Power supply system

Abstract

This power supply system not only compensates for load voltage during momentary voltage dips, but also compensates for emergency load voltage during power outages. [Solution] The power outage compensation unit 5 includes a sub-transformer 51 provided on the power line P and connected in parallel to the emergency load L2, a sub-capacitor element 52 which serves as a power source for a voltage that compensates for the emergency load L2 in the event of a power outage, and a sub-power converter 53 which converts the DC power from the sub-capacitor element 52 into AC power and supplies that AC power to the emergency load L2 via the sub-transformer 51.

Description

Technical Field

[0001] The present invention relates to a power supply system.

Background Art

[0002] Conventionally, in a momentary voltage drop state where the voltage of the power system temporarily drops, there is a momentary voltage drop compensator that superimposes the voltage shortage of the power system in series to compensate the voltage of the load.

[0003] In this type of momentary voltage drop compensator, for example, as shown in Patent Document 1, an open / close switch is provided on the power line for supplying power from the power line to the load, and a power converter that operates in the momentary voltage drop state is connected in parallel to the open / close switch.

[0004] When the momentary voltage drop state occurs, first, the voltage output from the power converter is controlled so that the current flowing through the open / close switch becomes zero. Then, after the current flowing through the open / close switch becomes zero and the open / close switch is opened, the voltage output from the power converter is controlled to compensate for the voltage drop of the load.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] By the way, on the power line to which the above-mentioned momentary voltage drop compensator is connected, a circuit breaker that connects the power system and the load is provided separately from the open / close switch. This circuit breaker is not opened but is turned on in the momentary voltage drop state, but is opened in a power outage state where the voltage of the power system drops for, for example, several seconds to 60 seconds or more.

[0007] During a power outage, it is necessary to compensate for the voltage of the emergency load, which is the minimum load required to protect the equipment. However, since the circuit breaker is open during a power outage, conventional voltage sag compensation devices are electrically disconnected from the emergency load during a power outage and cannot compensate for the voltage of the emergency load.

[0008] Therefore, the present invention has been made in view of the above problems, and its main objective is to provide a power supply system that can not only compensate for the voltage of the load in a momentary voltage drop state, but also compensate for the voltage of the emergency load in a power outage state. [Means for solving the problem]

[0009] In other words, the power supply system according to the present invention is provided on a power line for supplying power from a power grid to a load, and comprises a switch for opening and closing the power line, a voltage applied to the switch to turn it off in a momentary sag state when a circuit breaker connecting the power grid and the load is closed, and compensating the voltage of the load after the switch has turned off, and a power outage compensation unit connected in series with the switch on the power line to compensate the voltage of an emergency load connected to the power line in a power outage state when the circuit breaker is open, wherein the voltage compensation unit comprises the switch The power outage compensation unit is characterized by comprising a main transformer connected in parallel to the switch, a main capacitor element that serves as a power source for the voltage applied during the momentary voltage drop, and a main power converter that converts the DC power from the main capacitor element into AC power and supplies the AC power to the switch and the load via the main transformer, and a sub-transformer provided on the power line and connected in parallel to the emergency load, a sub-capacitor element that serves as a power source for a voltage that compensates the emergency load during the power outage, and a sub-power converter that converts the DC power from the sub-capacitor element into AC power and supplies the AC power to the emergency load via the sub-transformer.

[0010] In such a power supply system, during a power outage, the voltage from the auxiliary capacitor element is applied to the emergency load via the auxiliary power converter and auxiliary transformer, thus compensating for the voltage of the emergency load during a power outage. In addition, in a momentary voltage sag, similar to conventional voltage sag compensation devices, a reverse voltage that forcibly reduces the current flowing through the switch to zero is applied to the switch via the main capacitor element, the main power converter, and the main transformer. Subsequently, the voltage from the main capacitor element is compensated for the load via the main power converter and the main transformer, thus compensating for the load voltage in a momentary voltage sag. Therefore, since the main capacitor element, main power converter, and main transformer operate in a momentary voltage sag state, and the sub-capacitor element, sub-power converter, and sub-transformer operate in a power outage state, it is possible to compensate for the voltage of the load in a momentary voltage sag state, as well as to compensate for the voltage of the emergency load in a power outage state. Furthermore, since the sub-capacitor element is used as the power source during a power outage, it is possible to prevent the degradation of the power source itself during a power outage compared to conventional uninterruptible power supplies that use a battery as the power source during a power outage.

[0011] The auxiliary transformer is connected in series with the load side of the switch in the power line, and in the momentary voltage drop state, the regenerative power supplied from the load in the direction from the load to the power system is absorbed by the auxiliary capacitor element via the auxiliary transformer. In this configuration, the sub-capacitor element can absorb regenerative power from the load before the main capacitor element during a voltage sag. Therefore, even if the load includes large power equipment, the voltage sag compensation unit can compensate for the load voltage during a voltage sag. Consequently, the equipment constraints on the load can be reduced.

[0012] The sub-capacitor element may have a larger capacitance than the main capacitor element. In this configuration, the capacitance of the sub-capacitor element is greater than that of the main capacitor element, so the sub-capacitor element can be used as an emergency power source even in the event of a prolonged power outage. In addition, during momentary power dips, the sub-capacitor element can absorb more regenerative power from the load than the main capacitor element, further reducing the equipment constraints on the load.

[0013] The system further includes a voltage measuring unit provided on the power line for measuring the voltage of the load, and a sub-power converter control unit that controls the voltage output by the sub-power converter based on the voltage measured by the voltage measuring unit so that the voltage of the load remains constant in a normal state where the switch is ON and power is supplied to the load from the power system via the switch. With this configuration, while conventional voltage sag compensation devices only operate the power converter during voltage sags, the auxiliary power converter control unit operates the auxiliary power converter even under normal conditions, allowing the power supply system to contribute to production even under normal conditions. Furthermore, since the auxiliary power converter control unit performs constant load voltage control, high-quality power can be supplied from the power system to the load.

[0014] The system further includes a charging power supply that supplies power to charge the main capacitor element or the sub-capacitor element, wherein the sub-capacitor element is connected via a resistive element and a switching element to a wire between the output terminal of the charging power supply and the main capacitor element. With this configuration, the voltage of the sub-capacitor element can be made lower than the voltage of the main capacitor element, allowing the sub-capacitor element and the sub-power converter to operate under normal conditions. As a result, the sub-power converter control unit can suppress fluctuations in the load voltage by performing constant load voltage control under normal conditions.

[0015] A charging power source that supplies power for charging the main capacitor element or the auxiliary capacitor element, and a diode element interposed between the main capacitor element and the auxiliary capacitor element, wherein the main capacitor element is connected to the cathode side of the diode element, and the auxiliary capacitor element is connected to the anode side of the diode element. With this configuration, since the main capacitor element and the auxiliary capacitor element are electrically connected via the diode element, the stored electrical energy in the auxiliary capacitor element by the power from the charging power source can be transferred to the main capacitor element via the diode element. As a result, even when the momentary voltage drop state continues longer than the standard duration of the momentary voltage drop, the momentary voltage drop compensation unit can compensate the voltage of the load.

Advantages of the Invention

[0016] According to the present invention configured as described above, it is possible to provide a power supply system that can not only compensate the voltage of the load in the momentary voltage drop state but also compensate the voltage of the emergency load in the power outage state.

Brief Description of the Drawings

[0017] [Figure 1] It is a schematic diagram showing the power supply system in this embodiment. [Figure 2] It is a schematic diagram showing the power supply system in the normal state in the same embodiment. [Figure 3] It is a schematic diagram showing the power supply system in the momentary voltage drop state in the same embodiment. [Figure 4] It is a schematic diagram showing the power supply system in the power outage state in the same embodiment.

Embodiments for Carrying Out the Invention

[0018] Hereinafter, an embodiment of the power supply system according to the present invention will be described with reference to the drawings. Note that, for the sake of clarity, any of the following figures may be appropriately omitted or exaggerated and schematically drawn. For the same components, the same reference numerals are used and the description thereof is appropriately omitted.

[0019] <Device Configuration> As shown in FIG. 1, the power supply system 100 in the present embodiment is provided between the power grid G and the load L, and compensates the voltage of the load L in the event of an abnormality in the power grid G.

[0020] Here, the power grid G is the power supply network of an electric power company (electric utility) and has a power plant, a transmission system, and a distribution system. In the present embodiment, the load L is composed of an important load L1 and an emergency load L2.

[0021] The important load L1 is a load that should stably supply power in a momentary voltage drop state where the voltage of the power grid G drops in a time of, for example, several seconds or less. The emergency load L2 is a load that should supply power even in a power outage state of several seconds to 60 seconds or more, and is the minimum load required to protect equipment. Examples of the emergency load L2 include disaster prevention equipment, fire fighting equipment, etc. As shown in FIG. 1, the emergency load L2 is connected in parallel with the important load L1 on the power line P. Also, although there is one important load L1 and one emergency load L2 in FIG. 1, there may be a plurality of them.

[0022] Specifically, as shown in FIG. 1, the power supply system 100 is provided on the power line P for supplying power from the power grid G to the load L, and includes a switch 2 for opening and closing the power line P, a momentary voltage drop compensation unit 3 connected in parallel with the switch 2 on the power line P, a charging power source 4 serving as the power source of the momentary voltage drop compensation unit 3, and a power outage compensation unit 5 connected in series with the switch 2 on the power line P.

[0023] Here, as shown in Figure 1, the power line P is equipped with a circuit breaker S that connects the power system G and the critical load L1. Specifically, the circuit breaker S is connected in series with the switch 2 in the power line P. More specifically, as shown in Figure 1, the circuit breaker S comprises an input circuit breaker S1 located on the power system G side of the switch 2 in the power line P, and an output circuit breaker S2 located on the critical load L1 side of the switch 2 in the power line P.

[0024] In normal and momentary voltage dips, when power is supplied from the power system G to the load L, the input circuit breaker S1 and output circuit breaker S2 are closed. On the other hand, in a power outage, the input circuit breaker S1 and output circuit breaker S2 are open.

[0025] The following describes the various components that make up the power supply system 100 of this embodiment.

[0026] Switch 2 is a semiconductor switch, and an example of such a device is a thyristor or other high-speed conductive element that does not have self-extinguishing capabilities. Switch 2 may also be constructed using, for example, an IGBT.

[0027] The voltage sag compensation unit 3 applies a voltage to switch 2 that turns it off during a voltage sag, and then compensates for the voltage of the critical load L1 after switch 2 has turned off. Specifically, the voltage sag compensation unit 3 includes a main transformer 31 connected in parallel to switch 2, a main capacitor element 32 that provides the voltage applied during a voltage sag, and a main power converter 33 interposed between the main transformer 31 and the main capacitor element 32. Here, the off state of switch 2 refers to a state in which the current flowing through switch 2 is zero, and in the off state of switch 2, the power system G and the critical load L1 are electrically disconnected.

[0028] The main transformer 31 has its secondary winding connected in series with the power system G and critical load L1, and its secondary winding connected in parallel with switch 2. The capacity of the main transformer 31 is, for example, its rated capacity.

[0029] The main capacitor element 32 is connected to the charging power supply 4 and stores DC power, and in the event of a momentary voltage drop, it supplies the stored DC power to the power line P. Specifically, one terminal is connected to the output terminal of the charging power supply 4, and the other terminal is connected to the input terminal of the charging power supply 4.

[0030] The main power converter 33 converts the DC power from the main capacitor element 32 into AC power during a momentary voltage drop and supplies that AC power to the switch 2 and load L via the main transformer 31. Specifically, the AC output terminal of the main power converter 33 is connected to the primary winding of the main transformer 31, and the DC input terminal of the main power converter 33 is connected to the main capacitor element 32. The main power converter 33 can be, for example, a three-phase power converter or a combination of three single-phase power converters.

[0031] The charging power supply 4 supplies the power to be stored in the main capacitor element 32. Here, as shown in Figure 1, the charging power supply 4 comprises an AC power supply 41 that outputs AC power and an AC-DC converter 42 that converts the AC power from the AC power supply 41 into DC power.

[0032] The power outage compensation unit 5 compensates for the voltage of the emergency load L2 during a power outage. Specifically, the power outage compensation unit 5 includes a sub-transformer 51 installed on the power line P and connected in parallel to the emergency load L2, a sub-capacitor element 52 that serves as a power source for the voltage that compensates for the emergency load L2 during a power outage, and a sub-power converter 53 interposed between the sub-transformer 51 and the sub-capacitor element 52. During a power outage, the DC power from the sub-capacitor element 52 is converted into AC power by the sub-power converter 53, and this AC power is supplied to the emergency load L2 via the sub-transformer 51.

[0033] The auxiliary transformer 51 has its secondary winding connected in series with the switch 2 on the power line P, and its secondary winding connected in parallel with the emergency load L2. Specifically, the auxiliary transformer 51 is connected in series with the load side of the switch 2 on the power line P, and more specifically, it is located on the load side of the main transformer 31. In this embodiment, the auxiliary transformer 51 has a capacity of, for example, about 10% of the capacity of the main transformer 31. As shown in Figure 1, an isolation transformer T and a circuit breaker M are provided between the secondary winding of the auxiliary transformer 51 and the emergency load L2, but the isolation transformer T and circuit breaker M are not required.

[0034] The sub-capacitor element 52 is connected to the charging power supply 4 and stores DC power, supplying the stored DC power to the power line P in the event of a power outage. Specifically, one terminal is connected to the output terminal of the charging power supply 4, and the other terminal is connected to the input terminal of the charging power supply 4. More specifically, one terminal is connected to the wire from the output terminal of the charging power supply 4 to the main capacitor element 32, and the other terminal is connected to the wire from the main capacitor element 32 to the input terminal of the charging power supply 4. With this configuration, the charging power supply 4 becomes a common power source for both the main capacitor element 32 and the sub-capacitor element 52.

[0035] In this embodiment, the sub-capacitor element 52 has a larger capacitance than the main capacitor element 32, and here it has a capacitance that can absorb load voltage fluctuations of, for example, about 10%. Specifically, the sub-capacitor element 52 can be an element with a large energy storage capacity, such as an electric double-layer capacitor (EDLC) or a lithium-ion capacitor (LIC).

[0036] The auxiliary power converter 53 converts the DC power from the auxiliary capacitor element 52 into AC power and supplies that AC power to the emergency load L2 via the auxiliary transformer 51. Specifically, the AC output terminal of the auxiliary power converter 53 is connected to the primary winding of the auxiliary transformer 51, and the DC input terminal of the auxiliary power converter 53 is connected to the auxiliary capacitor element 52. The auxiliary power converter 53 can be, for example, a three-phase power converter or a combination of three single-phase power converters.

[0037] Furthermore, the power outage compensation unit 5 has a normal operation function that operates the auxiliary transformer 51, auxiliary capacitor element 52, and auxiliary power converter 53 under normal conditions. As a normal operation function, the power outage compensation unit 5 includes a voltage measuring unit 54 provided on the power line P and measuring the voltage of the load L, an auxiliary power converter control unit 55 that controls the auxiliary power converter 53 based on the voltage measured by the voltage measuring unit 54, and a resistive element 56 and a switching element 57 interposed between the main capacitor element 32 and the auxiliary capacitor element 52.

[0038] The voltage measuring unit 54 is, for example, an instrument transformer. In this embodiment, the voltage measuring unit 54 is located on the critical load L1 side of the output circuit breaker S2 and measures the voltage of the critical load L1. The voltage measuring unit 54 outputs the measured voltage to the auxiliary power converter control unit 55. In this embodiment, the voltage measuring unit 54 is connected to the power line P on the power system G side of the input circuit breaker S1 via a bypass circuit breaker B, but it does not have to be connected to the power line P on the power system G side of the input circuit breaker S1.

[0039] The auxiliary power converter control unit 55 controls the voltage output by the auxiliary power converter 53 based on the voltage measured by the voltage measurement unit 54, so that the voltage across the load L remains constant under normal conditions. The auxiliary power converter control unit 55 is installed in a control unit that is composed of a so-called computer equipped with a CPU, memory, input / output means, etc.

[0040] Specifically, the auxiliary power converter control unit 55 controls the magnitude of the voltage applied by the auxiliary power converter 53 to the power line P so that the voltage of the critical load L1 is between 90% and 110% of the rated voltage under normal conditions. Furthermore, the auxiliary power converter control unit 55 controls the phase of the voltage applied by the auxiliary power converter 53 to the power line P so that the voltage of the auxiliary capacitor element 52 is kept constant under normal conditions.

[0041] As shown in Figure 1, the resistive element 56 and the switching element 57 are provided on a branch line that branches off from the wire from the output terminal of the charging power supply 4 to the main capacitor element 32 and is connected to the sub-capacitor element 52. Under normal conditions, the switching element 57 is switched on and off by a control unit (not shown) provided in the arithmetic control unit so that the sub-capacitor element 52 is charged to a predetermined voltage.

[0042] Furthermore, the power outage compensation unit 5 has a sharing function that transfers the stored energy of the sub-capacitor element 52 to the main capacitor element 32. As part of this sharing function, the power outage compensation unit 5 further includes a diode element 58 interposed between the main capacitor element 32 and the sub-capacitor element 52.

[0043] The diode element 58 allows current to flow from the sub-capacitor element 52 towards the main capacitor element 32. Specifically, as shown in Figure 1, the main capacitor element 32 is connected to the cathode side of the diode element 58, and the sub-capacitor element 52 is connected to the anode side of the diode element 58.

[0044] <Power System Operation> Next, the operation of the power supply system 100 in the normal state, momentary voltage drop state, and power outage state will be explained with reference to Figures 2 to 4. In each figure, the dashed arrows indicate the flow of power.

[0045] (1) Normal state (see Figure 2) Under normal conditions, the input circuit breaker S1, the output circuit breaker S2, and switch 2 are closed, so the power system G and the load L are electrically connected through the power line P. As a result, power is supplied from the power system G to the load L.

[0046] Furthermore, under normal conditions, the voltage measurement unit 54 measures the voltage of the critical load L1, and the auxiliary power converter control unit 55 controls the magnitude and phase of the voltage applied by the auxiliary power converter 53 to the power line P based on the voltage measured by the voltage measurement unit 54, so that the voltage of the critical load L1 remains constant. By controlling the phase of the voltage output by the auxiliary power converter 53, the auxiliary capacitor element 52 is maintained at the voltage after charging is complete.

[0047] Furthermore, under normal conditions, the presence of the resistor 56 on the branch line ensures that DC power is supplied from the charging power supply 4 to the main capacitor element 32 until it reaches a predetermined voltage (e.g., 700V). Once the main capacitor element 32 is charged to the predetermined voltage, the switching element 57 is controlled to switch on and off, thereby supplying DC power from the charging power supply 4 to the sub-capacitor element 52 until it reaches a predetermined voltage. The sub-capacitor element 52 is charged to a voltage lower than that charged by the main capacitor element 32 (e.g., 600V).

[0048] (2) Momentary low state (see Figure 3) If the voltage of the power system G drops for a short period of time, such as a few seconds or less, a system anomaly detection unit (not shown) in the arithmetic control unit detects the momentary voltage drop. Note that a voltmeter (not shown), such as an instrument transformer, measures the voltage of the power system G, and the system anomaly detection unit detects the momentary voltage drop based on the voltage measured by that voltmeter.

[0049] When a momentary dip is detected, first, the control unit (not shown) in the calculation control unit controls the voltage applied between the terminals of switch 2 via the main transformer 31 by the main power converter 33 so that the current flowing through switch 2 becomes 0.

[0050] Next, when the current flowing through switch 2 becomes 0, switch 2 turns off. Then, in order to compensate for the voltage drop across critical load L1 during the momentary voltage sag, a control unit (not shown) provided in the calculation control unit controls the voltage that the main power converter 33 provides to the critical load L1 via the main transformer 31. Note that during the momentary voltage sag, the input circuit breaker S1 and output circuit breaker S2 remain closed.

[0051] In this case, if a large power equipment is installed at the critical load L1, regenerative power is supplied to the power line P in the direction from the critical load L1 to the power system G during a momentary voltage drop. In this embodiment, since the sub-capacitor element 52 is located on the load side of the power line P compared to the main capacitor element 32, the regenerative power supplied from the critical load L1 is absorbed by the sub-capacitor element 52 via the sub-transformer 51.

[0052] In addition, if the momentary voltage dip persists for longer than usual, the voltage charged to the main capacitor element 32 under normal conditions may be completely discharged. In that case, the voltage charged to the sub-capacitor element 52 is applied to the main capacitor element 32 via the diode element 58. This allows stored energy to be transferred from the sub-capacitor element 52 to the main capacitor element 32 via the diode element 58.

[0053] When the voltage of the power system G recovers to a predetermined voltage, such as the rated voltage, the control unit (not shown) in the calculation control unit controls switch 2, causing switch 2 to turn ON. This electrically connects the power system G and the critical load L1 via switch 2. When switch 2 is ON, the main power converter 33 stops. When switch 2 is ON, the power system G and the critical load L1 are electrically connected via switch 2.

[0054] (3) Power outage (see Figure 4) If the voltage of power system G drops for a period of time, for example, a few seconds to 60 seconds or more, a system anomaly detection unit (not shown) in the arithmetic control unit detects a power outage. Note that a voltmeter (not shown), such as an instrument transformer, measures the voltage of power system G, and the system anomaly detection unit detects the power outage based on the voltage measured by that voltmeter.

[0055] In the event of a power outage, the input circuit breaker S1 and the output circuit breaker S2 are opened. As a result, power is no longer supplied from the power system G to the critical load L1 and the emergency load L2, and the momentary sag compensation unit 3 is electrically disconnected from the power system G, the critical load L1, and the emergency load L2.

[0056] On the other hand, the power outage compensation unit 5 compensates for the voltage of the emergency load L2. Specifically, the DC power from the sub-capacitor element 52 is converted to AC power by the sub-power converter 53, and this AC power is supplied to the emergency load L2 via the sub-transformer 51. As a result, the power supply system 100 of this embodiment can supply power to the emergency load L2 even in the event of a power outage.

[0057] <Effects of this embodiment> According to the power supply system 100 of this embodiment, in the event of a power outage, the voltage from the sub-capacitor element 52 is applied to the emergency load L2 via the sub-power converter 53 and the sub-transformer 51, so that the voltage of the emergency load L2 can be compensated in the event of a power outage. In addition, in a momentary voltage sag, similar to conventional voltage sag compensation devices, a reverse voltage that forcibly reduces the current flowing through switch 2 to zero is applied to the switch via the main capacitor element 32, the main power converter 33, and the main transformer 31. Subsequently, the voltage from the main capacitor element 32 is compensated for the load L via the main power converter 33 and the main transformer 31, thus compensating the voltage of the load L in a momentary voltage sag. Therefore, since the main capacitor element 32, main power converter 33, and main transformer 31 operate in a momentary voltage sag state, and the sub-capacitor element 52, sub-power converter 53, and sub-transformer 51 operate in a power outage state, it is possible to compensate for the voltage of the load L in a momentary voltage sag state, as well as to compensate for the voltage of the emergency load L2 in a power outage state. Furthermore, since the sub-capacitor element 52 is used as the power source during a power outage, it is possible to prevent deterioration of the power source itself during a power outage compared to conventional uninterruptible power supplies where the battery is used as the power source during a power outage.

[0058] <Other Embodiments> However, the present invention is not limited to the embodiments described above.

[0059] In the above embodiment, the power outage compensation unit 5 was connected in series with the load L side of the switch 2. However, if the power outage compensation unit 5 only compensates for the voltage of the emergency load L2 in the event of a power outage, the power outage compensation unit 5 may be connected in series with the power system G side of the switch 2.

[0060] In the above embodiment, the power outage compensation unit 5 included a voltage measuring unit 54 and a sub-power converter control unit 55 in order to control the voltage of the load L to a constant value under normal conditions. However, if the purpose is only to compensate for the voltage of the emergency load L2 in the event of a power outage, the voltage measuring unit 54 and the sub-power converter control unit 55 may not be necessary.

[0061] In the above embodiment, the main capacitor element 32 and the sub-capacitor element 52 were connected to a common power source, the charging power source 4. However, separate power sources may be provided for the main capacitor element 32 and the sub-capacitor element 52, respectively.

[0062] In the above embodiment, a diode element 58 was interposed between the main capacitor element 32 and the sub-capacitor element 52. However, if the purpose is only to compensate for the voltage of the emergency load L2 in the event of a power outage, the diode element 58 may not be provided.

[0063] Furthermore, it goes without saying that the present invention is not limited to the embodiments described above, and various modifications are possible without departing from its spirit. [Explanation of Symbols]

[0064] 100... Power System 2 ···Switch 3... Momentary sag compensation section 31 ···Main transformer 32 ···Main Capacitor Element 33 ···Main power converter 4...Charging power supply 5...Outage compensation department 51... Sub-transformer 52 ···Sub-capacitor element 53...Auxiliary power converter 54...Voltage measurement section 55...Sub-power converter control unit 56 ···Resistor element 57 ··· Switching element 58... Diode element G...Electric power system P...power line L...Load L1...Important load L2...Emergency load

Claims

1. A switch is provided on a power line for supplying power from the power system to a load, and the switch opens and closes the power line. A voltage is applied to the switch to turn it off during a momentary voltage sag in the power line, which is connected in parallel to the switch and connects the power system and the load. After the switch is turned off, a momentary voltage sag compensation unit is provided to compensate for the voltage of the load. The power line is connected in series with the switch and includes a power outage compensation unit that compensates for the voltage of an emergency load connected to the power line in a power outage state where the circuit breaker is open. The aforementioned instantaneous sag compensation unit is The main transformer connected in parallel to the aforementioned switch, A main capacitor element that serves as the power source for the voltage applied in the aforementioned momentary low state, The system includes a main power converter that converts the DC power from the main capacitor element into AC power and supplies the AC power to the switch and the load via the main transformer. The aforementioned power outage compensation unit is, A sub-transformer provided on the power line and connected in parallel to the emergency load, A sub-capacitor element that provides a voltage to compensate for the emergency load in the aforementioned power outage state, A power supply system comprising a secondary power converter that converts DC power from the secondary capacitor element into AC power and supplies the AC power to the emergency load via the secondary transformer.

2. The auxiliary transformer is connected in series with the load side of the switch in the power line. The power supply system according to claim 1, wherein, in the instantaneous voltage drop state, the regenerative power supplied from the load in the direction from the load to the power system is absorbed by the sub-capacitor element via the sub-transformer.

3. The power supply system according to claim 1 or 2, wherein the sub-capacitor element has a larger capacitance than the main capacitor element.

4. A voltage measuring unit is provided on the power line for measuring the voltage of the load, The power supply system according to claim 1, further comprising: an auxiliary power converter control unit that controls the voltage output by the auxiliary power converter based on the voltage measured by the voltage measuring unit so that the voltage of the load remains constant in a normal state in which the switch is in the ON state and power is supplied to the load from the power system through the switch.

5. The system further comprises a charging power supply that supplies power for charging the main capacitor element or the sub-capacitor element, The power supply system according to claim 4, wherein the sub-capacitor element is connected via a resistive element and a switching element to a wire between the output terminal of the charging power supply and the main capacitor element.

6. A charging power supply that supplies power to charge the main capacitor element or the sub-capacitor element, The system further comprises a diode element interposed between the main capacitor element and the sub-capacitor element, The main capacitor element is connected to the cathode side of the diode element. The power supply system according to claim 1, wherein the sub-capacitor element is connected to the anode side of the diode element.

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