JP3723967B2 - Active filter control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an active filter control device, and more particularly to an active filter control device that compensates and reduces harmonic voltage distortion generated in a power system based on a harmonic component of a load current.
[0002]
[Prior art]
Generally, in power system load 2 is connected to electric power consumers in the system power source 1 as shown in FIG. 2, compensating the harmonic voltage distortion generated in the power system based on the harmonic components of the load current I _L -Active filter 3 (active filter) is installed as a countermeasure against harmonics to be reduced.
[0003]
The active filter 3 includes a control device and a high-frequency inverter (not shown), detects the load current I _L by the current transformer 4, and cancels out the harmonic current contained in the load current I _{L. C} is injected into the system bus 5 by the high-frequency inverter, and the inverter is driven by the control device.
[0004]
In the active filter 3, specifically, for the harmonic current contained in the load current I _L , the phase and amplitude of the harmonic components of different orders (eg, 5th, 7th, 11th, 13th, etc.) are Fourier transformed. Each is detected individually by series expansion. Then, a compensation current I _C having the same amplitude as each order harmonic component and a phase shifted by 180 ° is generated, the harmonic current is canceled by the compensation current I _C , and this harmonic current is applied to the system bus 5. I do not output.
[0005]
[Problems to be solved by the invention]
By the way, in recent years, a harmonic guideline for electric power consumers has been notified from the Ministry of International Trade and Industry, and an upper limit amount of harmonic current that can flow out to the system power supply 1 by the load 2 of the electric power consumer has been determined. As a result, there is no problem when the harmonic current generated in the load 2 of the power consumer is smaller than the upper limit of the harmonic guideline, but it is active when the above-described harmonic current is larger than the upper limit of the harmonic guideline. It is necessary to output the compensation current I _C from the filter 3 to reduce the harmonic current and suppress it within the upper limit of the harmonic guideline.
[0006]
At this time, the amount of compensation by the active filter 3 becomes a problem. That is, in the active filter 3, detects each order harmonic component contained within the load current I _L as described above, but so as to generate the compensation current I _C of the opposite phase at the same amplitude, the compensation A method is conceivable in which the amount is set with reference to the harmonic component of the order with the highest occurrence rate among the respective harmonic components.
[0007]
For example, when the generation rate of the fifth-order harmonic component is the highest, the required capacity in the active filter 3 is as follows. For example, when the generation amount of the fifth harmonic component is 200 kVA, but the upper limit amount of the harmonic guideline is 100 kVA, the compensation amount in the active filter 3 is determined from the generation amount of the harmonic component to the harmonic. Since it is an amount obtained by subtracting the upper limit amount of the guideline, it may be 100 kVA.
[0008]
Therefore, the target amount ratio of the compensation amount with respect to the generation amount of the harmonic component may be set to 0.5. The target amount ratio (0.5) of the compensation amount obtained in this way is also applied to each harmonic component other than the reference order, and the seventh and eleventh orders with the target amount ratio (0.5) described above. Each compensation amount of the 13th harmonic component may be set.
[0009]
For example, when the target amount ratio is set to 0.5 with the above-mentioned fifth-order harmonic component as a reference, the generation amounts of the seventh-order, eleventh-order, and thirteenth-order harmonic components are 160 kVA, 120 kVA, and 80 kVA, respectively. The 7th, 11th, and 13th order compensation amounts are 80 kVA, 60 kVA, and 40 kVA, respectively, according to the target amount ratio (0.5) based on the harmonic component of the reference order (5th order).
[0010]
However, for harmonic components other than the reference order, the target amount ratio of the compensation amount with respect to the generation amount of the harmonic component does not necessarily match the case of the harmonic component of the reference order. For example, even if the generation amounts of the 7th, 11th, and 13th harmonic components are 160 kVA, 120 kVA, and 80 kVA, respectively, the upper limit of the harmonic guideline is about the 7th, 11th, and 13th harmonic components. If 110 kVA, 95 kVA, and 80 kVA, respectively, the 7th-order, 11th-order, and 13th-order compensation amounts are 50 kVA, 25 kVA, and 0 kVA, respectively.
[0011]
Therefore, as the capacitance of the active filter 3, √100 ² +50 ² +25 ² +0 ² = 115 kVA is sufficient, but as described above, the compensation amounts of the 7th, 11th, and 13th orders are as follows. In the case of 80 kVA, 60 kVA, and 40 kVA, respectively, the capacity of the active filter 3 needs to be √100 ² +80 ² +60 ² +40 ² = 147 kVA, and a large-capacity active filter 3 must be installed. There was a problem.
[0012]
Therefore, the present invention has been proposed in view of the above problems, and an object thereof is to suppress the capacity of the active filter to a necessary minimum.
[0013]
[Means for Solving the Problems]
As a technical means for achieving the above object, the generation amount of harmonic components of different orders is detected from the harmonic current generated in the load connected to the system power supply via the system bus, and the respective harmonic components are detected. The harmonic component with the highest occurrence rate is used as a reference, and a predetermined mutual ratio is set for each harmonic component based on the harmonic component of the reference order. And the mutual ratio for each of the harmonic components, the compensation amount output from the active filter is the upper limit of the harmonic component regulated by the harmonic guidelines. It is characterized in that it matches the target amount subtracted from the amount.
[0014]
Specifically, the present invention is a harmonic detection circuit for detecting the generation amount of harmonic components of different orders by Fourier series expansion from harmonic current generated in a load connected to a system power supply via a system bus; and Based on the harmonic component of the highest occurrence rate among each harmonic component, set the target amount ratio for the generated amount of the harmonic component of the reference order based on the harmonic guideline, and other than the reference order A setting unit that sets a mutual ratio of a reference order to a target amount for each harmonic component for each harmonic component, and a target amount ratio for a harmonic component of a reference order that is output from the setting unit A first multiplier that multiplies the generation amount of each harmonic component output from the wave detection circuit, an averaging circuit that calculates an average amplitude value of each harmonic component from the output of the first multiplier, average A second multiplier that multiplies a mutual ratio of each harmonic component other than the reference order output from the setting device by an amplitude average value of the reference order harmonic component output from the control circuit; and the second multiplication A divider that divides the output of the divider by the average amplitude value of each harmonic component other than the reference order output from the averaging circuit, and a reference order other than the reference order output from the harmonic detection circuit to the output of the divider A third multiplier that multiplies the generation amount of each of the higher-order harmonic components, a compensation amount of the higher-order harmonic component output from the first multiplier, and a reference order other than the reference order output from the third multiplier And an adder for adding the compensation amount of each harmonic component.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described below with reference to FIG. In the following embodiment, a case where the present invention is applied to the active filter 3 of the power system shown in FIG. 2 will be described in detail, and the same parts are denoted by the same reference numerals, and redundant description will be omitted.
[0016]
The active filter 3 according to the embodiment shown in FIG. 1 has a circuit configuration as shown in FIG. The control device for the active filter 3 has different orders by the Fourier series expansion from the harmonic current generated in the load 2 connected to the system power supply 1 via the system bus 5, that is, the 5th, 7th, 11th, 13th. The harmonic detection circuits 11a to 11d that detect the generation amount of the next harmonic component, and the order with the highest occurrence rate among the respective harmonic components, for example, the fifth harmonic component, are the reference orders. A setting device 12a that sets a target amount ratio with respect to the generated amount of the fifth-order harmonic component and a mutual ratio with respect to the fifth-order target amount for the seventh-order, eleventh-order, and thirteenth-order harmonic components other than the fifth order. Setters 12b to 12d set for each harmonic component, and target values ratios for the fifth harmonic components output from the setter 12a are fifth and seventh outputs from the harmonic detection circuits 11a to 11d. Next, First multipliers 13a to 13d that multiply the generation amounts of the first and 13th harmonic components, and an averaging circuit that calculates an average amplitude value of each harmonic component from the outputs of the first multipliers 13a to 13d 14a-14d and the relative ratio of the seventh, eleventh, and thirteenth harmonic components output from the setting devices 12b-12d with the average amplitude value of the fifth harmonic component output from the averaging circuit 14a. The second multipliers 15b to 15d for multiplying the second multipliers 15b to 15d and the amplitude average values of the seventh, eleventh and thirteenth harmonic components output from the averaging circuits 14b to 14d. Dividers 16b to 16d that divide, and a third multiplier that multiplies the outputs of the dividers 16b to 16d by the generation amounts of seventh, eleventh, and thirteenth harmonic components output from the harmonic detection circuits 11b to 11d. 17b-17d and harmonic detection times An adder 18 that adds the compensation amount of the fifth-order harmonic component output from 11a and the compensation amounts of the seventh-order, eleventh-order, and thirteenth-order harmonic components output from the third multipliers 17b to 17d. It has.
[0017]
The required capacity of the active filter 3 of the present invention is as follows. For example, if the generation amount of the fifth harmonic component, which is the highest occurrence order among the respective harmonic components, is 200 kVA and the upper limit of the harmonic guideline is 100 kVA, the target amount of compensation current in the active filter 3 Is an amount obtained by subtracting the upper limit amount of the harmonic guideline from the amount of generation of harmonic components, and may be 100 kVA. Accordingly, the target amount ratio of the compensation current to the generation amount of the fifth harmonic component is set to 0.5. The target amount ratio (0.5) of this compensation current is set in the setting device 12a.
[0018]
In addition, the generation amounts of the 7th, 11th, and 13th harmonic components are 160 kVA, 120 kVA, and 80 kVA, respectively, and the upper limit amount of the harmonic guideline is 110 kVA for the 7th, 11th, and 13th harmonic components, respectively. In the case of 95 kVA and 80 kVA, the target amount of the compensation current in the active filter 3 is an amount obtained by subtracting the upper limit amount of the harmonic guideline from the amount of generation of harmonic components. The target amount of current is 50 kVA, 25 kVA, and 0 kVA, respectively, and the target amount ratio of the compensation current to the amount of harmonic components generated does not match that of the fifth-order harmonic component.
[0019]
Therefore, the mutual ratio of the seventh-order, eleventh-order, and thirteenth-order harmonic components to the target amount (100 kVA) of the fifth-order harmonic component is set in the setting devices 12b to 12d for each higher-order harmonic component. In other words, the mutual ratios of the 7th, 11th, and 13th orders are 0.5 (50 kVA / 100 kVA), 0.25 (25 kVA / 100 kVA), and 0 (0 kVA / 100 kVA) to the setting devices 12 b to 12 d. Set.
[0020]
The generation amounts (200 kVA, 160 kVA, 120 kVA, 80 kVA) of the fifth, seventh, eleventh, and thirteenth harmonic components detected by the harmonic detection circuits 11a to 11d The first multipliers 13a to 13d multiply the target amount ratio 0.5 with respect to the generated amount (200 kVA). The outputs (100 kVA, 80 kVA, 60 kVA, 40 kVA) of the first multipliers 13a to 13d are averaged by the averaging circuits 14a to 14d, and the output (100) of the averaging circuit 14a for the fifth harmonic component is obtained. The second multipliers 15b to 15d multiply the outputs of the setters 12b to 12d for the 7th, 11th, and 13th harmonic components, that is, 0.5, 0.25, and 0, respectively. Then, the outputs (0.5 × 100, 0.25 × 100, 0 × 100) of the second multipliers 15b to 15d are averaged for the above-mentioned 7th, 11th, and 13th harmonic components. Divide by the dividers 16b to 16d by the outputs (80, 60, 40) of the circuits 14b to 14d. The outputs (50/80, 25/60, 0/40) of the dividers 16b to 16d for the seventh, eleventh, and thirteenth harmonic components are set to the seventh, eleventh, and thirteenth harmonic components. The outputs (80 kVA, 60 kVA, 40 kVA) of the first multipliers 13b to 13d are multiplied by the third multipliers 17b to 17d. The adder 18 outputs the outputs (50 kVA, 25 kVA, 0 kVA) of the third multipliers 17b to 17d for the 7th, 11th, and 13th harmonic components and the output (100 kVA) for the 5th harmonic component. Add and output.
[0021]
As a result, the compensation amount for the fifth-order harmonic component is 100 kVA, and the compensation amount for the seventh-order harmonic component is 80 × (0.5 × 100) / 80 = 50 kVA, and the eleventh-order harmonic component. The compensation amount for is about 60 × (0.25 × 100) / 60 = 25 kVA, and the compensation amount for the 13th harmonic component is 40 × (0 × 100) / 40 = 0 kVA. In this way, the compensation amounts (100 kVA, 50 kVA, 25 kVA, 0 kVA) for the fifth, seventh, eleventh, and thirteenth harmonic components are the target amounts (100 kVA, 50 kVA, 25 kVA, 0 kVA).
[0022]
In the conventional apparatus, √100 ² +80 ² +60 ² +40 ² = 147 kVA is required as the capacity of the active filter 3, whereas in the present invention apparatus, √100 ² +50 ² +25 ² +0 ² = 115 kVA. .
[0023]
In the above-described embodiment, the case where the fifth-order harmonic component is used as a reference has been described. However, the present invention is not limited to this, and harmonics of other orders (7th, 11th, and 13th). When the generation rate of the wave component is the highest, it is possible to use the higher order harmonic component as a reference, and the fifth order harmonic component may be replaced with the higher order harmonic component to configure the circuit.
[0024]
【The invention's effect】
According to the present invention, even if the target amount ratio of the compensation current to the generation amount of each harmonic component other than the reference order does not necessarily match the case of the harmonic component of the reference order, The compensation amount of the active filter can be matched with the target amount based on the harmonic guideline, and it becomes easy to realize the active filter capacity to the minimum necessary, and a compact active filter can be provided.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a circuit configuration of an embodiment of the present invention attached to an active filter control circuit. FIG. 2 is a circuit block diagram showing a power system in which an active filter is installed.
1 System power supply 2 load
3 Active filter
5 System bus
11a-11d Harmonic detection circuit
12a-12d Setting device
13a-13d First multiplier
14a-14d Average circuit
15b-15d Second multiplier
16b-16d Divider
17b-17d Third multiplier 18 Adder

Claims (2)

From the harmonic current generated in the load connected to the system power supply via the system bus, the amount of generation of harmonic components of different orders is detected, and the harmonic component of the highest-order harmonic component among the respective harmonic components And a predetermined mutual ratio is set for each harmonic component based on the harmonic component of the reference order, and the generation amount of each harmonic component and the mutual ratio for each harmonic component The amount of compensation output from the active filter is equal to the target amount obtained by subtracting the upper limit amount of the harmonic component regulated by the harmonic guidelines from the generated amount of each of the higher harmonic components. An active filter control device. A harmonic detection circuit for detecting the generation amount of harmonic components of different orders by Fourier series expansion from the harmonic current generated in a load connected to the system power supply via the system bus; Based on harmonic components with high occurrence rate as a reference, based on the harmonic guideline, set the target amount ratio for the generation amount for the harmonic component of the reference order, and set the reference order for each harmonic component other than the reference order A setting unit that sets a mutual ratio to a target amount for each of the harmonic components, and a target amount ratio for a harmonic component of a reference order that is output from the setting unit is output from the harmonic detection circuit. A first multiplier that multiplies the generation amount of the second harmonic component, an averaging circuit that calculates an average amplitude value of each harmonic component from the output of the first multiplier, and an output from the averaging circuit. A second multiplier that multiplies the mutual ratio of each harmonic component other than the reference order output from the setter by an amplitude average value for the harmonic component of the reference order, and an average value of the output of the second multiplier A divider that divides by the average amplitude value of each harmonic component other than the reference order that is output from the control circuit, and each harmonic component other than the reference order that is output from the harmonic detection circuit to the output of the divider A third multiplier that multiplies the generation amount of the first harmonic, a compensation amount of the harmonic component of the reference order that is output from the first multiplier, and each harmonic component other than the reference order that is output from the third multiplier. An active filter control device comprising an adder for adding a compensation amount.

Images