Power System

Abstract

To provide a power system capable of continuing power supply to each load as much as possible at the time of autonomous operation.SOLUTION: A power system S1 to which a plurality of loads L1 to Ln are connected can perform autonomous operation. The power system S1 comprises: a storage battery 3 capable of supplying power to the plurality of loads L1 to Ln; a power source 1 capable of supplying power to the plurality of loads L1 to Ln; and an autonomous operation control unit 5 for performing control of the autonomous operation. For each of the plurality of loads L1 to Ln, a degree of importance showing order of priority of power supply in the autonomous operation is set. During the autonomous operation, the autonomous operation control unit 5 performs switching between a connection state and a cut-off state on each of power supply paths to the plurality of loads L1 to Ln on the basis of a charging rate of the storage battery 3, power which the power source 1 can supply, and respective degrees of importance of the plurality of loads L1 to Ln.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to power systems. [Background technology]

[0002] Conventionally, there are power systems that are connected to a power grid and supply power obtained from the power grid to loads. Some power systems operate autonomously by disconnecting from the power grid in the event of a power grid abnormality (e.g., a power outage). Power systems that operate autonomously include distributed power sources, and during autonomous operation, supply power obtained from the distributed power sources to loads without receiving power from the power grid. This allows power to be supplied to loads even during a power grid abnormality. For example, Patent Document 1 discloses a power system that operates autonomously. The power system described in Patent Document 1 includes batteries as distributed power sources, and during autonomous operation, supplies power to loads by discharging the batteries. At this time, the number of loads to which power is supplied is changed depending on the battery's state of charge (SoC). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2020 / 230264 Summary of the Invention [Problem to be solved by the invention]

[0004] In the configuration described in Patent Document 1, during autonomous operation, only the battery supplies power to the loads, and when the battery's charging rate falls below a predetermined threshold (the third threshold in Patent Document 1), power supply to each load stops.

[0005] The present disclosure has been made in view of the above circumstances, and its purpose is to provide a power system that can continue to supply power to each load as long as possible during independent operation. [Means for solving the problem]

[0006] The power system disclosed herein is a power system capable of independent operation with multiple loads connected thereto, and comprises a storage battery capable of supplying power to the multiple loads, a power source capable of supplying power to the multiple loads, and an independent operation control unit that controls the independent operation, wherein an importance level is set for each of the multiple loads indicating the priority of power supply during the independent operation, and during the independent operation, the independent operation control unit switches each power supply path to the multiple loads between a connected state and a disconnected state based on the charging rate of the storage battery, the supplyable power of the power source, and the importance of each of the multiple loads.

[0007] In a preferred embodiment of the power system, the independent operation control unit estimates the current available power supply of the power source based on the current state of the power source.

[0008] In a preferred embodiment of the power system, the independent operation control unit estimates future available power supply of the power source based on a schedule of changes in the state of the power source.

[0009] In a preferred embodiment of the power system, the power system further includes a battery charge / discharge control unit that charges and discharges the battery, wherein the power source supplies power based on the output voltage of the battery charge / discharge control unit during the independent operation, the plurality of loads includes a most important load having the highest importance, and when the available power falls below the power consumption of the most important load and the charging rate of the battery falls below a first threshold, the independent operation control unit suspends the independent operation while continuing only a part of the battery charge / discharge control unit, and the first threshold is a value corresponding to a lower limit value for continuing operation for continuing only a part of the battery charge / discharge control unit.

[0010] In a preferred embodiment of the power system, the independent operation control unit resumes the independent operation when the supplyable power becomes equal to or greater than a second threshold value based on the power consumption of the most important load while the independent operation is suspended. [Effects of the Invention]

[0011] According to the power system of the present disclosure, the power supply paths to multiple loads are switched between connected and disconnected states, taking into consideration not only the charge rate of the storage battery but also the available power supply of the power source. Therefore, during autonomous operation, it is possible to continue the power supply to each load as long as possible depending on the state of the power source. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a diagram illustrating an example of the overall configuration of a power system; [Figure 2] FIG. 2 is a diagram showing the basic processing of the independent operation control performed by the independent operation control unit. [Figure 3] FIG. 10 is a diagram showing a process of pausing the independent operation control performed by the independent operation control unit. DETAILED DESCRIPTION OF THE INVENTION

[0013] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the power system of the present disclosure will be described below with reference to the accompanying drawings. In the following, identical or similar components will be designated by the same reference numerals, and redundant description will be omitted.

[0014] Fig. 1 shows an example of the overall configuration of a power system S1 according to this embodiment. The power system S1 includes multiple loads L1-Ln, multiple switches SW1-SWn, multiple power sources 1, multiple power control devices 2, a storage battery 3, a storage battery power conditioner 4 (hereinafter referred to as "storage battery PCS4"), and an interconnection board C1 (n is an integer of 2 or more). In the power system S1, the storage battery PCS4 also includes an independent operation control unit 5. In Fig. 1, thick connection lines are power lines, and thin connection lines are signal lines.

[0015] When connected to power system K, power system S1 performs grid-connected operation. On the other hand, when power system S1 experiences a power outage or abnormality in power system K, power system S1 is disconnected from power system K and performs isolated operation (non-grid-connected operation). FIG. 1 shows a state in which power system S1 is disconnected from power system K. During isolated operation, power system S1 selectively switches to which of multiple loads L1 to Ln it supplies power. The isolated operation of power system S1 is controlled by an isolated operation control unit 5.

[0016] Each of the loads L1 to Ln is connected to the interconnection board C1 via a corresponding one of the switches SW1 to SWn. The i-th load Li (i = an integer from 1 to n) is connected to the interconnection board C1 via the i-th switch SWi. The switches SW1 to SWn can communicate with the isolated operation control unit 5 (described later) and are switched between a connected state (on) and an open state (off) by a switching signal input from the isolated operation control unit 5. When the switch SWi is in the connected state, the power supply path from the interconnection board C1 to the load Li is connected, and power is supplied from the interconnection board C1 to the load Li. On the other hand, when the switch SWi is in the open state, the power supply path from the interconnection board C1 to the load Li is interrupted, and no power is supplied to the load Li. FIG. 1 shows an example in which all of the switches SW1 to SWn are in the connected state. When the switches SW1 to SWn are in the open state, the state shown by the two-dot chain line in FIG. 1 is achieved. Each of the multiple switches SW1 to SWn is, for example, a vacuum circuit breaker. In the power system S1, power is selectively supplied to multiple loads L1 to Ln under the isolated operation control of the isolated operation control unit 5. Hereinafter, of the multiple loads L1 to Ln, one that is supplied with power during isolated operation control will be referred to as a closed load Lo, and one that is not supplied with power will be referred to as an open load Lx. Furthermore, of the multiple switches SW1 to SWn, one that is connected to the closed load Lo will be referred to as a switch SWo, and one that is connected to the open load Lx will be referred to as a switch SWx.

[0017] The interconnection board C1 has a power distribution function and a grid interconnection function (e.g., a grid interconnection protection function, an FRT function, a reverse power flow power limiting function, a voltage adjustment function, a constant power factor control function, etc.). In the power distribution function, the interconnection board C1 supplies input power to multiple loads L1 to Ln. In addition, in the power distribution function, the interconnection board C1 also supplies input power to the storage battery PCS4 and some of the multiple power control devices 2 (EV (Electric Vehicle) chargers / dischargers 22 described below) as necessary. In the grid interconnection function, for example, when the interconnection board C1 detects a power outage in the power grid K, it disconnects the power system S1 from the power grid K. In addition, in the grid interconnection function, when the interconnection board C1 detects recovery of the power grid K from the power outage, it connects the power system S1 to the power grid K.

[0018] The multiple power sources 1 and storage battery 3 are each capable of supplying power to multiple loads L1 to Ln. In the power system S1, the multiple power sources 1 include a solar cell 11, an electric vehicle 12, and a generator 13. The solar cell 11 generates power by converting light energy such as sunlight into electrical energy (power). The electric vehicle 12 runs on power stored in an internal battery. In this disclosure, charging and discharging of the electric vehicle 12 refers to charging and discharging of this internal battery. The generator 13 generates power by converting energy other than electrical power into electrical energy (power). Examples of the generator 13 include a hydroelectric generator using a water wheel, a wind power generator using a wind wheel, and an internal combustion generator (e.g., a diesel generator) using an internal combustion engine (e.g., a diesel engine). The storage battery 3 is capable of being repeatedly charged and discharged, and is, for example, a secondary battery or a capacitor.

[0019] Each of the multiple power control devices 2 controls each of the multiple power sources 1. Each power control device 2 is connected between the grid interconnection panel C1 and each power source 1. Each power control device 2 is capable of communicating with a storage battery PCS 4 (independent operation control unit 5). In the example shown in FIG. 1, the multiple power control devices 2 include a solar power PCS 21, an EV charger / discharger 22, and a generator controller 23.

[0020] The solar PCS21 controls the output of the solar cell 11. The solar PCS21 includes a solar power generation control unit 211. The solar power generation control unit 211 is electrically connected between the solar cell 11 and the grid connection board C1. The solar power generation control unit 211 outputs the power generated by the solar cell 11 to the grid connection board C1. In the example shown in FIG. 1 , one solar cell 11 is connected to one solar PCS21, but multiple solar cells 11 may be connected to one solar PCS21.

[0021] EV charger / discharger 22 controls the charging and discharging of electric vehicle 12. EV charger / discharger 22 includes an EV charge / discharge control unit 221. EV charge / discharge control unit 221 is electrically connected between electric vehicle 12 and grid connection panel C1. EV charge / discharge control unit 221 discharges electric vehicle 12 by outputting power stored in electric vehicle 12 to grid connection panel C1, and charges electric vehicle 12 by outputting power supplied from grid connection panel C1 to electric vehicle 12. In the example shown in FIG. 1 , one electric vehicle 12 is connected to one EV charger / discharger 22, but multiple electric vehicles 12 may be connected to one EV charger / discharger 22.

[0022] The generator controller 23 controls the output of the generator 13. The generator controller 23 includes a generator control unit 231. The generator control unit 231 is electrically connected between the generator 13 and the grid interconnection board C1. The generator control unit 231 outputs the power generated by the generator 13 to the grid interconnection board C1. The generator controller 23 may be configured to operate the generator 13 only when the power system S1 is in independent operation, or may be configured to operate the generator 13 both when the power system S1 is in independent operation and when it is in grid-connected operation.

[0023] Although not shown in the figures, the solar power generation control unit 211, the EV charge / discharge control unit 221, and the generator control unit 231 each include at least an inverter circuit, a control circuit, and a communication circuit. The inverter circuit performs power conversion in each power control device 2. The control circuit controls the inverter circuit. The communication circuit communicates with the isolated operation control unit 5.

[0024] The storage battery PCS4 controls charging and discharging of the storage battery 3 and controls the independent operation of the power system S1. The storage battery PCS4 operates using the power stored in the storage battery 3. The storage battery PCS4 includes a storage battery charge / discharge control unit 411 and an independent operation control unit 5.

[0025] The battery charge / discharge control unit 411 is electrically connected between the storage battery 3 and the grid interconnection board C1. The battery charge / discharge control unit 411 discharges the storage battery 3 by outputting the power stored in the storage battery 3 to the grid interconnection board C1, and charges the storage battery 3 by outputting the power supplied from the grid interconnection board C1 to the storage battery 3. In the example shown in FIG. 1 , one storage battery 3 is connected to one storage battery charge / discharge control unit 411, but multiple storage batteries 3 may be connected to one storage battery charge / discharge control unit 411. Although not shown, the battery charge / discharge control unit 411 includes at least an inverter circuit, a control circuit, and a communication circuit. The inverter circuit performs power conversion in the storage battery PCS4. The control circuit controls the inverter circuit. The communication circuit communicates with the isolated operation control unit 5.

[0026] The independent operation control unit 5 controls independent operation when the power system S1 is disconnected from the power system K. The independent operation control unit 5 does not control independent operation when the power system S1 is connected to the grid. The independent operation control unit 5 determines whether the power system S1 is disconnected from the power system K, for example, based on information from the grid interconnection panel C1. The independent operation control unit 5 is provided in the storage battery PCS4, and during independent operation, causes the storage battery charge / discharge control unit 411 to control the storage battery PCS4 to serve as a voltage source. During independent operation control, the independent operation control unit 5 switches each switch SW1 to SWn between a connected state and an open state, and selectively cuts off the power supply path from the grid interconnection panel C1 to each load L1 to Ln. In other words, during independent operation control, the independent operation control unit 5 divides the multiple loads L1 to Ln into connected loads Lo to which power is supplied and open loads Lx to which power is not supplied. At this time, the independent operation control unit 5 uses the charge rate of the storage battery 3, the supplyable power of the multiple power sources 1, and information on the importance of each of the multiple loads L1 to Ln to select between the connected load Lo and the disconnected load Lx.

[0027] The importance of the multiple loads L1 to Ln is set in the independent operation control unit 5 in advance or by user input. The importance is information indicating the priority of power supply to the multiple loads L1 to Ln. The higher the importance, the higher the priority of power supply during independent operation. In other words, during independent operation, the power system S1 is more likely to continue power supply to loads with higher importance, and more likely to cut off power supply to loads with lower importance. In this embodiment, load L1 has the highest importance and is the most important load. Next, load L2, load L3, ..., load Ln-1, and load Ln have increasing importance in this order. Note that some of the multiple loads L1 to Ln may have the same importance. For example, in a certain business establishment, the power supply for the main system within the business establishment has the highest importance, followed by emergency lighting, employees' personal computers, ventilation equipment, air conditioning equipment, general lighting, elevators, etc. in decreasing order of importance. Furthermore, the importance of each of the loads L1 to Ln may be set for each of the loads L1 to Ln, and the independent operation control unit 5 may acquire information on the importance of each of the loads L1 to Ln from each of the loads L1 to Ln.

[0028] The charging rate of the storage battery 3 is acquired by communication from the storage battery charge / discharge control unit 411. In an example in which the independent operation control unit 5 is installed in the storage battery PCS 4, the independent operation control unit 5 may acquire the charging rate of the storage battery 3 directly from the storage battery 3.

[0029] The suppliable power of each power source 1 is estimated based on information indicating the state of each power source 1 acquired through communication with each power control device 2. In the power system S1, the independent operation control unit 5 acquires information indicating the current state of each power source 1 (hereinafter referred to as "current state data") through communication with each power control device 2, and estimates the current suppliable power of each power source 1 based on the acquired current state data. The independent operation control unit 5 also acquires information indicating planned (or predicted) changes in the future state of each power source 1 (hereinafter referred to as "transition prediction data") through communication with each power control device 2, and estimates the future suppliable power of each power source 1 based on the acquired transition prediction data. For example, the independent operation control unit 5 acquires the following information about each power source 1 as current state data or transition prediction data, and estimates the current and future suppliable power of each power source 1:

[0030] The independent operation control unit 5 acquires, through communication with the solar PCS 21, information on the current solar radiation intensity (e.g., measurement values ​​from an actinometer) at the installation location of the solar cell 11 as current state data of the solar cell 11. Then, using the acquired current state data of the solar cell 11, it estimates the current power generation capacity of the solar cell 11. Furthermore, through communication with the solar PCS 21, the independent operation control unit 5 acquires information on predicted future changes in solar radiation intensity at the installation location of the solar cell 11 (e.g., weather forecasts, past solar radiation information, seasons, etc.) as change prediction data of the solar cell 11. Then, using the acquired change prediction data of the solar cell 11, it estimates the future power generation capacity of the solar cell 11. Note that specification information of the solar cell 11 (e.g., maximum output and conversion efficiency, etc.) used when estimating the power generation capacity may be acquired from the solar PCS 21 or may be set in advance in the independent operation control unit 5. Furthermore, the locations from which the current state data of the solar cell 11 and the change prediction data of the solar cell 11 are acquired are not limited to the above examples. For example, the autonomous operation control unit 5 may obtain the current solar radiation intensity directly from a pyranometer, or may obtain weather forecasts and past solar radiation information from the Internet or other management devices, or may obtain (determine) seasonal information from a timer (not shown) in the autonomous operation control unit 5.

[0031] The autonomous driving control unit 5 communicates with the EV charger / discharger 22 to acquire information such as whether the electric vehicle 12 is connected to the EV charger / discharger 22 and the charging rate of the electric vehicle 12 as current state data of the electric vehicle 12. The acquired current state data of the electric vehicle 12 is then used to estimate the current dischargeable amount of the electric vehicle 12. The autonomous driving control unit 5 also communicates with the EV charger / discharger 22 to acquire information such as the planned connection of the electric vehicle 12 as predicted change data of the electric vehicle 12. The acquired predicted change data of the electric vehicle 12 is then used to estimate the future dischargeable amount of the electric vehicle 12. Note that specification information of the electric vehicle 12 (e.g., rated discharge capacity and discharge C rate) used to estimate the dischargeable amount may be acquired from the EV charger / discharger 22 or may be set in advance in the autonomous driving control unit 5. The locations where the current state data of the electric vehicle 12 and the predicted change data of the electric vehicle 12 are acquired are not limited to the examples described above. For example, the autonomous driving control unit 5 may obtain information on whether the electric vehicle 12 is connected or not and information on the planned connection of the electric vehicle 12 from the Internet or another management device, or may obtain the charging rate of the electric vehicle 12 directly from the electric vehicle 12.

[0032] The independent operation control unit 5 communicates with the generator controller 23 to acquire, as current state data for the generator 13, information on the remaining fuel if the generator 13 is an internal combustion generator, the flow rate (e.g., a flow meter measurement value) at the location where the water turbine is installed if the generator 13 is a hydroelectric generator, and the wind volume and wind speed (e.g., the measurement values ​​of an air volume meter and an anemometer) at the location where the wind turbine is installed if the generator 13 is a wind turbine. The independent operation control unit 5 then estimates the current power generation capacity of the generator 13 using the acquired current state data for the generator 13. The independent operation control unit 5 also communicates with the generator controller 23 to acquire, as predicted transition data for the generator 13, information on expected changes in the remaining fuel (e.g., replenishment schedule and consumption forecast, etc.) if the generator 13 is an internal combustion generator, expected changes in the flow rate (e.g., weather forecast, past flow rate information, season, etc.) at the location where the water turbine is installed if the generator 13 is a hydroelectric generator, and expected changes in the wind volume and wind speed (e.g., weather forecast, past wind volume information and wind speed information, season, etc.) at the location where the wind turbine is installed if the generator 13 is a wind turbine. The future power generation capacity of the generator 13 is then estimated using the acquired predicted change data of the generator 13. Note that specification information of the generator 13 (such as maximum output, rated capacity, and conversion efficiency) used when estimating the possible power generation capacity may be acquired from the generator controller 23 or may be set in advance in the independent operation control unit 5. Furthermore, the locations where the current state data of the generator 13 and the predicted change data of the generator 13 are acquired are not limited to the above examples. For example, the independent operation control unit 5 may directly acquire the remaining fuel amount from the internal combustion generator, the flow rate from a flow meter, or the wind volume and wind speed from an air volume meter and an anemometer, respectively, or may acquire the expected change in the remaining fuel amount, the expected change in the flow rate, or the expected change in the wind volume and wind speed, respectively, from the Internet or another management device.

[0033] During autonomous operation, the autonomous operation control unit 5 makes a comprehensive judgment based on the charging rate of the storage battery 3, the supplyable power of each of the multiple power sources 1, and the importance of each of the multiple loads L1 to Ln, and switches each power supply path to the multiple loads L1 to Ln between a connected state and a disconnected state.

[0034] In the example shown in Fig. 1, the independent operation control unit 5 is provided in the storage battery PCS 4, but instead of this configuration, it may be provided in any of the multiple power control devices 2 (the solar PCS 21, the EV charger / discharger 22, and the generator controller 23). In other words, any of the solar PCS 21, the EV charger / discharger 22, or the generator controller 23 may perform independent operation control. In this case, the power control device 2 provided with the independent operation control unit 5 operates as a voltage source, rather than the storage battery PCS 4. Alternatively, the independent operation control unit 5 may be configured as a single device on its own.

[0035] Figures 2 and 3 are flowcharts showing the independent operation control performed by the independent operation control unit 5. Figure 2 is an example of the basic processing of the independent operation control, and Figure 3 is an example of the pause processing performed in parallel with the basic processing shown in Figure 2. The independent operation control unit 5 continues to repeatedly perform each of the processing shown in Figures 2 and 3 until the system power supply of the power system S1 is turned off.

[0036] First, the basic processing of the independent operation control will be described with reference to FIG. 2. The independent operation control unit 5 repeatedly executes the basic processing shown in FIG. 2, for example, every 1 second to 1 minute, while the power system S1 is disconnected from the power system K. The independent operation control unit 5 does not execute the basic processing shown in FIG. 2 while the power system S1 is connected to the power system K. The independent operation control unit 5 determines whether the power system S1 is connected to or disconnected from the power system K based on information from the interconnection panel C1. The control cycle of the basic processing is not limited to the numerical example (1 second to 1 minute) described above. The independent operation control unit 5 may also execute the basic processing triggered by some processing or change, rather than time. For example, the independent operation control unit 5 may execute the basic processing every time the charging rate of the storage battery 3 is checked.

[0037] 2, in the basic processing of the isolated operation control, the isolated operation control unit 5 first acquires predicted fluctuation data of the power source 1 from each power control device 2, and estimates the future available power supply from the acquired predicted fluctuation data (S101). Next, the isolated operation control unit 5 acquires current state data of the power source 1 from each power control device 2, and estimates the current available power supply from the acquired current state data (S102). Note that the order of steps S101 and S102 may be reversed.

[0038] Next, the autonomous operation control unit 5 calculates the available power supply for each predetermined time period and creates a schedule of the available power supply (S103). The time periods may be divided into periods of time, but are not limited to, for example, 10 minutes, 30 minutes, 1 hour, 2 hours, or 3 hours. The available power supply for each time period may be the total value of the multiple power sources 1, or an individual value for each of the multiple power sources 1. The period for creating the available power supply schedule is not limited to, but may be, for example, 24 hours, one week, or one month. When creating the available power supply schedule in step S103, operating conditions for each power source 1 may be set as appropriate. For example, if the generator 13 is a diesel generator, power generation by the generator 13 is limited to when the solar cell 11 cannot generate power (e.g., at night) or when the amount of power generated by the solar cell 11 is low (e.g., on rainy days). If the charging rate of the electric vehicle 12 is below a predetermined value, discharging of the electric vehicle 12 is prohibited.

[0039] Next, the independent operation control unit 5 comprehensively determines the power consumption and importance of each of the multiple loads L1 to Ln, the schedule of available power supply (such as changes in the current available power supply and future available power supply), the discharge amount and duration of discharge calculated from the charge rate and discharge C rate of the storage battery 3, and so on, and sorts the multiple loads L1 to Ln into an applied load Lo to which power is supplied and an open load Lx to which power is not supplied (S104). At this time, the independent operation control unit 5 sorts each load L1 to Ln into an applied load Lo or an open load Lx at the current time. At this time, the independent operation control unit 5 may further schedule each load L1 to Ln as an applied load Lo or an open load Lx for each predetermined time slot in step S104. By scheduling the applied load Lo and the open load Lx for each predetermined time slot in this way, the user can be notified of the scheduling information, allowing the user to check the future availability status of each load L1 to Ln.

[0040] In the sorting in step S104, power supply to the load L1 with the highest importance is continued as long as possible. In other words, the load L1 is set to be the applied load Lo for as long as possible. Also, in the sorting in step S104, the number of applied loads Lo may be reduced to intentionally lower the power consumption below the available power supply, and the surplus power may be used to charge the storage battery 3 or the electric vehicle 12. For example, the applied load Lo may be set to ensure the respective charging rates of the storage battery 3 and the electric vehicle 12 in preparation for when the solar cell 11 is unable to generate power (e.g., at night) or when the amount of power generated by the solar cell 11 is low (e.g., on a rainy day). Also, in the sorting of the applied loads Lo and the open loads Lx in step S104, among the multiple loads L1 to Ln, those with a predetermined or lower importance may be uniformly set to the open loads Lx during autonomous operation.

[0041] In step S104, the independent operation control unit 5 selects whether to set the applied load Lo or the open load Lx, for example, as follows: From the current time and the schedule of available power supply, the future available power supply of the solar cell 11 and the future available power supply of the generator 13 are confirmed, and the remaining hours of independent operation are calculated based on the discharge of the storage battery 3 and the discharge of the electric vehicle 12. Alternatively, the future available power supply of the solar cell 11 is confirmed, and the remaining hours of power generation by the solar cell 11 are calculated. Then, from the charge rates of the storage battery 3 and the electric vehicle 12, the maximum kW that can be discharged before the solar cell 11 starts generating power is calculated, or the maximum kW that can be discharged after the solar cell 11 has finished generating power until the solar cell 11 starts generating power the following morning is calculated to continue independent operation, and the applied load Lo is determined based on the calculated data (a load that is not the applied load Lo is the open load Lx).

[0042] Next, the independent operation control unit 5 switches each of the switches SW1 to SWn based on the selection result in step S104 (S105). Specifically, for a load selected as an applied load Lo from the selection result in step S104, the independent operation control unit 5 connects the switch SWo to which the applied load Lo is connected, and connects the power supply path from the interconnection panel C1 to the applied load Lo. Furthermore, for a load selected as an open load Lx, the independent operation control unit 5 opens the switch SWx to which the open load Lx is connected, and cuts off the power supply path from the interconnection panel C1 to the open load Lx.

[0043] In the power system S1, by performing the basic processing of the isolated operation control described above, it is possible to appropriately change the operation method of the isolated operation control by scheduling the available power supply and sorting between the applied loads Lo and the open loads Lx. For example, by reducing the number of applied loads Lo and using the power supply from each power source 1 as the main power supply and the secondary discharge of the storage battery 3, the power supply time of the most important load (the load L1 with the highest importance) can be extended, and at the same time, the isolated operation can be operated so that the power supply is continued as much as possible in descending order of importance. Furthermore, by increasing the number of applied loads Lo and actively supplying power from each power source 1 and discharging the storage battery 3, the isolated operation can be operated so that the number of applied loads Lo is increased.

[0044] Next, the pause processing of the independent operation control will be described with reference to Fig. 3. As described above, the pause processing of the independent operation control is performed in parallel with the basic processing shown in Fig. 2. However, while part of the pause processing shown in Fig. 3 is being executed, the basic processing shown in Fig. 2 is interrupted.

[0045] As shown in FIG. 3, in the suspension process of the autonomous driving control, the autonomous driving control unit 5 determines whether the current available power Pt is less than the power consumption PL1 of the load L1, which is the most important load, in a state where only the load L1, which is the most important load, is the input load Lo (S201). If it is determined in step S201 that it is not less than (Pt≧PL1) (S201: NO), the determination in step S201 is repeated. On the other hand, if it is determined in step S201 that it is less than (Pt<PL1), then it is determined whether the charge rate of the storage battery 3 is less than or equal to a predetermined first threshold value (S202). This first threshold value is a value for not completely stopping the storage battery PCS4 operating with the power of the storage battery 3 for a predetermined period, and is set based on the amount of power (lower limit value for continuous operation) required to continuously operate a part (for example, a communication circuit) of the storage battery charge / discharge control unit 411 and the autonomous driving control unit 5 for a predetermined time. In the present embodiment, the above-mentioned first threshold value, that is, the lower limit value for continuous operation is, for example, 5 “%”. In a configuration where the autonomous driving control unit 5 is not provided in the storage battery PCS4, the above-mentioned first threshold value is the lower limit value for continuous operation for continuously operating the communication circuit of the storage battery charge / discharge control unit 411 for a predetermined period. If it is determined in step S202 that it is not less than the first threshold value (greater than the first threshold value) (S202: NO), the storage battery 3 is discharged to supply power to the load L1. Then, the process returns to the determination in step S201. On the other hand, if it is determined in step S202 that it is less than or equal to the first threshold value (S202: YES), the autonomous driving is suspended (S203). The suspension of the autonomous driving is, for example, to stop the power supply from the storage battery 3 to the inverter circuit and the control circuit of the storage battery charge / discharge control unit 411. At this time, the power supply from the storage battery 3 to the communication circuit of the storage battery charge / discharge control unit 411 and the autonomous driving control unit 5 is not stopped. When the autonomous driving is suspended in step S203, the basic process shown in FIG. 2 is interrupted.

[0046] Next, during the suspension of autonomous operation in step S203, it is determined whether the current available power Pt is equal to or greater than a second threshold value based on the power consumption of load L1, which is the most important load. Specifically, as shown in FIG. 3, the autonomous operation control unit 5 determines whether the current available power Pt is greater than or equal to a certain value α more than the power consumption PL1 of load L1, which is the most important load (S204). That is, in the present embodiment, the above-mentioned second threshold value is the sum of the power consumption PL1 and the certain value α, and the autonomous operation control unit 5 determines in step S204 whether Pt ≧ PL1 + α. Note that the certain value α may include 0 (zero). In this case, the autonomous operation control unit 5 determines in step S204 whether the current available power Pt is equal to or greater than the power consumption PL1. If it is determined in step S204 that it is not equal to or greater than the second threshold value (Pt < PL1 + α) (S204: NO), the suspension of autonomous operation is continued, and the determination in step S204 is repeated. On the other hand, if it is determined in step S204 that it is equal to or greater than the second threshold value (Pt ≧ PL1 + α) (S204: YES), the autonomous operation control unit 5 resumes the power supply from the storage battery 3 to the inverter circuit and the control circuit of the battery charge / discharge control unit 411 to resume autonomous operation. For example, when a new electric vehicle 12 is newly connected to the EV charger 22 or the solar radiation intensity on the solar cell 11 increases, the current available power Pt increases. When the autonomous operation control unit 5 resumes autonomous operation, the basic process shown in FIG . 2 is also resumed. Then, the autonomous operation control unit 5 returns to the determination in step S204.

[0047] The operations and effects of the power system S1 are as follows.

[0048] The power system S1 includes a power source 1 capable of supplying power to multiple loads L1 to Ln. The power source 1 is, for example, a solar cell 11, an electric vehicle 12, or a generator 13. During the independent operation of the power system S1, the independent operation control unit 5 switches between connected and disconnected states for each power supply path from the interconnection panel C1 to the multiple loads L1 to Ln based on the state of charge of the storage battery 3, the power that can be supplied by the power source 1, and the importance of each of the loads L1 to Ln. With this configuration, even if the state of charge of the storage battery 3 drops to a level where it cannot be discharged, the independent operation can be continued as long as power can be supplied from the power source 1. Furthermore, during the independent operation, the power system S1 can continue to supply power to each load as long as possible depending on the state of the power source 1.

[0049] In the power system S1, the independent operation control unit 5 acquires information (current state data) indicating the current state of each power source 1 and estimates the current suppliable power of each power source 1 from this current state data. The independent operation control unit 5 also acquires information (transition prediction data) indicating a planned change in the future state of each power source 1 and estimates the future suppliable power of each power source 1 from this transition prediction data. The independent operation control unit 5 then creates a schedule of suppliable power using the current suppliable power and future suppliable power of each power source 1. With this configuration, the independent operation control unit 5 can take into account the future suppliable power of each power source 1 when sorting multiple loads L1 to Ln into applied loads Lo to which power will be supplied and open loads Lx to which power will be supplied. This allows the independent operation control unit 5 to control the independent operation while referring to the future suppliable power. Therefore, for example, it is possible to operate the independent operation so as to extend the time for which power is supplied to the load L1, which is the most important load, as long as possible while also supplying power to the other loads L2 to Ln as much as possible. Alternatively, for example, it is also possible to operate the isolated operation so that the number of input loads Lo to which power is supplied increases. Therefore, the power system S1 can flexibly operate the isolated operation by controlling the power system S1 while taking into account the future available power supply of each power source 1.

[0050] In the power system S1, when the current available power supply Pt of the power source 1 falls below the power consumption PL1 of the load L1, which is the most important load, and the charging rate of the storage battery 3 falls below a first threshold (a lower limit for continuous operation for continuously operating only the communication circuit of the storage battery charge / discharge control unit 411), the independent operation control unit 5 stops the inverter circuit and control circuit of the storage battery charge / discharge control unit 411 and suspends independent operation. This configuration prevents over-discharge of the storage battery 3 due to auxiliary equipment loss in the storage battery PCS4. As a result, if the current available power supply Pt of the power source 1 subsequently exceeds a second threshold (the sum of the power consumption PL1 and a fixed value α) based on the power consumption of the most important load (load L1), the stopped part of the independent operation control unit 5 (the inverter circuit and control circuit) can be restarted, allowing independent operation to be resumed. In other words, independent operation can be resumed automatically without user intervention. Furthermore, if the storage battery 3 becomes over-discharged, the storage battery PCS4 will enter an irrecoverable state. Therefore, the storage battery 3 cannot be charged by the storage battery PCS4, and the user must go to the installation location of the storage battery 3 and separately charge the storage battery 3. In other words, stopping part of the storage battery charge / discharge control unit 411 to suppress over-discharge of the storage battery 3 enables the power system S1 to quickly resume independent operation from a state in which independent operation has been suspended.

[0051] In the power system S1, if the expected transition in power consumption of each load L1-Ln is known, the isolated operation control unit 5 may further take the expected transition in power consumption of each load L1-Ln into consideration when controlling the isolated operation. For example, if multiple loads L1-Ln are installed in a business establishment, the power consumption of some of the multiple loads L1-Ln (e.g., lighting or personal work computers) will vary between weekday daytime and weekday nighttime or holidays. On the other hand, the power consumption of some of the multiple loads L1-Ln (e.g., the power supply for the main system) will remain constant regardless of whether it is a weekday or a holiday. Taking into consideration such expected transition in power consumption of each load L1-Ln enables more flexible operation of the isolated operation.

[0052] In the power system S1, if a power outage schedule (scheduled disconnection from the power grid K) is known due to planned power outages, the independent operation control unit 5 may further take the power outage schedule into consideration in the independent operation control. By taking such a power outage schedule into consideration, it is possible to increase the charge rate of the storage battery 3, for example, when the system is connected to the grid before independent operation begins. In addition, since it is possible to know the time until recovery from a power outage, it is also possible to make maximum use of the discharge of the storage battery 3.

[0053] In the power system S1, an example has been shown in which the independent operation control unit 5 is provided in the storage battery PCS4, but the independent operation control unit 5 may be provided in any of the multiple power control devices 2 (the solar PCS 21, the EV charger / discharger 22, and the generator controller 23). In other words, any of the solar PCS 21, the EV charger / discharger 22, or the generator controller 23 may perform independent operation control. In this case, the power control device 2 provided with the independent operation control unit 5 operates as a voltage source, rather than the storage battery PCS4. Alternatively, the independent operation control unit 5 may be configured as a single device on its own.

[0054] Although the power system S1 has been described as having a plurality of power sources 1, the number of power sources 1 may be one. For example, the power system S1 may be configured such that only a solar cell 11 is provided in addition to the storage battery 3, or only an electric vehicle 12 is provided in addition to the storage battery 3, or only a generator 13 is provided in addition to the storage battery 3.

[0055] In the power system S1, the connected load Lo and the disconnected load Lx may be selected by considering only the current available power supply of each power source 1. In this configuration, the independent operation control unit 5 does not need to estimate the future available power supply of each power source 1, nor does it need to create a schedule for the available power supply. In the power system according to this modification, during independent operation, power supplied from the power source 1 can be supplied to each of the loads L1 to Ln. Therefore, even if the charge rate of the storage battery 3 drops to a level where it cannot be discharged, the independent operation can be continued as long as power can be supplied from the power source 1. Furthermore, in the power system according to this modification, during independent operation, it is possible to continue the supply of power to each load as long as possible depending on the state of the power source 1.

[0056] In the power system S1, when creating a schedule for available power supply, it is not necessary to take into account the current available power supply. In the power system according to this modification, it is also possible to continue independent operation as long as power can be supplied from the power source 1. Furthermore, in the power system according to this modification, during independent operation, it is also possible to continue supplying power to each load as long as possible depending on the state of the power source 1. However, taking the current available power supply into account will result in an estimated value of the available power supply at the current time being closer to the actual available power supply, thereby suppressing errors (surpluses or shortages) in the available power supply.

[0057] The power system according to the present disclosure is not limited to the above-described embodiment, and the specific configuration of each part of the power system according to the present disclosure can be freely modified in various ways. [Explanation of symbols]

[0058] S1: Power system, 1: Power source, 3: Storage battery, 4: Storage battery power conditioner (storage battery PCS), 5: Independent operation control unit, 11: Solar cell, 12: Electric vehicle, 13: Generator, 411: Storage battery charge / discharge control unit, K: Power system, L1 to Ln, Li: Load

Claims

1. A power system that is connected to multiple loads and is capable of independent operation, a storage battery capable of supplying power to the plurality of loads; a power source capable of supplying power to the plurality of loads; an independent operation control unit that controls the independent operation; a battery charge / discharge control unit that charges and discharges the battery; Equipped with a degree of importance indicating a priority of power supply during the independent operation is set for each of the plurality of loads, the independent operation control unit, during the independent operation, switches between a connected state and a cut-off state of each power supply path to the plurality of loads based on the charging rate of the storage battery, the suppliable power of the power source, and the importance of each of the plurality of loads; During the independent operation, the power source supplies power based on an output voltage of the storage battery charge / discharge control unit, the plurality of loads includes a most important load having the highest importance; When the suppliable power falls below the power consumption of the most important load and the charging rate of the storage battery falls below a first threshold, the independent operation control unit suspends the independent operation while continuing only a part of the storage battery charge / discharge control unit, The power system, wherein the first threshold is a value corresponding to a lower limit value for continuous operation for continuously operating only a part of the storage battery charge / discharge control unit.

2. The power system according to claim 1 , wherein the independent operation control unit estimates a current available power supply of the power source based on a current state of the power source.

3. 3 . The power system according to claim 1 , wherein the independent operation control unit estimates a future available power supply of the power source based on a schedule of changes in the state of the power source. 4 .

4. The power system of claim 1, wherein the independent operation control unit resumes the independent operation when the supplyable power becomes equal to or greater than a second threshold based on the power consumption of the most important load while the independent operation is suspended.

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