore, it is possible to implement high-safety operation of the power system by avoiding damage due to burnout and harmonics of the high-voltage capacitors provided in various parts of the power system.

[0056]

As described above, according to the present invention, the variable means is provided so that the harmonic current flowing into and out of the power system and the harmonic generation source to be measured and the harmonic voltage of the harmonic generation source are provided. , The harmonic current and the harmonic voltage that have been changed are detected, and the harmonic source is calculated based on the detected harmonic current and harmonic voltage. The source can be easily calculated. In addition, since the harmonic generation source of the customer to be evaluated and the harmonic generation source of the external customer or the like can be clearly specified, a more accurate harmonic reduction measure can be taken.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a state in which a harmonic measurement device according to each embodiment of the present invention is applied to a measurement target.

FIG. 2 is a circuit diagram showing a state in which a number of external customers other than an evaluation target customer are connected to a power system, and a circuit diagram equivalent thereto.

FIG. 3 is a circuit diagram for calculating a harmonic current of the customer to be evaluated and a harmonic current of an external customer according to the first embodiment of the present invention.

FIG. 4 is a circuit diagram for calculating a harmonic current of a customer to be evaluated and a harmonic current of an external customer according to a second embodiment of the present invention.

FIG. 5 is a circuit diagram for measuring a harmonic current of a customer to be evaluated according to a third embodiment of the present invention.

FIG. 6 is a circuit diagram for calculating a harmonic current of an evaluation target customer and a harmonic current of an external customer according to a fourth embodiment of the present invention.

FIG. 7 is a circuit diagram for specifying a harmonic generation source according to the related art.

FIG. 8 is a circuit diagram for explaining a problem of a method for specifying a harmonic generation source according to the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Harmonic measuring device 10 Customer to be evaluated 11 Harmonic sensor unit 12 Harmonic measurement unit 13 Harmonic variable unit 2 Measurement object 3 Power system 14 External customer 16 nth harmonic blocking (blocking) filter Ian Evaluation target demand Harmonic current source of house Zan Impedance of customer to be evaluated Ibn Harmonic current source of external customer Zbn Impedance of external customer Zsn nth harmonic short circuit (absorption) filter Isn Harmonic injection source

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Yoshiaki Matsui 1-1-1, Kokubuncho, Hitachi City, Ibaraki Pref. Hitachi, Ltd. Kokubu Plant (72) Inventor Shinichi Kumagi 1-1, Uchisaiwaicho, Chiyoda-ku, Tokyo No. 3 Inside Tokyo Electric Power Company (72) Inventor Tadao Hasumi 1-3-1 Uchisaiwaicho, Chiyoda-ku, Tokyo Inside Tokyo Electric Power Company (56) References JP-A-9-229981 (JP, A) (58) Survey Field (Int.Cl. ⁷ , DB name) G01R 29/00 G01R 23/20

Claims (7)

(57) [Claims] 1. A detecting means for detecting a harmonic current flowing into and out of a harmonic generation source from a power system and a harmonic voltage of the harmonic generation source, and calculating the detected harmonic current and harmonic voltage. And a measuring means for calculating a harmonic generation source by using the variable means for changing the detected harmonic current and harmonic voltage, wherein the measuring means varies the variable means. A plurality of detected harmonic currents and a plurality of detected harmonic currents, thereby calculating a harmonic generation source. 2. The harmonic measurement apparatus according to claim 1, wherein the variable means inserts and removes impedance in parallel with the harmonic generation source. 3. The impedance according to claim 2, wherein the impedance is low with respect to a harmonic of a harmonic order of the harmonic generation source and high with respect to a fundamental wave of the power system. Harmonic measurement device. 4. The method according to claim 1, wherein
In one claim, an impedance is provided between the harmonic generation source and the power system, the impedance being high with respect to the harmonic of the harmonic order of the harmonic generation source and low with respect to the fundamental wave of the power system. A harmonic measuring device, characterized in that: 5. The harmonic measurement device according to claim 1, wherein the variable means inserts and removes a harmonic generation means in parallel with the harmonic generation source. 6. The harmonic measuring device according to claim 5, wherein the harmonic generating means is an active filter. 7. A harmonic current flowing into and out of a harmonic source connected to a power system and a harmonic voltage of the harmonic source are detected, and the detected harmonic current and harmonic voltage are calculated. A first step of detecting the harmonic current and the harmonic voltage, wherein the harmonic current and the harmonic voltage are changed, and the changed harmonics are changed. A second step of detecting a wave current and a harmonic voltage, and at least calculating the harmonic current and the harmonic voltage detected in the first step and the second step, respectively, and calculating the harmonic generation source. Calculating the harmonics.