JP2006060923A - Voltage compensation system and voltage compensation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce an excessive or insufficient amount of voltage adjustment in a voltage compensation system and a voltage compensation device that compensates a variation in compensated voltage such as a system voltage by outputting a voltage by combining a plurality of inverters in series. <P>SOLUTION: The voltage compensation system selectively actuates the plurality of inverters 5 to 7 that the connected in series and generate AC voltages by using DC power accumulated in energy accumulation means 8 to 10, in accordance with the magnitude of a voltage V4 that is a difference between a system voltage V1 in a power system and a target output voltage Vs, and outputs an output voltage V3 that is obtained by adding a compensation voltage V2 generated by the selective actuation of the inverters to the system voltage V1. A time point is adjusted when the magnitude of the compensation voltage is changed to a direction where a substantial difference between the target output voltage Vs and the output voltage V3 becomes small. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a voltage compensation system and a voltage compensation apparatus that selectively start and stop a plurality of inverters connected in series to compensate for fluctuations in system voltage.

  For example, the system voltage of the power system temporarily decreases due to lightning or the like. For example, a precision device such as a factory malfunctions or is temporarily stopped, which may cause a bad effect such as a great damage on the production line. In order to prevent such damage, a voltage compensator is used when voltage fluctuations such as a temporary voltage drop of the power system are monitored to compensate for the voltage fluctuations.

  For example, as disclosed in Japanese Patent Laid-Open No. 2002-300725 (Patent Document 1), a conventional voltage compensator includes a power system voltage (hereinafter simply referred to as “system voltage”) and a voltage compensator. The target output voltage (hereinafter simply referred to as “target output voltage”) is compared, and multiple inverters are selected according to the difference voltage between the system voltage and the target output voltage (hereinafter referred to as “difference voltage”). It is configured to selectively start and stop, and to output an output voltage obtained by adding a compensation voltage generated by selectively starting and stopping the inverter to the system voltage.

  According to the method of selectively starting a plurality of inverters according to the magnitude of the difference voltage, in Japanese Patent Laid-Open Publication No. 2003-259542, the magnitude of each output voltage of three series-connected inverters determined by the charging voltage of the corresponding capacitor, respectively. Are set to 1 (1 gradation): 2 (2 gradations): 4 (4 gradations), respectively, and compensation voltages of 1 gradation to multiple gradations are set according to the magnitude of the difference voltage. Each inverter is selectively activated to generate.

Japanese Patent Laid-Open No. 2002-300725 (FIGS. 3-5 and description thereof)

  By the way, the fluctuation width of the system voltage, that is, the difference voltage is actually different and is not exactly a voltage of one gradation or a voltage of two gradations. Therefore, in a voltage compensation method or voltage compensation device that generates a voltage of one gradation to a plurality of gradations to compensate for fluctuations in the system voltage, the instantaneous value of the output voltage is about 1/2 of the maximum gradation voltage. Therefore, it is difficult to compensate for fluctuations in the system voltage without excess or deficiency. Therefore, in a voltage compensation system or a voltage compensator that selectively starts / stops inverters connected in series (here, “stop” means that the inverter outputs 0V equivalent) and compensates for fluctuations in the system voltage. It is preferable to suppress excessive or insufficient voltage compensation.

  The present invention has been made in view of the above-described circumstances, and a plurality of inverters connected in series that generate AC voltage using DC power stored in the energy storage means are compensated. The system is selectively started and stopped according to the magnitude of the difference between the system voltage, which is a voltage, and the target output voltage, and the compensation of the system voltage is compensated by the compensation voltage generated by the selective start and stop of this inverter. It is an object of the present invention to suppress excess or deficiency of voltage compensation in a voltage compensation method or voltage regulator.

The voltage adjustment method according to the present invention includes a plurality of inverters connected in series that generate AC voltage using DC power stored in an energy storage means, a system voltage that is a voltage to be compensated, and a target output. In a voltage compensation system that selectively starts and stops according to the magnitude of the voltage difference from the voltage, and outputs an output voltage obtained by adding a compensation voltage generated by the selective start and stop of the inverter to the system voltage. ,
The time point at which the magnitude of the compensation voltage changes is adjusted so that the substantial difference between the target output voltage and the output voltage becomes smaller.

  The voltage compensator according to the present invention includes a plurality of inverters connected in series that generate AC voltage using DC power stored in the energy storage means, and target output voltage output means that outputs a target output voltage. And selectively starting and stopping the plurality of inverters according to the magnitude of the difference between the system voltage, which is a voltage to be compensated, and the target output voltage, and selectively starting the inverters. In the voltage compensator that outputs the output voltage obtained by adding the compensation voltage generated by the stop to the system voltage, the inverter to be started is selected according to the voltage difference between the target output voltage and the system voltage Threshold setting means for setting a plurality of thresholds having different sizes as a reference to be used, and a direction in which a substantial difference between the target output voltage and the output voltage is reduced. It is provided with a with a threshold value adjustment means for adjusting.

  According to the present invention, a plurality of inverters connected in series that generate an AC voltage using DC power stored in an energy storage means is connected to a difference between a system voltage that is a voltage to be compensated and a target output voltage. In the voltage compensation system for selectively starting and stopping according to the magnitude of the voltage, and outputting an output voltage obtained by adding the compensation voltage generated by the selective starting and stopping of the inverter to the system voltage, the target output voltage Since the time when the magnitude of the compensation voltage changes in a direction in which the substantial difference between the output voltage and the output voltage decreases, a plurality of inverters connected in series are connected to a system voltage that is a voltage to be compensated. And the target output voltage is selectively started and stopped according to the magnitude of the voltage, and the compensation voltage generated by the selective start and stop of the inverter is the system voltage. There is an effect capable of suppressing excessive or insufficient voltage compensation in the voltage compensation scheme and voltage compensation device for outputting an output voltage obtained by adding.

  The present invention also includes a plurality of inverters connected in series for generating an AC voltage using DC power stored in the energy storage means, and a target output voltage output means for outputting the target output voltage. And selectively starting and stopping the plurality of inverters according to the magnitude of the voltage difference between the system voltage and the target output voltage, and outputs of the selectively started and stopped inverters In a voltage compensation device that compensates for fluctuations in the system with a compensation voltage having a magnitude corresponding to the voltage, the inverter to be started and stopped is selected according to the magnitude of the difference between the target output voltage and the system voltage A threshold setting means for setting a plurality of thresholds of different magnitudes as a reference to be used, and the threshold value is substantially equal to a difference voltage between the system voltage and the target output voltage and the compensation voltage. Since the difference is provided with a threshold value adjusting means for adjusting the direction becomes smaller, there is an effect capable of providing a specific voltage compensation device capable of suppressing the excess and deficiency of voltage compensation.

Embodiment 1 FIG.
Embodiment 1 of the present invention will be described below with reference to FIGS. FIG. 1 is a block diagram showing an example of a voltage compensation device. FIG. 2 is an explanatory diagram of the principle of voltage compensation. The power system grid voltage (hereinafter simply referred to as “system voltage”) and the target output voltage of the voltage compensation device (hereinafter simply referred to as “target output voltage”). The relationship between the voltage of the difference (hereinafter referred to as “difference voltage”) and the voltage generated by the voltage compensation device (hereinafter referred to as “compensation voltage”) is shown for a half-cycle period. The state before the adjustment is shown, and (b) shows the state after the compensation voltage is adjusted. FIG. 3 shows the relationship between the differential voltage, the target output voltage, and the output voltage of the voltage compensator (the voltage obtained by adding the compensation voltage to the system voltage), the state before adjusting the compensation voltage, and the compensation voltage. It is a figure shown about the period of 1 cycle comparing with the state after adjusting. FIG. 4 is a diagram for explaining the principle of voltage compensation when the difference voltage is larger than that in FIG. 2. FIG. 4 shows the relationship between the difference voltage and the compensation voltage over a half-cycle period. The state before adjusting the voltage is shown, and (b) shows the state after adjusting the compensation voltage. FIG. 5 shows the relationship among the differential voltage, the target output voltage, and the output voltage of the voltage compensation device by comparing the state before adjusting the compensation voltage with the state after adjusting the compensation voltage. It is a figure shown about this period. In addition, in each figure, the same code | symbol shows the same part.

  In FIG. 1, a voltage compensation device 100 connected in series between a system power supply 1 and a load 2 includes a system voltage detection means 3, an output voltage detection means 4, inverters 5 to 7, and energy storage means 8 to 10, voltage measuring means 11 to 13, threshold value setting means 14, threshold value adjusting means 15, target output voltage output means 16, and inverter combination setting means 17.

  The system power source 1 outputs, for example, an AC system voltage (system voltage to be compensated by the voltage compensator 100) V1, such as a commercial power source in a power system, a power source in a private power generation system, and a power source at a power selling site. It is a power supply.

  The load 2 is a general load to which so-called AC power is supplied, for example, a factory, a building, a medical institution, or the like.

  The voltage compensator 100 generates the compensation voltage V2 having a magnitude corresponding to the fluctuation range when the system voltage fluctuates due to, for example, a lightning strike, and outputs the compensation voltage V2 added to the system voltage V1. It is a device having a function of outputting a voltage V3 and compensating so that the input voltage of the load 2 does not fluctuate as much as possible.

  The system voltage detection means 3 is a means having a function of detecting the system voltage V1.

  The output voltage detection means 4 is a means having a function of detecting the output voltage V3 of the voltage compensator 100.

The inverters 5 to 7 are inverters connected in series with different output voltages. The output voltage V5 of the inverter 5, the output voltage V6 of the inverter 6, and the output voltage V7 of the inverter 7. (V5: V6: V7) is, for example, 1: 2: 4. That is, the relationship between the output voltages of the inverters 5 to 7 is 2 ^K (K = 0, 1, 2).

  Here, the output voltage of the inverter having the lowest output voltage is referred to as “one gradation” with one unit voltage. When the ratio of the output voltages V5, V6 and V7 of the inverters 5 to 7 is 1: 2: 4, the inverter 5 outputs a voltage of one gradation, and the inverter 6 has two gradations. The inverter 7 outputs four gradation voltages. Therefore, a voltage of 1 to 7 gradations can be output by a combination of starting the inverters 5 to 7. That is, when the inverter 5 is activated, a voltage of one gradation is output, when the inverter 6 is activated, a voltage of two gradations is output, and when the inverter 5 and the inverter 6 are activated, a gradation of three gradations is output. When the inverter 7 is activated, four gradation voltages are output. When the inverter 5 and the inverter 7 are activated, five gradation voltages are output. The inverter 6 and the inverter 7 When 6 is activated, a voltage of 6 gradations is output, and when all the inverters 5 to 7 are activated, a voltage of 7 gradations can be output. For example, when the voltage of one gradation is 40V, 40V, 80V, 120V, 160V, 200V, 240V, and 280V can be generated by the combination of starting the inverters 5-7.

  The energy storage means 8 to 10 are, for example, capacitors, storage batteries, etc., which are connected to the DC input terminals of the corresponding inverters 5 to 7 and serve as DC power sources for the corresponding inverters 5 to 7. It is. The output voltage of the inverters 5-7 depends on the DC output voltage of the corresponding energy storage means 8-10. For example, when the ratio of the output voltages V5, V6, V7 of the inverters 5-7 is 1: 2: 4, the ratio of the DC output voltages V8, V9, V10 of the energy storage means 8-10 is 1: 2: 4.

  The internal configuration of the energy storage means 8 to 10 is not shown, but see FIG. 3 in the above-mentioned Patent Document 1 as an example.

  The voltage measuring units 11 to 13 are units having a function of measuring the voltages of the corresponding energy storage units 8 to 10. That is, the voltage measuring means 11 measures the output voltage of the corresponding energy storage means 8, the voltage measuring means 12 measures the output voltage of the corresponding energy storage means 9, and the voltage measuring means 13 Then, the output voltage of the corresponding energy storage means 10 is measured. The outputs of these voltage measuring means 11 to 13 are used for monitoring the output voltage of the corresponding energy storage means and various controls.

The threshold setting means 14 is a difference voltage V4 between the system voltage V1 detected by the system voltage detection means 3 and the target output voltage Vs output from the target output voltage output means 16, that is, the difference voltage V4 (FIG. 2). And a plurality of sizes serving as an inverter selection criterion for selecting an inverter to be activated from the inverters 5 to 7 and an inverter activation criterion for activating the selected inverter. This means has a function of setting different threshold values. For example, when the ratio of the output voltages V5, V6, and V7 of the inverters 5 to 7 is 1: 2: 4, the voltage of 1 to 7 gradations is obtained depending on the combination of starting the inverters 5 to 7 as described above. Therefore, the first threshold value is applied to one gradation voltage and the second threshold value is applied to two gradation voltages corresponding to each of the 1 to 7 gradation voltages. The third threshold value is set for three gradation voltages, and the fourth to seventh threshold values are similarly set. The relationship between the magnitudes of the first to seventh thresholds is the same as the relationship between the magnitudes of the voltages of the first to seventh gradations. First threshold <second threshold <third threshold <fourth threshold < It is assumed that the fifth threshold <the sixth threshold <the seventh threshold.
For example, when the voltage of one gradation is 40V, the threshold value setting unit 14 uses, for example, 20V, 60V, 100V, 140V, 180V as the initial value of each threshold for each voltage of the first gradation to the seventh gradation. , 220V and 260V.

  The threshold adjuster 15 receives the output voltage V3 of the voltage regulator 100 from the output voltage detector 4, and the target value of the input effective value of the output voltage (hereinafter referred to as “output voltage effective value”). Means having a function of adjusting the initial threshold value to be increased or decreased according to the excess or deficiency with respect to the effective value obtained from the output voltage Vs (hereinafter referred to as “target effective value”). It is. Specifically, when the output voltage effective value is smaller than the target effective value and insufficient, the threshold is adjusted to a value smaller than the initial value by an amount corresponding to the degree, and the output voltage effective value is When the state is larger than the target effective value and excessive, the threshold value is adjusted to a value larger than the initial value by an amount corresponding to the degree.

  The target output voltage output means 16 has a function of generating a target output voltage Vs that is a target of the output voltage V3. For example, the target output voltage output means 16 has the same voltage waveform and the same frequency as the system voltage V1 in a steady state without voltage fluctuation. Output.

  The inverter combination setting means 17 is a combination of inverters to be activated among the inverters 5 to 7 when the differential voltage V4 generated when the system voltage V1 decreases exceeds the thresholds. It is a means which has a function which each sets the combination of the inverter which should be stopped among the said inverters 5-7 when it falls below a threshold value. Since the difference voltage V4 increases with the passage of time during the half cycle and decreases after the peak, the compensation voltage V2 increases in the process of increasing the difference voltage V4. As the difference voltage V4 decreases, the inverters 5 to 7 are selectively started and stopped so that the compensation voltage V2 decreases. A combination is set.

That is, specifically, the inverter combination setting unit 17 receives the system voltage V1 from the system voltage detection unit 3, the target output voltage Vs from the target output voltage output unit 16, and the first output from the threshold setting unit 14. To the seventh threshold value (however, when there are three inverters connected in series and the ratio of the output voltages V5, V6, V7 is 1: 2: 4), the inverter combination setting is obtained. Based on the half cycle period,
1. In the process of increasing the difference voltage V4,
(1) If the differential voltage V4 exceeds the first threshold value, the inverter 5 is selected and started (hereinafter, “selective start” is referred to as “selective start”);
(2) If the difference voltage V4 exceeds the second threshold value, the inverter 5 is selected and stopped (hereinafter referred to as “selection stop”) and the inverter 6 is selected. Start
(3) If the differential voltage V4 exceeds the third threshold value, the inverter 5 is selectively activated and the selective activation state of the inverter 6 is continued.
(4) If the difference voltage V4 exceeds the fourth threshold value, the inverter 7 is selectively activated,
Selectively stop the inverter 5 and the inverter 6,
(5) If the difference voltage V4 exceeds the fifth threshold, the inverter 5 is selectively activated and the selective activation state of the inverter 7 is continued.
(6) If the difference voltage V4 exceeds the sixth threshold value, the inverter 5 is selectively stopped, the inverter 6 is selectively activated, and the selective activation state of the inverter 7 is continued.
(7) If the difference voltage V4 exceeds the seventh threshold value, the inverter 5 is selectively activated and the inverter 6 and the inverter 7 are selectively activated.
2. In the process in which the differential voltage V4 decreases,
(1) If the difference voltage V4 is lower than the seventh threshold value from a state where it exceeds the seventh threshold value,
The inverter 5 is selected and stopped, and the selection start state of the inverter 6 and the inverter 7 is continued.
(2) Further, if the difference voltage V4 falls below the sixth threshold value, the inverter 6 is selectively stopped, the inverter 5 is selectively activated, and the selective activation state of the inverter 7 is continued.
(3) Further, if the difference voltage V4 falls below the fifth threshold value, the inverter 5 is selected and stopped, and the state of selective activation of the inverter 7 is continued.
(4) Further, when the difference voltage V4 falls below the fourth threshold value, the inverter 7 is selectively stopped and the inverter 5 and the inverter 6 are selectively activated.
(5) Further, if the difference voltage V4 falls below the third threshold value, the inverter 5 is selected and stopped, and the selective start state of the inverter 6 is continued.
(6) Further, if the difference voltage V4 falls below the second threshold value, the inverter 6 is selectively stopped and the inverter 5 is selectively activated.
(7) Further, when the difference voltage V4 falls below the first threshold value, the inverter 5 is selectively stopped.

  On the other hand, the threshold adjustment unit 15 compares the output voltage effective value with the target effective value and adjusts the magnitude of the threshold according to the degree of excess or deficiency of the output voltage effective value. Then, the timing of selective activation and selection stop of each of the inverters 5 to 7 by the inverter combination setting means 17 is different from the timing of selective activation and selection stop according to the initial setting threshold, and as a result, The time during which each of the gradation voltages (the voltages of the above-described 1 to 7 gradations (plural gradations)) is generated is adjusted to adjust the compensation voltage V2, and the output voltage effective value is set to the target value. It approaches the effective value. In other words, the difference between the output voltage effective value and the target effective value becomes smaller. In other words, excessive or insufficient compensation voltage is suppressed when the compensation voltage is changed by simply changing the number of gradations without adjusting the threshold as described above.

  Specifically, when the output voltage effective value is smaller than the target effective value and in an insufficient state, the threshold value is adjusted to a value smaller than its initial value. The timing at which the regulated voltage occurs is earlier than when the threshold value is the initial value, and the timing at which each gradation voltage disappears is later than when the threshold value is the initial value. The compensation voltage V2 increases accordingly, the output voltage effective value approaches the target effective value, the difference between the output voltage effective value and the target effective value decreases, and the compensation voltage is insufficient. Is suppressed.

  When the output voltage effective value is larger than the target effective value and is in an excessive state, the threshold value is adjusted to a value larger than its initial value, so that each gradation voltage is generated by the inverter combination setting means 17. The timing is delayed compared to the case where the threshold value is the initial value, the timing at which each gradation voltage disappears is earlier than the case where the threshold value is the initial value, and the time during which each gradation voltage is generated is shortened. Therefore, the compensation voltage V2 becomes smaller, the output voltage effective value approaches the target effective value, the difference between the output voltage effective value and the target effective value becomes smaller, and excessive compensation voltage is suppressed.

  That is, by adjusting the threshold value as described above, the effective value accuracy of the output voltage can be increased as compared with the case where the threshold value is not adjusted (that is, the difference between the output voltage effective value and the target effective value). Can be reduced) and excessive or insufficient compensation voltage can be suppressed. In other words, by adjusting the start and stop times of the inverters 5 to 7 as described above, the effective value accuracy of the output voltage is increased more accurately than when the start and stop times are not adjusted. It is possible to suppress the excess or deficiency of the compensation voltage. In other words, by adjusting the generation and extinction time points of each gradation voltage, the effective value accuracy of the output voltage can be increased more accurately than when the generation and extinction time points are not adjusted. Shortage can be suppressed. In other words, the compensation voltage V2 is adjusted by adjusting the time point when the magnitude of the compensation voltage V2 changes with the change in the magnitude of the difference voltage V4, compared with the case where the time point when the magnitude changes is not adjusted. The effective value accuracy of the output voltage can be increased, and the excess or deficiency of the compensation voltage can be suppressed.

  Next, as described above, by adjusting the threshold value, the time point at which the compensation voltage is generated or extinguished is adjusted, and the principle that the substantial magnitude (compensation range) of the compensation voltage V2 can be adjusted. This will be described with reference to FIGS.

  Here, when the output voltage effective value and the target effective value are the same, that is, when the area in the half cycle of the square of the output voltage V3 and the area in the half cycle of the square of the target output voltage Vs are the same. Qualitatively, it can be said that the average value of compensation voltage V2 (area in half cycle) and the average value of difference voltage V4 (area in half cycle) are the same. The principle description that can adjust the substantial magnitude (compensation range) of V2 will be described by relating the area of the compensation voltage V2 in the half cycle and the area of the difference voltage V4 in the half cycle.

  FIG. 2A shows the relationship between the differential voltage V4, the compensation voltage V2, and the threshold before adjusting the initial value of the threshold, and FIG. 2B shows the difference after adjusting the initial value of the threshold. The relationship among the voltage V4, the compensation voltage V2, and the threshold is shown. 2A and 2B, the horizontal axis represents time, the vertical axis represents voltage, and the case where the voltage of one gradation is 40 V is illustrated. Further, FIG. 2A illustrates a case where the initial value of each threshold value is set to the middle of the upper and lower gradation voltages. In FIG. 2B, the value after adjustment by the threshold value adjusting means 15 is illustrated. The case where each threshold value is 5 V lower than the initial value is illustrated according to the degree of shortage of the output voltage effective value with respect to the target effective value. Further, in both FIG. 2A and FIG. 2B, the case where the compensation voltage V2 is up to a voltage of two gradations is illustrated for the sake of simplicity.

  First, in FIG. 2A, as the system voltage V1 (see FIG. 1) decreases, the difference voltage V4 gradually increases with the passage of time from the time point 0, and the first voltage is reached at t1. When the threshold value (20V) is exceeded, a voltage of one gradation is generated. The one gradation voltage is generated because the inverter 5 (see FIG. 1) is activated as described above.

When the time further elapses and the difference voltage V4 further increases and exceeds the second threshold value (60V) at t2, a voltage of two gradations is generated. The two gradation voltages are generated because the inverter 5 is stopped and the inverter 6 (see FIG. 1) is started as described above.
When the time further elapses, the differential voltage V4 becomes a peak at π / 2, and then gradually decreases. At t3, the voltage drops below the second threshold value (60V), and the voltage of two gradations disappears. A gradation voltage is generated. The reason why the two gradation voltages disappear and the one gradation voltage is generated is that, as described above, the inverter 6 is stopped and the inverter 5 is started.

  Further, when time elapses and t4 is reached, the difference voltage V4 falls below the first threshold (20V), and the voltage of one gradation disappears. The voltage of one gradation disappears because the inverter 5 is stopped as described above.

  The one gradation voltage between t1 and t2, the two gradation voltage between t2 and t3, and the one gradation voltage between t1 and t2 between t3 and t4 are the compensation voltage V2. The decrease (difference voltage) of the system voltage V1 in the half cycle (0 to π) is compensated.

  Here, the sum S2 (S2 = S21 + S22 + S23 + S24) of the areas S21, S22, S23, and S24 of the region where the compensation voltage V2 exceeds the difference voltage V4, and the area S41 of the region where the difference voltage V4 exceeds the compensation voltage V2 When comparing the total S4 of S42, S43, S44, and S45 (S4 = S41 + S42 + S43 + S44 + S45), as can be seen from FIG. 2 (a), S2 <S4 and the state of insufficient compensation. In this state, the output voltage V3 (see FIG. 1) of the voltage compensation device 100 is generally lower than the target output voltage Vs indicated by the dotted line, as indicated by a dashed line in FIG. In such a state, the effective value (output voltage effective value) of the output voltage V3 is smaller than the effective value (target effective value) of the target output voltage Vs.

  When the output voltage effective value is smaller than the target effective value, as described above, the threshold value adjusting means 15 (see FIG. 1) sets the threshold value from its initial value, and the output voltage effective value becomes the target effective value. Adjust the direction closer to. This threshold adjustment is reflected at the time of voltage compensation in the next cycle, and as shown in FIG. 2B, the first threshold and the second threshold in the next cycle are the target of the output voltage effective value. In accordance with the degree of shortage with respect to the effective value, both are adjusted to small thresholds 15V and 55V, which are the same amount, for example, 5V lower than the initial value.

  Therefore, as shown in FIG. 2B, at time point t1-x1 earlier than t1, the difference voltage V4 exceeds the first threshold value 15V to generate a voltage of one gradation, and at time point t2- earlier than t2. At x2, the difference voltage V4 exceeds the second threshold 55V, and a two-gradation voltage is generated. Further, at a time point t3 + x3 later than t3, the difference voltage V4 falls below the second threshold 55V, the voltage of two gradations disappears and a voltage of one gradation is generated, and at time point t4 + x4 later than t4, the difference voltage V4 becomes lower. The voltage of one gradation disappears below the first threshold value 15V. That is, the compensation voltage V2 increases (suppresses compensation voltage shortage). As the compensation voltage V2 increases, the output voltage V3 of the voltage compensation device 100 increases, the output voltage effective value increases, and approaches the target effective value (the output voltage effective value and the target effective value). The difference is small).

  As a result, compared to the case of FIG. 2A before the threshold adjustment, the area S21, where the compensation voltage V2 exceeds the difference voltage V4 in the case of FIG. 2B after the threshold adjustment. S22, S23, S24 and their total area S2 are widened, while areas S41, S42, S44, S45 of the region where the differential voltage V4 exceeds the compensation voltage V2 and their total area S4 are narrowed, The total area S2 and the total area S4 are substantially the same, as can be seen from FIG. 2B, and are in an appropriate compensation state. In this state, the output voltage V3 of the voltage compensator 100 is substantially the same as the target output voltage Vs indicated by the dotted line as shown by a solid line in FIG. 3, and the output voltage effective value is also the target voltage. It is substantially the same as the effective value, and the effective value accuracy of the output voltage is higher than before the threshold adjustment.

  In this way, by adjusting the threshold value, the effective value accuracy of the output voltage can be made higher than when the threshold value is not adjusted (the state of FIG. 2A), and insufficient compensation by the compensation voltage can be suppressed. If the viewpoint is changed, the start and stop times of the inverters 5 to 7 are adjusted, and if the viewpoint is further changed, the generation and extinction times of the respective grayscale voltages are adjusted (t1 → t1-x1, t2 → t2-x2). , T3 → t3 + x3, t4 → t4 + x4), the effective value accuracy of the output voltage can be increased compared with the case where the relevant time point is not adjusted, and insufficient compensation due to the compensation voltage can be suppressed. Further, if the viewpoint is further changed, the time point at which the compensation voltage V2 changes with the change in the difference voltage V4 is adjusted (t1 → t1-x1, t2 → t2-x2, t3 → t3 + x3, t4 → t4 + x4). ), The substantial magnitude of the compensation voltage V2 changes compared to the case where the time when the magnitude changes is not adjusted, the effective value accuracy of the output voltage can be increased, and insufficient compensation due to the compensation voltage can be suppressed. .

  Next, a case where the threshold is adjusted to a value larger than the initial value will be described with reference to FIG.

  FIG. 4 illustrates a case where the peak value of the difference voltage V4 is larger than that of FIG.

  In FIG. 4A showing the state before adjusting the initial value of the threshold value, the difference voltage is reduced as the system voltage V1 (see FIG. 1) decreases, as in the case of FIG. V4 gradually increases with the passage of time from the time point 0, a voltage of one gradation is generated at the time t1 exceeding the first threshold (20V), and the voltage exceeds the second threshold (60V) at t2. Thus, a voltage of 2 gradations is generated, and a voltage of 3 gradations is generated exceeding the third threshold value (100 V) at t3.

  When the difference voltage V4 falls below the third threshold (100V) at t4 after the peak, the voltage of 3 gradations disappears to generate a voltage of 2 gradations, and the second threshold ( When the voltage falls below 60V), the voltage of 2 gradations disappears and a voltage of 1 gradation is generated. When the voltage falls below the first threshold (20V) at t6, the voltage of 1 gradation disappears.

  Here, the total area S2 of the region where the compensation voltage V2 exceeds the difference voltage V4 is compared with the area S4 of the region where the difference voltage V4 exceeds the compensation voltage V2, as shown in FIG. As can be seen, S2> S4, which is an overcompensated state. The output voltage V3 of the voltage compensator 100 in this state is in a state generally exceeding the target output voltage Vs indicated by the dotted line, as shown by a one-dot chain line in FIG. The effective value (output voltage effective value) of the output voltage V3 is larger than the effective value (target effective value) of the target output voltage Vs.

  When the output voltage effective value is larger than the target effective value, as described above, the threshold value adjusting means 15 (see FIG. 1) sets the threshold value from its initial value, and the output voltage effective value becomes the target effective value. Adjust the direction closer to. This threshold adjustment is reflected at the time of voltage compensation in the next cycle, and as shown in FIG. 4B, the first threshold, the second threshold, and the third threshold in the next cycle are the output voltage. In accordance with the degree of excess of the effective value with respect to the target effective value, all are adjusted to large threshold values 23V, 63V and 103V, which are increased by the same amount, for example, 3V from the initial value.

  Therefore, as shown in FIG. 4B, at time point t1 + x1 later than t1, a difference voltage V4 exceeds the first threshold value 23V and a voltage of one gradation is generated, and at time point t2 + x2 later than t2, the difference is generated. The voltage V4 exceeds the second threshold 63V to generate a two-gradation voltage, and at a time t3 + x3 later than t3, the difference voltage V4 exceeds the third threshold 103V to generate a three-gradation voltage. Further, at time t4-x4 earlier than t4, the difference voltage V4 falls below the third threshold 103V, the voltage of 3 gradations disappears and a voltage of 2 gradations is generated, and at time t5-x5 earlier than t5, The difference voltage V4 falls below the second threshold 63V, the voltage of two gradations disappears and a voltage of one gradation is generated, and at a time t6-x6 earlier than t6, the difference voltage V4 falls below the first threshold 23V. The voltage of one gradation disappears. That is, the compensation voltage V2 is reduced (excessive compensation voltage is suppressed). The output voltage V3 of the voltage compensator 100 is reduced by the amount of the compensation voltage V2, and the output voltage effective value is also reduced to approach the target effective value (the output voltage effective value and the target effective value The difference is small).

  As a result, the total area of the region where the compensation voltage V2 exceeds the difference voltage V4 is greater in the case of FIG. 4B after the threshold adjustment than in the case of FIG. 4A before the threshold adjustment. On the other hand, the total area S4 of the areas where the differential voltage V4 exceeds the compensation voltage V2 is widened, and the total area S2 and the total area S4 are shown in FIG. As will be understood from the above, it becomes almost the same, and the state of proper compensation is obtained. In this state, the output voltage V3 of the voltage compensator 100 is substantially the same as the target output voltage Vs indicated by the dotted line as shown by the solid line in FIG. 5, and the output voltage effective value is also the target voltage. It is substantially the same as the effective value, and the effective value accuracy of the output voltage is higher than before the threshold adjustment.

  Thus, by adjusting the threshold value, the effective value accuracy of the output voltage can be made higher than when the threshold value is not adjusted (the state in FIG. 4A), and excessive compensation due to the compensation voltage can be suppressed. If the viewpoint is changed, the start and stop times of the inverters 5 to 7 are adjusted, and if the viewpoint is further changed, the generation and extinction times of the gradation voltages are adjusted (t1 → t1 + x1, t2 → t2 + x2, t3 → t3 + x3). , T4 → t4-x4, t5 → t5-x5, t6 → t6-x6), the accuracy of the effective value of the output voltage can be increased compared with the case where the time is not adjusted, and the compensation voltage is excessively compensated. Can be suppressed. Further, if the viewpoint is further changed, the time point at which the compensation voltage V2 changes with the change in the difference voltage V4 is adjusted (t1 → t1 + x1, t2 → t2 + x2, t3 → t3 + x3, t4 → t4-x4, t5). → t5-x5, t6 → t6-x6), the substantial magnitude of the compensation voltage V2 changes compared to the case where the time when the magnitude changes is not adjusted, and the effective value accuracy of the output voltage is increased. And overcompensation due to the compensation voltage can be suppressed.

  When the voltage compensator 100 performs a compensation operation with the threshold value of the initial value due to the fluctuation of the system voltage V1 and the output voltage effective value is insufficient, the output voltage detection means 4 makes the output voltage effective value constant from the target effective value. When the threshold value adjusting means 15 detects that the output voltage value is insufficient, the threshold value adjusting means 15 subtracts the voltage corresponding to the shortage of the output voltage effective value from each threshold value to lower each threshold value and substantially increase the compensation voltage. As shown, the effective value of the output voltage V3 can be increased and adjusted in a direction approaching the effective value of the target output voltage Vs.

  When the output voltage effective value exceeds, the output voltage detection means 4 detects that the output voltage effective value exceeds a target output voltage effective value by a certain value or more, and the threshold adjustment means 15 exceeds the output voltage effective value. Each threshold value is increased by adding a voltage corresponding to minutes to each threshold value to substantially reduce the compensation voltage, and the effective value of the output voltage V3 approaches the effective value of the target output voltage Vs as shown in FIG. Decrease in the direction can be adjusted.

  In the first embodiment of the present invention, as described above, a plurality of the inverters 5 to 7 that convert and output the DC voltage stored in the energy storage means 8 to 10 into AC are connected in series. In the voltage compensator 100 that combines the inverters 5 to 7 and obtains a plurality of gradation voltages by the sum of the output voltages, threshold setting means 14 for setting thresholds corresponding to the plurality of gradation voltages, and a target output When the target output voltage output means 16 for generating a waveform and the voltage V4 of the difference between the voltage waveform generated by the target output voltage output means 16 and the system voltage V1 exceed the threshold set by the threshold setting means 14, When the voltage is changed to a combination with a voltage higher by one gradation and when the voltage falls below the threshold, the inverter combination setting means 17 changes to a combination with a voltage lower by one gradation and the output detected by the output voltage detection means 4. When the voltage V3 is compared with the target output voltage Vs of the target output voltage output means 16, and the effective value of the output voltage V3 is larger, the threshold value set by the threshold setting means 14 is changed to be higher and the output voltage V3 is set. In the case where the effective value is smaller, the threshold value adjusting means 15 for changing and setting the threshold value set by the threshold value setting means 14 lower is provided.

  In other words, in other words, as described above, a plurality of inverters 5 to 7 that are connected in series and convert the DC voltage stored in the energy storage means 8 to 10 into AC and output, and the target And a target output voltage output means 16 for generating an AC output waveform of the plurality of inverters 5 to 5 according to the difference between the target output voltage Vs of the target output voltage output generation means 16 and the system voltage V1. In the voltage compensator 100 that selectively starts and stops 7 and outputs a plurality of gradation voltages having different generation points according to the output voltage of the inverter that is selectively started and stopped to compensate for fluctuations in the system voltage A plurality of criteria for selecting the inverter to be started and stopped according to the difference between the target output voltage Vs of the target output voltage output means and the system voltage V1. Threshold setting means 14 for setting thresholds of different magnitudes, and the output voltage V3 compensated by the selective activation of the inverter and the threshold set in the threshold setting means 14 for the target output voltage output means 16 The voltage compensation device 100 includes a threshold adjustment unit 15 that changes according to a substantial difference such as an effective value from the target output voltage Vs. The threshold adjustment unit 15 is set by the threshold setting unit 14. The threshold value is changed to a high value when the output voltage after starting the inverter is substantially higher than the output voltage of the target output voltage output means 16 such as an effective value, and after the selective starting of the inverter When the output voltage V3 is substantially lower, such as when the effective value is lower than the output voltage of the target output voltage output means 16, the effective value of the output voltage V3 is changed to a lower value. The output voltage V3 is substantially brought close to the output voltage Vs of the target output voltage output means, such as being close to the effective value of the force voltage Vs, thereby suppressing the substantial excess or deficiency of the voltage compensation, and the effective value accuracy of the output voltage Vs. Can be improved.

  In other words, in other words, as described above, a plurality of inverters 5 to 7 connected in series that generate an AC voltage using the DC power stored in the energy storage means 8 to 10 are compensated. Is selectively activated and deactivated according to the magnitude of the voltage V4 which is the difference between the system voltage V1 and the target output voltage Vs, which is a target voltage to be compensated, and the compensation voltage V2 generated by the selective activation and deactivation of the inverter is obtained. In the voltage compensation method for outputting the output voltage V3 in addition to the system voltage V1, there is a substantial difference between the compensation voltage V2 due to the output of a plurality of gradation voltages at different generation points and the fluctuation width V4 of the system voltage V1. The generation point of the gradation voltage is adjusted in a decreasing direction.

  In other words, in other words, as described above, a plurality of inverters 5 to 7 connected in series that generate AC voltage using DC power stored in the energy storage means 8 to 10 are compensated. Is selectively activated and deactivated according to the magnitude of the voltage V4 which is the difference between the system voltage V1 and the target output voltage Vs, which is the target voltage to be compensated, and the compensation voltage V2 generated by the selective activation and deactivation of this inverter In the voltage compensation method of outputting the output voltage V3 obtained by adding the above to the system voltage V1, the difference between the compensation voltage V2 due to the output of a plurality of gradation voltages at different generation points and the fluctuation width V4 of the system voltage V1 becomes small. In the direction, the start time and the stop time of the selectively started inverters 5 to 7 are respectively adjusted.

  Therefore, as described above, in the voltage compensation method and the voltage compensation device that compensates for the fluctuation of the system voltage V1 by combining the plurality of inverters 5 to 7 in series and outputting the voltage, it is possible to suppress the excess or deficiency of the voltage compensation. . Further, the effective value accuracy of the output voltage V3 can be increased without increasing the number of inverters 5 to 7 connected in series to increase the gradation.

  However, if the number of inverters 5 to 7 connected in series is increased to increase the gradation, and the first embodiment of the present invention described above is applied, the effective value accuracy of the output voltage V3 can be further increased.

  In the first embodiment of the present invention described above, as illustrated in FIGS. 2 and 4, the output voltage effective value is set to the target effective value only by adjusting the threshold value once from the initial value. In the case where the fluctuation range of the system voltage is not constant, the threshold value is adjusted a plurality of times from the initial value, and the output voltage effective value is substantially equal to the target effective value. It may be the same.

  In the first embodiment of the present invention described above, the effective value of the output voltage is compared with the target effective value. When the output voltage effective value is smaller than or larger than the target effective value, both effective values are obtained. Although the case where the threshold value is adjusted in the direction in which the difference becomes smaller according to the difference in value has been described, when the output voltage effective value and the target effective value are the same, that is, in the half cycle of the square of the output voltage V3 When the area output voltage effective value and the area of the target output voltage Vs in the square half cycle are the same, qualitatively, the average value of the compensation voltage V2 (area in the half cycle) and the average value of the differential voltage V4 ( The average value of the compensation voltage V2 (area in the half cycle) and the average value of the differential voltage V4 (area in the half cycle) are compared. , The average value of the compensation voltage V2 is If smaller than the average value of voltage V4 and large, be threshold adjustment in a direction in which the difference becomes smaller in accordance with the difference between the average value can be suppressed excessive or insufficient compensation voltage. Similarly, it is possible to suppress the excess or deficiency of the compensation voltage even if the threshold value is adjusted in a direction in which the difference decreases according to the difference between the average value of the output voltage V3 and the average value of the target output voltage Vs. In addition, the difference decreases in accordance with the difference between the peak value of the compensation voltage V2 and the peak value of the differential voltage V4, or the difference between the peak value of the output voltage V3 and the peak value of the target output voltage Vs. Even if the threshold value is adjusted, excessive or insufficient compensation voltage can be suppressed. That is, it is possible to suppress the excess or deficiency of the compensation voltage by adjusting the time point when the magnitude of the compensation voltage changes in a direction in which the substantial difference between the target output voltage Vs and the output voltage V3 becomes smaller.

Embodiment 2. FIG.
In the above-described first embodiment of the present invention, as shown in FIGS. 2 and 4, the case where the respective threshold values are simultaneously adjusted by the same amount is exemplified. However, in the second embodiment of the present invention, each threshold value is individually The case where it adjusts is illustrated.

  That is, as shown in FIG. 6B, in the next cycle, only the second threshold value is made smaller than the initial value (see the second threshold value in FIG. 6A).

  FIG. 6 shows a case where the fluctuation range of the system voltage is slightly smaller and the peak value of the differential voltage V4 is smaller than that of FIG. In FIG. 6A, the sum S2 (S2 = S21 + S22 + S23 + S24) of the areas S21, S22, S23, and S24 of the region where the compensation voltage V2 exceeds the difference voltage V4, and the difference voltage V4 exceeds the compensation voltage V2. The difference between the total area S41, S42, S43, S44 and S45 of the region and S4 (S4 = S41 + S42 + S43 + S44 + S45) is smaller than in the case of FIGS. 2 and 4 described above. Even if not all of them are adjusted or one or a plurality of threshold values are individually adjusted, the same function as that of the first embodiment of the present invention can be provided.

  In FIG. 6, the same or corresponding parts as those in FIGS. 2 and 4 are given the same reference numerals. In the description of the second embodiment of the present invention, the characteristic points of the second embodiment of the present invention will be mainly described, and the same or corresponding parts as those of the first embodiment of the present invention will be described. Omitted.

Embodiment 3 FIG.
A third embodiment of the present invention will be described below with reference to FIGS. FIG. 7 shows an example in which the zero cross point between the positive period and the negative period of the output voltage V3 deviates from the zero cross point of the target output voltage Vs when the threshold adjustment amount is different before and after the zero cross point. FIG. 8 is a diagram showing an example of an error in the peak value of the output voltage V3 when the threshold value is adjusted without taking into consideration that the peak value error is not increased. FIG. 9 is a diagram showing the peak value of the output voltage V3 when the threshold value is adjusted. FIG. 10 is a diagram illustrating a case where the error becomes large and the peak value accuracy cannot be maintained, FIG. 10 is a diagram illustrating a case of the threshold adjustment period, and FIG. 11 is a diagram of the output voltage V3 when the threshold adjustment period illustrated in FIG. FIG. 12 is a diagram illustrating an example of the waveform of the compensation voltage V2 in the positive period and the negative period, FIG. 12 is a diagram illustrating the adjustable range of the threshold value so that the peak value accuracy can be maintained, and FIG. Illustrated threshold Is a diagram showing an example of a case to be not large error in the peak value of the output voltage V3 by applying an adjustable range so as to hold the peak value accuracy. In the figure, the same or corresponding parts as those in FIGS. 1 to 6 are denoted by the same reference numerals. In the description of the third embodiment of the present invention, the characteristic points of the third embodiment of the present invention will be mainly described, and the same or corresponding parts as those of the above-described first and second embodiments of the present invention will be described. I will omit the explanation.

  As described above, when the threshold value is adjusted, the zero cross point between the positive period and the negative period of the output voltage V3 may deviate from the zero cross point of the target output voltage Vs. In addition, the accuracy of the peak value of the output voltage V3 may not be maintained. Therefore, when the threshold value is adjusted as described above, the zero-cross point of the output voltage V3 is prevented from deviating from the zero-cross point (original correct zero-cross point) of the target output voltage Vs, It is also necessary to consider maintaining the accuracy of the peak value. Hereinafter, the reason why the zero cross point of the output voltage V3 is shifted and its countermeasure, and the reason why the accuracy of the peak value of the output voltage V3 cannot be maintained, and an example of the countermeasure will be described in order.

1. The reason why the zero cross point of the output voltage V3 is shifted and the countermeasures The fluctuation range of the system voltage V1 may increase or decrease in half cycle units. In this case, the target output voltage Vs and the output voltage V3 The difference in the effective value of may vary from half cycle to half cycle. In such a case, the threshold adjustment amount differs for each half cycle. In other words, the threshold adjustment amount is different before and after the zero cross point, and the peak value increases or decreases in half-cycle units especially when the decrease width of the system voltage V1 is large and the peak value of the system voltage is small. In such a case, the zero cross point of the output voltage V3 deviates from the zero cross point of the target output voltage Vs. That is, the zero cross point of the output voltage V3 deviates from the correct zero cross point.

  FIG. 7A shows the generation state of the compensation voltage V2 in the process in which the polarity of the system voltage V1 shifts from the negative period to the positive period via the zero cross point, as shown in FIG. 7A. In addition, in the negative period, the threshold value change occurs during the period in which the compensation voltage V2 is 0V, the first threshold value is adjusted from the initial value 20V to -25V, and the second threshold value is adjusted from the initial value 60V. -65V. In the positive period, the threshold value is not changed, the first threshold value is the initial value 20V, and the second threshold value is the initial value 60V. Therefore, the generation period of the compensation voltage V2 in the negative period is shorter than the generation period of the compensation voltage V2 in the positive period, and the time point of disappearance of one gradation voltage in the negative period and the zero cross point 0s of the target output voltage Vs. The magnitude relationship between the period tm between the period tm and the period tp between the generation point of the voltage of one gradation in the positive period and the zero cross point 0s of the target output voltage Vs is tm> tp.

  When the compensation voltage V2 in the negative period and the compensation voltage V2 in the positive period as shown in FIG. 7A are generated, the output voltage V3 obtained by adding the compensation voltage V2 to the system voltage V1 at the time of decrease is as shown in FIG. It becomes like b). Here, as shown in FIG. 7B, when the system voltage V1 at the time of the decrease is substantially considerably smaller than the compensation voltage V2, the zero-cross point 03 of the output voltage V3 disappears in the negative period of the output voltage V3. It is an intermediate point between the time point and the generation point of the output voltage V3 in the positive period. Therefore, the zero cross point 03 of the output voltage V3 is shifted from the zero cross point 0s (originally correct zero cross point) of the target output voltage Vs to the negative side by a period td. When the time period td is deviated, it is preferable that the period of the output voltage changes when the system voltage fluctuates even if the fluctuation of the system voltage is compensated, so that the time period td does not deviate.

  Therefore, in the third embodiment of the present invention, as illustrated in FIG. 10, each predetermined period T1 before and after the zero cross point 0s of the target output voltage Vs, for example, the target output voltage Vs is one gradation from the zero cross point 0s. A function that does not adjust the threshold is added to the threshold setting means 14 (see FIG. 1) during the period until the voltage reaches the minute voltage. Therefore, in both the negative period and the positive period, the threshold value is the same in each predetermined period T1 before and after the zero-cross point 0s of the target output voltage Vs.

  As long as the threshold value is the same in the predetermined period T1 in both the negative period and the positive period, as shown in FIG. 11A, the period tm with the zero cross point 0s in the negative period as a reference, The magnitude relationship with the period tp with respect to the zero cross point 0s in the period is tm = tp, and as shown in FIG. 11B, the zero cross point 03 of the output voltage V3 and the zero cross point 0s of the target output voltage Vs Becomes a simultaneous point, and the deviation td between the zero cross points 03 and 0s as shown in FIG.

2. Reason why the accuracy of the peak value of the output voltage V3 cannot be maintained and its countermeasure As described above, the selective activation of the inverters 5 to 7 allows the unit voltage to be one gradation to a plurality of gradations. When the compensation voltage V2 is generated and the output voltage V3 in which the fluctuation of the system voltage V1 is compensated by the compensation voltage V2 is output, the maximum value of the peak value error of the output voltage V3 with respect to the target output voltage Vs is In this method, the voltage is almost ½ of the voltage of one gradation. Here, when the threshold value is adjusted according to the magnitude of the effective value difference between the target output voltage Vs and the output voltage V3 of the previous cycle, the error of the peak value is a voltage of one gradation. Of the output voltage V3 may not be maintained.

  FIG. 8A shows the relationship between a certain difference voltage V4 and the compensation voltage V2 when the initial value of each threshold is not adjusted, and the output voltage V3 and the target output in such a relationship. The relationship with the voltage Vs is as shown in FIG. The peak value difference Pd between the output voltage V3 and the target output voltage Vs is about 18V, which corresponds to almost half of the voltage 40V of one gradation, as shown in FIG. 8B. .

  Here, when the effective value of the output voltage V3 in the previous cycle is smaller than the effective value of the target output voltage Vs, in order to increase the effective value of the output voltage V3 by the function of the threshold adjustment means 15 (see FIG. 1). As shown in FIG. 9A, for example, when each threshold value is lowered by 5V from the initial value, the difference voltage V4 exceeds the third threshold value 95V in the vicinity of the peak value. Therefore, a three-gradation voltage 120V is generated by the selective activation of the inverter. Therefore, as shown in FIG. 9B, the peak value of the output voltage V3 exceeds the peak value of the target output voltage Vs, and the difference Pd between the two peak values is the voltage of one gradation. It exceeds 1/2 and is about 22V. As described above, by adopting the threshold adjustment method, the difference Pd between the two peak values exceeds the maximum value in the case of the method without threshold adjustment, and the peak in the case of the method without threshold adjustment. In some cases, the accuracy of the key value cannot be maintained.

  Therefore, in the third embodiment of the present invention, as shown in FIG. 12, the range in which the threshold can be adjusted is considered. FIG. 12A shows an example in which the effective value of the output voltage V3 is smaller than the effective value of the target output voltage and the threshold value is lowered. FIG. 12B shows an example in which the effective value of the output voltage V3 is larger than the effective value of the target output voltage and the threshold value is increased.

  As shown in FIG. 12A, a threshold (such as a third threshold) having an initial value larger than the peak value of the differential voltage is adjusted within a range that does not become smaller than the peak value. Note that a threshold having an initial value larger than the peak value of the difference voltage may be left out of the adjustment as it is.

  As shown in FIG. 12B, the threshold value (first to third threshold values) whose initial value is smaller than the peak value of the differential voltage is adjusted within a range not larger than the peak value.

  FIG. 12 shows whether the effective value of the output voltage V3 is larger or smaller than the effective value of the target output voltage. However, a threshold whose initial value is always larger than the peak value of the differential voltage V4 is always peak. It is necessary not to be smaller than the peak value, and it is necessary to prevent a threshold having an initial value smaller than the peak value of the differential voltage V4 from becoming larger than the peak value.

  If the threshold is not adjusted in the predetermined period T2 in both the negative period and the positive period, as shown in FIG. 13A, the three gradations as shown in FIG. Since no voltage is generated, as shown in FIG. 13B, the peak value difference (Pd) does not exceed 1/2 of the voltage of one gradation, and the peak of the output voltage V3 is eliminated. The precision of the value can be maintained.

  Note that only the threshold adjustment is performed within a period excluding the predetermined period T1 including the zero cross point, and the adjustment range of the threshold may not be limited. Even in that case, there is an effect that the zero cross point is not shifted. Further, without restricting the period for performing threshold adjustment, a threshold having an initial value larger than the peak value of the difference voltage V4 is prevented from becoming smaller than the peak value, and is set to be smaller than the peak value of the difference voltage V4. The threshold value may be adjusted so that the threshold value having a small initial value does not become larger than the peak value. Even in this case, there is an effect that the accuracy of the peak value can be maintained.

  In the third embodiment of the present invention, the case where a function that does not perform threshold adjustment in both the predetermined periods T1 and T2 is added to the threshold setting unit 14, but the function is, for example, the threshold adjustment unit 15 Or the inverter combination setting means 17 or the like.

Embodiment 4 FIG.
The fourth embodiment of the present invention will be described below with reference to FIGS. FIG. 14 is a block diagram showing an example of a compensation voltage determination method of the voltage compensator, and FIG. 15 shows an example of a case where the zero cross at the output voltage V3 deviates from the zero cross point of the target output voltage Vs when the system voltage V1 decreases to 0V. FIG. 16 is a diagram illustrating an example in which the zero cross in the output voltage V3 is not shifted from the zero cross point of the target output voltage Vs even when the system voltage V1 is reduced to 0 V. FIG. 17 is an embodiment of the present invention. 6 is a diagram illustrating an example of a waveform of an output voltage V3 when the system voltage V1 is reduced to 0V when 4 is applied. In addition, in the figure, the same code | symbol is attached | subjected to the same or equivalent part as above-mentioned FIGS. In the description of the fourth embodiment of the present invention, the characteristic points of the fourth embodiment of the present invention will be mainly described, and the same or corresponding parts as those of the first to third embodiments of the present invention will be described. I will omit the explanation.

  FIG. 14 is obtained by adding the 0V adjusting means 18 to FIG. 1 described above. This 0 V time adjusting means 18 detects that the system voltage V1 has decreased to 0 V as shown in FIG. 17 (that is, when the peak value is 0), Means for adjusting the threshold value;

  FIG. 15 (a) shows that the system voltage V1 in the process in which the original polarity in the presence of the system voltage V1 shifts from the negative period to the positive period through the zero-cross point decreases to 0V. The generation state of the compensation voltage V2 in the case of the jam is shown. As shown in FIG. 15A, in the original negative period, a threshold value change occurs within a period in which the compensation voltage V2 is 0V, and the first threshold value is adjusted from the initial value -20V to -25V. The second threshold is −65V adjusted from the initial value −60V. In the original positive period, the threshold value is not changed within the period in which the compensation voltage V2 is 0V, the first threshold value is the initial value 20V, and the second threshold value is the initial value 60V.

  Therefore, the generation period of the compensation voltage V2 in the original negative period is shorter than the generation period of the compensation voltage V2 in the original positive period, and the disappearance point of the voltage of one gradation and the target output voltage Vs in the original negative period. The magnitude relationship between the period tm between the zero-cross point 0s and the period tp between the generation point of one gradation voltage in the positive period and the zero-cross point 0s of the target output voltage Vs is tm> tp. Yes.

  When the compensation voltage V2 in the original negative period and the compensation voltage V2 in the original positive period as shown in FIG. 15 (a) are generated, the system voltage V1 remains 0V, so that the output voltage V3 is compensated. This is the same as the voltage V2, as shown in FIG. Here, as shown in FIG. 15B, since the system voltage V1 remains 0V, the zero-cross point 03 of the output voltage V3 corresponds to the disappearance point of the output voltage V3 in the original negative period and the original positive period. The output voltage V3 becomes an intermediate point from the generation time point. Therefore, the zero cross point 03 of the output voltage V3 is shifted from the zero cross point 0s (originally correct zero cross point) of the target output voltage Vs to the negative side by a period td. When the time period td is deviated, it is preferable that the period of the output voltage changes when the system voltage fluctuates even if the fluctuation of the system voltage is compensated, so that the time period td does not deviate.

  Therefore, in the fourth embodiment of the present invention, the zero crossing point 0s of the target output voltage Vs is detected by the 0V time adjusting means 18, and as shown in FIG. When the number of gradations of the original negative side and the original positive side is corrected from 0 to, for example, 1, the voltage of one gradation on the negative side disappears at the zero cross point 0s, and one gradation on the positive side Is generated. That is, the period tm and the period tp are tm = tp = 0. The number of gradations is changed during a period when the compensation voltage is −40V.

  When tm = tp = 0, as shown in FIG. 16B, the zero-cross point 03 of the output voltage V3 and the zero-cross point 0s of the target output voltage Vs become simultaneous points, and the above-described case shown in FIG. The shift dt between the zero cross points 03 and 0s as shown in FIG. The period of the 0V voltage in FIG. 16A is only the timing of the zero crossing of the output voltage V3, and the accuracy of the zero crossing of the output voltage V3 is improved even when the system voltage V1 is reduced to 0V. Incidentally, FIG. 17 shows an example of the output voltage V3 when the system voltage V1 is reduced to 0V when the fourth embodiment of the present invention is applied when the number of gradations is seven.

  Note that FIG. 16 illustrates the case where the compensation gradation is corrected from 0 to 1 (minimum gradation), but it is not always specified as 1 (minimum gradation), but 1 (minimum gradation) or more. If it correct | amends to, the precision of the zero crossing of the output voltage waveform V3 will improve.

Embodiment 5. FIG.
The fifth embodiment of the present invention will be described below with reference to FIG. FIG. 18 is a block diagram showing an example of a compensation voltage determination method of the voltage compensator. In FIG. 18, the same or corresponding parts as those in FIGS. 1 and 14 are denoted by the same reference numerals. In the description of the fifth embodiment of the present invention, the characteristic points of the fifth embodiment of the present invention will be mainly described, and the same or corresponding parts as those of the above-described first to fourth embodiments of the present invention will be described. I will omit the explanation.

  FIG. 18 is the same as FIG. 1 described above except that the uppermost voltage shortage adjusting means 19, the inverter 20, the uppermost energy storage means 21 such as a capacitor and a storage battery, the voltage measurement means 22, and the unit voltage calculation means 23. Is added.

  The uppermost voltage shortage adjusting means 19 has a function of correcting when the voltage of the uppermost energy storage means 21 is insufficient. Details of this function will be described later.

The inverter 20 is an inverter having an output voltage different from those of the inverters 5 to 7, and an output voltage V5 of the inverter 5, an output voltage V6 of the inverter 6, and an output voltage V7 of the inverter 7. The ratio (V5: V6: V7: V20) of the output voltage V20 of the inverter 20 is, for example, 1: 2: 4: 8. That is, the relationship between the output voltages of the inverters 5 to 7 and 20 is 2 ^K (K = 0, 1, 2, 3). Therefore, the inverter 20 outputs a voltage of 8 gradations. The ratio of the output voltages of the inverters, V5: V6: V7: V20, may be 1: 3: 9: 27 (that is, 3 ^K (K = 0, 1, 2, 3)). For convenience, the case of 1: 2: 4: 8 is mainly described. In the following explanation, the case of 1: 2: 4: 8 will be explained as a main subject.

  The uppermost energy storage means 21 is, for example, a capacitor, a storage battery, or the like, and is connected to a DC input terminal of the corresponding inverter 20 and serves as a DC power source for the corresponding inverter 20. As in the case of the first embodiment of the present invention described above, the output voltages of the inverters 5 to 7 and 20 depend on the DC output voltages of the corresponding energy storage means 8 to 10 and 21. For example, when the ratio of the output voltages V5, V6, V7, V20 of the inverters 5-7, 20 is 1: 2: 4: 8, the DC output voltages V8, V8, The ratio of V9, V10, V21 is 1: 2: 4: 8.

  The voltage measuring means 22 is a means having a function of measuring the voltage of the corresponding uppermost energy storage means 21.

  The unit voltage calculating means 23 is a means for inputting the outputs of the voltage measuring means 11 to 13 and calculating a voltage corresponding to one gradation from the outputs.

  Hereinafter, the function and effect of the characteristic portion in the fifth embodiment of the present invention will be described.

  As described above, the voltage of the highest energy storage means 21 is the highest so that the ratio of the voltage of the highest energy storage means 21 to the voltage of the lowest energy storage means 8 is 8: 1, for example. If the voltage of the lower energy storage means 8 is much larger than the voltage of the lower energy storage means 8, the time required for completion of charging (charging from the system power supply 1) is higher for the highest energy storage means 21 than for the lowest energy storage means 21. Compared with the means 8, it takes time. Therefore, when a sudden voltage drop occurs due to an instantaneous power failure or a lightning strike on the power supply line (power supply line from the system power supply 1 to the load 2) to which the voltage compensation device 100 is connected, the lowest-order energy storage unit 8 Although charging is completed, the uppermost energy storage means 21 may be in an incomplete charging state.

  In this way, the inverter 20 corresponding to the energy storage means 21 is activated in a state where the uppermost energy storage means 21 is incompletely charged (insufficiently charged), that is, a state where a predetermined voltage cannot be output as a DC power supply. Thus, when a voltage compensation operation is performed for fluctuations such as a decrease in the compensated voltage (voltage of the power supply line from the system power supply 1 to the load 2), desired voltage compensation cannot be achieved. Therefore, when voltage compensation is performed in a state where the uppermost energy storage unit 21 is not fully charged (insufficiently charged), that is, in a state where a predetermined voltage cannot be output as a DC power supply, a function for compensating for the insufficient voltage is added. It is preferable.

  In the compensation voltage determination method having the configuration illustrated in FIG. 18, the stored voltages of the corresponding energy storage units 8 to 10 and 21 are measured by the voltage measurement units 11 to 13 and 22, and the unit voltage calculation unit 23 performs the first floor. The voltage corresponding to the tone is calculated from the outputs of the voltage measuring means 11-13. Since the energy storage units 8 to 10 are charged at a voltage ratio of 1: 2: 4, the unit voltage calculation unit 23 divides the total value of the voltage measurement units 11 to 13 by 7, and the result is expressed as “unit”. "Voltage".

  The highest energy calculated based on the unit voltage obtained by the unit voltage calculating means 23 (for example, one gradation voltage obtained by dividing the total value of the voltage measuring means 11 to 13 by 7). The ideal voltage value V2123 ((the voltage of one gradation obtained by dividing the total value of the voltage measuring means 11 to 13) × 8) as the DC voltage source of the storage means 21 and the voltage measuring means 22 The difference Vd21 (hereinafter referred to as Vd21 = V2122−V2123) from the measured voltage value of the highest energy storage means (DC voltage source) 21 (actual voltage value of the highest energy storage means 21) V2122 is referred to as “difference voltage”. ”) Is derived by the uppermost voltage shortage adjusting means 19, and the number of gradations of the output voltage when the inverter 20 is used is adjusted by the magnitude of the difference voltage.

  When the differential voltage Vd21 is, for example, −50% to −150% of the unit voltage (for example, one gradation voltage obtained by dividing the total value of the voltage measuring units 11 to 13 by 7), The inverter combination to be activated is a combination in which, for example, the number of gradations of the output voltage is increased by one gradation by the inverter combination setting means 17, and the shortage of the output voltage of the uppermost energy storage means 21 is compensated. Enable voltage compensation.

  Similarly, when the differential voltage Vd21 is, for example, -150% to -250% of the unit voltage, the inverter combination to be activated is, for example, a combination that increases the number of gradations of the output voltage by two gradations, and the difference When the voltage Vd21 is, for example, -250% to -350% of the unit voltage, the inverter combination to be activated is, for example, a combination in which the number of gradations of the output voltage is increased by three gradations, and the highest energy storage means 21 makes it possible to compensate for the shortage of the output voltage 21 and perform the desired voltage compensation.

  As described above, the output voltages (capacitor voltages, etc.) of the energy storage means 8 to 10 and 21 are measured to determine the voltage of the highest (maximum) energy storage means 21 and the remaining power lower than the highest. From the relationship with the voltage of the energy storage means 8 to 10, when the voltage of the uppermost energy storage means 21 is relatively low, the number of output gradations is increased according to the amount of decrease, and the output voltage is set to an appropriate value. The accuracy of the output voltage is improved by increasing and correcting the number of gradations according to the shortage of the voltage value of the highest energy storage means 21 such as adjustment.

  In the fifth embodiment of the present invention, as described above, a plurality of inverters that convert DC voltage into AC using the DC power stored in the energy storage means and output the AC voltage are connected in series. In the voltage compensator 100 that obtains a plurality of gradation voltages by the sum of the output voltages by combining .about.7,20, the voltage ratio of the plurality of energy storage means 8-10,21 is approximately equal to a common ratio of 2, etc. It is a ratio sequence (1: 2: 4: 8:...) (Or a geometric sequence with a common ratio of 3 (1: 3: 9: 27:...)), And the output of each energy storage means. Output voltage of one or a plurality of energy storage means 8-10 excluding the highest energy storage means 21 among the plurality of energy storage means 8-10, 21 and the voltage measurement means 11-13, 22 for measuring the voltage. Unit power from the measured value of Unit voltage calculation means 23 for calculating a value, target output voltage output means 16 such as target output voltage waveform generation means for generating a voltage having the same waveform as the voltage waveform of the target output voltage V3, and the target output voltage output means 16 and an inverter combination setting unit 17 for setting an output voltage gradation based on the target output voltage obtained from the unit voltage and the unit voltage value obtained by the unit voltage calculation unit 23, and obtained by the unit voltage calculation unit 23. Depending on the magnitude of the difference between the ideal voltage value of the highest energy storage means 21 calculated based on the unit voltage value and the actual voltage measurement value of the highest energy storage means measured by the voltage measurement means 22, the voltage compensation device 100 The output voltage gradation number is adjusted.

  In other words, the fifth embodiment of the present invention is expressed in a superordinate concept. A plurality of inverters 5 connected in series for generating an AC voltage using DC power stored in the energy storage means 8 to 10 and 21. 7 and 20 and target output voltage output means 16 for outputting the target output voltage Vs, according to the magnitude of the difference between the system output voltage V1 which is the voltage to be compensated and the target output voltage Vs. The plurality of inverters are selectively started and stopped, and by selectively starting and stopping the inverters, a compensation voltage V2 having a unit gradation of one gradation to a plurality of gradations is generated. In the voltage compensator that outputs the output voltage V3 obtained by adding the compensation voltage V2 to the system voltage V1, the output voltage of the energy storage means 21 having the maximum output voltage among the energy storage means is expressed as voltage Is measured by measuring means 22 obtains a shortage of the output voltage of the maximum of the energy storage means 21, is intended to increase the number of gradations in accordance with the shortage of the output voltage of said maximum energy storage means 21.

  When the ratio of the output voltages of the inverters 5 to 7 and 20, V5: V6: V7: V20, is set to 1: 2: 4: 8, for example, when a voltage of three gradations is output. , V5 + V6, that is, 1 + 2 (hereinafter expressed using this ratio) when expressed using a ratio. Similarly, 1 + 4 is output when 5 gradation voltages are output, and 1 + 2 + 4 is output when 7 gradation voltages are output. However, for example, 4-1 may be used to output 3 gradation voltages, and 8-2-1 or 8-4 + 1 may be used to output 5 gradation voltages. -There are several types of combinations of selective activation of data.

  Further, since charging may not be completed for V20, the ratio becomes 7, 6, 5... Depending on the degree of charging, and the differential voltage Vd21 = V2122−V2123 also has various values. There is a wide range of choice activation combinations.

Further, when the ratio of the output voltages of the inverters 5 to 7 and 20 and V5: V6: V7: V20 is set to 1: 3: 9: 27, for example, when a voltage of two gradations is output. 3-1, when outputting a voltage of 4 gradations, 1 + 4 when outputting a voltage of 5 gradations, 9-3-1, and so on. As a result, the range of combinations of selective activation of the inverter is wide.

  The differential voltage Vd21 may be obtained by “(the voltage value of the highest-order energy storage unit 21) − (the total value of the voltage values of the energy storage units 8 to 10)”.

Embodiment 6 FIG.
The sixth embodiment of the present invention will be described below with reference to FIG. FIG. 19 is a block diagram showing an example of a compensation voltage determination method of the voltage compensator. In FIG. 19, the same or corresponding parts as those in FIGS. 1, 14 and 18 are given the same reference numerals. In the description of the sixth embodiment of the present invention, the characteristic points of the sixth embodiment of the present invention will be mainly described, and the same or corresponding parts as those of the above-described first to fifth embodiments of the present invention will be described. I will omit the explanation.

  FIG. 19 is provided with an inverter activation point adjusting means 24 in place of the threshold setting means 14 and the threshold adjusting means 15 in FIGS. 1, 14 and 18 described above.

  The output voltage of each inverter 5-7 has a predetermined magnitude. Further, the energy storage means 8 to 10 that influence the magnitude of the output voltage of each of the inverters 5 to 7 are the current output voltages of the energy storage means 8 to 10 even if the charging is incomplete. ˜13. On the other hand, the difference voltage V4 that is the difference between the current system voltage V1 and the target output voltage Vs is, for example, a change in the difference voltage V4 in a half cycle, for example, from the change tendency of the difference voltage V4 in the predetermined period T1 in FIG. That is, the waveform and peak value of the differential voltage V4 can be predicted by calculation. Therefore, in order to generate the compensation voltage V2 corresponding to the predicted difference voltage V4 (the fluctuation range of the system voltage V1), which inverter among the inverters 5 to 7 should be started at which point, It can be obtained by calculation. For example, when the ratio of the output voltages of the inverters 5 to 7 is set to 1: 2: 4 or the like as in the first to fifth embodiments of the present invention, each of the inverters 5 to 5 described above is used. 7 can be performed in the same manner as the selection of the inverter to be activated, and the activation time of the selected inverter is obtained by calculating the time corresponding to the time when the differential voltage V4 exceeds the initial value of each threshold value. Then, the start signal to the inverter selected from the inverter combination setting means 17 may be output at the start time obtained by the calculation. The stop time of the selected inverter can also be obtained by calculation in the same manner. If the prediction of the difference voltage V4 slightly deviates from the actual difference voltage, it appears as the difference between the effective values of the output voltage V3 detected by the output voltage detection means 4 and the target output voltage Vs. Depending on the magnitude of the difference, the inverter start time adjusting means 24 can select and convert the inverter to be started and the start time and stop time of the inverter by calculation.

  If the inverter to be started and stopped and the start and stop times are obtained by calculation, the ratio of the output voltages of the inverters 5 to 7 can be calculated as in the first to fifth embodiments of the present invention. Even if it is not determined to be a geometric sequence such as 1: 2: 4, the unit voltage is determined to be one gradation and it is not a multiple of one gradation, and the threshold value as described above is not set. A plurality of inverters connected in series that generate AC voltage using DC power stored in the energy storage means, and the difference voltage between the system voltage, which is the voltage to be compensated, and the target output voltage In the voltage compensation system that selectively starts and stops according to the output and outputs an output voltage obtained by adding the compensation voltage generated by the selective start and stop of the inverter to the system voltage, the target output voltage and the output Substantial with voltage In the direction in which the difference is small, it is possible to adjust the start time and stop time of the inverter to be the selectively start and stop.

  In the first to sixth embodiments of the present invention described above, the target output voltage Vs is stored in the storage device as the normal system voltage V1 or the output voltage V3 as the target output voltage Vs. The target output voltage Vs that has been set may be used.

  In the first to sixth embodiments of the present invention described above, the term “exceed” is used as a term including both cases of “exceed” and “above”. Similarly, the term “below” is also used as a term including both cases “below” and “below”.

It is a figure which shows Embodiment 1 of this invention, and is a block diagram which shows the compensation voltage determination system of a voltage compensation apparatus. FIG. 5 is a diagram illustrating the first embodiment of the present invention, and is a diagram for explaining the principle of voltage compensation. The relationship between the difference voltage between the system voltage and the target output voltage and the compensation voltage generated by the voltage compensation device is shown in a half cycle. The period is shown, (a) shows the state before adjusting the compensation voltage, and (b) shows the state after adjusting the compensation voltage. In the figure which shows Embodiment 1 of this invention, the relationship between a difference voltage, a target output voltage, and the output voltage of a voltage compensation apparatus is the state before adjusting a compensation voltage, and the state after adjusting a compensation voltage. It is a figure shown about the period of 1 cycle by comparing these. FIG. 5 is a diagram illustrating the first embodiment of the present invention, and is a diagram illustrating the principle of voltage compensation when the difference voltage is larger than that in FIG. 2, and the relationship between the difference voltage and the compensation voltage is a half cycle period. (A) shows the state before adjusting the compensation voltage, and (b) shows the state after adjusting the compensation voltage. In the figure which shows Embodiment 1 of this invention, the relationship between a difference voltage, a target output voltage, and the output voltage of a voltage compensation apparatus is the state before adjusting a compensation voltage, and the state after adjusting a compensation voltage. It is a figure shown about the period of 1 cycle by comparing these. In the figure which shows Embodiment 2 of this invention, it is a figure which illustrates the case where each threshold value is adjusted variously, (a) is a figure in case a threshold value is an initial value, (b) is only a 2nd threshold value adjustment. It is a figure which shows the example in the case of having performed. In the diagram showing the third embodiment of the present invention, when the threshold adjustment amount is different before and after the zero cross point, the zero cross point between the positive period and the negative period of the output voltage V3 is the target output voltage Vs. It is a figure which shows the example in the case of shifting | deviating from a zero crossing point. It is a figure which shows Embodiment 3 of this invention, and is a figure which shows the example of the error of the peak value of the output voltage V3 in the case of adjusting a threshold value without considering the peak value error not increasing. It is a figure which shows Embodiment 3 of this invention, and is a figure which shows the example when the error of the peak value of output voltage V3 becomes large when a threshold value adjustment is carried out, and it becomes impossible to hold | maintain peak value precision. It is a figure which shows Embodiment 3 of this invention, and is a figure which shows the example of a threshold value adjustment range. FIG. 10 is a diagram illustrating the third embodiment of the present invention, and is a diagram illustrating an example of a waveform of the compensation voltage V2 in the positive period and the negative period of the output voltage V3 when the threshold adjustment range illustrated in FIG. 10 is applied. It is a figure which shows Embodiment 3 of this invention, and is a figure explaining the range which can adjust the threshold value so that a peak value precision can be hold | maintained. In the figure showing Embodiment 3 of the present invention, by applying the adjustable range of the threshold illustrated in FIG. 12, the peak value accuracy can be maintained without increasing the peak value error of the output voltage V3. It is a figure which shows the example of a case. It is a figure which shows Embodiment 4 of this invention, and is a block diagram which shows the compensation voltage determination system of a voltage compensation apparatus. It is a figure which shows Embodiment 4 of this invention, and is a figure which shows the example in case the zero cross in the output voltage V3 shifts | deviates from the zero cross point of the target output voltage Vs, when the system voltage V1 falls to 0V. FIG. 10 is a diagram illustrating a fourth embodiment of the present invention and is a diagram illustrating an example in which the zero cross in the output voltage V3 is not shifted from the zero cross point of the target output voltage Vs even when the system voltage V1 is reduced to 0V. It is a figure which shows Embodiment 4 of this invention, and is a figure which shows an example of the waveform of output voltage V3 when the system voltage V1 falls to 0V when Embodiment 4 of this invention is applied. It is a figure which shows Embodiment 5 of this invention, and is a block diagram which shows the example of the compensation voltage determination system of a voltage compensation apparatus. It is a figure which shows Embodiment 6 of this invention, and is a block diagram which shows the example of the compensation voltage determination system of a voltage compensation apparatus.

Explanation of symbols

1 system voltage,
2 load,
3 system voltage detection means,
4 output voltage detection means,
5-7,20 inverter,
8-10, 21 Energy storage means,
11-13, 22 Voltage measuring means,
14 threshold setting means,
15 threshold adjustment means,
16 Target output voltage waveform generation means,
17 Inverter combination setting means,
180 0V adjustment means,
19 Adjustment means when the top voltage is insufficient,
23 Unit voltage calculation means,
24 Inverter start time adjustment means,
V1 system voltage,
V2 compensation voltage,
V3 output voltage V4 differential voltage,
Vs Target output voltage.

Claims (11)

The magnitude of the difference between the system voltage and the target output voltage, which is the voltage to be compensated, for a plurality of inverters connected in series that generate AC voltage using DC power stored in the energy storage means In the voltage compensation method of selectively starting and stopping according to the output voltage, and outputting the output voltage obtained by adding the compensation voltage generated by the selective starting and stopping of the inverter to the system voltage,
A voltage compensation method characterized by adjusting a time point at which the magnitude of the compensation voltage changes in a direction in which a substantial difference between the target output voltage and the output voltage decreases. The magnitude of the difference between the system voltage and the target output voltage, which is the voltage to be compensated, for a plurality of inverters connected in series that generate AC voltage using DC power stored in the energy storage means In the voltage compensation method of selectively starting and stopping according to the output voltage, and outputting the output voltage obtained by adding the compensation voltage generated by the selective starting and stopping of the inverter to the system voltage,
A voltage compensation method, wherein at least one of a start time and a stop time of the selectively started inverter is adjusted so that a substantial difference between the target output voltage and the output voltage is reduced. A plurality of inverters connected in series that generate AC voltage using DC power stored in the energy storage means;
A target output voltage output means for outputting the target output voltage,
Generated by selectively starting and stopping the plurality of inverters according to the magnitude of the voltage difference between the system voltage, which is the voltage to be compensated, and the target output voltage. In a voltage compensator that outputs an output voltage obtained by adding the compensated voltage to the system voltage,
Threshold setting means for setting a plurality of different thresholds serving as a reference for selecting the inverter to be started according to the magnitude of the voltage difference between the target output voltage and the system voltage;
A voltage compensating apparatus, comprising: a threshold adjusting unit that adjusts the threshold in a direction in which a substantial difference between the target output voltage and the output voltage is reduced. A plurality of inverters connected in series that generate AC voltage using DC power stored in the energy storage means;
A target output voltage output means for outputting the target output voltage,
By selectively starting and stopping the plurality of inverters according to the magnitude of the voltage difference between the system voltage that is the voltage to be compensated and the target output voltage, by selectively starting and stopping the inverters, In a voltage compensator that generates a compensation voltage of a predetermined gradation in which a unit voltage determined based on the output voltage of the inverter is one gradation, and outputs an output voltage that compensates for fluctuations in the system voltage by the compensation voltage. ,
Threshold setting means for setting a plurality of different thresholds serving as a reference for selecting the inverter to be started according to the magnitude of the voltage difference between the target output voltage and the system voltage;
A voltage compensating apparatus, comprising: a threshold adjusting unit that adjusts the threshold in a direction in which a substantial difference between the target output voltage and the output voltage is reduced. In the voltage compensation device according to claim 3 or 4,
The threshold adjustment means includes
When the output voltage after starting the inverter is substantially higher than the target output voltage, the threshold is adjusted to a high value,
If the output voltage after starting the inverter is substantially lower than the target output voltage, the threshold is adjusted to a low value,
A voltage compensator, wherein the output voltage is made substantially close to the target output voltage. The voltage compensator according to claim 4,
When the voltage of the difference between the target output voltage and the system voltage exceeds the threshold, the inverter is selectively activated to generate the compensation voltage one gradation higher,
When the voltage of the difference between the target output voltage and the system voltage falls below the threshold value, the inverter is selectively activated so as to generate the compensation voltage one gradation lower. In the voltage compensation apparatus as described in any one of Claims 4-6,
A voltage compensation device, wherein the inverter is selectively activated so as to generate the compensation voltage of at least one gradation having a different sign before and after a zero cross point, which is a time when the target output voltage becomes zero. In the voltage compensation apparatus as described in any one of Claims 4-6,
Provide 0V time adjustment means to detect that the system voltage has dropped to 0V,
A voltage compensator for selectively starting the inverter so as to generate the compensation voltage of at least one gradation at the time of zero crossing of the target output voltage based on the output of the 0V time adjusting means . In the voltage compensation apparatus as described in any one of Claims 3-8,
The threshold value adjustment is performed within a remaining period excluding a predetermined period including a zero cross point. In the voltage compensation apparatus as described in any one of Claims 3-8,
The initial value of the threshold is an intermediate value between the compensation voltage at the gradation according to the threshold and the compensation voltage at the next lower gradation;
When the initial value of the threshold is smaller than the peak value of the difference voltage, the threshold is made smaller than the peak value;
The voltage compensation device according to claim 1, wherein when the initial value of the threshold value is larger than the peak value, the threshold value is larger than the peak value. A plurality of inverters connected in series that generate AC voltage using DC power stored in the energy storage means;
A target output voltage output means for outputting the target output voltage,
By selectively starting and stopping the plurality of inverters according to the magnitude of the voltage difference between the system voltage that is the voltage to be compensated and the target output voltage, by selectively starting and stopping the inverters, In a voltage compensation device for generating a compensation voltage of a predetermined gradation in which a unit voltage determined based on the output voltage of the inverter is one gradation, and outputting an output voltage obtained by adding the compensation voltage to the system voltage,
The output voltage of the energy storage means having the maximum output voltage among the energy storage means is measured by the voltage measurement means to determine the shortage of the output voltage of the maximum energy storage means,
The number of gradations for starting the inverter using the maximum energy storage means increases the number of gradations according to the shortage of the output voltage of the maximum energy storage means. apparatus.

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