Control method for power storage device and power storage device

Abstract

To provide a control method for a power storage device that does not require information on a power load.SOLUTION: The control method for a power storage device connected to a private power line of a power system together with a distributed power source and an emergency generator, generates a finite difference between an average value of the past results of output power PR of the distributed power source, averaged by a governor response time of the emergency generator and the current output power PR of the distributed power source as a command value for the output power of the power storage device.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a control method for a power storage device and a power storage device. [Background technology]

[0002] A microgrid is a system that combines distributed power sources such as solar power generation and wind power generation with power loads within a certain range to produce and consume energy locally. In a microgrid, the amount of power generated by the distributed power sources is unstable, so an emergency generator is connected to avoid power shortages. In addition, in a microgrid, the frequency of the differential power source fluctuates greatly, so the frequency needs to be stabilized. In general, a power storage device is installed in the microgrid to ensure frequency stability. In conventional power storage devices, past records of the amount of power generated by the distributed power sources connected to the microgrid and the amount of load of the power load in different seasons are accumulated, and a control method for the power storage device is determined by frequency analysis of the past records (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2012-16103 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the conventional control method for the power storage device, it is necessary to determine the control method for the power storage device by accumulating past performance data including the load amount of the power load or by performing a simulation instead of accumulating past performance data. Therefore, there are problems in that information on the power load is required to determine the control method for the power storage device and that the simulation becomes complicated and the accuracy decreases.

[0005] The present disclosure has been made to solve the above-mentioned problems, and has an object to provide a control method for a power storage device that does not require power load information or complex simulations. [Means for solving the problem]

[0006] The control method for a power storage device disclosed herein is a control method for a power storage device connected to a private power line together with a distributed power source and an emergency generator, and generates a command value for the output power of the power storage device by calculating the difference between an average value obtained by averaging the past performance of the output power of the distributed power source over the governor response time of the emergency generator and the current output power of the distributed power source. Effect of the Invention

[0007] The control method for the energy storage device disclosed herein generates a command value for the output power of the energy storage device by calculating the difference between the average value obtained by averaging the past performance of the output power of the distributed power source over the governor response time of the emergency generator and the current output power of the distributed power source, thereby eliminating the need for power load information and complex simulations to determine the control method for the energy storage device. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a configuration diagram of a microgrid according to a first embodiment. [Diagram 2] 5 is a diagram illustrating the operation of the power storage device control unit according to the first embodiment. FIG. [Diagram 3] FIG. 4 is a diagram illustrating a method for approximating a machine input in the first embodiment. [Figure 4] FIG. 4 is a diagram showing a change in frequency in the first embodiment. [Diagram 5] 4 is a diagram illustrating an example of a hardware configuration of a power storage device control unit according to the first and second embodiments. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, a control method for a power storage device according to an embodiment of the present disclosure will be described in detail with reference to the drawings. In addition, the same reference numerals in each drawing indicate the same or corresponding parts.

[0010] Embodiment 1 Fig. 1 is a configuration diagram of a microgrid according to a first embodiment. As shown in Fig. 1, the microgrid 1 is configured by connecting an emergency generator 11, a power storage device 12, a distributed power source 13, a load 14, and the like to a private line 10. The emergency generator 11 is also called a BCP (Business Continuity Plan) generator. This emergency generator 11 is provided to supply power to the private line 10 when the microgrid 1 faces an emergency situation such as an accident or disaster, or when the amount of power generated by the distributed power source 13 is insufficient, causing a power shortage on the private line 10.

[0011] The current flowing through the private line 10 of the microgrid 1 may be either DC or AC. Although not shown, a power conditioning system (PCS) is installed between the private line 10 and the emergency generator 11, the power storage device 12, the distributed power source 13, and the load 14. The PCS may be built into each device. Note that the microgrid 1 is often connected to another microgrid or a commercial power system.

[0012] The power storage device 12 is a chargeable and dischargeable power storage device, such as a secondary battery, a lead-acid battery, a nickel-metal hydride battery, or a lithium-ion battery. The distributed power source 13 is a renewable energy source, such as a solar power generation system, a wind power generation system, or a geothermal power generation system. The load 14 is a facility that consumes the power supplied from the private line 10, such as an ordinary home, a factory, or a commercial facility. There may be a plurality of each of the emergency generators 11, the power storage devices 12, the distributed power sources 13, and the loads 14 connected to the private line 10.

[0013] The power storage device 12 is connected to a power storage device control unit 15. Output information of the distributed power source 13 is input to the power storage device control unit 15. The power storage device control unit 15 outputs a command value for controlling the power storage device 12 to the power storage device 12 based on the input output information of the distributed power source 13.

[0014] Here, the power of each device in the microgrid 1 is expressed as follows. The output power of the emergency generator 11 is P E , the output power of the power storage device 12 is P B , the output power of the distributed power source 13 is P R , the power consumed by the load 14 is P M The output power P of the distributed power source 13 is expressed as R This fluctuation is constantly fluctuating due to weather, etc. E Therefore, P E In the microgrid 1 of this embodiment, the frequency of P E In order to suppress the frequency fluctuation of the output power P B Control.

[0015] Next, the operation of the power storage device control unit in this embodiment will be described. 2 is a diagram for explaining the operation of the power storage device control unit according to the present embodiment. As shown in FIG. 2, the power storage device control unit 15 calculates P R Average and current output power P R The difference between the output power of the power storage device 12 and the output power of the power storage device 12 is P B Generate it as a command value.

[0016] Here, the governor response time of the emergency generator 11 is the time required to keep the rotation speed of the prime mover that drives the emergency generator 11 constant. For example, the governor response time is the time required for the prime mover to recover to a preset constant rotation speed when the rotation speed changes due to some factor while rotating at a preset constant rotation speed. The governor response time is determined by the control characteristics and mechanical characteristics of the prime mover that drives the emergency generator 11, and is the time until the frequency fluctuation peaks when a sudden load change test of the emergency generator 11 is performed.

[0017] In the control method for the power storage device configured in this manner, the difference between the average value of the past performance of the output power of the distributed power sources, which is averaged over the governor response time of the emergency generator, and the current output power of the distributed power sources is generated as the command value for the output power of the power storage device, so that information on the power load and complex simulations are not required, and as a result, the time and cost required for determining the control method for the power storage device can be reduced.

[0018] Next, a method for designing the power storage device will be described. Output power of the power storage device P B The upper limit of the output power P of the distributed power source 13 is determined by the capacity of the power storage device. R The fluctuation value of the frequency f estimated from the equation of motion of the emergency generator described below with respect to the assumed change amount of is determined as a capacity within the allowable range of the storage device.

[0019] The equation of motion of the emergency generator is given by the following equation (1).

[0020]

number

[0021] Here, M is the moment of inertia of the rotor of the emergency generator, P T is the mechanical input of the emergency generator, and δ is the rotation angle of the rotor of the emergency generator. P E When the current fluctuates, the prime mover that drives the emergency generator is P EThe machine input P T The frequency fluctuation is suppressed by changing P T is determined by the control characteristics and mechanical characteristics of the prime mover that drives the emergency generator. If the control characteristics and mechanical characteristics of the prime mover are unknown, the mechanical input P is calculated by assuming that the output change from 0% to 100% of the rated output of the emergency generator changes linearly with the governor response time mentioned above. T can also be approximated.

[0022] Figure 3 shows the mechanical input P T 3 is a diagram for explaining a method for approximating the output P of the emergency generator. E As shown in Fig. 3, the output change from 0% to 100% of the rated output of the emergency generator is linearly changed with the governor response time mentioned above. T can be approximated.

[0023] The output power of the emergency generator 11 is P E is given by the following equation (2) based on the balance of power input and output in the private line 10.

[0024]

number

[0025] The frequency f estimated from the equation of motion of the emergency generator is given by the following equation (3).

[0026]

number

[0027] The output power P of the power storage device B follows the following equation (4).

[0028]

number

[0029] Here, P O is the capacity of the storage device (maximum output value), and P R_ave is the output of the distributed power source P R This is the average governor response time of the most recent governor. B If we calculate the frequency f using equations (1) to (3), the fluctuation value of f is P B Compared to the case of P = 0 O The reduction depends on the magnitude of

[0030] Capacity of the storage device P O is determined as a capacity at which the fluctuation value of the frequency f estimated in this manner falls within the allowable range of the load and the power storage device.

[0031] FIG. 4 is a diagram showing frequency fluctuations. In FIG. 4, the vertical axis represents frequency (assuming a 60 Hz area) and the horizontal axis represents time. R When the fluctuation value of is 6MW and the governor response time is 3 seconds, P O The results are shown in Fig. 4. O As the frequency fluctuation becomes smaller, the P O It is sufficient to determine the following.

[0032] In addition, a microgrid has been described as an example of the power system to which the power storage device according to the present embodiment is connected. The power system to which the power storage device according to the present embodiment is connected may be any power system in which a distributed power source and an emergency generator are connected to a private line.

[0033] Embodiment 2 In the microgrid according to the first embodiment, the power storage device is configured with a secondary battery such as a lead storage battery, a nickel-metal hydride battery, or a lithium-ion battery. In the microgrid according to the second embodiment, the power storage device is configured with a large-capacity capacitor. Other configurations of the microgrid according to the present embodiment are similar to those of the microgrid according to the first embodiment.

[0034] Therefore, like the power storage device control unit in the first embodiment, the power storage device control unit calculates P R Average and current output power P R The difference between this and the output voltage of the storage device is P B Generate it as a command value.

[0035] In the microgrid configured in this manner, as in the first embodiment, the difference between the average value obtained by averaging the past performance of the output power of the distributed power sources over the governor response time of the emergency generator and the current output power of the distributed power sources is generated as the command value for the output power of the power storage device, so that information on the power load and complex simulations are not required, and as a result, the time or cost required for determining the control method for the power storage device can be reduced.

[0036] The power storage device control unit 15 is configured with a processor 100 and a storage device 101, as shown in FIG. 5, which is an example of hardware. The storage device includes a volatile storage device such as a random access memory and a non-volatile auxiliary storage device such as a flash memory, although not shown. Also, instead of the flash memory, a hard disk auxiliary storage device may be included. The processor 100 executes a program input from the storage device 101. In this case, the program is input from the auxiliary storage device to the processor 100 via the volatile storage device. Also, the processor 100 may output data such as a calculation result to the volatile storage device of the storage device 101, or may store the data in the auxiliary storage device via the volatile storage device.

[0037] While the present disclosure describes various exemplary embodiments and examples, the various features, aspects, and functions described in one or more embodiments are not limited to application to a particular embodiment, but may be applied to the embodiments alone or in various combinations. Therefore, countless modifications not exemplified are assumed within the scope of the technology disclosed in this specification, including, for example, modifying, adding, or omitting at least one component, and further, extracting at least one component and combining it with a component of another embodiment. [Explanation of symbols]

[0038] 1 microgrid, 10 private line, 11 emergency generator, 12 power storage device, 13 distributed power source, 14 load, 15 power storage device control unit, 100 processor, 101 storage device.

Claims

1. A method for controlling a power storage device connected to a private line of a power grid together with a distributed power source and an emergency generator, comprising: A control method for a power storage device, comprising: generating a difference between an average value obtained by averaging past performance data of the output power of the distributed power source over a governor response time of the emergency generator and the current output power of the distributed power source as a command value for the output power of the power storage device.

2. A power storage device connected to a private line of a power grid together with a distributed power source and an emergency generator, The capacity of the power storage device is determined to be such that a frequency fluctuation value estimated by an equation of motion of the emergency generator is within an allowable range of a frequency fluctuation value of the private line.

3. 3. The power storage device according to claim 2, wherein the power storage device is configured with at least one of a chargeable and dischargeable secondary battery and a capacitor.

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