Control device, power conditioner, control method, and program

Abstract

To provide a control apparatus that enables continuous operation by keeping a DC bus voltage from exceeding a normal operation voltage range when a drop or a rise in the DC bus voltage is detected.SOLUTION: A control apparatus comprises: a voltage acquisition unit that acquires a voltage of a DC bus that connects a power conditioner with a storage battery unit; an output limiting unit that sets an output limit value of a PCS output power to zero when the voltage exceeds an upper limit threshold or is lower than a lower limit threshold, the PCS output power being electric power output to a load side by the power conditioner; and a limit cancelling unit that gradually increases or decreases the output limit value after the output limit value is set to zero.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a control device, a power conditioner, a control method, and a program.

Background Art

[0002] In recent years, power storage systems have been used in various places such as power generation facilities and factories that utilize renewable energy. The power storage system includes a plurality of power storage unit having a storage battery and a DC / DC converter, a PCS (Power Conditioning System), and a DC bus that connects the power storage unit and the PCS.

[0003] In addition, in the power storage system, when the total charge / discharge possible power of the entire power storage unit becomes smaller than the PCS output power output from the PCS to the load side (the power grid when the power storage unit discharges and the power storage unit when charging), for example, when the DC / DC converter trips, over-discharge of the storage battery and over-voltage of the DC bus occur, resulting in system shutdown. In order to continue the operation of the power storage system, it is necessary to limit the PCS output power when the voltage of the DC bus drops or rises significantly. For example, in Patent Document 1, when starting a load with a battery pack (power storage system) composed of a plurality of single cells, when over-discharge of any single cell is detected, power supply from the battery pack to the load is limited or stopped.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] FIG. 8 is a diagram showing an example of output limit processing of a power storage system in the prior art. As shown in FIG. 8, in a conventional power storage system, the output limit value for restricting the PCS output power P dc is changed according to an increase or decrease in the DC bus voltage V PCS . When the output limit value is a positive value, it represents charging of the battery unit, and when it is a negative value, it represents discharging from the battery unit.

[0006] For example, when a trip occurs during discharging from the battery unit, the total dischargeable power of the battery unit decreases (a1 in FIG. 8), and the DC bus voltage V dc decreases (a2 in FIG. 8). At this time, when the power storage system detects a decrease in the DC bus voltage V dc_t91 at time t91, it gradually reduces the PCS output power P PCS (gradually increases the value of the output limit value) to limit the discharging from the battery unit (a3 in FIG. 8). Then, at time t92, the PCS output power P PCS can be reduced to the total dischargeable power of the battery unit, so the power storage system stops the process of limiting the discharge power. However, the DC bus voltage V PCS continues to decrease until the PCS output power P dc matches the total dischargeable power. Then, the DC bus voltage V dc continues to decrease until time t94, and thereafter, the power storage system continues operation while maintaining the DC bus voltage in an abnormally low state (the value of the DC bus voltage V dc_t92 at time t92) (a4 in FIG. 8).

[0007] Similarly, during charging of the battery unit, assume that the DC / DC bus of one battery unit trips. Then, the total chargeable power of the battery unit decreases (b1 in FIG. 8), and the DC bus voltage V dc increases (b2 in FIG. 8). At this time, when the power storage system detects an increase in the DC bus voltage V dc_t93 at time t93, it gradually reduces the PCS output power P PCS (gradually decreases the value of the output limit value) to limit the charging of the battery unit (b3 in FIG. 8). Then, at time t94, the PCS output power P PCSSince it can be reduced to the total rechargeable power of the battery unit, the battery system stops limiting the charging power. However, the PCS output power P PCS The DC bus voltage V dc It continues to rise. Then, until time t94, the DC bus voltage V dc The voltage continued to rise, and thereafter the energy storage system maintained an abnormally high DC bus voltage (DC bus voltage at time t94 V dc_t94 The system continues operating while maintaining the value (Figure 8, b4).

[0008] The object of this disclosure is to provide a control device, power conditioner, control method, and program that can continue operation while suppressing the DC bus voltage from exceeding the normal operating voltage range when a drop or rise in DC bus voltage is detected. [Means for solving the problem]

[0009] According to one aspect of the present disclosure, the control device includes a voltage acquisition unit that acquires the voltage of a DC bus connecting a power conditioner (PCS) and a battery unit; an output limiting unit that sets an output limit value of the PCS output power, which is the power that the PCS outputs to the load side, to zero when the voltage exceeds an upper limit threshold or falls below a lower limit threshold; and a limit release unit that gradually increases or decreases the output limit value after setting it to zero.

[0010] According to one aspect of the present disclosure, the control method includes the steps of: acquiring the voltage of a DC bus connecting a power conditioner (PCS) and a battery unit; setting the output limit value of the PCS output power, which is the power that the PCS outputs to the load side, to zero when the voltage exceeds an upper threshold or falls below a lower threshold; and gradually increasing or decreasing the output limit value after setting it to zero.

[0011] According to one aspect of the present disclosure, the program causes the control device to perform the following steps: acquire the voltage of a DC bus connecting a power conditioner (PCS) and a battery unit; set the output limit value of the PCS output power, which is the power that the PCS outputs to the load side, to zero if the voltage exceeds an upper threshold or falls below a lower threshold; and gradually increase or decrease the output limit value after setting it to zero. [Effects of the Invention]

[0012] According to the above embodiment, when a decrease or increase in DC bus voltage is detected, operation can be continued while suppressing the DC bus voltage from exceeding the normal operating voltage range. [Brief explanation of the drawing]

[0013] [Figure 1] This figure shows the overall configuration of an energy storage system according to one embodiment. [Figure 2] This is a block diagram showing the functional configuration of a control device according to one embodiment. [Figure 3] This figure illustrates the upper and lower threshold values ​​for DC bus voltage according to one embodiment. [Figure 4] This flowchart shows an example of the output control process of a control device according to one embodiment. [Figure 5] This is a first diagram illustrating the output control process according to one embodiment. [Figure 6] This is a second figure illustrating the output control process according to one embodiment. [Figure 7] This flowchart shows an example of the process for updating the output limit value of a control device according to one embodiment. [Figure 8] This diagram illustrates an example of output limiting processing in a conventional energy storage system. [Modes for carrying out the invention]

[0014] (Overall configuration of the energy storage system) Figure 1 shows the overall configuration of an energy storage system according to one embodiment. As shown in Figure 1, the energy storage system 1 comprises a PCS (Power Conditioning System; power conditioner) 2, a control device 3, a DC bus 4, and multiple battery units 5.

[0015] PCS2 is a power conditioner connected to the power grid. PCS2 is equipped with an inverter 21, which is a bidirectional inverter that converts AC power to DC power. PCS2 converts the DC power discharged from each battery unit 5 into AC power using the inverter 21 and outputs it to the power grid. PCS2 also converts the AC power supplied from the power grid into DC power using the inverter 21 and outputs it to each battery unit 5. The power output from PCS2 to the load side is called PCS output power P. PCS It is also written as: PCS output power P PCS This refers to the power output from PCS2 to the power grid when the battery unit 5 is discharging, and the power output from PCS2 to the battery unit 5 when the battery unit 5 is charging.

[0016] The control device 3 controls the power output by PCS2 to the load side (PCS output power P). PCS ) is the total power that can be charged and discharged across the entire battery unit 5 (P1 + P2 + ... + P N The output limit value LM2 of the PCS2 is set so that it falls within the specified range. Normally, the control device 3 receives the output limit value LM1 of the PCS2 from the host device 6 and controls the PCS2 according to this output limit value LM1. The specific functional configuration of the control device 3 will be described later.

[0017] The DC bus 4 is a bus for connecting the PCS2 with multiple battery units 5.

[0018] Multiple battery units 5 are connected in parallel to the PCS2 via a DC bus 4. Each battery unit 5 includes a DC / DC converter 51 and a battery 52. ​​The DC / DC converter 51 converts the DC power supplied from the PCS2 to a predetermined voltage to charge the battery 52. ​​The DC / DC converter 51 also converts the discharge power of the battery 52 to a predetermined voltage and supplies it to the PCS2.

[0019] Although Figure 1 shows an example configuration in which the PCS2 incorporates the control device 3, the system is not limited to this configuration. In other embodiments, the control device 3 may be provided as separate hardware outside of the PCS2.

[0020] (Functional configuration of the control unit) Figure 2 is a block diagram showing the functional configuration of a control device according to one embodiment. As shown in Figure 2, the control device 3 comprises a processor 31, memory 32, storage 33, and a communication interface 34.

[0021] The processor 31 operates according to a predetermined program, performing functions as a voltage acquisition unit 310, an output limiting unit 311, a limit release unit 312, and a limit value setting unit 313.

[0022] The voltage acquisition unit 310 receives the voltage of the DC bus 4 connecting the PCS2 and the battery unit 5 from a voltage sensor (not shown) provided on the DC bus 4 (hereinafter referred to as the DC bus voltage V dc It is also written as follows.)

[0023] The output limiting unit 311 controls the DC bus voltage V dc When the power exceeds the upper threshold VUL or falls below the lower threshold VLL, the PCS output power P is the power that PCS2 outputs to the load side. PCS Set the output limit value LM2 to zero. Details of the upper threshold VUL and lower threshold VLL will be described later.

[0024] The limit release unit 312 sets the output limit value LM2 to zero, and then gradually increases or decreases the output limit value LM2.

[0025] The limit value setting unit 313 is set to the DC bus voltage V dc When the output power P reaches the upper limit Vmax or lower limit Vmin of the predetermined normal operating voltage range R, the output limit value LM2 is fixed at its current value. Furthermore, the limit value setting unit 313 receives the PCS output power P from the higher-level device 6. PCS When the output limit value LM1 is received, if output limit value LM1 ≤ output limit value LM2, output limit value LM2 is overwritten with the value of output limit value LM1. Details of the normal operating voltage range R will be described later.

[0026] The predetermined program executed by the processor 31 is stored on a computer-readable recording medium. A computer-readable recording medium refers to a magnetic disk, magneto-optical disk, CD-ROM, DVD-ROM, semiconductor memory, etc. Alternatively, this computer program may be distributed to a computer via a communication line, and the computer that receives the distribution may execute the program. Furthermore, this program may be intended to implement only a part of the functions described above. Moreover, it may be a program that can implement the above functions in combination with a program already recorded in the computer system, a so-called differential file (differential program).

[0027] Memory 32 has a memory area necessary for the operation of the processor 31.

[0028] The storage 33 is a so-called auxiliary storage device, such as an HDD (Hard Disk Drive) or SSD (Solid State Drive). The storage 33 stores data that each part of the processor 31 acquires, generates, and references during processing.

[0029] The communication interface 34 is an interface for sending and receiving various data and control signals between the PCS2, the higher-level device 6, and other devices.

[0030] (Regarding the upper and lower thresholds for DC bus voltage) Figure 3 is a diagram illustrating the upper and lower threshold values ​​of the DC bus voltage according to one embodiment. Figure 3 shows the DC bus voltage V dc This shows an example of the upper threshold VUL, lower threshold VLL, and normal operating voltage range R.

[0031] The DC bus voltage of each battery unit 5 when it is unloaded (not charging or discharging) is defined as the reference voltage V0.

[0032] The normal operating voltage range R is the voltage fluctuation range due to droop during normal operation of the battery unit 5, centered on the reference voltage V0. The upper limit of the normal operating voltage range is also referred to as Vmax, and the lower limit as Vmin.

[0033] The upper threshold VUL and lower threshold VLL are thresholds for detecting abnormalities in the DC bus 4 voltage. Taking into account transient voltage fluctuations due to overshoot and resonance during voltage control, as well as errors in the voltage sensor, the upper threshold VUL is set to be a value that is a predetermined amount α greater than the upper limit Vmax of the normal operating voltage range. Similarly, the lower threshold VLL is set to be a value that is a predetermined amount α less than the lower limit Vmin of the normal operating voltage range. This predetermined amount α may be arbitrarily changed depending on the characteristics of the battery unit 5.

[0034] (Processing flow of the control unit) Figure 4 is a flowchart showing an example of the output control process of a control device according to one embodiment. Figure 5 is a first diagram illustrating the output control process according to one embodiment. Figure 6 is a second diagram illustrating the output control process according to one embodiment. The following describes the output control process in response to fluctuations in the DC bus voltage of the control device 3, with reference to Figures 4 to 6.

[0035] During the series of processes shown in Figure 3, the voltage acquisition unit 310 acquires the DC bus voltage V at each time point. dc The output limiting unit 311 obtains the DC bus voltage V acquired by the voltage acquisition unit 310. dcIt is determined whether the value has exceeded the upper threshold VUL or fallen below the lower threshold VLL (step S01).

[0036] When the battery unit 5 is being charged, the output limiting unit 311 is limited by the DC bus voltage V dc If the value does not exceed the upper threshold VUL (step S01; NO), the process returns to step S01 and continues monitoring of the DC bus 4. Also, when the battery unit 5 is discharged, the output limiting unit 311 limits the DC bus voltage VUL. dc If the value is not below the lower threshold VLL (step S01; NO), return to step S01 and continue monitoring DC bus 4.

[0037] On the other hand, the output limiting unit 311 controls the DC bus voltage V dc If the value exceeds the upper threshold VUL, or falls below the lower threshold VLL (step S01; YES), the output control process of PCS2 is executed.

[0038] First, the output control process during discharge of the energy storage system 1 will be explained. Figure 5 shows, for example, the PCS output power P of battery unit 5_2 during discharge, among the three battery units 5_1, 5_2, and 5_3 of the energy storage system 1. PCS and DC bus voltage V dc This is an example of the time series. Figure 6 shows the DC bus voltage V of the battery unit 5_2 measured at each time t01 to t05 in Figure 5. dc This illustrates the correspondence with the output limit value LM2.

[0039] In the example shown in Figure 5, battery unit 5_2 tripped at time t01. Consequently, the total power that can be discharged by the entire battery unit 5 is P1+P2+P3 before time t01, but decreases to P1+P3 after time t01. Furthermore, at this time, PCS2 cannot detect the tripping of battery unit 5_2. Therefore, at time t01, the PCS output power P PCS It does not change. Therefore, from time t01 onward, the PCS output power P PCS >The total dischargeable power P1 + P3 of the battery unit 5 is, as shown in the example in Figure 5, the DC bus voltage Vdc It decreases over time.

[0040] Here, as a comparative example, we will describe the case in which the output control processing of this embodiment is not performed. Of the battery units 5_1 and 5_3 that are in continuous operation, the voltage of battery unit 5_1 is V BAT1 If V is the highest, BAT1 is V dc This is approximately equal to the above. In this case, the battery unit 5_1 compensates for the insufficient load without being controlled by the DC / DC converter 51 of the battery unit 5_1. As a result, the battery unit 5_1 may be over-discharged.

[0041] In order to suppress over-discharge of such a battery unit 5_1, the control device 3 according to this embodiment performs the output control processing described below.

[0042] In the examples in Figures 5 and 6, the DC bus voltage V is maintained from time t01 when the trip occurs. dc It decreases over time, and at time t02 the DC bus voltage V dc_t02 The output power P falls below the lower threshold VLL (Step S01; YES). In this case, the output limiting unit 311 sets the output limit value LM2 of the PSC2 to zero (Step S02). When the output limit value LM2 of the PCS2 becomes zero, at time t03, the PCS output power P of the PCS2 PCS The value becomes zero, and the DC bus voltage V dc_t03 The voltage returns (rises) to the reference voltage V0 under no-load conditions.

[0043] After setting the output limit value LM2 of PCS2 to zero, the limit release unit 312 gradually decreases the output limit value LM2 of PCS2 (step S03).

[0044] Next, the limit value setting unit 313 sets the DC bus voltage V dc It is determined whether the voltage has reached the lower limit value Vmin of the normal operating voltage range R (step S04).

[0045] At time t04 in Figures 5 and 6, the DC bus voltage V dc_t04The voltage has not reached the lower limit Vmin of the normal operating voltage range R (Step S04; NO). In this case, the limit value setting unit 313 waits until the next determination timing.

[0046] Furthermore, at time t05 in Figures 5 and 6, the DC bus voltage V dc_t05 = The lower limit value Vmin is set (Step S04; YES). In this case, the limit value setting unit 313 stops the gradual decrease of the output limit value LM2 and fixes the output limit value LM2 at its current value (Step S05). Note that the limit value setting unit 313 uses the DC bus voltage V dc_t05 If the value of is within a predetermined range from the lower limit Vmin, then the DC bus voltage V dc_t05 If it is determined that the lower limit Vmin has been reached (Step S04; YES), the output limit LM2 may be fixed at its current value (Step S05).

[0047] DC bus voltage V dc When the normal operating voltage range R reaches its lower limit value Vmin, the output power P of the PCS2 is as shown in the example in Figure 6. PCS This approximately matches the maximum power that can be discharged from the entire battery unit 5. Therefore, even if battery unit 5_2 trips during discharge, the control device 3 will discharge at the maximum power that the other operating battery units 5 can discharge, and the DC bus voltage V dc The operation of the energy storage system 1 can be continued by controlling it so that it stays within the normal operating voltage range R.

[0048] Furthermore, the output control during charging of the energy storage system 1 will be explained with reference to Figure 6. Figure 6 shows the DC bus voltage V measured at times t11 to t15 during charging. dc The correspondence with the output limit value LM2 is illustrated as an example.

[0049] For example, suppose the battery unit 5_2 tripped at time t11. Then, at time t11, the output limit value LM2 and PCS output power P of PCS2 are... PCS Although the value remains unchanged, the DC bus voltage Vdc rises over time and exceeds the upper threshold VUL at time t12 (Step S01; YES).

[0050] Then, the output limiting unit 311 sets the output limit value LM2 of the PSC2 to zero (step S02). When the output limit value LM2 of the PCS2 becomes zero, at time t13, the PCS output power P of the PCS2 PCS The value becomes zero, and the DC bus voltage V dc_t13 The voltage returns (decreases) to the reference voltage V0 under no load conditions.

[0051] After setting the output limit value LM2 of PCS2 to zero, the limit release unit 312 gradually increases the output limit value LM2 of PCS2 (step S03).

[0052] Next, the limit value setting unit 313 sets the DC bus voltage V dc It is determined whether the voltage has reached the upper limit Vmax of the normal operating voltage range R (step S04).

[0053] At time t14 in Figure 6, the DC bus voltage V dc_t14 The voltage has not reached the upper limit Vmax of the normal operating voltage range R (Step S04; NO). In this case, the limit value setting unit 313 waits until the next determination timing.

[0054] Also, at time t15 in Figure 6, the DC bus voltage V dc_t15 = Upper limit value Vmax (Step S04; YES). In this case, the limit value setting unit 313 stops the gradual increase of the output limit value LM2 and fixes the output limit value LM2 at its current value (Step S05). Note that the limit value setting unit 313 uses the DC bus voltage V dc_t15 If the value of is within a predetermined range from the upper limit Vmax, then the DC bus voltage V dc_t15 It is determined that the upper limit value Vmax has been reached (Step S04; YES), and the output limit value LM2 may be fixed at its current value (Step S05).

[0055] DC bus voltage V dc When the voltage reaches the upper limit Vmax of the normal operating voltage range R, the output power P of the PCS2 is as shown in the example in Figure 6. PCSThis approximately matches the maximum power that can be charged to the entire battery unit 5. Therefore, even if battery unit 5_2 trips during charging, the control device 3 will charge the other operating battery units 5 with the maximum power that can be charged, and the DC bus voltage V dc The operation of the energy storage system 1 can be continued by controlling it so that it stays within the normal operating voltage range R.

[0056] After fixing the output limit value LM2, the control device 3 returns to step S01. In this way, the control device 3 repeatedly performs the series of processes shown in Figure 3 while the energy storage system 1 is in operation.

[0057] In step S03, it is desirable for the limit release unit 312 to set a time constant that is sufficiently larger than that used during normal voltage control, thereby gradually increasing or decreasing the output limit value LM2. For example, the limit release unit 312 sets the time constant so that the time it takes from when the DC bus voltage becomes the reference voltage V0 until it reaches the upper limit Vmax or lower limit Vmin of the normal operating voltage range R is X seconds. The value of X may be arbitrarily changed depending on the characteristics of the battery unit 5, etc.

[0058] Figure 7 is a flowchart showing an example of the process for updating the output limit value of a control device according to one embodiment. The control device 3 may perform the process shown in Figure 7 to update the output limit value LM2 of the PCS2 in accordance with the command from the higher-level device 6.

[0059] For example, in step S01 of Figure 3, the control device 3 controls the DC bus voltage V dc The system may also be configured to send an abnormality notification to the higher-level device 6 when it detects that the output limit value LM1 of the PCS2 has exceeded the upper threshold VUL or fallen below the lower threshold VLL. In addition, the higher-level device 6 accepts an operation from the administrator of the energy storage system 1 to specify the output limit value LM1 of the PCS2 and transmits this output limit value LM1 to the control device 3.

[0060] Then, the control device 3 executes the process shown in Figure 7. Specifically, when the limit value setting unit 313 of the control device 3 receives a new output limit value LM1 from the host device 6 (step S11), it determines whether the output limit value LM1 is less than or equal to the output limit value LM2 (step S12). If the output limit value LM1 ≤ output limit value LM2 (step S12; YES), the limit value setting unit 313 sets the value of the output limit value LM2 to the value of the output limit value LM1 received from the host device 6 (step S13). On the other hand, if the output limit value LM1 > output limit value LM2 (step S12; NO), the limit value setting unit 313 terminates the process without changing the value of the output limit value LM2.

[0061] In other words, the control device 3 controls the DC bus voltage V dc When an abnormality is detected (step S01 in Figure 3; YES), the control device 3 performs the series of processes shown in Figure 3 to perform automatic control to provisionally change the output limit value LM2. In addition, the control device 3 operates under normal conditions (DC bus voltage V dc When the output limit value LM1 is received from the higher-level device 6 (when the normal operating voltage range R is within the normal operating voltage range), if the output limit value LM1 ≤ output limit value LM2, the output limit value LM2 is reset according to the output limit value LM1. From there, the energy storage system 1 continues to operate in accordance with the output limit value LM1 specified by the higher-level device 6. For example, after repairing or replacing the battery unit 5_2 and making it operational, resetting the output limit value LM2 according to the output limit value LM1 from the higher-level device 6 makes it possible to maximize the power that can be charged and discharged by the entire energy storage system 1.

[0062] (Effect, Action) As described above, the control device 3 according to this embodiment uses the DC bus voltage V of the DC bus 4 that connects the PCS2 and the battery unit 5. dc A voltage acquisition unit 310 acquires the DC bus voltage V dc When the power exceeds the upper threshold VUL or falls below the lower threshold VLL, the PCS output power P is the power that PCS2 outputs to the load side. PCSThe system includes an output limiting unit 311 that sets the output limit value LM2 to zero, and a limit release unit 312 that gradually increases or decreases the output limit value LM2 after setting it to zero.

[0063] In this way, the control device 3 controls the DC bus voltage V dc When an abnormality is detected, the output limit value LM2 of PCS2 is temporarily set to zero and the DC bus voltage V dc After returning it to the reference voltage V0, the DC bus voltage V is gradually increased or decreased by gradually increasing or decreasing the output limit value LM2. dc This allows for continued operation by suppressing the voltage from exceeding the normal operating voltage range R.

[0064] Furthermore, the control device 3 controls the DC bus voltage V dc The system further includes a limit value setting unit 313 that stops and fixes the gradual increase or decrease of the output limit value LM2 when it reaches the upper limit Vmax or lower limit Vmin of the predetermined normal operating voltage range R.

[0065] DC bus voltage V dc When the output power P of the PCS2 approximately coincides with the upper limit Vmax or lower limit Vmin of the normal operating voltage range R, PCS This approximately matches the maximum power that can be charged and discharged from the entire battery unit 5. Therefore, because the control device 3 has the above configuration, even if an abnormality (such as a trip) occurs in a part of the battery unit 5, the operating battery unit 5 will charge and discharge at the maximum power that it can charge and discharge, and the DC bus voltage V dc The operation of the energy storage system 1 can be continued by controlling it so that it stays within the normal operating voltage range R.

[0066] Furthermore, the limit value setting unit 313 receives a new output limit value LM1 from the higher-level device 6, and if the new output limit value LM1 is smaller than the output limit value LM2, it overwrites the output limit value LM2 with the value of the new output limit value LM1.

[0067] In this way, the control device 3 can maximize the total power that can be charged and discharged throughout the entire energy storage system 1 by resetting the output limit value LM2 according to the output limit value LM1 newly instructed by the higher-level device 6 after, for example, the battery unit 5 has been repaired or replaced and is operational again.

[0068] As described above, embodiments relating to this disclosure have been explained, but these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented 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 variations are included in the scope and spirit of the invention, as well as in the claims and their equivalents.

[0069] <Note> The control device, power conditioner, control method, and program described in the above-described embodiment can be understood, for example, as follows.

[0070] (1) According to a first aspect of the present disclosure, the control device 3 controls the voltage V of the DC bus 4 connecting the PCS 2 and the battery unit 5. dc A voltage acquisition unit 310 acquires the voltage, and V dc When the power exceeds the upper threshold VUL or falls below the lower threshold VLL, the PCS output power P is the power that PCS2 outputs to the load side. PCS The system includes an output limiting unit 311 that sets the output limit value LM2 to zero, and a limit release unit 312 that gradually increases or decreases the output limit value LM2 after setting it to zero.

[0071] In this way, the control device 3 controls the DC bus voltage V dc When an abnormality is detected, the output limit value LM2 of PCS2 is temporarily set to zero and the DC bus voltage V dc After returning it to the reference voltage V0, the DC bus voltage V is gradually increased or decreased by gradually increasing or decreasing the output limit value LM2. dc This allows for continued operation by suppressing the voltage from exceeding the normal operating voltage range R.

[0072] (2) According to the second aspect of the present disclosure, the control device 3 according to the first aspect stops the gradual increase or decrease of the output limit value LM2 and fixes it when the voltage V dc becomes the upper limit value Vmax or the lower limit value Vmin of the predetermined normal operation voltage range R, and further includes a limit value setting unit 313.

[0073] The DC bus voltage V dc When it substantially coincides with the upper limit value Vmax or the lower limit value Vmin of the normal operation voltage range R, the output power P of the PCS2 PCS substantially coincides with the maximum power that can be charged and discharged from the entire battery unit 5. Therefore, since the control device 3 has the above-described configuration, even if a part of the battery unit 5 trips, for example, the operating battery 5 unit operates at the maximum power that can be charged and discharged, and the DC bus voltage V dc is controlled to be within the normal operation voltage range R, and the operation of the power storage system 1 can be continued.

[0074] (3) According to the third aspect of the present disclosure, in the control device 3 according to the second aspect, when the limit value setting unit 313 receives a new output limit value LM1 from the upper-level device 6 and the new output limit value LM1 is smaller than the output limit value LM2, the output limit value LM2 is overwritten with the value of the new output limit value LM1.

[0075] By doing so, after the control device 3 repairs or replaces the battery unit 5 and becomes operable again, the output limit value LM2 is reset according to the command value from the upper-level device 6, so that the power that can be charged and discharged in the entire power storage system 1 can be maximized.

[0076] (4) According to the fourth aspect of the present disclosure, the PCS2 includes the control device 3 according to any one of the first to third aspects.

[0077] (5) According to the fifth aspect of the present disclosure, the control method is the voltage V of the DC bus 4 that connects the PCS2 and the battery unit 5 dcThe steps to obtain the voltage V dc When the power exceeds the upper threshold VUL or falls below the lower threshold VLL, the PCS output power P is the power that PCS2 outputs to the load side. PCS The method includes the steps of setting the output limit value LM2 to zero, and then gradually increasing or decreasing the output limit value LM2 after setting it to zero.

[0078] (6) According to a sixth aspect of the present disclosure, the program controls the voltage V of the DC bus 4 connecting the PCS2 and the battery unit 5. dc The steps to obtain the voltage V dc When the power exceeds the upper threshold VUL or falls below the lower threshold VLL, the PCS output power P is the power that PCS2 outputs to the load side. PCS The control device 3 is instructed to perform the steps of setting the output limit value LM2 to zero, and then, after setting the output limit value LM2 to zero, gradually increasing or decreasing the output limit value LM2. [Explanation of symbols]

[0079] 1. Energy storage system 2 PCS 21 Inverter 3. Control device 31 processors 310 Voltage acquisition unit 311 Output limiting unit 312 Restriction Release Section 313 Limit value setting section 32 memory 33 Storage 34 Communication Interfaces 4 DC buses 5. Battery Unit 51 DC / DC Converter 52 Storage batteries 6. Higher-level equipment

Claims

1. A voltage acquisition unit that acquires the voltage of the DC bus connecting the power conditioner (PCS: Power Conditioning System) and the battery unit, An output limiting unit that sets the output limit value of the PCS output power, which is the power output by the power conditioner to the load side, to zero when the voltage exceeds an upper threshold or falls below a lower threshold, A limit release unit that sets the output limit value to zero and then gradually increases or decreases the output limit value, A control device equipped with the following features.

2. The system further includes a limit value setting unit that stops gradually increasing or decreasing the output limit value and fixes it when the voltage reaches the upper or lower limit of a predetermined normal operating voltage range. The control device according to claim 1.

3. The limit value setting unit receives a new output limit value from a higher-level device, and if the new output limit value is smaller than the previous output limit value, it overwrites the previous output limit value with the value of the new output limit value. The control device according to claim 2.

4. A power conditioner comprising the control device according to any one of claims 1 to 3.

5. The steps include obtaining the voltage of the DC bus connecting the power conditioner (PCS: Power Conditioning System) and the battery unit, The steps include: setting the output limit value of the PCS output power, which is the power output by the power conditioner to the load side, to zero when the voltage exceeds an upper threshold or falls below a lower threshold; After setting the output limit value to zero, the step of gradually increasing or gradually decreasing the output limit value, A control method having

6. The steps include obtaining the voltage of the DC bus connecting the power conditioner (PCS: Power Conditioning System) and the battery unit, The steps include: setting the output limit value of the PCS output power, which is the power output by the power conditioner to the load side, to zero when the voltage exceeds an upper threshold or falls below a lower threshold; After setting the output limit value to zero, the step of gradually increasing or gradually decreasing the output limit value, A program that causes the control device to execute.

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