Battery diagnostic method and battery diagnostic device

Abstract

This approach balances suppressing the decrease in power generation with ensuring opportunities for battery degradation diagnosis. [Solution] A battery diagnostic method for a power generation system in which a first power source utilizing hydropower, other power sources utilizing renewable energy, and a battery capable of charging with the generated power of the first power source and the other power sources are connected to a power grid and a load, wherein the controller transitions the battery to a first charging state, then to a second charging state, diagnoses the degree of battery degradation based on the cumulative current amount from the first charging state to the second charging state, performs charging during a charging period in which the predicted amount of power generated by one or a combination of the first power source or other power sources is equal to or greater than the amount of power required for the transition to the charging state, performs discharging during a discharge period in which the amount of power demanded by the power grid or load increases, and suppresses the rise in battery temperature by controlling the current value when the battery temperature reaches a protection temperature during charging and discharging.

Description

Technical Field

[0001] The present invention relates to a battery diagnosis method and a battery diagnosis device.

Background Art

[0002] It is known to diagnose the degree of battery deterioration using the state of health (SOH), which is the ratio of the current capacity to the initial capacity of the battery. The current capacity is generally calculated from the difference in the open circuit voltage (OCV) at two different states of charge (SOC) and the integrated current value during the transition from one of these two states of charge to the other. That is, in order to diagnose battery deterioration, it is necessary to charge or discharge to change the SOC of the battery and measure the open circuit voltage at each state of charge.

[0003] Patent Document 1 discloses a control for a system including a power generation device and a power storage device, in which the power storage device is opened when there is no requirement for either charging or discharging of the power storage device, and the power storage device is opened if a predetermined condition is satisfied when there is either requirement, and the power storage device is not opened if the predetermined condition is not satisfied.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] When determining whether to allow or deny the opening of the energy storage device, as described in the above-mentioned document, the power generation device will be unable to generate electricity while the battery is open. In other words, the amount of electricity generated will decrease due to the degradation diagnosis. In particular, if the power generation device is one that is expected to generate electricity continuously, such as a hydroelectric power generation system that uses renewable energy, there is a problem that the amount of electricity that would normally be obtained will not be obtained due to the degradation diagnosis. On the other hand, periodic degradation diagnosis is essential for the continuous use of the energy storage device.

[0006] Therefore, the present invention aims to provide a control system that can suppress the reduction in power generation while ensuring opportunities for battery degradation diagnosis. [Means for solving the problem]

[0007] According to one aspect of the present invention, a battery diagnostic method is provided for a power generation system in which a first power source that generates electricity using hydropower, one or more other power sources that generate electricity using renewable energy, and a battery capable of charging the electricity generated by the first power source and the other power sources are connected to a power grid and a load. In this method, the controller transitions the battery to a first charge state by charging or discharging it, and then transitions it from the first charge state to a second charge state by discharging or charging it, and diagnoses the degree of battery degradation based on the cumulative current amount from the first charge state to the second charge state. Furthermore, charging is performed during a rechargeable period when the predicted amount of power generated by one or a combination of the first power source or other power sources is equal to or greater than the amount of power required for the transition to the charge state, and discharging is performed during a dischargeable period when the amount of power demanded by the power grid or load increases. In addition, if the battery temperature reaches a protection temperature during charging or discharging, the rise in battery temperature is suppressed by controlling the current value during charging or discharging. [Effects of the Invention]

[0008] According to the above embodiment, a control system is provided that can suppress the reduction in power generation and ensure an opportunity for battery degradation diagnosis. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a block diagram showing the schematic configuration of the power generation system. [Figure 2] Figure 2 is an example of a graph showing the relationship between the open-circuit voltage and charge state of battery 8. [Figure 3] Figure 3 shows the first example of a time chart when a degradation diagnosis is performed. [Figure 4] Figure 4 shows a second example of a time chart when a degradation diagnosis is performed. [Figure 5] Figures 5(A) and (B) are examples of graphs showing the relationship between the amount of electricity generated by the first and second power sources and the amount of electricity required for charging. [Figure 6] Figure 6 shows an example of a time chart when charging with power from the first power source. [Figure 7] Figure 7 shows an example of a time chart when charging with power from the second power source. [Figure 8] Figure 8 shows an example of a time chart when control is implemented to suppress the rise in battery temperature. [Figure 9] Figure 9 shows an example of a time chart regarding the frequency of deterioration diagnosis. [Figure 10] Figure 10 shows an example of a time chart when charging using power from the power grid. [Figure 11] Figure 11 is an example flowchart showing a control routine for deterioration diagnosis. [Modes for carrying out the invention]

[0010] Embodiments of the present invention will be described below with reference to the drawings.

[0011] [System Configuration] Figure 1 is a block diagram showing the schematic configuration of the power generation system 100 according to this embodiment.

[0012] The power generation system 100 includes a first power source 1 that generates power using hydraulic power, second and third power sources 2 and 3 that generate power using renewable energy, a battery 8 that can be charged with the generated power from the first to the third power sources, and a controller 7. These power sources are connected to the power grid 4 and the load 13.

[0013] The first power source 1 includes a generator 5 and a power conversion device 6. The generator 5 is a three-phase AC rotating electrical machine, which is connected to a water turbine 14 arranged in a first water flow path 15, and generates power by the rotation of the water turbine 14 due to the energy of the flowing water. The power conversion device 6 converts the AC power generated by the generator 5 into DC power. A first valve 16 for adjusting the flow rate is installed in the first flow path 15. Further, a second flow path 17 is provided that branches from the first flow path 15 upstream of the water turbine 14 and the first valve 16 and merges into the first flow path 15 downstream of the water turbine 14 and the first valve 16. A second valve 18 for adjusting the flow rate is installed in the second flow path 17.

[0014] The second power source 2 is, for example, a solar power generation system, and the third power source 3 is, for example, a wind power generation system.

[0015] In addition, the power generation system 100 includes a battery 8 capable of storing the generated power and supplying power to the load 13, and a PCS (Power Conditioning System) 10. A relay 9 is installed between the PCS 10 and the first power source 1. Further, the power generation system 100 includes an ammeter 12 for detecting the battery current value and a voltmeter 11 for detecting the battery voltage value.

[0016] The controller 7 performs various controls such as control of the generation torque of the generator 5, switching control of the power conversion device 6, charge and discharge control of the battery 8, etc. In this embodiment, the controller 7 performs control of all the power sources, but it is not limited to this. For example, each of the second power source 2 and the third power source 3 may be provided with a power generation controller, and the controllers may be communicably connected. Also, a configuration including an integrated controller for integrally controlling each controller may be adopted.

[0017] The above power generation system 100 can be installed in a facility equipped with a waterway available for hydroelectric power generation, such as a water supply facility or a factory. That is, the load 13 is an electrical device within the facility. The power generated by the power generation system 100 may be consumed by supplying it to the load 13 (self-consumption), stored in the battery 8, or fed back to the power grid 4 for power purchase.

[0018] In this embodiment, the case of having three power sources, i.e., the first power source 1 to the third power source 3, is described. However, the number of power sources is not limited to this, and four or more power generation systems using renewable energy may be provided.

[0019] [Battery Deterioration Diagnosis] In order to appropriately operate the power generation system 100 over a long period, it is necessary to grasp the degree of deterioration of the battery 8. In this embodiment, the degree of deterioration of the battery 8 is determined by Equation (1).

[0020] [Number]

[0021] Here, SOH (State Of Health) is the degree of deterioration.

[0022] The initial capacity is measured before use.

[0023] The current capacity is calculated by the following method. Figure 2 is an example of a graph showing the relationship between the open-circuit voltage (OCV) and state of charge (SOC) of the battery 8. In this embodiment, depending on the charge state SOCn at the start of degradation diagnosis, the battery is charged or discharged to bring the charge state to either SOC1 or SOC2, whichever is closer. If the battery is discharged to SOC1, the open-circuit voltage OCV is measured, then the battery is charged until it reaches SOC2, and the open-circuit voltage OCV is measured again. The integrated current value during the transition from SOC1 to SOC2 is then detected, and the current capacity is calculated using equation (2). In this case, SOC1 is also called the first charge state, and SOC2 is also called the second charge state.

[0024]

number

[0025] On the other hand, if the battery is initially charged to state of charge (SOC2), the open-circuit voltage (OCV) is measured, then the battery is discharged until it reaches state of charge (SOC1), and the open-circuit voltage (OCV) is measured again. The integrated current value during the transition from SOC2 to SOC1 is then detected, and the current capacity is calculated using equation (2). In this case, SOC2 is also called the first charge state, and SOC1 is also called the second charge state.

[0026] While SOC1 and SOC2 can be set arbitrarily, it is desirable to avoid the low SOC region where the rate of change in OCV relative to the change in SOC is abrupt, as shown in Figure 2.

[0027] As described above, in order to perform a degradation diagnosis, it is necessary to charge and discharge the battery 8. Charging requires power, and discharging requires that the discharged power be able to be reverse-flowed to the power grid 4 or consumed by the load 13. However, if the power generated by the power generation system 100 is supplied to the battery 8 for charging, there is a risk that the power supplied to the load 13, etc., will be insufficient. Also, while stopping the power generation of the power generation system 100 would allow the discharged power to be consumed by the load 13, stopping power generation every time a degradation diagnosis is performed would negate the benefits of stable power generation, such as that offered by hydroelectric power generation.

[0028] Therefore, in this embodiment, in order to diagnose the degradation of the battery 8 without stopping the power generation of the power generation system 100 and without affecting the operation of the load 13, the degradation diagnosis is performed using the method described below.

[0029] [Timing of charging and discharging] The timing for charging the battery 8 for degradation diagnosis is determined by the timing when the power generated by one or a combination of the first power source 1, the second power source 2, or the third power source 3 is expected to exceed the power required for charging while ensuring sufficient power supply to the load 13, etc. This allows charging for degradation diagnosis to be performed without affecting the operation of the load 13, etc.

[0030] Figure 3 shows an example of a time chart for first bringing the battery to the second charge state (SOC2) for degradation diagnosis. Note that here, the power generation system consists only of the first power source 1 and the second power source 2 (i.e., there is no third power source 3). The same applies to the time charts described below. Also, the vertical axis scales of the power generation chart and the battery power chart are different.

[0031] In Figure 3, time t1 to t3 is defined as the period during which the combined power generation of the first power source 1 and the second power source 2 exceeds the amount of energy required to move from the current charge state to the second charge state (SOC2). In this case, charging can be performed at any time between t1 and t3, for example, starting at time t2 as shown in the figure. The method for predicting power generation during charging will be described later.

[0032] Furthermore, the timing for performing discharge for degradation diagnosis is preferable when the self-consumption of load 13 is increasing or when the price of electricity sold back to the grid is rising. As a method of consuming the discharged power, for example, one could consider supplying it to a resistive load to convert it into heat, but if it is supplied to load 13 for self-consumption, the power can be used without waste, and if the power is reversed when the price of electricity sold back to the grid is high, the cost required for degradation diagnosis can be suppressed.

[0033] Figure 4 shows an example of a time chart for a transition from the second charge state (SOC2) to SOC1 by discharging for degradation diagnosis. Similar to Figure 3, the battery is initially charged to reach the second charge state (SOC2).

[0034] Furthermore, it is predicted that the self-consumption by load 13 will increase to a level that can consume the discharged power after time t4. In this case, discharge is possible after time t4, and for example, discharge will start at time t5 as shown in Figure 4. The timing of the increase in self-consumption is predicted based on, for example, past power consumption data of load 13.

[0035] In some cases, charging for degradation diagnosis is performed using power from the power grid, but this will be discussed later.

[0036] [Select power source] The priority order for power sources used to charge battery 8 is basically first power source 1, other power sources, and then power system 4. However, power system 4 will be selected only if the amount of power generated by first power source 1, the other power sources, or a combination of both is insufficient to charge the battery.

[0037] In other words, the priority order in this embodiment is first power source 1, second power source 2, and power system 4, and power system 4 is selected when the amount of power required for charging cannot be supplied by first power source 1 and second power source 2.

[0038] The following four patterns are possible in which the amount of electricity required for charging can be supplied by the first power source 1 and the second power source 2.

[0039] (a) Power generation from the first power source 1 > Power required for charging (b) Amount of power generated by the second power source 2 > Amount of power required for charging (c) Total power generation from the first power source 1 and the second power source 2 > Amount of electricity required for charging (d) The amount of power required for charging can be secured by switching between the first power source 1 and the second power source 2.

[0040] Figure 5(A) shows an example of a time chart for pattern (b) described above. As shown in the figure, the amount of electricity generated by the first power source 1 is insufficient to secure the amount of electricity needed for charging, but the amount of electricity generated by the second power source 2 is sufficient. In this case, the second power source 2 is selected as the power source to be used for charging.

[0041] Figure 5(B) is an example of a time chart for pattern (d) described above. As shown in the figure, at the start of charging timing ts, it is the second power source 2, not the first power source 1, that can secure the amount of power required for charging. However, during charging, the amount of power generated by the second power source 2 decreases and becomes less than the amount of power required for charging, while the amount of power generated by the first power source 1 increases and becomes greater than the amount of power required for charging. In such cases, the power source is switched from the second power source 2 to the first power source 1 at the timing when the amount of power generated by the first power source 1 becomes greater than the amount of power required for charging.

[0042] Pattern (d) is one in which the relative magnitudes of the power generation of the first power source 1 and the second power source 2 are reversed compared to (B) in Figure 5. In this case, the system switches from the first power source 1 to the second power source 2.

[0043] [Method for predicting power generation] Next, we will explain how to predict the amount of electricity generated by power sources.

[0044] In this embodiment, the amount of power generated is predicted based on past operating data of the power generation system, weather, season, time of day, or a combination thereof. The prediction of power generation here includes not only the amount of power generated but also the prediction of the change in power generation over time. Weather also includes ambient temperature. When the predicted amount of power generated is sufficient to cover the amount of electricity required for charging, the amount of power generated and the associated controls are performed when it is time to charge. In order for the amount of power generated to cover the amount of electricity required for charging to be sufficient, it is sufficient for the amount of power generated to be greater than the amount of electricity required for charging, but it is more preferable that the amount of electricity obtained by subtracting the amount of electricity required during normal operation from the amount of power generated (surplus electricity) is greater than the amount of electricity required for charging.

[0045] For the first power source 1, i.e., the hydroelectric power generation system, the water flow rate is predicted based on data such as past power generation, season, or weather, or a combination thereof, and the amount of power generated is predicted using that flow rate. If it is determined that the amount of power generated by the first power source 1 is sufficient to cover the amount of electricity needed for charging, the power generation torque of the first power source 1 and the opening and closing of the first valve 16 and the second valve 18 are controlled in accordance with the charging period.

[0046] Figure 6 shows an example of a time chart when charging with the first power source 1. The predicted water flow rate starts to increase from timing t1 and continues to increase until timing t4. Then, at timing t2, the amount of power generated is increased by increasing the generating torque of generator 5, and charging begins.

[0047] Furthermore, at timing t2, the opening operation of the first valve 16 and the closing operation of the second valve 18 begin simultaneously with the start of the increase in generated torque. More specifically, the opening operation of the first valve 16 and the closing operation of the second valve 18 are coordinated to maintain a constant pressure downstream of the turbine 14 (also called secondary pressure). This makes it possible to apply this system to facilities where it is necessary to maintain a constant secondary pressure, such as the pressure reduction mechanism of a water supply facility.

[0048] For the second power source, namely the solar power generation system, the amount of power generated is predicted based on data such as weather, time of day, or season, or a combination thereof.

[0049] Figure 7 shows an example of a time chart when charging with the second power source 2. The predicted power generation between timings t1 and t2 is assumed to be greater than the amount of power required for charging. In this case, charging is started by increasing the PCS input voltage at timing t1.

[0050] [Battery protection during charging and discharging] Battery 8 generates heat during charging and discharging. Battery 8 has a protection temperature set to protect it from degradation due to heat. The protection temperature may be set lower than the temperature at which degradation will be significantly accelerated (upper temperature). If the battery temperature reaches the protection temperature during use, the controller 7 controls the current value during charging and discharging to suppress the temperature rise. This also applies to charging and discharging for degradation diagnosis. In other words, during charging and discharging for degradation diagnosis, the controller 7 monitors the temperature of battery 8 and controls the current value so as not to exceed the protection temperature. Note that the battery temperature may be detected by a temperature sensor (not shown) or estimated by a known calculation method.

[0051] Figure 8 shows an example of a time chart when battery protection control is performed during charging and discharging. Timings t1 to t2 represent the charging period, and timings t2 to t3 represent the discharging period. In the figure, the solid line shows the case when the protection control of this embodiment is performed, and the dashed line shows the case when the protection control is not performed.

[0052] When charging begins at timing t1, the battery temperature starts to rise. At timing t2, the system switches to discharging, but at this point the battery temperature has reached the protection temperature, so the controller 7 reduces the current value by adjusting the PCS input voltage (DC-DC voltage). This suppresses the rise in battery temperature.

[0053] [Frequency of deterioration diagnosis] Since the battery 8 deteriorates with each charge and discharge cycle, the more times a deterioration diagnosis is performed, the faster the deterioration will progress. Therefore, in this embodiment, a diagnosis prohibition period is set between the end of the previous deterioration diagnosis and the start of the next deterioration diagnosis. The diagnosis prohibition period can be set arbitrarily, but for example, it can be set to about one month.

[0054] In other words, once the degradation diagnosis is complete, the next degradation diagnosis is performed when the battery becomes chargeable again after the aforementioned charging / discharging timing has elapsed following the expiration of the diagnostic prohibition period. This reduces the number of charge / discharge cycles and suppresses the degradation of battery 8 associated with the degradation diagnosis.

[0055] Furthermore, degradation diagnosis is essential for the stable long-term use of battery 8. In other words, the longer the period without degradation diagnosis, the higher the possibility that degradation will not be detected. Therefore, in this embodiment, the next degradation diagnosis will be performed within a predetermined period (hereinafter also referred to as the undiagnosed upper limit period) after the completion of the previous degradation diagnosis. The undiagnosed upper limit period can be set arbitrarily, but for example, it is set to about six months to one year.

[0056] One example of a situation where the maximum period for non-diagnosis has expired is when there is no opportunity to charge the battery after the diagnostic prohibition period has passed. In this case, the battery 8 is charged using power from power system 4.

[0057] Figure 9 is a time chart showing the frequency of degradation diagnosis. Timings t1-t3 and t5-t7 represent the periods during which degradation diagnosis is performed. Additionally, the period from timing t3, after the first degradation diagnosis is completed, to timing t4 is a period during which diagnosis is prohibited.

[0058] The next degradation diagnosis is initiated at timing t5, when charging becomes possible after timing t4. If it is predicted that there will be no charging / discharging opportunities between timing t4 and timing t8, charging will be performed using power from power system 4 before the upper limit of the undiagnosed period expires.

[0059] [When using electricity from the power grid] When performing degradation diagnosis using power from power grid 4, the timing of charging can be set arbitrarily, but it is preferable to do so when the electricity purchase price is low. This is to reduce the cost required for degradation diagnosis.

[0060] On the other hand, the timing of the discharge is as described above.

[0061] Figure 10 shows an example of a time chart when performing a degradation diagnosis using power from power system 4.

[0062] As shown in the diagram, the electricity purchase price decreases during the period from timing t1 to t3. Therefore, charging is started at timing t2. The timing t4, when discharging is started, is when self-consumption of electricity is increasing or when the electricity selling price is high.

[0063] [Control example] Next, we will describe specific control examples for the degradation diagnosis mentioned above.

[0064] Figure 11 is a flowchart showing the control routine for degradation diagnosis performed by the controller 7. In this control example, the charge and discharge for degradation diagnosis are performed in the order of charge → discharge.

[0065] In step S10, it is determined whether or not the diagnostic prohibition period has elapsed. If it has elapsed, the process in step S20 is performed; otherwise, the determination in this step is repeated.

[0066] In step S20, the system switches to a mode for performing deterioration diagnosis.

[0067] In step S30, it is determined whether the amount of electricity generated using renewable energy is greater than the amount of electricity required for degradation diagnosis. Specifically, as described above, the amount of electricity generated by the first power source 1 and the second power source 2 is predicted, and it is determined whether there is a timing that can cover the amount of electricity required for charging for degradation diagnosis. If the result of the determination is positive, the process in step S40 is performed; otherwise, the process in step S160 is performed.

[0068] In step S40, the power source to be used for charging for degradation diagnosis is determined based on the judgment result in step S30. The method of determination here is as explained in Figure 5, etc.

[0069] In step S50, the system determines whether to charge or discharge first based on the current state of charge (SOC). For example, in Figure 2, if the current SOC is close to SOC2, charging is performed; if it is close to SOC1, discharging is performed. In this control example, charging is performed as described above.

[0070] In Step S60, charging begins when charging becomes possible.

[0071] In step S70, it is determined whether the battery temperature is lower than the protection temperature. If it is lower, the process in step S90 is performed; otherwise, the process in step S80 is performed.

[0072] In step S80, the PCS input voltage (high voltage) is reduced to suppress the temperature rise caused by charging, and the process returns to step S70.

[0073] In step S90, the open-circuit voltage (OCV) is measured.

[0074] In step S100, it is determined whether the power demand of load 13 or power system 4 has increased. In other words, it is determined whether the timing is suitable for discharge. If the determination result is positive, the process in step S110 is performed; otherwise, the determination in this step is repeated.

[0075] In step S110, discharge is initiated. The discharged power is supplied to load 13 if, for example, the power demand of load 13 is increasing, or it is returned to power grid 4 if the demand of power grid 4 is increasing (if the price of electricity sold is rising).

[0076] In step S120, the battery temperature is determined in the same way as in step 70. If the determination result is positive, the process in step S140 is performed; otherwise, the process in step S130 is performed.

[0077] In step S130, the PCS input voltage (high voltage) is increased to suppress the temperature rise due to discharge, and the process returns to step S120.

[0078] In step S140, the open-circuit voltage (OCV) is measured, similar to step S90.

[0079] In step S150, SOH is calculated using the formula (1) described above.

[0080] If the result of step S30 is negative, step S160 is performed to determine whether the upper limit period of undiagnosed cases has expired. If the result is positive, the process in step S170 is performed; otherwise, the process returns to step S30.

[0081] In step S170, the power source to be used for degradation diagnosis is determined to be power system 4, and the process in step S50 is performed.

[0082] Furthermore, if the charge-discharge process for degradation diagnosis is performed in the order of discharge → charge, that is, if it is decided to discharge in step S50, then discharge will begin in step S60. Then, in step S100, it is determined whether or not the timing for charging has arrived as described above, and charging will begin in step S110. In addition, in step S80, which is for battery temperature control, the PCS input voltage (high voltage) is increased, and in step S130, the PCS input voltage (high voltage) is decreased.

[0083] Once the above degradation diagnosis control routine is complete, the controller 7 determines whether or not the battery 8 is degraded based on the calculated SOH. If it determines that the battery is not degraded, the process ends there. As a result, the battery 8 will continue to be used at least until the next degradation diagnosis. On the other hand, if it determines that the battery is degraded, the controller 7 notifies the system that manages the facility equipped with the power generation system 100 that the battery 8 is degraded, and the system then notifies the administrator of the battery 8's degradation. As a result, the degraded battery 8 will be replaced.

[0084] As described above, this embodiment provides a battery diagnostic method for a power generation system 100, which includes a first power source 1 that generates electricity using hydropower, one or more other power sources 2, 3 that generate electricity using renewable energy, and a battery 8 capable of charging the electricity generated by the first power source 1 and the other power sources 2, 3, all connected to a power grid 4 and a load 13. In this method, the controller 7 transitions the battery 8 to a first charge state by charging or discharging it, then transitions it from the first charge state to a second charge state by discharging or charging it again, and diagnoses the degree of battery degradation based on the cumulative current amount from the first charge state to the second charge state. Furthermore, charging is performed during a rechargeable period when the predicted amount of power generated by the first power source 1 or any combination of the other power sources 2, 3 is equal to or greater than the amount of power required for the transition to the charge state, and discharging is performed during a dischargeable period when the amount of power demanded by the power grid 4 or the load 13 increases. During charging and discharging, the battery temperature is maintained below the protection temperature by controlling the charging and discharging current. According to this diagnostic method, charging is performed at the timings mentioned above, allowing charging to be carried out without stopping a system capable of stable power generation, such as hydroelectric or solar power generation. Furthermore, by performing discharge at the timings mentioned above, the power charged for degradation diagnosis can be used efficiently. In other words, the efficiency of renewable energy utilization can be increased. In addition, the rise in battery temperature during charging and discharging is suppressed, thus suppressing the degradation of battery 8.

[0085] In this embodiment, the controller 7 controls the current value by controlling the voltage connected to the battery 8 (PCS input voltage) based on data from the ambient temperature, water temperature, or the power generation status of the power generation system, or a combination thereof. That is, it determines the timing for charging and discharging based on the above data and controls the current value for charging and discharging. This makes it possible to improve the efficiency of renewable energy utilization.

[0086] In this embodiment, the controller 7 calculates the predicted power generation value based on data from the past power generation of the first power source 1 and the other power sources 2 and 3, as well as weather, season, time of day, or a combination thereof. This ensures that the amount of power necessary for degradation diagnosis is secured.

[0087] In this embodiment, the controller 7 determines that charging by the first power source is possible if it can predict, based on past power generation data, weather, season, time of day, or a combination thereof, that the water flow rate will increase to a degree that the amount of power generated by the first power source 1 will exceed the amount of power required for charging. This allows for accurate prediction of the amount of power generated by the first power source 1 and improves the accuracy of determining whether or not charging by the first power source 1 is possible.

[0088] In this embodiment, the other power source is a second power source 2 that generates electricity using sunlight, and the controller 7 determines that charging by the second power source 2 is possible if it can predict, based on past power generation data, weather, season, time of day, or a combination thereof, that the amount of electricity generated by the second power source 2 will be greater than the amount of electricity required for charging. This allows for accurate prediction of the amount of electricity generated by the second power source 2 and improves the accuracy of determining whether or not charging by the second power source 2 is possible.

[0089] In this embodiment, if the first power source 1 and the other power sources 2 and 3 cannot supply the amount of power necessary to charge the battery 8, the controller 7 acquires data on the electricity purchase price and charges the battery using the power from the power grid 4 when the electricity purchase price falls. This reduces the cost of using the power from the power grid 4.

[0090] In this embodiment, the controller 7 performs the next diagnosis within a predetermined period (upper limit of undiagnosed period) after the completion of the previous diagnosis. This prevents the battery 8 from being used for a long period of time while in a deteriorated state.

[0091] In this embodiment, if the predicted power generation amount of the first power source 1 and / or the other power sources 2 and 3, or a combination thereof, does not exceed the amount of power required for the transition of the battery 8's charge state, the controller 7 will charge the battery using power from the power system 4 before the upper limit period of undiagnosed activity has elapsed. This makes it possible to diagnose degradation regardless of the power generation amount of the first power source 1 and / or the other power sources 2 and 3, or a combination thereof. [Explanation of Symbols]

[0092] 1...First power source, 2...Second power source, 3...Third power source, 4...Power system, 5...Generator, 6...Power converter, 7...Controller, 8...Battery, 10...PCS, 13...Load

Claims

1. The first power source generates electricity using hydropower, One or more other power sources that generate electricity using renewable energy, A battery capable of charging the power generated by the first power source and the other power source, In a battery diagnostic method for a power generation system connected to a power grid and load, The controller is The battery is brought to a first charge state by charging or discharging it, and then brought to a second charge state by discharging or charging it again. The degree of battery degradation is diagnosed based on the cumulative current from the first charge state to the second charge state. The charging described above is performed during a charging period in which the predicted amount of power generated by either the first power source or the other power sources, or a combination thereof, is equal to or greater than the amount of energy required for the transition of the charging state. The discharge is performed during a dischargeable period when the amount of power demanded by the power system or the load increases. A battery diagnostic method characterized by suppressing the rise in battery temperature by controlling the current value during charging and discharging if the battery temperature reaches a protection temperature during charging and discharging.

2. In the battery diagnostic method described in claim 1, The aforementioned controller, A battery diagnostic method that controls the current value by controlling the voltage connected to the battery based on data of the outside air temperature, water temperature, or the power generation status of the power generation system, or a combination thereof.

3. In the battery diagnostic method described in claim 2, The aforementioned controller, A battery diagnostic method for calculating a predicted power generation amount based on data from past power generation amounts, weather, season, or time of day, or a combination thereof, of the first power source and the other power sources.

4. In the battery diagnostic method described in claim 3, The aforementioned controller, A battery diagnostic method that determines that charging by the first power source is possible if it can be predicted, based on past power generation data, weather, season, time of day, or a combination thereof, that the water flow rate will increase to such an extent that the amount of power generated by the first power source becomes greater than the amount of power required for charging.

5. In the battery diagnostic method described in claim 2, The aforementioned other power source is a second power source that generates electricity using solar energy. The aforementioned controller, A battery diagnostic method that determines that charging by the second power source is possible if it can be predicted, based on past power generation data, weather, season, time of day, or a combination thereof, that the amount of power generated by the other power source will be greater than the amount of power required for charging.

6. In the battery diagnostic method described in claim 2, The aforementioned controller, A battery diagnostic method that, if the first power source and the other power sources cannot supply the amount of electricity necessary to charge the battery, obtains data on the electricity purchase price and charges the battery using the power of the power grid when the electricity purchase price falls.

7. In the battery diagnostic method described in claim 2, The controller is a battery diagnostic method that performs the next diagnosis within a predetermined period of time after the completion of the previous diagnosis.

8. In the battery diagnostic method described in claim 7, The aforementioned controller, A battery diagnostic method comprising: if, within the predetermined period, the predicted power generation amount of either the first power source or the other power sources, or a combination thereof, does not exceed the amount of power required for the transition of the battery's charge state, charging is performed using the power of the power system.

9. The first power source generates electricity using hydropower, One or more other power sources that generate electricity using renewable energy, A battery capable of charging the power generated by the first power source and the other power source, In a battery diagnostic device for a power generation system connected to the power grid and load, The battery is brought to a first charge state by charging or discharging it, and then brought to a second charge state by discharging or charging it again. The degree of battery degradation is diagnosed based on the cumulative current from the first charge state to the second charge state. The charging described above is performed during a charging period in which the predicted amount of power generated by either the first power source or the other power sources, or a combination thereof, is equal to or greater than the amount of energy required for the transition of the charging state. The discharge is performed during a dischargeable period when the amount of power demanded by the power system or the load increases. A battery diagnostic device characterized by having a controller programmed to suppress the rise in battery temperature by controlling the current value during charging and discharging if the battery temperature reaches a protection temperature during charging and discharging.

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