TW201944693A - Power supply system - Google Patents

Abstract

To provide a novel power supply system having both an uninterrupted power supply function and a load leveling function using common distributed power supplies while satisfying FRT requirements. The power supply system is provided with: distributed power supplies connected to a power line for supplying power from a commercial power system to an important load; a changeover switch provided on the commercial power system side with respect to the distributed power supplies in the power line and switching the power line; an impedance element connected in parallel with the changeover switch in the power line; a voltage detection unit for detecting voltage on the commercial power system side with respect to the changeover switch; a system abnormality detection unit for detecting, from the voltage detected by the voltage detection unit, a system abnormality on the commercial power system side; and a control unit for opening the changeover switch on the basis of the system abnormality detected by the system abnormality detection unit and connecting the distributed power supplies and the commercial power system through the impedance element. While the distributed power supplies and the commercial power system are connected with each other through the impedance element, the distributed power supplies continue operations including reverse power flow operation, and the system abnormality detection unit detects another system abnormality in addition to an instantaneous voltage drop and a frequency variation.

Description

Power system

The invention relates to a power supply system.

Power systems can be classified into non-blackout power systems and decentralized power systems. The non-blackout power system compensates for important loads by disconnecting from a commercial power system for power outages or transient voltage drops (hereinafter also referred to as transient drops). The power supply system is a power supply system that achieves load leveling such as peak cut or peak shift by charging and discharging a storage battery.

In recent years, with the improvement of battery performance, especially in large-capacity (500 kW capacitor level or above) battery systems, consideration is being given to simultaneously achieving a power supply function without interruption and a load leveling function. For example, as shown in Patent Document 1, a secondary battery system has been conceived that simultaneously realizes a non-blackout power supply function and a load leveling function. The system is configured to provide power to important loads by disconnecting power outages or transient drops.

However, the increase of distributed power sources interconnected with commercial power systems. If these distributed power sources are disconnected at the same time, it may have a significant impact on the maintenance of the voltage or frequency of the entire commercial power system. Therefore, technology is being sought to continue operation (unnecessary conditions for Fault Ride Through (FRT) during accidents) without disconnecting the distributed power source from the commercial power system even during a transient drop.

However, in the power supply system, the connection is disconnected at the time of the instantaneous drop, so the necessary conditions for FRT cannot be met. Also, as shown in Patent Document 2, a power supply system is also conceived to be a system that uses a battery for non-interruptible power supply and a battery for load leveling to individually perform each function, but the cost and size increase.
[Prior Art Literature]
[Patent Literature]

Patent Literature 1: Japanese Patent No. 3402886 Patent Literature 2: Japanese Patent Laid-Open No. 2004-289980

[Problems to be Solved by the Invention]

Therefore, the present invention has been made to solve the above-mentioned problems, and its main task is to provide a non-stop power supply function and a load for a normal commercial power supply method while simultaneously meeting the necessary conditions of FRT and using a common distributed power supply. Novel power system with leveling function.
[Technical means to solve the problem]

That is, the power supply system of the present invention is provided between a commercial power system and an important load, and the power system for supplying the important load includes a distributed power source connected to the important load from the commercial power system. A power line for supplying power; a switch disposed on the power line closer to the commercial power system than the distributed power source to open and close the power line; an impedance element connected in parallel to the switch on the power line ; A system-side voltage detection unit that detects a voltage closer to the commercial power system than the changeover switch; a system abnormality detection unit that detects the system on the commercial power system side based on the detection voltage of the system-side voltage detection unit An abnormality; and a control unit that turns on the switch based on a system abnormality detected by the system abnormality detection unit, and connects the distributed power source and the commercial power system via the impedance element; and In a state where the power source and the commercial power system are connected via the impedance element, the distributed power source continues Run line contains the backward flow (reverse power flow), the system detects abnormality detection unit in addition to the instantaneous voltage drop and the frequency variation, the system also detects other anomalies.

In the case of such a power supply system, a switch is provided on the side of the power line closer to the commercial power system than a distributed power supply, and an impedance element is connected in parallel to the switch. Based on the system detected by the system abnormality detection unit The changeover switch is turned on due to an abnormality, and therefore, even when the system is abnormal, the required equipment is connected to a commercial power system via an impedance element.
Especially in the present invention, for instantaneous voltage drop and frequency fluctuation, the equipment on the demand side becomes a state that is interconnected with the commercial power system via the impedance element, so that it can meet the FRT necessary conditions of the distributed power supply on the one hand and prevent system abnormality on the other. Voltage drop and frequency fluctuation to the important load. As a result, it is possible to provide a novel power supply system that satisfies the necessary conditions of the FRT on the one hand and uses a common decentralized power supply on the other hand to realize the power supply function without interruption and the load leveling function at the same time.

In addition, in the present invention, in addition to the instantaneous voltage drop and frequency fluctuations, in response to other system abnormalities, the demand-side equipment is also in a state of being interconnected with the commercial power system via the impedance element, so that it is possible to prevent unnecessary solution of the distributed power system. And prevent adverse effects on important loads when the system is abnormal. Here, it is considered that the system abnormality detection unit detects at least one of a phase change, a voltage imbalance, a harmonic abnormality, or a flicker as another system abnormality.

Here, it can be read from the interconnection rules that the phase variation, voltage imbalance, high-order harmonic abnormality or flicker are taken into account as system abnormal elements, and if three-phase to two-phase conversion is performed on the three-phase system voltage ( α-β-0 conversion) The plural expressions of the α component (set it as a real number component) and the β component (set it as an imaginary number component) are expressed by Equation 1.

[Equation 1]

Here, each element is as follows.
v: system voltage
V1: System voltage amplitude
f: System voltage frequency θ: The phase variation with the system voltage phase and phase jump is a change in the above-mentioned elements.
Σn ≠ 1vn: components other than the normal phase component of the fundamental wave, an inverse phase component with n = n1, and a higher harmonic component with | n | ≠ 1. In addition, flicker is a low-cycle fluctuation of several Hz to several tens Hz of V1.

As a result of the addition of system abnormalities based on this inspection, usually in non-blackout power supply systems, for phase changes, voltage imbalances, high-order harmonic abnormalities, or flickers that cannot be handled by non-blackout power supply systems of ordinary commercial power supply methods, The "compatible power supply system in which a parallel circuit portion of an impedance element and a switching switch is provided on the power line" can cope with the abnormality of the system at a low cost and in the same way as a higher-priced inverter-less power supply-free system Elements. As an example, the abnormality of the power supply system (overcurrent abnormality of the distributed power source in the simulation) can be prevented in advance as shown in the "simulation of the first embodiment" described later.

Furthermore, in the present invention, as long as a parallel circuit portion of the impedance element and the changeover switch is provided on the power line, the circuit structure of the device can be simplified, and the current flows into the changeover switch during normal operation, so the reactor (reactor) can be eliminated. ) Losses in iso-impedance components.

As the specific content of the control unit at the time of the instantaneous voltage drop, when the instantaneous voltage drop tolerance of the important load or the distributed power supply does not satisfy a predetermined stable range, the system abnormality detection unit detects the When the instantaneous voltage drop is greater than the instantaneous voltage drop tolerance and is included in the predetermined stable range, the switch is turned on. Here, the transient voltage drop tolerance of the important load or the distributed power source is an allowable voltage drop range in which the important load or the distributed power source can operate. The predetermined stable range of the instantaneous voltage drop is a voltage range required for the FRT. For example, it is a range in which the residual voltage is 20% or more and the duration is within 0.3 seconds.

In addition, as a specific control content of the frequency fluctuation control unit, when the frequency fluctuation tolerance of the important load or the distributed power source does not satisfy a predetermined stable range, the system abnormality detection unit When the detected frequency variation is equal to or more than the frequency variation tolerance and is included in the predetermined stable range, the switch is turned on. Here, the frequency tolerance of the important load or the distributed power source is an allowable frequency variation range in which the important load or the distributed power source can operate. The predetermined stable range of the frequency fluctuation is the frequency range required for the FRT. When the frequency variation is a step-up, the predetermined stable range is, for example, the range (50 Hz to 50.8 Hz, 60 Hz to 61.0) from the normal frequency (50 Hz or 60 Hz) to the predetermined variation value (50.8 Hz or 61.0 Hz). Hz). In addition, when the frequency fluctuation is ramp up and down, the predetermined stable range is within a range of a predetermined rate of change (± 2 Hz / second) from the normal frequency (50 Hz or 60 Hz), and reaches The range up to the upper or lower stable value of the specified amount.

At this time, it is desirable that, in a state where the distributed power source and the commercial power system are connected via the impedance element, the distributed power source continues to include inversion within the frequency tolerance range. The running of the tide. According to the configuration, even in the case of a system abnormality, the operation can be continued without disconnecting the distributed power source from the commercial power system, so that power can be supplied to an important load.
For example, when the frequency fluctuates, it can meet the necessary FRT requirements of the distributed power supply, and prevent the important load from falling off. Specifically, the distributed power source is connected to a commercial power system via an impedance element. When the voltage on the distributed power source side continues to operate below the frequency limit of the frequency tolerance, the voltage and frequency of the commercial power system side And the phases are different. On the other hand, by using an impedance element to suppress the cross-flow caused by these potential differences and the accompanying voltage fluctuations, the voltage supplied to the important load can be maintained while the voltage on the important load side is maintained at the limit frequency. · The current is stable.

As a specific operation mode of the distributed power source, it is desirable that, in a state where the distributed power source and the commercial power system are connected via the impedance element, the distributed power source is in the important load or state. The system described above continues to operate with reverse flow within a relatively small range of system abnormal tolerance.

In addition, the power supply system further includes a decoupling switch disposed on the power line closer to the commercial power system than the distributed power supply, and the control unit is configured to detect a voltage detected by the system-side voltage detection unit. The component of the disconnection switch is turned on when a predetermined disconnection condition is established. When the disconnection switch is turned on, the decentralized power supply supplies power to the important load and becomes an independent operation mode.

Further, it is desirable that the power supply system further includes a power supply-side voltage detection section that detects a voltage on the power line that is closer to the distributed power source than the decoupling switch. The control unit releases the predetermined disconnection condition from the detection voltage of the system-side voltage detection unit, and the detection voltage of the system-side voltage detection unit and the detection voltage of the power-side voltage detection unit meet predetermined synchronization identification conditions. At that time, the disconnection switch is turned on. Here, the predetermined synchronization identification condition means that the magnitude, frequency, and phase of the detection voltage of the system-side voltage detection section and the magnitude, frequency, and phase of the detection voltage of the power-side voltage detection section correspond to each other.

In addition, it is desirable that the power supply system further includes a protection device for system interconnection provided on the power line closer to the commercial power system than the disconnection switch, and detecting that the power line The disconnection switch is closer to the power-supply-side voltage detection section of the voltage on the side of the distributed power supply, the control section becomes inoperative in the system interconnection protection device, and the system-side voltage detection section When the detection voltage and the detection voltage of the power-supply-side voltage detection section satisfy the synchronization identification condition, the disconnection switch is turned on.
[Effect of the invention]

According to the present invention constituted as described above, a novel power supply system that satisfies the necessary conditions of FRT on the one hand, and uses a common distributed power supply at the same time to simultaneously realize the function as a non-interruptible power supply system and the function as a distributed power supply can be provided. .

<First Embodiment>
Hereinafter, a first embodiment of a power supply system according to the present invention will be described with reference to the drawings. As shown in FIG. 1, the power supply system 100 of this embodiment functions as a non-interruptible power supply system (non-interruptible power supply function) and as a distributed power supply system (load leveling function). The non-interruptible power supply system is provided. A power supply system that supplies power to the important load 30 when the commercial power system 10 is abnormal between the commercial power system 10 and the important load 30. The decentralized power system is performed by forming forward and reverse flows relative to the commercial power system. Load leveling power system.

Here, the commercial power system 10 is a power supply network of a power company (power provider), and includes a power station, a power transmission system, and a power distribution system. In addition, the important load 20 is a load that should stably supply power even when the system is abnormal such as power failure or instantaneous drop. One is shown in FIG. 1, but it may be plural.

Specifically, the power supply system 100 includes: a decentralized power supply 2; a changeover switch 3 that connects the commercial power system 10, a decentralized power supply 2 and an important load 30; an impedance element 4 connected in parallel with the changeover switch 3; and a system-side voltage detection The unit 5 detects a voltage closer to the commercial power system 10 than the switch 3; the system abnormality detecting unit 6 detects a system abnormality based on the detection voltage of the system-side voltage detecting unit 5; and the control unit 7 detects the system abnormality The detection signal of the unit 6 turns on the switch 3.

The distributed power source 2 is connected to a power line L1 for supplying power to the important load 30 from the commercial power system 10. The distributed power source 2 is a device interconnected with a commercial power system 10, and is, for example, a device including a direct current power generating device 21a such as solar power generation or a fuel cell and a power conversion device 22, and a power storage device including a secondary battery (battery). Power storage device) 21b and power conversion device 22, power generation equipment (not shown) that uses the power conversion device for system interconnection after rectifying the AC output power such as wind power or micro gas turbines into DC Or an AC power generating device 21c such as a synchronous generator or an induction generator. Furthermore, the power supply system 100 includes at least a power storage device 21b, and may also include any of the distributed power sources 2 described above.

The changeover switch 3 is provided on the power line L1 and is closer to the commercial power system 10 than the connection point of the distributed power source 2 to open and close the power line L1. For example, a semiconductor switch or a combination of a semiconductor switch and a mechanical switch can be used. High-speed switchable switches such as hybrid switches. For example, when a semiconductor switch is used, the switching time can be set to 2 milliseconds or less, and it can be turned off regardless of the zero point. In addition, when a hybrid switch is used, not only the switching time can be set to less than 2 milliseconds, it can be cut off regardless of the zero point, and the conduction loss can be made zero. It should be noted that the changeover switch 3 is opened and closed by the control unit 7.

The impedance element 4 is a member connected in parallel to the changeover switch 3 on the power line L1, and is a current-limiting reactor in the present embodiment.

The system-side voltage detection unit 5 is a component that detects the voltage on the power line L1 on the side of the commercial power system 10 than the switch 3 via the meter transformer 51. Specifically, the system-side voltage detection unit 5 is connected via the instrument transformer 51 to a side closer to the commercial power system 10 than the parallel circuit including the changeover switch 3 and the impedance element 4.

The system abnormality detection unit 6 is a component that detects each system abnormality closer to the commercial power system 10 than the switch 3 based on the detection voltage detected by the system-side voltage detection unit 5. The system abnormalities in this embodiment include voltage drop, voltage rise, frequency variation, phase variation, voltage imbalance, abnormal harmonics, and flicker including instantaneous drop.

Therefore, the system abnormality detection section 6 includes: a voltage drop detection section 61 that detects a voltage drop including a transient drop; a frequency change detection section 62 that detects a frequency change; a voltage rise detection section 63 that detects a voltage rise; a phase change detection section 64 that detects Phase variation; voltage imbalance detection section 65 detects voltage imbalance; abnormal harmonic detection section 66 detects abnormal harmonics; and flicker detection section 67 detects flicker.

The voltage drop unit 61 is a means for detecting a voltage drop by comparing the detection voltage of the system-side voltage detection unit 5 with a predetermined stable value. Here, the stable value used to detect a voltage drop is a voltage value used to detect a transient drop, for example, the remaining voltage is 20%.

The frequency variation detection unit 62 is a component that detects a frequency variation (frequency increase (OF), frequency decrease (UF)) based on the detection voltage of the system-side voltage detection unit 5. In addition, the frequency fluctuation is, for example, a step-up, a ramp-up, or a ramp-down.

The voltage rise detection unit 63 is a means for detecting a voltage rise by comparing the detection voltage of the system-side voltage detection unit 5 with a predetermined stable value. Here, the stable value for detecting the voltage rise is, for example, a voltage of 107% with respect to the system voltage.

The phase change detection unit 64 is a component that detects a phase change such as a phase jump of 10 ° based on the phase of the detection voltage of the system-side voltage detection unit 5.

The voltage imbalance detection unit 65 detects the amplitude of the three phases and the phase difference between the three phases by 120 ° based on the detection voltage of the system-side voltage detection unit 5.

The abnormal harmonic detection unit 66 is a means for detecting a harmonic voltage based on the detection voltage of the system-side voltage detection unit 5. The flicker detection unit 67 is a component that detects a voltage fluctuation (flicker) based on the detection voltage of the system-side voltage detection unit 5.

The control unit 7 outputs a control signal to the changeover switch 3 based on each detection signal detected by the system abnormality detection unit 6 and turns on the changeover switch 3. The control unit 7 of the present embodiment receives the detection signals from each of the detection units 61 to 67, and turns on the switch 3 when any one of the detection signals satisfies a condition (OR condition).

Specifically, when the transient drop tolerance of the important load 30 or the distributed power source 2 does not satisfy the predetermined stable range, the control section 7 detects that the transient drop detected by the voltage drop detection section 61 is greater than or equal to the transient drop tolerance and When it is within the predetermined stable range, turn on the switch 3. As a result, the commercial power system 10, the distributed power source 2, and the important load 30 are connected to each other via the impedance element 4. In this state, the distributed power source 2 continues to operate including reverse flow.

In addition, when the frequency variation tolerance of the important load 30 or the distributed power source 2 does not satisfy the predetermined stable range, the control unit 7 includes the frequency variation detected by the frequency variation detection unit 62 that is equal to or greater than the frequency variation tolerance and included in When the changeover switch 3 is turned on within a predetermined stable range, the commercial power system 10, the distributed power source 2, and the important load 30 are connected to each other via the impedance element 4. In this state, the distributed power source 2 continues to operate including reverse flow.

Further, the control unit 7 turns on the switch 3 when other system abnormalities detected by the system abnormality detection unit 63 to system abnormality detection unit 67 are greater than the tolerance of the important load 30 or the distributed power source 2 to other system abnormalities. As a result, the commercial power system 10, the distributed power source 2, and the important load 30 are connected to each other via the impedance element 4. In this state, the distributed power source 2 continues to operate including reverse flow.

The specific opening / closing control of the changeover switch 3 and the operation of the distributed power supply 2 by the control unit 7 will be described with reference to FIGS. 2 to 5.

In the normal state, as shown in FIG. 4, the power supply system 100 is in a state in which the switch 3 is closed, and the distributed power source 2 and the important load 30 are connected to the commercial power system 10 via the switch 3. Furthermore, the reactor 4 is connected in parallel with the switch 3, but the impedance of the switch 3 is smaller than the impedance of the reactor 4, so the commercial power system 10 exchanges power with the distributed power source 2 and the important load 30 on the switch 3 side. Peak reduction and peak shift can be achieved by the reverse flow of the distributed power supply 2.

Hereinafter, it is divided into (A) the opening / closing control of the changeover switch 3 and the operation of the decentralized power supply 2 (see FIG. 2), which are the elements (instantaneous drops and frequency fluctuations) described in the FRT requirements for the system interconnection rules (see Figure 2) Opening and closing control and dispersion of changeover switch 3 for elements not described in the FRT requirements for system interconnection rules (voltage drop, voltage rise, phase jump, voltage imbalance, harmonic anomalies, flicker) other than transient drops The operation of the power supply 2 (see FIG. 3) will be described.

(A) Opening / closing control of changeover switch 3 and operation of decentralized power supply 2 for elements (instantaneous drops and frequency fluctuations) described in FRT requirements for system interconnection rules (see Figure 2)

(1) When the system's abnormal tolerances (immediate drop tolerance, frequency fluctuation tolerance) of the distributed power supply 2 and the important load 30 meet the range of the FRT necessary conditions (the prescribed stability range), that is, when the commercial power system When the system abnormality of 10 (instantaneous drop, frequency change) is within the range required by the FRT ((1) in FIG. 2), the control unit 7 maintains the state where the changeover switch 3 is turned on. At this time, the distributed power source 2 continues to operate following the system abnormality (instantaneous drop, frequency fluctuation) of the commercial power system 10 (see FIG. 4).

(2) When the system abnormal tolerance (instantaneous drop tolerance, frequency change tolerance) of at least one of the distributed power source 2 or the important load 30 does not satisfy the range of the FRT necessary conditions, and when the commercial power system When the system abnormality of 10 (transient drop, frequency variation) is smaller than the system abnormal tolerance of the important load 30 or the distributed power source 2 (the (2) in FIG. 2), the control unit 7 maintains the The switch 3 is turned on. At this time, the distributed power source 2 continues to operate following the system abnormality (instantaneous drop, frequency fluctuation) of the commercial power system 10 (see FIG. 4).

(3) When the system abnormal tolerance (instantaneous drop tolerance, frequency change tolerance) of at least one of the distributed power source 2 or the important load 30 does not meet the range of the FRT necessary conditions, and when the commercial power system When the system abnormality (temporary drop, frequency variation) of 10 is greater than the relatively small system abnormal tolerance and is within the range required for FRT ((3) in FIG. 2), the control unit 7 turns on the switch 3. Then, the distributed power source 2 and the important load 30 are connected to the commercial power system 10 via the reactor 4. In this state, the distributed power supply 2 continues to operate within the range of the critical tolerance 30 where the system abnormal tolerance of the important load 30 or the distributed power supply 2 is relatively small (see FIG. 5).

Furthermore, the voltage drop detection unit 61 and the frequency change detection unit 62 detect the instantaneous drop and frequency variation of the commercial power system 10 regardless of whether the switch 3 is open or closed. The control unit 7 does not reach the instantaneous drop and frequency variation of the commercial power system 10. When the relatively small system abnormal tolerance (immediate drop tolerance, frequency fluctuation tolerance) is closed, the switch 3 is closed.

(B) Opening and closing of switch 3 for elements not described in the FRT requirements for system interconnection rules (voltage drop, voltage rise, phase jump, voltage imbalance, harmonic anomaly, flicker) other than transient drop Control and operation of distributed power supply 2 (see Figure 3)

(1) System anomaly of commercial power system 10 (voltage drop, voltage rise, phase jump, voltage imbalance, high-order harmonic abnormality, flicker) other than transient drop System anomaly smaller than important load 30 or distributed power source 2 When the system tolerance is relatively small among the tolerances ((1) in FIG. 3), the control unit 7 maintains the state in which the changeover switch 3 is turned on. At this time, the decentralized power supply 2 continues to operate following the system abnormality (voltage drop, voltage rise, phase jump, voltage imbalance, high-order harmonic abnormality, flicker) of the commercial power system 10 (refer to the figure) 4).

(2) The system abnormality (voltage drop, voltage rise, phase jump, voltage imbalance, high-order harmonic abnormality, flicker) of the commercial power system 10 is higher than the relatively small system abnormal tolerance In the case ((2) in FIG. 3), the control unit 7 turns on the changeover switch 3. Then, the distributed power source 2 and the important load 30 are connected to the commercial power system 10 via the reactor 4. In this state, the distributed power supply 2 continues to operate within the range of the critical tolerance 30 where the system abnormal tolerance of the important load 30 or the distributed power supply 2 is relatively small (see FIG. 5).

In addition, each of the detection unit 62, the detection units 64 to the detection unit 67 detects the system abnormality of the commercial power system 10 regardless of whether the switch 3 is open or closed. When the system has a small abnormal tolerance, the switch 3 is closed.

<Simulation of the first embodiment>
As an example of a system abnormality, the influence of a distributed power source when a phase jump (a phase jump of 10 °) occurs in a commercial power system is simulated. The simulated system model and the monitoring control model of the phase jump Δθ of the distributed power supply voltage v are shown in FIG. 6.

The voltage v, current i, and phase jump Δθ of the distributed power supply when the changeover switch is not operated are shown in FIG. 7. At a time of 0.5 seconds, a phase jump of 10 ° is generated in a commercial power system, and an overcurrent of 2.5 times the normal amplitude is generated in the current of the distributed power supply immediately.

The voltage v, current i, and phase jump Δθ of the distributed power supply when the changeover switch is operated are shown in FIG. 8. A phase jump of 10 ° is generated in the commercial power system at 0.5 seconds at the time, and the switch is turned on after 2 milliseconds by the phase jump detection. Turn on the switch at 0.6 seconds. As a transient phenomenon, the current i in the distributed power source generates a transient current of about 1.5 times the normal amplitude (a normal transient current caused by turning on the switch). In addition, in the phase control of the decentralized power supply when the switch is turned on (control that sequentially matches the phase of the commercial power system) or the phase change caused by the switch being turned on, the control is set to not detect.

From the simulation results, it can be seen that the voltage fluctuation when the phase jump occurs is about 10% of the voltage amplitude, and an overcurrent is generated. In this case, as long as the phase jump is monitored and the changeover switch (inserted impedance element) is turned on before a large phase jump occurs, it can prevent the distributed power supply from overcurrent if the overcurrent tolerance of the distributed power supply is 2.5 times. And unlinking.

<Effects of the First Embodiment>
According to the power supply system 100 of the present embodiment thus constituted, a switch 3 is provided on the power line L1 closer to the commercial power system 10 than the distributed power source 2, and an impedance element 4 is connected in parallel to the switch 3. Since the system abnormality detection unit 6 detects the system abnormality and turns on the switch 3, even when the system is abnormal, the demand-side equipment (important load 30) is in a state of being interconnected with the commercial power system 10 via the impedance element 4.

In particular, in this embodiment, the demand-side equipment is connected to the commercial power system via the impedance element 4 with respect to the instantaneous voltage drop and frequency fluctuation, so that it can meet the FRT necessary conditions of the distributed power source 2 and prevent A voltage drop and a frequency change supplied to the important load 30 when the system is abnormal. As a result, it is possible to provide a novel power supply system 100 that satisfies the necessary conditions of the FRT on the one hand, and uses the common decentralized power supply 2 on the other hand to simultaneously realize a non-blackout power supply function and a load leveling function.

In addition, in this embodiment, in addition to the instantaneous voltage drop and frequency fluctuation, for other system abnormalities, the demand-side equipment is also connected to the commercial power system 10 via the impedance element 4 to prevent the system from being important when the system is abnormal. Adverse effects of load 30.

Furthermore, in this embodiment, it is only necessary to provide a parallel circuit portion of the impedance element 4 and the changeover switch 3 on the power line L1. Therefore, the circuit structure of the device can be simplified, and the current flows into the changeover switch 3 during normal operation. The loss generated in the impedance element 4 such as a reactor is eliminated.

<Second Embodiment>
Next, a second embodiment of the power supply system of the present invention will be described with reference to the drawings. Although the first invention is omitted, as shown in FIG. 9, in the power supply system 100, a disconnection switch (power receiving point switch) is provided on the power line L1 side of the commercial power system 10 rather than the distributed power source 2. 8. In addition, in the power supply system 100 of the present embodiment, a power supply-side voltage detection section 9 is provided, which detects a voltage on the power line L1 that is closer to the distributed power supply 2 than the decoupling switch 8. .

The disconnection switch 8 according to this embodiment is an on-off switch for disconnecting the commercial power system 10 and the distributed power source 2, and is, for example, a mechanical switch. In FIG. 9, the decoupling switch 8 is disposed on the side of the commercial power system 10 more than the switch 3, but may also be disposed on the side of the decentralized power supply 2 than the switch 3. The disconnection switch 8 is controlled to be opened and closed by the control unit 7.

Then, the control unit 7 opens the disconnection switch 8 when the detection voltage of the system-side voltage detection unit 5 satisfies a predetermined disconnection condition. Here, the predetermined disconnection condition means that the continuous time of the voltage drop of the system voltage (the state where the detection voltage has fallen below a stable value) is equal to or greater than the predetermined value (a time longer than the duration of the transient drop). When the disconnection switch 8 is turned on, the decentralized power supply 2 becomes an independent operation mode and supplies power to the important load 30. Furthermore, since the change-over switch 3 has been turned off, an overcurrent generated due to the opening of the decoupling switch 8 is suppressed by the reactor 4.

In addition, the control unit 7 turns on when the detection voltage of the system-side voltage detection unit 5 releases a predetermined disconnection condition, and the detection voltage of the system-side voltage detection unit 5 and the detection voltage of the power-supply-side voltage detection unit 9 satisfy the synchronization identification condition, and then turns on. Disconnect switch 8. Here, the synchronization identification condition means, for example, that the magnitude, frequency, and phase of the voltage of the distributed power source 2 are consistent with the magnitude, frequency, and phase of the voltage of the commercial power system 10.

In addition, the control unit 7 opens the disconnection switch 8 even when other systems such as frequency fluctuations abnormally meet predetermined disconnection conditions. At this time, the control unit 7 turns on the disconnection switch 8 when the detected system abnormality becomes within the normal range.

＜ Other modified embodiments ＞
The present invention is not limited to the embodiments described above.

For example, in the embodiment described above, when any one of the system abnormalities satisfies the conditions, the switch is turned on, or when the combination of two or more system abnormalities satisfies a predetermined condition, the switch is turned on.

In addition, as the impedance element 4, a capacitor may be used, or any member of a reactor, a resistor, or a capacitor may be combined.

Furthermore, the system-side voltage detection unit according to the embodiment may include a protection device for system interconnection. Examples of protective devices for system interconnection specified in the system interconnection rules include overvoltage relay (OVR), undervoltage relay (UVR), and directional shortcircuit relay (DSR) , Overvoltage ground relay (OVGR), overfrequency relay (OFR), low frequency relay (UFR), transmission cut-off device, etc. In this case, it may be considered that the control unit turns on the disconnection switch when any of the interconnection protection devices is operating. In addition, the control unit may turn on the disconnection switch when the protection devices for system interconnection become inactive and the detection voltage of the system-side voltage detection unit and the detection voltage of the power-supply-side voltage detection unit meet the synchronization qualification conditions. . According to the above-mentioned structure, the voltage detection section included in the interconnection protection device is used, so there is no need to separately provide a system-side voltage detection section, and the device structure can be simplified.

In addition, although the power supply-side voltage detection unit of the embodiment is provided between the disconnection switch and the changeover switch, it may be used instead of a function of measuring a system connection point voltage of the distributed power supply.

It is needless to say that the present invention is not limited to the above-mentioned embodiment, and various modifications can be made without departing from the spirit thereof.

2‧‧‧ Distributed Power

3‧‧‧ switch

4‧‧‧Impedance element / reactor

5‧‧‧System-side voltage detection section

6‧‧‧System anomaly detection department

7‧‧‧Control Department

8‧‧‧ Disconnect switch (power receiving point switch)

9‧‧‧Power-side voltage detection section

10‧‧‧Commercial Power System

21a‧‧‧DC Power Generation Equipment

21b‧‧‧Power storage device

21c‧‧‧AC power generation equipment

22‧‧‧Power Conversion Device

30‧‧‧Important load

51‧‧‧ instrument transformer

61‧‧‧Voltage drop detection section

62‧‧‧Frequency change detection section

63‧‧‧Voltage rise detection section

64‧‧‧Phase change detection section

65‧‧‧Voltage imbalance detection section

66‧‧‧Anomaly harmonic detection section

67‧‧‧ flicker detection section

100‧‧‧ Power System

L1‧‧‧Power Line

FIG. 1 is a schematic diagram showing a configuration of a power supply system according to a first embodiment.

FIG. 2 is a table showing a list of operating states of the instantaneous drop and frequency fluctuations in the first embodiment.

FIG. 3 is a table showing a list of abnormal operating states of other systems in the first embodiment.

FIG. 4 is a schematic diagram showing a state of the power supply system in a normal state in the first embodiment.

FIG. 5 is a schematic diagram showing a state of the power supply system when the system is abnormal in the first embodiment.

FIG. 6 is a diagram showing a simulation model of a compensation operation during a phase jump.

FIG. 7 is a diagram showing a simulation result when the changeover switch is not operated.

FIG. 8 is a diagram showing a simulation result when the changeover switch is operated.

FIG. 9 is a schematic diagram showing a configuration of a power supply system according to a second embodiment.

Claims (9)

A power system is provided between a commercial power system and an important load, and supplies power to the important load. The power system includes: A distributed power source connected to a power line used to supply the important load from the commercial power system; A switch is disposed on the power line closer to the commercial power system than the distributed power source, so as to open and close the power line; An impedance element connected in parallel with the switch on the power line; A system-side voltage detection unit that detects a voltage closer to the commercial power system than the switch; A system abnormality detecting unit that detects a system abnormality of the commercial power system side based on a detection voltage of the system-side voltage detecting unit; and The control unit turns on the switch based on a system abnormality detected by the system abnormality detection unit, Connecting the distributed power source and the commercial power system via the impedance element, In a state where the distributed power source and the commercial power system are connected via the impedance element, the distributed power source continues to operate including reverse flow, The system abnormality detection section detects other system abnormalities in addition to the instantaneous voltage drop and frequency fluctuation. The power supply system according to item 1 of the patent application scope, wherein The system abnormality detection unit detects at least one of a voltage rise, a phase change, a voltage imbalance, a harmonic abnormality, or a flicker as the other system abnormality. The power supply system as described in claim 1 or 2, In the case where the instantaneous voltage drop tolerance of the important load or the distributed power supply does not satisfy a predetermined stable range, the control unit may detect the instantaneous voltage drop detected by the system abnormality detection unit as the instantaneous voltage drop. When the voltage drop tolerance is more than and is within the predetermined stable range, the switch is turned on, When the frequency variation tolerance of the important load or the distributed power supply does not satisfy a predetermined stable range, the frequency variation detected by the system abnormality detection unit is equal to or greater than the frequency variation tolerance and When it is included in the predetermined stable range, the switch is turned on. The power supply system according to any one of claims 1 to 3, wherein The control unit turns on the switch when the other system abnormality detected by the system abnormality detection unit is greater than the tolerance of the important load or the distributed power source to the other system abnormalities. The power supply system according to any one of claims 1 to 4 in the scope of patent application, wherein In a state where the distributed power source and the commercial power system are connected via the impedance element, the distributed power source is allowed to continue operation including reverse flow within a range of system abnormal tolerance. The power supply system according to item 5 of the patent application, wherein In a state where the distributed power source and the commercial power system are connected via the impedance element, the system abnormal tolerance of the distributed power source to the important load or the distributed power source is relatively small. Continuing operation including reverse flow within range. The power supply system according to any one of claims 1 to 6 of the scope of patent application, further including: A disconnection switch is provided on the power line closer to the commercial power system than the distributed power source; and The control unit turns on the decoupling switch when a detection voltage of the system-side voltage detection unit meets a predetermined decoupling condition, In a state where the decoupling switch is turned on, the decentralized power supply supplies power to the important load. The power supply system described in item 7 of the patent application scope further includes: A power-supply-side voltage detection unit that detects a voltage on the power line closer to the distributed power source than the decoupling switch; and The control unit releases the predetermined decoupling condition from the detection voltage of the system-side voltage detection unit, and the detection voltage of the system-side voltage detection unit and the detection voltage of the power-supply-side voltage detection unit satisfy the synchronization identification condition At that time, the disconnection switch is turned on. The power supply system described in item 7 of the patent application scope further includes: A protection device for system interconnection, which is arranged on the power line closer to the commercial power system than the disconnection switch; and A power supply side voltage detection unit that detects a voltage on the power line that is closer to the distributed power source than the decoupling switch; and The control unit turns on all the protection devices for system interconnection when the detection voltage of the system-side voltage detection unit and the detection voltage of the power-side voltage detection unit meet the synchronization identification conditions. Describe the combination switch.