Power generation plan control device, control method and program for power generation plan control device

Abstract

A power generation plan control device according to an embodiment of the present invention is for controlling a power generation plan of a battery energy storage system having a grid forming inverter function, in a power supply grid that is equipped with at least one synchronous power generator, at least one renewable energy power generator, and the battery energy storage system. The power generation plan control device comprises: a calculation unit that performs calculation such that grid inertia reserved in the synchronous power generator and in the battery energy storage system is equal to or more than a required amount for each time slot, a restriction related to reservation of increase / decrease adjusting force in the whole power supply grid is satisfied, and other restriction conditions are satisfied; and a control unit that controls the battery energy storage system on the basis of the calculation result.

Description

[Technical Field]

[0001] An embodiment of the present invention relates to a power generation planning control device, a control method for a power generation planning control device, and a program. [Background technology]

[0002] As renewable energy becomes the main power source, asynchronous power sources such as solar power generation and wind power generation are increasing, while synchronous power sources such as thermal power generation are decreasing. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-50041 Summary of the Invention [Problem to be solved by the invention]

[0004] While synchronous power supplies have their own rotational energy and inertia, asynchronous power supplies do not. Therefore, the inertia decreases as the number of asynchronous power supplies increases, which creates the problem of an increased rate of frequency change when a power supply fails.

[0005] Incidentally, power control functions (hereinafter referred to as GFM functions) that use inverters with phase control functions (grid-forming inverters) have a control function (virtual synchronous generator simulation (VSG) function) that generates frequency changes similar to those of a synchronous generator when a discrepancy occurs between the active power command of the PCS (power conditioning system) and the output active power.By utilizing the GFM function, it is desirable to formulate power generation plans that overcome the issue of reduced inertia force mentioned above.

[0006] The present invention has been made in view of the above, and aims to provide a power generation planning control device, a control method for a power generation planning control device, and a program for a power generation planning control device that can provide an asynchronous power supply system that has synchronizing force and inertia force and can be operated integrally with a synchronous generator. [Means for solving the problem]

[0007] The power generation planning control device of the embodiment is a power generation planning control device that controls the power generation plan of a battery energy storage system in a power supply system including one or more synchronous generators, one or more renewable energy generators, and a battery energy storage system having a grid forming inverter function, and is configured to control the power generation plan of the battery energy storage system when the system inertia force secured by the synchronous generator and the battery energy storage system is equal to or greater than the required amount in each time period and satisfies the constraints regarding securing the upward adjustment capability / downward adjustment capability of the entire power supply system. Su and a control unit that controls the battery energy storage system based on the results of the calculation. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is an explanatory diagram of a phase control block corresponding to the VSG function of the GFM. [Figure 2] FIG. 2 is a diagram illustrating an example of a target system. [Figure 3] FIG. 3 is a schematic block diagram of the power storage unit. [Figure 4] FIG. 4 is a block diagram showing the general configuration of the EMS. [Figure 5] FIG. 5 is a diagram illustrating an example of the relationship between the output change rate and the inertia constant. [Figure 6] FIG. 6 is a flowchart showing an outline of the process according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] The embodiments will be described in detail with reference to the drawings. First, the principle of the embodiment will be described. Inverters with phase control functions (grid forming inverters, hereafter abbreviated as GFM) have a control function (virtual synchronous generator simulation (VSG) function) that causes frequency changes similar to the characteristics of a synchronous generator when a difference occurs between the PCS active power command and the output active power.

[0010] FIG. 1 is an explanatory diagram of a phase control block corresponding to the VSG function of the GFM. The phase control block of the GFM can continuously change the parameter corresponding to the inertia constant M. If inertial force can be secured using GFM, it will be possible to reduce the number of synchronous generators (hereafter abbreviated as DG) connected in parallel to secure inertial force, which is expected to have a CO2 reduction effect or an economic effect.

[0011] However, since the inertia constant M of the GFM corresponds to the time constant of the first-order delay in response to commands from the EMS, etc., increasing the parameter corresponding to the inertia constant M means that the responsiveness to commands from the EMS, etc. will deteriorate, and the adjustment ability will be reduced. To avoid this, it is necessary that the inertia constant M of the entire system, which includes the synchronous power source and the grid-forming inverter, is above a certain value, and that the adjustment capability of the synchronous power source and the grid-forming inverter combined is above a certain amount.

[0012] However, since these are contradictory constraints, it is desirable to formulate a power generation plan that satisfies both of them at the same time.

[0013] FIG. 2 is a diagram illustrating an example of a target system. The example in Figure 2 assumes a situation in which a large amount of renewable energy is introduced into an independent, relatively small-scale grid (microgrid), such as on a remote island. In this case, the grid-forming inverter is often provided as a function attached to a battery energy storage system (BESS), and the following description will be given on this assumption.

[0014] The power supply system 10 that constitutes the microgrid includes a first DG power plant 11, a second DG power plant 12, a BESS 13, a first solar cell power generation device (PV) 14, a first wind turbine power generation device (WT) 15, a three-phase three-winding transformer 16, a second solar cell power generation device 17, and a second wind turbine power generation device 18.

[0015] The first DG power plant 11 includes a plurality of synchronous generators 21 to 25 and a three-phase three-winding transformer . The synchronous generators 21 to 25 each perform synchronous power generation in a low voltage system (6 kV system in the example of FIG. 2). The three-phase three-winding transformer 26 converts between the voltage of the power generated by the synchronous generators 21 to 25 and the voltage of the high-voltage system (33 kV in the example of FIG. 2).

[0016] The second DG power plant 12 includes a plurality of synchronous generators 31 to 35, a first three-phase three-winding transformer 36, and a second three-phase three-winding transformer 37. The synchronous generators 31 to 35 each perform synchronous power generation in the low-voltage system.

[0017] The first three-phase three-winding transformer 36 converts between the power generated by the synchronous generators 31 to 35 and the power of the high-voltage system. The second three-phase three-winding transformer 37 converts the power generated by the second solar cell power generation device 17 or the second wind power generation device 18 into low-voltage system power corresponding to the power generated by the synchronous generators 31-35.

[0018] The BESS 13 includes a plurality of (four in the example of FIG. 2) power storage units 41 to 44, a plurality of first transformers 45 to 48, a second transformer 49, and an energy management system (EMS) 51.

[0019] FIG. 3 is a schematic block diagram of the power storage unit. In this case, the power storage units 41 to 44 have the same configuration, so the power storage unit 41 will be described as an example. Each storage unit 41 is equipped with a GFM unit 55 and a storage battery unit 56, and outputs the stored power of the storage battery unit 56 to the first transformer 45 via the GFM unit 55, and stores the power input from the first transformer 45 in the storage battery unit 56 via the GFM unit 55.

[0020] The first transformers 45-48 convert the power of the second transformer 49 and the power of the power storage units 41-44 back and forth. The second transformer 49 converts between the power of the first transformers 45 to 48 and the power of the low-voltage system.

[0021] FIG. 4 is a block diagram showing the general configuration of the EMS. The EMS 51 functions as a power generation planning control device, and functions as a calculation unit and a control unit. Specifically, as a power generation plan control device, the EMS 51 functions as a calculation unit when controlling the power generation plan of the battery energy storage system in the power supply system 10 including the first DG power plant 11 and the second DG power plant 12 corresponding to a plurality of synchronous generators, the first photovoltaic power generation device (PV) 14, the first wind turbine (WT) 15, the second photovoltaic power generation device 17, and the second wind turbine 18 which are a plurality of renewable energy generators, and the BESS 13 having a grid forming inverter function, so that the system inertia force secured by the synchronous generators and the BESS 13 is equal to or greater than the required amount in each time period, and so that the constraints on securing the upward / downward adjustment capability of the entire power supply system 10 are satisfied, as well as other constraints. Note that the operation as a calculation unit will be described in detail later.

[0022] Furthermore, based on the results of the calculations performed by the EMS51 as a calculation unit, the EMS51 functions as a control unit that controls the BESS13 to charge and discharge the BESS13, and ultimately to interconnect the BESS13 with a commercial grid consisting of the first DG power plant 11, the second DG power plant 12, the first solar cell power generation plant 14, the first wind power generation plant 15, the three-phase three-winding transformer 16, the second solar cell power generation plant 17, and the second wind power generation plant 18.

[0023] By controlling the EMS 51, it is possible to provide an asynchronous power supply system having synchronizing force and inertia force that can be operated integrally with the first DG power plant 11 and the second DG power plant 12 equipped with synchronous generators within the microgrid.

[0024] This will be explained in more detail below. In this case, the EMS 51 includes an MPU 61, a ROM 62, a RAM 63, an operation input unit 64, a display unit 65, a communication interface (I / F) unit 66, and an external storage device 67, and is configured as a so-called computer. The MPU 61 controls the entire EMS 51 based on a control program stored in the ROM 62 and RAM 63, and further controls the GFM units 55 in the power storage units 41 to 44. The ROM 62 stores the control program and control data in a non-volatile manner. The RAM 63 is used as a work area for the control program and stores various data. The operation input unit 64 is used by the operator to perform various operations, and is configured as a touch panel or the like. The display unit 65 includes a liquid crystal display panel or the like, and displays various information. The communication interface unit 66 performs an interface operation so that the MPU 61 can control the GFM units 55 of the power units 41 to 44 via a communication network (not shown).

[0025] The first solar cell power generating device 14 utilizes the photovoltaic effect to convert the light energy of sunlight into electrical energy (power) and outputs it to the low-voltage system. The first wind turbine generator 15 uses the power of wind to rotate the windmill, converting the rotational motion of the windmill into electrical energy via a generator and outputting it to the low-voltage system. The three-phase three-winding transformer 16 converts the output power of the BESS 13 and the power generated by the first solar cell power generation device 14 or the first wind power generation device 15 into power for the high-voltage system, and also converts power from the high-voltage system into power for the BESS 13.

[0026] The second solar cell power generating device 17 converts the light energy of sunlight into electrical energy (power) by utilizing the photovoltaic effect, and outputs the power to the second three-phase three-winding transformer 37. The second wind power generation device 18 uses the power of the wind to rotate the windmill, converting the rotational motion of the windmill into electrical energy via a generator and outputting it to the second three-phase three-winding transformer 37 .

[0027] Next, the operation of the embodiment will be described. First, the prerequisites will be described. For example, when considering the operation of one day, the required amount of inertial force and the required amount of adjustment force required of the power supply system 10 change in each time period.

[0028] FIG. 5 is a diagram illustrating an example of the relationship between the output change rate and the inertia constant. As shown in FIG. 5, the relationship between the output change rate V [kW / min] of the GFM and the inertia constant M [s] is assumed to be given as a relationship that can be approximated by a downward convex piecewise linear relationship, for example. The relationship between the GFM output change rate V [kW / min] and the inertia constant M [s] can be created from actual measurements of the step response to the control block shown in Figure 1.

[0029] In the phase control block of the GFM shown in FIG. 1, since it is generally a first-order lag system, the relationship shown in FIG. 5 is assumed to hold approximately. If the shape is not downward convex, this can be taken into consideration by approximating the whole shape as a straight line or by introducing a 0-1 variable.

[0030] In this case, the arbitrary inertia constant and output change rate of the GFM can be expressed as follows using the variable αk, which sums to 1:

number

[0031]

number

[0032]

number

[0033]

number

[0034] Next, the formulation will be explained. First, the objective function is to minimize the sum (=total) of the fuel cost and start-up cost of the synchronous generator (DG) over a predetermined period. That is, the following equation is minimized:

[0035]

number

number

[0036] In addition, by satisfying the following supply and demand balance constraints (corresponding to other constraints), the supply and demand balance can be maintained by the synchronous generator (DG) and the BESS 13.

number

number

[0037] In addition, by satisfying the following constraints on the grid inertia force, the grid inertia force secured by the synchronous generator (DG) and BESS can be made equal to or greater than the required amount in each time period.

number

[0038] where:

number

[0039] In addition, by satisfying the following constraints on ensuring the upward and downward control capability of the entire system, the control capability ensured by the synchronous generator (DG) and BESS can be made greater than the required amount in each time period.

number

[0040] where:

number

[0041] In addition, by satisfying the following constraints (corresponding to other constraints) on the increase / decrease adjustment capability of the synchronous generator (DG), the increase adjustment capability of the synchronous generator (DG) can be made equal to or less than the difference between the upper limit output and the current output, and can be made equal to or less than the output range that can be changed by the output change speed. Furthermore, the downward adjustment power of the synchronous generator (DG) can be set to be equal to or less than the difference between the current output and the lower limit output, and equal to or less than the output range that can be changed at the output change speed.

number

number

[0042] In addition, by satisfying the following constraints (corresponding to other constraints) on the BESS's up / down adjustment capability, the BESS's up adjustment capability will be equal to or less than the difference between the upper limit output and the current output, and the BESS's up adjustment capability will be equal to or less than the output range that can be changed at the output change speed. In addition, the downward adjustment capability of the BESS is equal to or less than the difference between the current output and the lower limit output, and the downward adjustment capability of the BESS is equal to or less than the output range that can be changed at the output change speed. Furthermore, the output change rate of the BESS is governed by a piecewise linear approximation of the inertia constant-change rate characteristic.

[0043]

number

[0044] where:

number

[0045] In addition, the piecewise linear approximation expression of the inertia constant of the BESS with GFM function is as follows: Here, the inertia constant of a BESS with a GFM function is governed by a piecewise linear approximation of the inertia constant-change rate characteristic, as shown below.

[0046]

number

[0047] where:

number

[0048] Furthermore, the charging output of the BESS is in the range of 0 to the upper output limit value.

number

[0049] where:

number

[0050] Furthermore, the discharge output of the BESS is in the range of 0 to the upper output limit.

number

[0051] where:

number

[0052] The EMS 51 functions as a calculation unit and performs calculations to satisfy equation (1) so that the system inertia force secured by the synchronous generator and the battery energy storage system is equal to or greater than the required amount in each time period.

[0053]

number

[0054] where:

number

[0055] Next, the EMS 51 functions as a calculation unit and performs calculations to satisfy the formulas (2) and (3) with respect to the constraints on ensuring the upward / downward adjustment capability of the entire power supply system, as shown in formula (1).

number

[0056] where:

number

[0057] FIG. 6 is a flowchart showing an outline of the process according to the embodiment. First, the EMS 51 reads parameters (for example, the upper and lower output limits of each synchronous generator) required for performing calculations based on the above constraints (step S11).

[0058] Next, the EMS 51 collects data from the first DG power plant 11, the second DG power plant 12, the BESS 13, the first solar cell power generation device (PV) 14, the first wind power generation device (WT) 15, the three-phase three-winding transformer 16, the second solar cell power generation device 17, and the second wind power generation device 18 that make up the power supply system 10 to identify their status (operating status, output status, etc.) at that time (step S12).

[0059] Next, the EMS 51 functions as a calculation unit and calculates the conditions that satisfy the remaining constraints based on the obtained data so as to reliably satisfy the above constraints (1) to (3), thereby calculating the control procedure for the BEESS 13 (step S13).

[0060] As a result, EMS51 functions as a control unit and controls the multiple storage units 41-44, multiple first transformers 45-48, and second transformer 49 that constitute BESS13 according to the calculated control procedure for BESS13, and ultimately controls the GFM unit 55 and storage unit 56 that constitute the storage units 41-44 so that the total inertia constant M of the synchronous generators (DG) 21-25, the synchronous generators (DG) 31-35, and the storage units 41-44 with GFM function in the entire power supply system 10 is equal to or greater than a predetermined constant amount, while controlling the GFM unit 55 and storage unit 56 to control the entire BESS13 so that the total adjustment power of the synchronous generators (DG) 21-25, the synchronous generators (DG) 31-35, and the storage units 41-44 with GFM function in the entire power supply system 10 is equal to or greater than a predetermined constant amount (step S14).

[0061] Unless the configuration of the power supply system 10 is changed due to a failure of a component, replacement of a device, or the like, the process returns to step S12 and the above-described process is performed as needed.

[0062] As a result, according to this embodiment, by satisfying the constraints on the system inertia force, the system inertia force secured by the synchronous generators (DG) 21 to 25, 31 to 35 and BESS 13 can be made to be more than the required amount in each time period, and by satisfying the constraints on the system adjustment capacity (mainly the increase adjustment capacity / decrease adjustment capacity of the entire power supply system), the system adjustment capacity secured by the synchronous generators (DG) 21 to 25, 31 to 35 and BESS 13 can also be made to be more than the required amount in each time period.

[0063] The EMS51 of this embodiment has a hardware configuration that utilizes a normal computer, and the program executed by the EMS51 is provided as a file in an installable or executable format recorded on a computer-readable recording medium such as a USB memory, a semiconductor memory device such as an SSD (Solid State Drive), or a DVD (Digital Versatile Disk).

[0064] The program executed by the EMS 51 of this embodiment may be stored on a computer connected to a network such as the Internet and provided by being downloaded via the network.The program executed by the EMS 51 of this embodiment may be provided or distributed via a network such as the Internet.

[0065] The program of this embodiment may be provided in a state where it is pre-installed in a ROM or the like.

[0066] The program executed by the EMS51 of this embodiment has a modular structure including the above-mentioned units (calculation unit and control unit), and in actual hardware, the CPU (processor) reads the program from the above-mentioned storage medium and executes it, thereby loading the above-mentioned units onto the main memory device and generating the calculation unit and control unit on the main memory device.

[0067] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0068] 10 Power system 11. No. 1 DG Power Plant 12 No. 2 DG Power Plant 13 BESS 14. First solar cell power generation device (PV) 15. First Wind Turbine (WT) 16 Three-phase three-winding transformer 17 Second solar cell power generation device 18. Second Wind Power Generation Device 21~25, 31~35 Synchronous generator 26 Three-phase three-winding transformer 36 1st three-phase three-winding transformer 37 No. 2 Three-phase Three-winding Transformer 41~44 Energy storage unit 45~48 Transformer No. 1 49 Transformer No. 2 51 Energy Management System (EMS: calculation unit, control unit) 55 GFM units 56 Battery Unit

Claims

1. A power generation plan control device for controlling a power generation plan of a battery energy storage system in a power supply system including one or more synchronous generators, one or more renewable energy generators, and a battery energy storage system having a grid-forming inverter function, a calculation unit that performs calculations so that the system inertia force secured by the synchronous generator and the battery energy storage system is equal to or greater than the required amount in each time period and so that constraints on securing the increase / decrease adjustment capability of the entire power supply system are satisfied; a control unit that controls the battery energy storage system based on the result of the calculation; A power generation planning control device equipped with:

2. The calculation unit performs calculations to satisfy the constraints and at least one of the following constraint conditions: a supply-demand balance constraint, a constraint on the raising / lowering adjustment capability of a synchronous generator (DG), and a constraint on the raising / lowering adjustment capability of a BESS. The power generation planning control device according to claim 1 .

3. The calculation unit performing a calculation to satisfy formula (1) so that the system inertia force secured by the synchronous generator and the battery energy storage system is equal to or greater than the required amount in each time period; [Equation 1] where: [Equation 2] is. Furthermore, regarding the constraints on ensuring the up-regulation capability / down-regulation capability of the entire power supply system, calculations are performed so as to satisfy the formulas (2) and (3). [Equation 3] where: [Equation 4] is. The power generation planning control device according to claim 1.

4. A control method for a power generation plan control device that controls a power generation plan of a battery energy storage system in a power supply system including one or more synchronous generators, one or more renewable energy generators, and a battery energy storage system having a grid-forming inverter function, the control method comprising: a step of performing a calculation so that the system inertia force secured by the synchronous generator and the battery energy storage system is equal to or greater than the required amount in each time period and satisfies the constraints on securing the up-regulation capability / down-regulation capability of the entire power supply system; controlling the battery energy storage system based on the results of the calculation; A control method for a power generation planning control device comprising:

5. A program for controlling, by a computer, a power generation plan control device that controls a power generation plan of a battery energy storage system in a power supply system including one or more synchronous generators, one or more renewable energy generators, and a battery energy storage system having a grid-forming inverter function, The computer a calculation means for performing calculations so that the system inertia force secured by the synchronous generator and the battery energy storage system is equal to or greater than the required amount in each time period and so that constraints on securing the adjustment capability for raising / lowering the power supply system as a whole are satisfied; means for controlling the battery energy storage system based on the results of the calculation; A program that makes it work.

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