Power supply units, energy management systems, and power systems

Abstract

To provide a power supply device, an energy management system, and a power system that can improve the stability of power supply.SOLUTION: The power supply device to be connected to the power system includes an inverter, control means for controlling the operation of an inverter using a first parameter value so as to simulate the characteristics of a synchronous generator, and acquisition means for acquiring a second parameter value different from the first parameter value. The control means controls the operation of the inverter by changing the first parameter value to the acquired second parameter value.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] Embodiments of the present invention relate to a power supply device, an energy management system, and a power system.

Background Art

[0002] Towards the realization of a low-carbon society, instead of thermal power generation that depends on fossil fuels, a power supply device that supplies electric power converted from renewable energy (hereinafter referred to as a renewable energy power source) is being introduced into the power grid both domestically and internationally. Note that many of such renewable energy power sources are connected to the power grid in alternating current via a current control inverter (hereinafter simply referred to as an inverter). Compared with the synchronous generator used for the above-described thermal power generation, the inverter has the advantage of fast response.

[0003] By the way, a synchronous generator has a rotating body (rotor), and it is possible to suppress fluctuations in the system frequency (that is, improve the stability of power supply) by the inertial force of the rotating body. However, since an inverter is composed of switching elements (that is, it does not have a rotating body), unlike a synchronous generator, it does not have an inertial force (and a damping force). Therefore, when the ratio of renewable energy power sources in the entire power system increases, there is a concern that the stability of power supply will decrease.

[0004] Therefore, in recent years, it has been considered to suppress the decrease in the stability of power supply by applying a virtual synchronous inverter control technique that controls the operation of an inverter so as to simulate the characteristics of a synchronous generator (generator in a real environment) to a renewable energy power source. According to the virtual synchronous inverter control technique, the operation of the inverter is controlled based on parameter values such as an inertia constant for simulating the inertial force of the above-described synchronous generator and an adjustment force constant for simulating an adjustment force with respect to a fluctuating system frequency.

[0005] However, because the parameter values ​​for renewable energy sources are fixed during operation, control based on these parameter values ​​may not be able to maintain the stability of the power supply in the event of disturbances such as sudden load changes. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2021-151081 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] Therefore, the problem that the present invention aims to solve is to provide a power supply device, an energy management system, and a power system that can improve the stability of power supply. [Means for solving the problem]

[0008] According to one embodiment, a power supply device connected to a power grid is provided. The power supply device comprises an inverter, control means for controlling the operation of the inverter using a first parameter value to simulate the characteristics of a synchronous generator, and acquisition means for acquiring a second parameter value different from the first parameter value. The control means controls the operation of the inverter by changing the first parameter value to the acquired second parameter value. The aforementioned power supply device is It is connected to a partial power system which is part of the aforementioned power system. The acquisition means is The system has a first table that holds a plurality of second parameter values ​​applicable to on-grid systems where the subsystem is connected to the power system, and a second table that holds a plurality of second parameter values ​​applicable to off-grid systems where the subsystem is not connected to the power system, and retrieves a second parameter value specified by the system operator from among the plurality of second parameter values ​​held in the first or second table. The plurality of second parameter values ​​held in the first table and the plurality of second parameter values ​​held in the second table differ in at least some respects. [Brief explanation of the drawing]

[0009] [Figure 1] A diagram showing an example of the configuration of a power system according to the embodiment. [Figure 2] A diagram showing an example of the screen for specifying the inertial force constant. [Figure 3] A diagram showing an example of an inertia force constant table. [Figure 4]A diagram showing an example of the adjustment force constant specification screen. [Figure 5] A diagram showing an example of a table of adjustment force constants. [Figure 6] A diagram showing another example of the inertia force constant specification screen. [Figure 7] A diagram showing another example of the adjustment force constant specification screen. [Figure 8] A diagram illustrating a first modified example of this embodiment. [Figure 9] A diagram illustrating a second modified example of this embodiment. [Figure 10] A diagram illustrating a third modified example of this embodiment. [Modes for carrying out the invention]

[0010] The embodiments will be described below with reference to the drawings. Figure 1 shows an example of the configuration of a power system according to this embodiment. As shown in Figure 1, the power system 1 consists of a power grid 11, a plurality of power supply devices 12, and loads 13, etc.

[0011] Multiple power supply units 12 are connected to the power grid 11. Each of the multiple power supply units 12 is equipped with a power conditioning system (PCS) and corresponds to a renewable energy power source that operates to convert electricity converted from renewable energy sources such as solar power (electricity obtained by power generation using renewable energy) from direct current to alternating current and output it.

[0012] Although Figure 1 shows multiple power supply units 12, the number of such power supply units 12 may be, for example, just one.

[0013] The load 13 includes, for example, consumer devices (load devices) that consume electric power in households, schools, factories, and businesses, etc. The load 13 is supplied with the electric power (alternating current power) output from each of the plurality of power supply devices 12 via a transformer. Note that the load 13 may be composed of a plurality of consumer devices. Further, the load 13 may include, for example, a power storage device that stores surplus power in the power system 11.

[0014] In the above-described power system 1, the plurality of power supply devices 12, the load 13, etc. are connected to the power system 11 via switches not shown in the drawings. In the present embodiment, it can be said that the plurality of power supply devices 12 are connected to a partial power system (microgrid) that is a part of the distribution network of the power system 11. However, for example, when an abnormality occurs in the power system 11 due to an accident or a disaster, etc., the switch of the power system 11 is opened, and the partial power system is electrically separated from the power system 11 and becomes off-grid. In this case, the power supply from the power system 11 is stopped (cut off), and the partial power system functions as a distributed power system that can operate independently using the electric power output from each of the plurality of power supply devices 12.

[0015] On the other hand, when no abnormality has occurred in the power system 11, the above-described switch is closed, and for example, the electric power output from each of the plurality of power supply devices 12 is supplied to the power system 11.

[0016] Hereinafter, the power supply device 12 according to the present embodiment will be described. As shown in FIG. 1, the power supply device 12 includes a power storage device 121, an inverter (voltage inverter) 122, a control unit 123, a current sensor 124, and a voltage sensor 125.

[0017] The power storage device 121 includes a rechargeable battery, and is configured to store, for example, the electric power generated using renewable energy as described above, and discharge the stored electric power.

[0018] Here, the power converted from renewable energy (i.e., the power stored in the power storage device 121) is DC, and the inverter 122 operates to convert the power from DC to AC and output it. Note that the inverter 122 corresponds to the power conversion device described above.

[0019] The control unit 123 controls the charge and discharge operations in the power supply device 12 (power storage device 121). Also, the control unit 123 controls the operation of the inverter 122 to simulate the characteristics of a synchronous generator having a rotor (rotational energy) by means of virtual synchronous inverter control technology (i.e., executes virtual synchronous inverter control on the inverter 122). That is, the power supply device 12 according to the present embodiment is a virtual synchronous inverter (device). Note that the control unit 123 is realized by a processor including, for example, a microcomputer or the like.

[0020] The current sensor 124 is connected to the inverter 122 via, for example, an electromagnetic contactor (MC), and detects (measures) the output current of the inverter 122. Also, the voltage sensor 125 detects (measures) the output voltage of the inverter 122. The output current detected by the current sensor 124 and the output voltage detected by the voltage sensor 125 (i.e., the information of the current sensor 124 and the voltage sensor 125) are used for the above-described virtual synchronous inverter control.

[0021] Here, the above-described virtual synchronous inverter control is executed based on parameter values, and the parameter values include an inertia force constant for simulating the inertia force of a synchronous generator and an adjustment force constant (droop rate) for simulating the adjustment force for a fluctuating system frequency, etc. According to the virtual synchronous inverter control, it is possible to realize the same inertia force and adjustment force as those of a synchronous generator in the power supply device 12 and suppress fluctuations in the system frequency (i.e., improve the stability of power supply).

[0022] However, the parameter values ​​used in the virtual synchronous inverter control described above are often fixed. For example, if the amount of power required by the load 13 (i.e., the load on each of the multiple power supply units 12) changes suddenly, the virtual synchronous inverter control using these fixed parameter values ​​may not be able to maintain a stable power supply.

[0023] Furthermore, in order to maintain a stable power supply, it is necessary to stabilize the grid frequency as quickly as possible when disturbances such as sudden load changes occur as described above. However, the time required to stabilize the grid frequency largely depends on the parameter values ​​(inertia force constant and adjustment force constant) mentioned above.

[0024] In this case, in order to stabilize the grid frequency in a short time, it is conceivable to implement control such as continuously increasing the inertial force constant as described above. However, in such a configuration, the load on the power supply unit 12 (virtual synchronous inverter unit) is large, and there is a possibility that the operation of the power supply unit 12 (and the inverter 122 provided in it) may stop. In other words, as a result, it may not be possible to maintain the stability of the power supply.

[0025] Therefore, the power supply unit 12 according to this embodiment has a configuration that allows adjustment of the parameter values ​​(for example, the inertia force constant and the adjustment force constant) used in the virtual synchronous inverter control described above, in order to appropriately control the grid frequency within a range in which the operation of the power supply unit 12 does not stop. In this embodiment, "adjusting the parameter values" includes changing the parameter values ​​used in the virtual synchronous inverter control (hereinafter referred to as the first parameter values) to new parameter values ​​(hereinafter referred to as the second parameter values) (i.e., setting the second parameter values ​​as the first parameter values).

[0026] Specifically, as shown in Figure 1, the power supply unit 12 is equipped with a parameter value acquisition unit 126, which acquires a second parameter value specified, for example, by the system operator.

[0027] The power supply unit 12 is assumed to have, for example, a housing, and the housing is equipped with a control panel device. This control panel device has the function of acquiring and displaying information regarding the operating status of the power supply unit 12 (for example, voltage, current, power, frequency, inertia, droop rate, and temperature, etc.), and also functions as an interface for the system operator to specify the second parameter value.

[0028] In this case, the control panel device displays, for example, a screen for specifying the inertial force constant as a second parameter value (hereinafter referred to as the inertial force constant specification screen) and a screen for specifying the adjustment force constant as a second parameter value (hereinafter referred to as the adjustment force constant specification screen).

[0029] Figure 2 shows an example of the inertia force constant specification screen. As shown in Figure 2, the inertia force constant specification screen 100 is provided with a "Large" button 101, a "Medium" button 102, a "Small" button 103, and a "Set" button 104.

[0030] The system operator can press (specify) one of the buttons 101 to 103 on the inertial force constant specification screen 100 as shown in Figure 2, and then press the "Set" button 104. This allows the system operator to specify the inertial force constant corresponding to the button that was specified (selected) when the "Set" button 104 was pressed as the second parameter value.

[0031] The parameter value acquisition unit 126 described above acquires the inertial force constant as a second parameter value based on the button selected on the inertial force constant specification screen 100 displayed on such a control panel device (i.e., the operation of the system operator on the inertial force constant specification screen 100).

[0032] The parameter value acquisition unit 126 is assumed to have an inertia force constant table 126a as shown in Figure 3. As shown in Figure 3, the inertia force constant table 126a holds multiple inertia force constants (i.e., second parameter values) corresponding to the button types "large," "medium," and "small" provided on the inertia force constant specification screen 100 described above. Specifically, the inertia force constant table 126a holds "inertia force constant 1" corresponding to "large," holds "inertia force constant 2" corresponding to "medium," and holds "inertia force constant 3" corresponding to "small."

[0033] The parameter value acquisition unit 126 can acquire the inertia force constants by referring to such an inertia force constant table 126a. For example, if the "Large" button 101 is selected on the inertia force constant specification screen 100, the parameter value acquisition unit 126 acquires "Inertia Force Constant 1". Also, if the "Medium" button 102 is selected on the inertia force constant specification screen 100, the parameter value acquisition unit 126 acquires "Inertia Force Constant 2". Also, if the "Small" button 103 is selected on the inertia force constant specification screen 100, the parameter value acquisition unit 126 acquires "Inertia Force Constant 3".

[0034] Furthermore, "Inertial force constant 1" is the inertial force constant corresponding to the "large" button 101, and is assumed to be a larger value than "Inertial force constant 2" and "Inertial force constant 3". On the other hand, "Inertial force constant 2" is the inertial force constant corresponding to the "medium" button 102, and is assumed to be a smaller value than "Inertial force constant 1" and a larger value than "Inertial force constant 3". In addition, "Inertial force constant 3" is the inertial force constant corresponding to the "small" button 103, and is assumed to be a smaller value than "Inertial force constant 1" and "Inertial force constant 2".

[0035] As described above, when the parameter value acquisition unit 126 acquires the inertia force constant as the second parameter value, the control unit 123 changes the inertia force constant used as the first parameter value in the virtual synchronous inverter control described above to the inertia force constant acquired by the parameter value acquisition unit 126. In this case, virtual synchronous inverter control is executed using the changed inertia force constant.

[0036] This section described the adjustment of the inertial force constant used in virtual synchronous inverter control, but the adjustment force constant is adjusted in a similar manner.

[0037] Figure 4 shows an example of the adjustment force constant specification screen. As shown in Figure 4, the adjustment force constant specification screen 200 is provided with a "Large" button 201, a "Medium" button 202, a "Small" button 203, and a "Set" button 204.

[0038] The grid operator can press (specify) one of the buttons 201 to 203 on the adjustment force constant specification screen 200 as shown in Figure 4, and then press the "Set" button 204. This allows the grid operator to specify the adjustment force constant corresponding to the button that was specified (selected) when the "Set" button 204 was pressed as the second parameter value.

[0039] The parameter value acquisition unit 126 described above acquires the adjustment force constant as a second parameter value based on the button selected on the adjustment force constant specification screen 200 displayed on such a control panel device (i.e., the operation of the system operator on the adjustment force constant specification screen 200).

[0040] The parameter value acquisition unit 126 is assumed to have an adjustment force constant table 126b as shown in Figure 5. As shown in Figure 5, the adjustment force constant table 126b holds multiple adjustment force constants (i.e., second parameter values) corresponding to the button types "large," "medium," and "small" provided on the adjustment force constant specification screen 200 described above. Specifically, the adjustment force constant table 126b holds "adjustment force constant 1" corresponding to "large," holds "adjustment force constant 2" corresponding to "medium," and holds "adjustment force constant 3" corresponding to "small."

[0041] The parameter value acquisition unit 126 can acquire the adjustment force constants by referring to such an adjustment force constant table 126b. For example, if the "Large" button 201 is selected on the adjustment force constant specification screen 200, the parameter value acquisition unit 126 acquires "Adjustment Force Constant 1". Also, if the "Medium" button 202 is selected on the adjustment force constant specification screen 200, the parameter value acquisition unit 126 acquires "Adjustment Force Constant 2". Also, if the "Small" button 203 is selected on the adjustment force constant specification screen 200, the parameter value acquisition unit 126 acquires "Adjustment Force Constant 3".

[0042] Note that "Adjustment force constant 1" is the adjustment force constant corresponding to the "large" button 201, and is a larger value than "Adjustment force constant 2" and "Adjustment force constant 3". On the other hand, "Adjustment force constant 2" is the adjustment force constant corresponding to the "medium" button 202, and is a smaller value than "Adjustment force constant 1" and a larger value than "Adjustment force constant 3". Furthermore, "Adjustment force constant 3" is the adjustment force constant corresponding to the "small" button 203, and is a smaller value than "Adjustment force constant 1" and "Adjustment force constant 2".

[0043] As described above, when the adjustment force constant is obtained as the second parameter value by the parameter value acquisition unit 126, the control unit 123 changes the adjustment force constant, which is used as the first parameter value in the virtual synchronous inverter control described above, to the adjustment force constant obtained by the parameter value acquisition unit 126. In this case, virtual synchronous inverter control is executed using the changed adjustment force constant.

[0044] In this embodiment, the inertia force constant and the adjustment force constant have been described as being adjusted. However, this embodiment may be configured in which the parameter values ​​used in virtual synchronous inverter control are changed, and for example, it may be configured in which only one of the inertia force constant or the adjustment force constant is changed.

[0045] In the following, for the sake of clarity, the inertia force constant and adjustment force constant described above as the first parameter values ​​will simply be referred to as the first parameter values, and the inertia force constant and adjustment force constant described as the second parameter values ​​will simply be referred to as the second parameter values. Similarly, the inertia force constant specification screen and the adjustment force constant specification screen will be referred to as the parameter value specification screen, and the inertia force constant table and the adjustment force constant table will be referred to as the parameter value table.

[0046] In this embodiment, it has been explained that the system operator selects one of the "Large," "Medium," and "Small" buttons presented on the parameter value specification screen to obtain the corresponding second parameter value. However, the parameter value specification screen may be designed to directly present (display) multiple second parameter values ​​held in the parameter value table. In this case, the parameter value acquisition unit 126 only needs to acquire the second parameter value specified (selected) on the parameter value specification screen.

[0047] Furthermore, the parameter value specification screens described above (the inertial force constant specification screen 100 shown in Figure 2 and the adjustment force constant specification screen 200 shown in Figure 4) are merely examples, and the system operator may specify the second parameter value through a different type of interface.

[0048] As described above, the power supply device 12 according to this embodiment includes a control unit 123 that controls the operation of the inverter 122 using a first parameter value to simulate the characteristics of a synchronous generator (performing virtual synchronous inverter control), and a parameter value acquisition unit 126 that acquires a second parameter value different from the first parameter value. The control unit 123 controls the operation of the inverter 122 by changing the first parameter value (default parameter value) to the second parameter value acquired by the parameter value acquisition unit 126.

[0049] In this embodiment, the above-described configuration makes it possible to improve the stability of the power supply.

[0050] Here, for example, if an abnormality occurs in the power system 11 due to an accident or disaster, the partial system transitions from an on-grid state where it is connected to the power system 11 (i.e., an environment where the power supply unit 12 is operating on the on-grid) to an off-grid state where it is not connected to the power system 11 (i.e., an environment where the power supply unit 12 is operating off-grid). In an off-grid state, it is expected that the load fluctuation relative to the power capacity will be large and the system frequency will fluctuate significantly. However, in this embodiment, by adopting a configuration in which a second parameter value manually specified by the system operator is acquired and virtual synchronous inverter control is performed using this second parameter value, it is possible to flexibly adjust the parameter value in the virtual synchronous inverter control even in situations such as a transition from on-grid to off-grid, thereby improving the stability of the power supply. Thermal power generation and hydroelectric power generation convert the kinetic energy of a fluid into rotational motion via a turbine, and then convert the rotational motion into electrical energy using a synchronous generator. Furthermore, since the size of the turbine in a synchronous generator is fixed and the inertial force in such a generator cannot be physically changed, the ability to change the parameter value (inertial force constant) used to simulate this inertial force is one of the advantages of synchronous generators over other types of generators. On-grid power plants have turbines in thermal and hydroelectric power plants that have large inertial forces. On the other hand, diesel synchronous generators and gas engine synchronous generators, which are expected to be used as the main power source in off-grid environments, are reciprocating engines, which are internal combustion engines, and therefore do not have a large rotating body like a turbine, resulting in a smaller inertial force than a turbine.

[0051] Furthermore, one might consider a configuration in which the parameter values ​​used in virtual synchronous inverter control are changed simply to maximize the contribution to power supply stability (grid stability) (for example, by continuously increasing the inertial force constant). However, such a configuration would place an excessive load on the power supply unit 12 (inverter 122), potentially causing the power supply unit 12 to stop operating. In contrast, in this embodiment, by specifying a second parameter value that prevents the load from concentrating on the power supply unit 12, the operation of the power supply unit 12 can be continued, thereby further improving the stability of the power supply.

[0052] In this embodiment, the grid operator can manually adjust the parameter values ​​(i.e., change the first parameter value used in virtual synchronous inverter control to the second parameter value). Such parameter value adjustments may be performed, for example, when a predetermined grid frequency fluctuation is detected in the power supply unit 12, or at a timing instructed by the grid operator. The grid operator can also specify the second parameter value by considering, for example, the balance between power demand and supply (power supply and demand situation) or a decrease in grid frequency.

[0053] Furthermore, parameter value adjustments are performed, for example, by presenting the grid operator with multiple second parameter values ​​and obtaining the second parameter value specified by the grid operator from among those multiple values. With this configuration, the grid operator can adjust the parameter values ​​more easily compared to directly specifying the second parameter value (numerical value). Also, as shown in Figures 2 and 4 above, if the grid operator is asked to specify one of the "large," "medium," and "small" buttons, they can adjust the parameter values ​​more intuitively.

[0054] In this embodiment, for example, multiple second parameter values ​​held in a parameter value table are presented, and one second parameter value is selected from among these multiple second parameter values. However, the numerical value corresponding to the second parameter value may be directly specified by the system operator. Specifically, for example, Figure 6 shows another example (a different example from Figure 2) of the inertia force constant specification screen displayed on the control panel device, and the system operator can specify (input) a numerical value representing the inertia force constant on such an inertia force constant specification screen. Similarly, for example, Figure 7 shows another example (a different example from Figure 4) of the adjustment force specification screen displayed on the control panel device, and the system operator can specify (input) a numerical value representing the adjustment force constant on such an adjustment force specification screen. With such a configuration, it is possible to specify a value other than the parameter values ​​held in the parameter value table in advance as the second parameter value, which may allow for more appropriate adjustment of the parameter value.

[0055] Furthermore, although this embodiment has been described as having multiple power supply units 12 connected to a microgrid, which is part of a power system, the parameter values ​​of each of the multiple power supply units 12 connected to the microgrid can be adjusted independently. In this case, the second parameter value specified for one of the multiple power supply units 12 (hereinafter referred to as the first power supply unit 12) may be different from the second parameter value specified for a power supply unit 12 different from the first power supply unit 12 (hereinafter referred to as the second power supply unit 12). With this configuration, the system operator can appropriately adjust the load distribution to each of the multiple power supply units 12, taking into account the remaining battery capacity, rating, etc. of each power supply unit 12.

[0056] Here, we have described the case where the second parameter value specified in the first power supply unit 12 and the second parameter value specified in the second power supply unit 12 are different. However, for example, the first power supply unit 12 may be set as the master and the second power supply unit 12 as the slave, and the second parameter value specified in the first power supply unit 12 may be used as the second parameter value in the second power supply unit 12 (i.e., the result of adjusting the parameter value in the first power supply unit 12 is applied to the second power supply unit 12). In this case, for example, multiple power supply units 12 (e.g., control units 123) including the first and second power supply units 12 are connected to each other in a communicative manner, and the second parameter value specified in the first power supply unit 12 is notified from the first power supply unit 12 to the second power supply unit 12 (i.e., the second parameter value is acquired in the second power supply unit 12). With such a configuration, the parameter values ​​used in the virtual synchronous inverter control performed in each of the multiple power supply units 12 can be efficiently adjusted.

[0057] Furthermore, as described above, the power supply unit 12 performs virtual synchronous inverter control based on the output current of the inverter 122 detected by the current sensor 124 and the output voltage of the inverter 122 detected by the voltage sensor 125. However, the output current and output voltage may be used to adjust the parameter values. Specifically, for example, in a configuration where the inertial force constant is continuously increased, focusing solely on the stability of power supply, as described above, it is conceivable that the operation of the power supply unit 12 (inverter 122) may stop. To avoid such a situation, in this embodiment, the parameter values ​​are adjusted so as not to exceed the rated output (power or current) of the power supply unit 12 (inverter 122). In this case, for example, an output voltage or range (threshold) of the output voltage that does not exceed the rated output is set in advance, and a configuration is conceivable in which the system operator is presented with a second parameter value from among a plurality of second parameter values ​​held in the parameter value table such that the output current detected by the current sensor 124 or the output voltage detected by the voltage sensor 125 falls within the preset output voltage or output voltage range.

[0058] Furthermore, if, for example, the output current detected by the current sensor 124 or the output voltage detected by the voltage sensor 125 can be narrowed down to a single second parameter value that falls within a preset output voltage or output voltage range, it is also possible to configure the system to automatically acquire that second parameter value (i.e., automatically change the first parameter value to that second parameter value). In other words, in this embodiment, the parameter values ​​used in virtual synchronous inverter control may be manually adjusted by the system operator, or they may be automatically adjusted.

[0059] Incidentally, this embodiment mainly assumes a case where parameter values ​​are adjusted when transitioning from on-grid to off-grid (i.e., when off-grid), but parameter values ​​may also be adjusted when on-grid. In such a case, the parameter value acquisition unit 126 can have, for example, a parameter value table applicable to on-grid (hereinafter referred to as the first table) and a parameter value table applicable to off-grid (hereinafter referred to as the second table), and when on-grid, the second parameter value specified by the grid operator is acquired from among the multiple second parameter values ​​held in the first table, and when off-grid, the second parameter value specified by the grid operator is acquired from among the second parameter values ​​held in the second table. With such a configuration, it is possible to appropriately adjust parameter values ​​both when on-grid and when off-grid.

[0060] Furthermore, since the parameter values ​​(appropriate values) used for virtual synchronous inverter control in an on-grid environment are considered to be different from the parameter values ​​(appropriate values) used for virtual synchronous inverter control in an off-grid environment, it is assumed that at least some of the multiple second parameter values ​​held in the first table and the multiple second parameter values ​​held in the second table are set to be different.

[0061] The first and second tables used to adjust the parameter values ​​described above can be manually switched by, for example, a system operator, but the power supply unit 12 may have a configuration that automatically switches between the first and second tables (hereinafter referred to as the first modified example of this embodiment).

[0062] Now, with reference to Figure 8, a power supply device 12 according to the first modified example of this embodiment will be described. In Figure 8, the same reference numerals are used for parts that are the same as those in Figure 1, and detailed descriptions of those parts are omitted.

[0063] As shown in Figure 8, the power supply unit 12 according to the first variant of this embodiment further comprises a first determination unit 127. The first determination unit 127 determines whether the power supply unit 12 is operating on the grid (i.e., whether the power supply unit 12 is connected to the power system 11) by, for example, a manual instruction for off-grid operation by the system operator, or by using a sensor (detection unit) that detects the state of the switch described above. With a configuration that includes such a first determination unit 127, if it is determined that the power supply unit 12 is operating on the grid (i.e., the power supply unit 12 is connected to the power system 11), the parameter values ​​can be adjusted using the first table, and if it is determined that the power supply unit 12 is operating off-grid (i.e., the power supply unit 12 is not connected to the power system 11), the parameter values ​​can be adjusted using the second table.

[0064] In other words, in the first modified example of this embodiment, the parameter value table can be automatically switched according to the determination result by the first determination unit 127 (i.e., the actual environment of the microgrid).

[0065] Furthermore, the power system in this embodiment may also be configured to include an energy management system 20 (external server device) that performs centralized control of multiple power supply devices 12, as shown in Figure 9 (hereinafter referred to as the second modified example of this embodiment). In Figure 9, the same reference numerals are used for parts that are the same as in Figure 1, and a detailed explanation of those parts is omitted.

[0066] In a second modified example of this embodiment, the energy management system 20 is communicably connected to each of the multiple power supply units 12 via a network and includes a determination unit 21 and a transmission unit 22.

[0067] The determination unit 21 determines a second parameter value used to control the operation of the inverter 122 provided in each of the multiple power supply units 12. The determination unit 21 may determine the second parameter value in response to instructions from, for example, the administrator of the energy management system 20, or it may determine the second parameter value based on the status of the multiple power supply units 12 (multiple power supply units 12 subject to centralized control) that are communicably connected to the energy management system 20. The transmission unit 22 transmits the second parameter value determined by the determination unit 21 to each of the multiple power supply units 12.

[0068] In this case, a parameter value acquisition unit 126 provided in each of the multiple power supply units 12 acquires a second parameter value transmitted from the energy management system 20, and a control unit 123 provided in each of the multiple power supply units 12 can change the first parameter value to the second parameter value and control the operation of the inverter 122 (i.e., perform virtual synchronous inverter control).

[0069] In the second modified example of this embodiment, the second parameter values ​​transmitted from the energy management system 20 to each of the multiple power supply units 12 may be the same or different. Furthermore, the energy management system 20 (transmitting unit 22) does not necessarily need to transmit the second parameter value to multiple power supply units 12; it may be configured to transmit the second parameter value to at least one of the multiple power supply units 12.

[0070] Furthermore, the power supply unit 12, which is connected to the energy management system 20 via a network, may be configured to include a second determination unit 128, as shown in Figure 10 (hereinafter referred to as the third modified example of this embodiment). In Figure 10, the same reference numerals are used for parts that are the same as those in Figure 9, and detailed explanations of those parts are omitted.

[0071] In a third modified example of this embodiment, the second determination unit 128 detects whether or not communication with the energy management system 20 is taking place and determines whether or not the power supply unit 12 is in a state where it can communicate with the energy management system 20. With a configuration that includes such a second determination unit 128, if it is determined that the power supply unit 12 is in a state where it can communicate with the energy management system 20, it is possible to obtain a second parameter value from the energy management system 20 (i.e., adjust the parameter value according to a command from the energy management system 20), and if it is determined that the power supply unit 12 is not in a state where it can communicate with the energy management system 20, it is possible to obtain a second parameter value specified by the grid operator as described above (i.e., adjust the parameter value using the parameter value table described above).

[0072] In other words, in the third modified example of this embodiment, even if a communication failure occurs between the power supply unit 12 and the energy management system 20 while the power supply unit 12 is being operated to acquire a second parameter value from the energy management system 20, it is possible to continue operating the power supply unit 12 using a parameter value manually adjusted by the grid operator.

[0073] In this explanation, it is assumed that when the power supply unit 12 is in a state where it can communicate with the energy management system 20, it obtains the second parameter value from the energy management system 20 (i.e., adjusts the parameter value according to the command from the energy management system 20). However, if the second parameter value is obtained from the energy management system 20 and the second parameter value specified by the grid operator is obtained, the second parameter value specified by the grid operator may be given priority (i.e., the first parameter value is changed to the second parameter value specified by the grid operator to control the operation of the inverter 122).

[0074] As described above, this embodiment provides a power supply device, an energy management system, and a power system that can improve the stability of power supply.

[0075] In this embodiment, the parameter values ​​used in virtual synchronous inverter control have been mainly described as including the inertial force constant and the adjustment force constant. However, these parameter values ​​may be either the inertial force constant or the adjustment force constant. Furthermore, this embodiment may also be applied when adjusting parameter values ​​other than the inertial force constant and the adjustment force constant used in virtual synchronous inverter control that contribute to improving the stability of the power supply.

[0076] Furthermore, the configurations described in the above-mentioned embodiment and the first to third modified examples of this embodiment may be combined as appropriate, or some may be omitted.

[0077] While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These embodiments can be carried out in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims and their equivalents.

[0078] With regard to the embodiments described above, the following additional information is disclosed. [1] In a power supply unit connected to a power grid, Inverter and A control means that controls the operation of the inverter using a first parameter value to simulate the characteristics of a synchronous generator, An acquisition means for obtaining a second parameter value different from the first parameter value, It is equipped with, The control means controls the operation of the inverter by changing the first parameter value to the acquired second parameter value. power supply. [2] The power supply device according to [1], wherein the control means controls the operation of the inverter based on the output power and output voltage of the inverter. [3] The power supply device according to [1] or [2], wherein the acquisition means acquires a second parameter value specified by the system operator from among a plurality of second parameter values ​​presented to the system operator. [4] The power supply unit is connected to a partial system which is part of the power system, The acquisition means is, The system has a first table that holds a plurality of second parameter values ​​that apply to on-grid systems where the subsystem is connected to the power system, and a second table that holds a plurality of second parameter values ​​that apply to off-grid systems where the subsystem is not connected to the power system. Obtain the second parameter value specified by the system operator from among the multiple second parameter values ​​held in the first or second table, The multiple second parameter values ​​held in the first table and the multiple second parameter values ​​held in the second table are at least partially different. [3] The power supply unit described in [3]. [5] The system further comprises determination means for determining whether the power supply unit is connected to the off-grid, The acquisition means, when it is determined that the power supply is not connected to the off-grid, acquires a second parameter value specified by the grid operator from among a plurality of second parameter values ​​held in the first table, and when it is determined that the power supply is connected to the off-grid, acquires a second parameter value specified by the grid operator from among a plurality of second parameter values ​​held in the second table. [4] The power supply unit described in [4]. [6] The power supply device described in any one of the items [1] to [5], wherein the second parameter value includes a numerical value specified by the system operator. [7] The power supply unit is connected to a partial system which is part of the power system, The aforementioned subsystem is further connected to other power supply units different from the aforementioned power supply unit. The first parameter value used to control the operation of the inverter provided in the aforementioned other power supply device is changed to a third parameter value that is different from the second parameter value. A power supply device as described in any one of the items [1] to [6]. [8] The power supply unit is connected to a partial system which is part of the power system, The aforementioned subsystem is further connected to other power supply units different from the aforementioned power supply unit. When the first parameter value is changed to the second parameter value, the first parameter value used to control the operation of the inverter provided in the other power supply device is changed to the second parameter value. A power supply device as described in any one of items [1] to [7]. [9] The power supply device according to [1] to [8], wherein the acquisition means acquires the second parameter value based on the output current and output voltage of the inverter.

[10] The power supply according to any one of the following [1] to [9], wherein the acquisition means is communicably connected to the power supply and acquires a second parameter value from an energy management system that performs centralized control of a plurality of power supply units, including the power supply.

[11] The power supply according to

[10] , wherein the acquisition means acquires a second parameter value specified by the grid operator when the power supply is not in a state where it can communicate with the energy management system.

[12] The power supply device according to

[10] , wherein the acquisition means acquires a second parameter value specified by the grid operator and the second parameter value is acquired from the energy management system, and the control means changes the first parameter value to the second parameter value specified by the grid operator and controls the operation of the inverter.

[13] The power supply device according to any one of the following [1] to

[12] , wherein the first and second parameter values ​​include at least one of an inertial force constant for simulating the inertial force of the synchronous generator and a regulating force constant for simulating the regulating force for a fluctuating system frequency.

[14] An energy management system that is communicatively connected to each of a plurality of power supply devices, including the power supply device described in claim 1, and performs centralized control of the plurality of power supply devices, A determination means for determining a second parameter value used to control the operation of an inverter provided in at least one of the plurality of power supply devices, A transmission means for transmitting the determined second parameter value to the power supply device. It is equipped with, The acquisition means acquires the transmitted second parameter value. Energy management system.

[15] A power system comprising a plurality of power supply devices, including the power supply device described in claim 1, and an energy management system that performs centralized control over the plurality of power supply devices, The aforementioned energy management system is A determination means for determining a second parameter value used to control the operation of an inverter provided in at least one of the plurality of power supply devices, A transmission means for transmitting the determined second parameter value to the power supply device. Includes, The acquisition means acquires the transmitted second parameter value. Power system. [Explanation of Symbols]

[0079] 11...Power system, 12...Power supply unit, 13...Load, 20...Energy management system, 21...Decision unit, 22...Transmission unit, 121...Energy storage device, 122...Inverter, 123...Control unit, 124...Current sensor, 125...Voltage sensor, 126...Parameter value acquisition unit, 127...First determination unit, 128...Second determination unit.

Claims

1. In a power supply unit connected to a power grid, Inverter and A control means that controls the operation of the inverter using a first parameter value to simulate the characteristics of a synchronous generator, An acquisition means for obtaining a second parameter value different from the first parameter value, It is equipped with, The control means controls the operation of the inverter by changing the first parameter value to the acquired second parameter value. The power supply unit is connected to a partial system which is part of the power system, The acquisition means is, The system has a first table that holds a plurality of second parameter values ​​applicable to on-grid systems where the subsystem is connected to the power system, and a second table that holds a plurality of second parameter values ​​applicable to off-grid systems where the subsystem is not connected to the power system. Obtain the second parameter value specified by the system operator from among the multiple second parameter values ​​held in the first or second table, The multiple second parameter values ​​held in the first table and the multiple second parameter values ​​held in the second table are at least partially different. power supply.

2. In a power supply unit connected to a power grid, Inverter and A control means that controls the operation of the inverter using a first parameter value to simulate the characteristics of a synchronous generator, An acquisition means for obtaining a second parameter value different from the first parameter value, It is equipped with, The control means controls the operation of the inverter by changing the first parameter value to the acquired second parameter value. The acquisition means is connected to the power supply unit in a communicative manner and acquires a second parameter value from an energy management system that performs centralized control of a plurality of power supply units, including the power supply unit. When the acquisition means acquires a second parameter value specified by the grid operator and also acquires a second parameter value from the energy management system, the control means changes the first parameter value to the second parameter value specified by the grid operator and controls the operation of the inverter. power supply.

3. The power supply device according to claim 1 or 2, wherein the control means controls the operation of the inverter based on the output power and output voltage of the inverter.

4. The system further comprises determination means for determining whether the power supply unit is connected to the off-grid, The acquisition means, when it is determined that the power supply is not connected to the off-grid, acquires a second parameter value specified by the grid operator from among a plurality of second parameter values ​​held in the first table, and when it is determined that the power supply is connected to the off-grid, acquires a second parameter value specified by the grid operator from among a plurality of second parameter values ​​held in the second table. The power supply device according to claim 1.

5. The power supply device according to claim 1 or 2, wherein the second parameter value specified by the system operator includes a numerical value specified by the system operator.

6. The aforementioned subsystem is further connected to other power supply units different from the aforementioned power supply unit. The first parameter value used to control the operation of the inverter provided in the other power supply device is changed to a third parameter value that is different from the second parameter value. The power supply device according to claim 1.

7. The aforementioned subsystem is further connected to other power supply units different from the aforementioned power supply unit. When the first parameter value is changed to the second parameter value, the first parameter value used to control the operation of the inverter provided in the other power supply device is changed to the second parameter value. The power supply device according to claim 1.

8. The power supply device according to claim 1 or 2, wherein the acquisition means acquires the second parameter value based on the output current and output voltage of the inverter.

9. The power supply device according to claim 2, wherein the acquisition means acquires a second parameter value specified by the grid operator when the power supply device is not in a state where it can communicate with the energy management system.

10. The power supply device according to claim 1 or 2, wherein the first and second parameter values ​​include at least one of an inertial force constant for simulating the inertial force of the synchronous generator and a regulating force constant for simulating the regulating force for a fluctuating system frequency.

11. An energy management system that is communicatively connected to each of a plurality of power supply devices, including the power supply device described in claim 2, and performs centralized control of the plurality of power supply devices, A determination means for determining a second parameter value used to control the operation of an inverter provided in at least one of the plurality of power supply devices, A transmission means for transmitting the determined second parameter value to the power supply device. It is equipped with, The acquisition means acquires the transmitted second parameter value. Energy management system.

12. A power system comprising a plurality of power supply devices, including the power supply device described in claim 2, and an energy management system that performs centralized control over the plurality of power supply devices, The aforementioned energy management system is A determination means for determining a second parameter value used to control the operation of an inverter provided in at least one of the plurality of power supply devices, A transmission means for transmitting the determined second parameter value to the power supply device. Includes, The acquisition means acquires the transmitted second parameter value. Power system.

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