JP2012029425A - Harmonic current suppressor and energy saving system by harmonic current suppression - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a harmonic current suppressor and energy saving system by harmonic current suppression, capable of suppressing generation of a harmonic current by suppressing a harmonic current with a simple configuration capable of being installed at lower cost.SOLUTION: An energy saving system includes a transformer 6 attached to between power lines 5 provided between a power supply 3 and a load 4 on the primary side; a capacitor 8 that forms a parallel resonance circuit 7 resonating at a frequency of a power fundamental wave in a space relative to a winding 6b of the transformer 6 by being attached to the secondary side of the transformer 6.

Description

  The present invention provides a harmonic current suppression device and an energy saving system using harmonic current suppression.

  Conventionally, the input circuit of a general-purpose inverter is generally charged at the peak portion of the power supply voltage waveform because a large-capacity smoothing capacitor is connected after the diode rectifier circuit, thereby generating a harmonic component in the input current. . Particularly in the case of three-phase alternating current, harmonic currents of the fifth, seventh, eleventh, etc. appear greatly, and there is a problem that adverse effects such as malfunctions occur in various electric devices by superimposing these on the power source.

In addition, the flow of unnecessary harmonic current induces a decrease in capacitive impedance, an increase in inductive impedance, a resonance phenomenon between capacitive impedance and inductive impedance, etc., and an increase in copper loss due to the skin effect of the conductor. The problem of increased iron loss due to the magnetostriction phenomenon occurs.

The increase in copper loss and iron loss may be accompanied by abnormal overheating and abnormal noise, and the high-pressure fuse may be blown out. Therefore, various devices for suppressing the harmonic current have been invented and put into practical use.

  FIG. 6 is a diagram for explaining the configuration of a conventional harmonic current suppressing device 90. As shown in FIG. 6, the conventional harmonic current suppression device 90 is connected to a power line 93 that connects an AC power source 91 and a load 92, and is connected in series according to the size of the load 92. Further, passive filters 94p5, 94p7,... 94pn, which are made up of coils Lp5, Lp7,. The AC power supply 91 is a three-phase AC, and the harmonic current suppression device 90 is provided in each layer.

When the first-order harmonic current suppressing device 90 is properly used, harmonic components can be effectively consumed and absorbed by the resistors Rp5, Rp7,... Rpn of the respective passive filters 94p5, 94p7,. However, there is a problem that overheating may occur due to the influence of the impedance of the power supply 91 system side and the load 92 system, which may cause overheating and burning.

  Therefore, in Patent Document 1 (Japanese Patent Laid-Open No. 2004-254429) described below, a harmonic current suppressing device configured to flow a correction current using a PWM inverter is considered. Such a harmonic current suppressing device is generally called an active filter, and a current error can be compensated by the control system when the load state changes.

JP 2004-25442 A

However, the harmonic current suppressing device as in Patent Document 1 has a problem that its configuration is very complicated and requires a large device, so that it cannot be easily installed. By the way, the harmonic current is also generated in small-capacity AC-DC adapters and inverter devices, which may adversely affect the operation of peripheral devices. In particular, in a transformer placed in the power supply section, harmonic current generated in each section flows in a concentrated manner, causing a problem that energy is wasted as heat by causing iron loss and copper loss. However, they are often overlooked if they do not have a significant impact on the user's reach.

In addition, if the harmonic components superimposed on the power supply are left without being removed, a distorted current flows over a long period of time, causing a biased magnetization (biased magnetism) around the physical unbalance. May also occur. In other words, there may be a habit of long-term effects on each part of the power system. Such imbalance and wrinkles can cause electrical and physical vibrations that gradually increase, and it can be considered to increase the power consumption accordingly. In addition, since the harmonic current is higher in frequency than the fundamental wave by an order of magnitude, it is considered that the energy is large and the loss due to the harmonic component becomes a large loss.

  The present invention has been made in consideration of the above-mentioned matters, and its purpose is to prevent generation of unbalance due to harmonics by efficiently suppressing harmonic currents with a simple configuration that can be installed at a lower cost. It is an object of the present invention to provide a harmonic current suppressing device that can be suppressed and an energy saving system using harmonic current suppression.

  In order to solve the above-described problems, the first aspect of the present invention provides a transformer having a primary side attached between power lines between a power source and a load, and a secondary winding of the transformer by being attached to a secondary side of the transformer. And a capacitor that forms a parallel resonance circuit that resonates with the frequency of the power source fundamental wave between the two and a harmonic current suppressing device.

Since the capacitor forms a parallel resonance circuit (LC circuit) that resonates with the secondary winding of the transformer at the frequency of the power source fundamental wave, the signal frequency is f [Hz], and the secondary side of the transformer When the inductance viewed from L is H [H] and the capacitance of the capacitor is C [F], the combined impedance Z [Ω] shown in Equation (1) is obtained. Infinite. Therefore, a large current does not flow from the power supply that vibrates at the power supply frequency in this parallel resonance circuit, and energy that vibrates at the power supply frequency can be stored.
Z = 2πfL / (1- (2πf) ² LC) j Equation (1)

On the other hand, the impedance of the parallel resonant circuit is very small for harmonic components that fluctuate at 5 times, 7 times the frequency of the power supply frequency, and becomes a capacitive impedance. It is absorbed and can be reused. Since the parallel resonant circuit separated from the power supply circuit by the transformer is connected to the primary power supply circuit by electromagnetic coupling, it is less affected by changes in the capacitance of the power supply circuit and the load and is less affected by disturbance. It is a current suppression device.

The capacitance of the capacitor is preferably set so that the inductive reactance seen from the secondary side of the transformer and the capacitive reactance of the capacitor are substantially equal, the power frequency is f [Hz], and from the secondary side of the transformer When the seen inductance is L [H] and the capacitance of the capacitor is C [F], it is preferable to satisfy the following expression (2).
√LC = 1 / (2πf) Equation (2)

The transformer is preferably an insulating transformer that insulates the primary side from the secondary side, and the frequency characteristic is such that at least the fifth harmonic component having a high harmonic current ratio due to the inverter can flow efficiently. It is preferable that the seventh harmonic component, more preferably the eleventh order, and still more preferably the nineteenth harmonic component flow efficiently.

  When the transformer includes a winding number adjustment unit that can adjust the number of turns on the primary side or the secondary side (Claim 2), the parallel resonance is performed by the winding number adjustment unit according to the state on the load or power source side. The resonant frequency of the circuit can be adjusted to match the power supply frequency. In other words, it can flexibly cope with any power supply and load conditions.

  Note that the winding number adjusting unit is configured to connect one of switch circuits such as a relay to each tap of a transformer having a plurality of winding taps and selectively connect the other of these switch circuits. In this case, any tap connected to the selected switch circuit can be used by connecting only one of the switch circuits. Further, the winding number adjusting unit may perform tap switching by rotating a rotating unit like a slidac. In this case, the winding number adjusting unit may include a servo motor that rotates the rotating unit for adjusting the winding number.

  In the case where the capacitor includes a capacitance adjustment unit that can switch or adjust the capacitance (Claim 3), the parallel resonance circuit is adjusted according to the state of the load or the power supply side by adjusting the capacitance of the capacitor by the capacitance adjustment unit. Can be adjusted to match the power supply frequency. In other words, it can flexibly cope with any power supply and load conditions.

  In addition, it is conceivable that the capacitance adjusting unit is a unit in which a large number of capacitor elements are connected in parallel via a switch circuit such as a relay. In this case, any capacitor element can be connected in parallel by switching the switch circuit. As a whole, the capacitance of the capacitor can be the added value of the capacitance of each capacitor element. However, it is preferable that the capacitor is a variable-capacitance type capacitor in which the capacitance can be continuously changed by the rotation of the rotating portion because the capacitance can be adjusted continuously. In this case, the capacity adjustment unit preferably includes a servo motor that rotates a rotation unit that adjusts the capacitance.

The transformer includes a winding number adjustment unit that can adjust the number of turns on the primary side or the secondary side, and the capacitor includes a capacitance adjustment unit that enables switching or adjustment of the capacitance, while the current flowing through the power supply line And a control unit that measures the potential difference between the power supply lines and adjusts the number of turns of the transformer and the capacity of the capacitor in real time according to the state on the power supply side (Claim 4), In addition, since the parallel resonant circuit can be adjusted so as to resonate most efficiently in the power source fundamental wave and the maximum energy can be stored in the parallel resonant circuit, the maximum effect can always be obtained.

  2nd invention measures the magnitude | size and / or calorific value of the vibration which generate | occur | produces from the said harmonic current suppression apparatus, the wattmeter which measures the electric power which flows through a load and / or a transformer, and / or a transformer. Reduction by harmonic current suppression by obtaining time-dependent changes in the magnitude of vibration and / or the amount of heat generated based on the relationship between the sensor, the clock circuit for measuring time, and the measured value of the power meter and sensor and the time There is provided an energy saving system by suppressing harmonic current, characterized by having an arithmetic processing unit for obtaining an electric energy.

  According to the energy saving system based on the harmonic current suppression, the calculation processing unit obtains the reduced electric energy by the harmonic current control from the vibration with respect to the power consumption of the load and / or the temporal change of the heat generation amount. The effect obtained by demagnetizing by the wave current suppressing device and eliminating the imbalance can be confirmed numerically.

It is a figure which shows the structure of the energy saving system by the harmonic current suppression apparatus and harmonic current suppression which concern on embodiment of this invention. It is a figure which shows the harmonic current of the single phase alternating current suppressed by the said harmonic current suppression apparatus. It is a figure explaining each component of the said harmonic current. It is a figure which shows the harmonic current which can be reduced with the said harmonic current suppression apparatus. It is a figure explaining the measuring method of the energy-saving achievement rate by the energy-saving system by the said harmonic current suppression. It is a figure explaining the structure of the conventional harmonic current suppression apparatus.

  FIG. 1 is a diagram illustrating the configuration of a harmonic current suppressing device 1 and an energy saving system 2 using harmonic current suppression according to the first embodiment of the present invention. As shown in FIG. 1, the harmonic current suppressing device 1 of the present invention includes a transformer 6 whose primary side is attached between power lines 5 a and 5 b between a power source 3 and a load 4, and a secondary side of the transformer 6. And a control unit 9. The capacitor 8 forms a parallel resonance circuit 7 that resonates with the secondary winding 6 b of the transformer 6 according to the frequency of the power source fundamental wave.

10 is a control computer of the energy saving system 2, 11 is an arithmetic processing unit of the control computer 10, 12 is a clock circuit, 13 is a storage circuit, 14 is a sensor for measuring the magnitude of vibration of the load 4, and 15 is applied to the load 4 A voltmeter 16 for measuring the voltage V to be measured, and an ammeter 16 for measuring the current I flowing through the load 4. That is, the energy saving system 2 by harmonic current suppression of the present invention includes the harmonic current suppression device 1, the control computer 10, and the sensor 14 that measures the magnitude of vibration generated from the load 4.

The power source 3 is, for example, a single-phase AC power source, and applies a voltage of AC 100 V between a pair of power source lines 5 (5a, 5b). In this embodiment, an example in which the power source 3 is a single-phase AC power source is described for the sake of simplicity. However, when the power source 3 is a three-phase AC power source, each power source line 5 is connected to each other. The harmonic current suppressing device 1 is configured to be inserted.

The load 4 is an arbitrary one that can have various configurations. For example, the load 4 is an electric load using a device that generates a harmonic current, such as an inverter of an air conditioner.

The transformer 6 includes a primary winding 6a, a secondary winding 6b, and a winding number adjusting unit 6c that can adjust the secondary winding number 6b. In the present embodiment, the winding number adjusting unit 6c includes a plurality of switches 6c1 and 6c2 composed of relay circuits connected in parallel so that taps to be used among the taps of the secondary winding 6b can be selectively connected. , 6c3, 6c4. These switches 6c1, 6c2,... May use not only relay circuits but also circuit breakers and analog switches. Alternatively, a slidac may be used as the transformer 6, and in this case, the winding number adjusting unit 6 c includes a servo motor that enables the number of windings to be increased or decreased by turning.

The capacitor 8 is, for example, a plurality of capacitor elements 8a, 8b, 8c having different capacities, and relay circuits (switches) connected in parallel so that any one of these capacitor elements 8a, 8b, 8c can be connected. A capacity adjusting unit 8d including 8d1, 8d2, and 8d3 is provided. The capacities of the capacitor elements 8a, 8b, and 8c are preferably different from each other. For example, the capacity of the capacitor element 8b is half of the capacity of the capacitor element 8a, and the capacity of the capacitor element 8c is half of the capacity of the capacitor element 8b. Sometimes, the capacitance of the capacitor 8 can be adjusted in eight steps at equal intervals by switching the switches 8d1, 8d2,. These switches 8d1, 8d2,... May be circuit breakers or analog switches as well as relay circuits. Further, the capacitor 8 may be formed by a variable capacitor. In this case, the capacity adjusting unit 8d includes a servo motor that can change the capacity by rotating.

The control unit 9 is connected to the voltmeter 15 and the ammeter 16 to measure the power W and the phase θ consumed by the load 4, and uses the phase θ obtained by the power measurement unit 9a. The resonance adjusting unit 9b for adjusting the resonance frequency of the parallel resonance circuit 7 by the inductor and the capacitor 8 viewed from the secondary winding 6b side of the transformer 6 according to the fundamental wave of the power source 3, and the winding number adjusting unit 6c. And a drive circuit 9c for outputting a control signal to the capacity adjusting unit 8d. Therefore, the wattmeter of this embodiment includes the voltmeter 15, the ammeter 16, and the power measuring unit 9a.

  FIG. 2 is a diagram for explaining a harmonic current that flows when a single-phase alternating current is applied to a load 4 including an inverter. That is, when the rectifier circuit built in the inverter rectifies the AC voltage V to generate the DC voltage Vd, the current I flows only at the peak, and the current I containing a lot of harmonic components flows. Become.

  FIG. 3 is a diagram showing the harmonic current generated when full-wave rectification of the single-phase AC voltage V is compared with the fundamental wave. As shown in FIG. 3, in the single-phase AC rectifier circuit, the third, fifth, seventh, ninth, eleventh, and thirteenth harmonic currents I3, I5, I7, and I9 with respect to the amplitude of the fundamental wave I0. Since the amplitude of ... is as large as 86%, 66%, 44%, 24% ..., these harmonic components I3, I5 ... flow through each part, causing iron loss and copper loss to increase. Increases energy loss. Further, there is a concern that the current I containing a large amount of the harmonic currents I2, I5,...

FIG. 4 is a diagram showing an example of the harmonic current that is reduced by using the harmonic current suppressing device 1 of the present invention. That is, by attaching the harmonic current suppressing device 1 of the present invention, the harmonic currents I3, I5... Flow into the parallel resonant circuit 7 through the transformer 6, and most of them are absorbed by flowing into the capacitor 8. .

The control unit 9 measures the voltage V applied to the load 4 and the current I flowing through the load 4, so that the power measurement unit 9a confirms whether the phase θ of the current I with respect to the voltage V is advanced or delayed. Accordingly, the capacitance of the capacitor 8 is adjusted using the capacitance adjusting unit 8d, and the number of turns of the secondary tap 6b of the transformer 6 is adjusted using the winding number adjusting unit 6c according to the capacitance of the capacitor 8. By changing, the resonance frequency of the parallel resonance circuit 7 can be adjusted in accordance with the fundamental wave of the power source 3.

As described above, since the resonance frequency of the parallel resonance circuit 7 is adjusted in real time, the parallel resonance circuit 7 can always be used in the resonance state even when the state of the load 4 varies greatly. The parallel resonance circuit 7 can flow a current Ir that is adjusted while being suppressed at the resonance frequency. Therefore, since the parallel resonant circuit 7 has an infinite impedance with respect to the fundamental wave, there is no theoretical attenuation of the fundamental wave by the parallel resonant circuit 7.

On the other hand, since the impedance of the parallel resonant circuit 7 with respect to the harmonic currents I3, I5, I7... Higher than that of the fundamental wave becomes small and has a capacitive impedance, the harmonic currents I3, I5, I7 ... can be absorbed. Further, the harmonic currents I3, I5, I7... Absorbed by the capacitor 8 can be reused, and the current Ir adjusted to the resonance frequency can be supplied to the power supply 3 side.

  In FIG. 3, Ir3, Ir5, Ir7,... Represent the respective harmonic currents attenuated by being absorbed by the parallel resonance circuit 7, and Ir0 represents the harmonic currents I3, I5, I7,. Represents the fundamental current applied by the charge stored by.

  That is, the harmonic current suppression device 1 of the present invention reduces harmonic currents I3, I5, I7,... To prevent power imbalance, suppresses losses due to copper loss and iron loss, and generates energy loss. In addition to preventing, it is possible to achieve further energy saving by effectively using these harmonic currents I3, I5, I7... Energy.

  In addition, the effect produced by the suppression of the harmonic currents I3, I5, I7,... Also, the effects of the demagnetization of each part and the improvement of physical balance can be expected.

  The energy saving system 2 by suppressing the harmonic current is for verifying the achievement of energy saving by verifying the effect of the demagnetization by the harmonic currents I3, I5, I7.

  The control computer 10 shown in FIG. 1 measures the time measured by the clock circuit 12, the vibration displacement D of the load 4 measured by the sensor 14, and the wattmeter comprising the power measuring unit 9 a, the voltmeter 15 and the current 16. The total power W is recorded by the meter calculation processing unit 11 as log data L in the memory 13. The memory 13 has a capacity capable of recording several months to several years of log data L when the log data L is intermittently recorded at intervals of, for example, 30 minutes.

  By analyzing the log data L using the control computer 10 or an externally connected computer (not shown), the magnitude of the energy loss associated with the occurrence of imbalance from the relationship of the magnitude of the vibration displacement to the power consumption. Can be compared.

  FIG. 5 is a diagram showing the transition of power consumption W and vibration displacement D obtained by analyzing the log data L. FIG. D1 is a straight line showing the relationship between the power consumption W and the vibration displacement D based on the log data L recorded without attaching the harmonic current suppression device 1 when the harmonic current suppression device 1 is installed, and D2 is the harmonic current suppression device 1 A straight line indicating the relationship between the power consumption W and the vibration displacement D based on the log data L after operating for one year with the attached, points L1, L2,... Are used to derive the straight lines D1, D2 by linear approximation. Indicates log data.

As shown in FIG. 5, the relationship between the power consumption W and the vibration displacement D before the harmonic current suppressing device 1 is attached and after several months (one year in this example) has elapsed after the attachment. Thus, when performing the same power consumption, that is, in the same operating state, it is possible to compare the magnitude of the vibration generated by the demagnetization and imbalance, and apply the mass of the load 4 to this vibration displacement D. By calculating the amount of wasted energy, etc., the energy saving achievement rate can be derived.

Since the sensor 14 is a vibrometer in the above-described embodiment, the vibration displacement D of the load 4 is used, and the amount of wasted energy is shown based on the vibration displacement D. This is vibration acceleration. Or it may be the vibration speed. Similarly, when a temperature sensor is used as the sensor 14, it is possible to measure the amount of wasted energy using the amount of heat generated from the load 4. The sensor 14 may be attached not only to the load 4 but also to a transformer of the power source 3 or the like.

DESCRIPTION OF SYMBOLS 1 Harmonic current suppression apparatus 2 Energy saving system by harmonic current suppression 3 Power supply 4 Load 5 Power supply line 6 Transformer 6b Secondary side winding 6c Winding number adjustment part 7 Parallel resonance circuit 8 Capacitor 8d Capacity adjustment part 9 Control part 9a Power measurement Department (power meter)
11 arithmetic processing unit 12 clock circuit 14 sensor W power

Claims (5)

  Parallel resonance in which the primary side resonates with the frequency of the power source fundamental wave between the transformer attached between the power supply line between the power source and the load and the secondary winding of the transformer by being attached to the secondary side of the transformer A harmonic current suppressing device comprising a capacitor that forms a circuit.   The harmonic current suppression device according to claim 1, wherein the transformer includes a winding number adjustment unit that makes it possible to adjust the number of turns on the primary side or the secondary side.   The harmonic current suppression device according to claim 1 or 2, further comprising a capacitance adjusting unit that enables the capacitor to switch or adjust its capacitance.   The transformer includes a winding number adjusting unit that can adjust the number of turns on the primary side or the secondary side, and the capacitor includes a capacitance adjusting unit that can switch or adjust the capacity, while the current flowing in the power supply line 2. The harmonic current suppressing device according to claim 1, further comprising a control unit that measures a potential difference between the power supply lines and adjusts the number of turns of the transformer and the capacity of the capacitor in real time according to the state on the power supply side.   The harmonic current suppression device according to any one of claims 1 to 4, a power meter that measures power flowing in a load and / or a transformer, and a magnitude of vibration generated from the load and / or transformer. Sensor for measuring length and / or calorific value, clock circuit for measuring time, and magnitude of vibration with respect to power consumption and / or temporal change of calorific value based on relationship between measured value and time by power meter and sensor And an arithmetic processing unit for obtaining a reduced electric energy by suppressing the harmonic current, and an energy saving system by suppressing the harmonic current.

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