JP2020183658A - Wave power generating system and wave power generation method - Google Patents

Abstract

To provide a wave power generating system which levels wave power generating power and can stably output a system.SOLUTION: In a wave power generating system WGS, when power generating power P1 (P2) by a wave power generating part 2 is transmitted to a system 7, in the case in which the wave power generating power P1 (P2) is small with respect to effective power setting APS to be transmitted, a shortage is compensated by discharge from a storage battery 9, in the case in which the wave power generating power P1 (P2) is large with respect to the effective power setting APS to be transmitted, surplus is recovered by charge to the storage battery 9, and thereby power variation is leveled, and the effective power setting APS is changed by following up the wave power generating power P1 (P2).SELECTED DRAWING: Figure 1

Description

The present invention relates to a wave power generation system and a wave power generation method in which wave power generation power is leveled and can be stably output to a grid or the like.

Examples of those using wave power generation include those shown in Patent Document 1. This wave power generation system is a wave power generation device that generates electricity by raising and lowering a float that receives wave force against a pile erected on the coast, and uses the generated electricity as power for the load. , The electric power generated by the wave power generation device and the electric power from the commercial power source are input, and the electric power from the wave power generation device is obtained at a predetermined ratio with respect to the desired electric power for the load. It is configured to include a power control facility that mixes power from the commercial power source and outputs the power to the load.

The electric power control facility includes a power storage means for storing surplus electric power, which is larger than the electric power consumed in proportion to the electric power generated by the wave power generation device.

By the way, it is conceivable to output wave power generation to the grid in the future. In this case as well, the wave power generation repeatedly increases and decreases significantly in half the cycle (3 to 7 seconds) based on the wave cycle (6 to 14 seconds), but because it is interconnected to the grid of an electric power company or the like. Since it is necessary to suppress power fluctuations, it is necessary to level the generated power.

In such a case, according to the conventional method, the leveling is performed by using a lithium storage battery (one having good characteristics for taking in and out a large amount of power) for power leveling.

JP-A-2016-205273

However, since wave power generation is constantly changing due to the influence of nature, in order to keep the interconnection output constant, the power generated is discharged from the storage battery to cover the shortage, while the surplus power is used to charge the storage battery. In such an operation, there is a concern that the storage battery will be significantly deteriorated.

That is, in the case of transmitted power (active power setting)> wave power generation, the amount of stored electricity gradually decreases because the shortage of transmission is output (discharged) from the storage battery.

On the contrary, in the case of transmission power (active power setting) <wave power generation power, the amount of electricity stored gradually increases because the transmission surplus is input (charged) to the storage battery.
If the amount of electricity stored continues to decrease or increase in this way, the amount of electricity stored reaches the upper and lower limits and cannot play the role of power leveling, and there is a problem that the system must be shut down to protect the storage battery system. ..

The present invention focuses on such a problem, and solves the problem by automatically changing the active power setting and controlling the discharge output of the storage battery so as to be stable, and a new wave power generation system. The purpose is to realize a wave power generation method.

The present invention has taken the following measures in order to achieve such an object.

That is, in the wave power generation system of the present invention, when the power generated by the wave power generation unit is transmitted to the grid, when the wave power generation power is small with respect to the active power setting to be transmitted, the shortage is reduced by discharging from the storage battery. It is a wave power generation system that equalizes power fluctuations by recovering the surplus by charging the storage battery when the wave power generation power is larger than the active power setting to be transmitted, and the active power setting is set. It is characterized in that it is configured to follow the wave power generation power and change it.

By doing so, the deviation between the active power setting and the wave power generation power becomes smaller than when the active power setting is constant, so that it is effectively avoided that the storage amount of the storage battery that compensates for the power fluctuation reaches the upper limit or the lower limit. Therefore, the discharge output of the storage battery can be stabilized.

In this case, the storage capacity of the storage battery should be monitored and the increase / decrease control of the active power setting according to the storage capacity should be performed. Specifically, when the storage capacity exceeds the appropriate range, the active power setting is increased. However, it is desirable to reduce the active power setting when the amount of electricity stored falls below the appropriate range. Since the wave power generation is irregular, the active power setting can be set while protecting the storage battery by indirectly reflecting it in the active power setting through the charge amount of the storage battery instead of directly reflecting it in the active power setting. It is possible to prevent irregular fluctuations.

In particular, it is effective to increase or decrease the active power setting step by step at a predetermined timing. According to this, the change of the active power setting can be made to follow the global change of the wave power generation power.

Further, it is preferable that the change in the amount of electricity stored in an appropriate range is set as a dead zone that is not reflected in the active power setting. By not changing the active power setting within the permissible range, it is possible to prevent the active power setting from fluctuating in small steps and to perform stable power transmission.

Further, according to the present invention, as a wave power generation method, when the power generated by the wave power generation unit is supplied, when the wave power generation power is small with respect to the active power setting to be supplied, the shortage is supplemented by discharging from the storage battery. When the wave power generation power is larger than the active power setting to be supplied, the active power setting is followed by the wave power generation power in order to level the power fluctuation by recovering the surplus by charging the storage battery. It is characterized by changing.

As described above, the present invention is not limited to the system connected to the grid, and even if it is regarded as a wave power generation method, the action and effect similar to the above can be obtained.

Since the present invention has the configuration described above, it is possible to avoid operating the storage battery in an excessive charge / discharge pattern (frequency and depth of charge / discharge), so that deterioration of the storage battery and stabilization of transmitted power can be achieved, and waves can be achieved. It is possible to suppress the occurrence of abnormalities in the power generation system.

The system block diagram of the wave power generation system WGS which concerns on one Embodiment of this invention. Explanatory drawing about leveling of wave power generation. FIG. 3 is a control block diagram for setting active power incorporated in the main controller 1 in FIG. A partially enlarged view of FIG.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a system configuration diagram of the wave power generation system WGS according to this embodiment, and FIG. 2 is an explanatory diagram of leveling of wave power generation power.

First, the wave power generation system WGS converts the AC power generated by the wave power generation unit 2 (2a, 2b) having the synchronous generators a and b into DC power by the generator inverter 3 (3a, 3b). It is configured to flow through the DC bus 4, convert the DC bus 4 into AC power by the DC / AC converter 5 for grid interconnection, and output it to the system 7 via the transformer 6.

A storage battery 9 is connected to the DC bus 4 via a DC / DC converter 8 for a storage battery, and the power on the DC bus 4 is charged to the storage battery module 9b in the storage battery 9, or the power of the storage battery module 9b is charged to the DC bus. Discharge on 4.

The inverter 3 for the generator performs a switching operation to convert the AC wave power generation power P1 (P1a + P1b) into the DC wave power generation power P2 (P2a + P2b).

For this purpose, the grid interconnection DC / AC converter 5 and the storage battery DC / DC converter 8 are connected to the main controller 1 via the converter control board 10, and the command S10 from the main controller 1 is the converter control board. The gate signals S5 and S8 are output from the converter control board 10 to the grid interconnection DC / AC converter 5 and the storage battery DC / DC converter 8 accordingly.

The main controller 1 outputs the active power setting APS portion set as the power to be transmitted to the system 7 to the system 7 through the transformer 6 through the system interconnection DC / AC converter 5, and also outputs the DC / DC converter 8 for the storage battery. Through this, the active power setting APS is controlled to cover the surplus or insufficient power ΔP on the DC bus 4 by charging and discharging the storage battery 9.

Here, the power fluctuation and leveling of the wave power generation power P1 (P2) will be described. The wave power generation unit 2 (2a, 2b) is mainly composed of synchronous generators a and b, and power running operation or regenerative operation is controlled by torque control through the generator inverters 3 (3a, 3b). When torque is applied in the regenerative direction, the synchronous generators a and b rotate to generate a voltage. Then, the AC generators 3a and 3b convert the alternating current into direct current and supply it to the direct current bus 4. The power generation capacity in this embodiment is, for example, 25 kW for each of the synchronous generators a and b.

The electric power P2 (P2a + P2b) on the DC bus 4 is converted into AC power having a predetermined frequency by the DC / AC converter 5 for grid interconnection, and is output to the grid 7 through the transformer 6. In parallel with this, when the power on the DC bus 4 becomes excessive with respect to the active power setting APS, the main controller 1 controls the DC / DC converter 8 for the storage battery through the converter control board 10, and the DC bus 4 When the power on the DC bus 4 is insufficient for the active power setting APS, the main controller 1 sets the DC / DC converter 8 for the storage battery through the converter control board 10 to store the power in the storage battery 9 at a predetermined voltage. The leveling is performed by controlling the power of the storage battery 9 to a predetermined voltage and superimposing it on the power of the DC bus 4.

The fluctuation of the electric power P2 (P2a + P2b) on the DC bus 4 is linked to the wave period. When the wave power generation power P1 shown in FIG. 2 (a) is full-wave rectified, it becomes a wave in which half a cycle of a sine wave repeats as shown in FIG. The portion of the storage battery 9 charged and below the target power setting APS is supplemented by the discharge from the storage battery 9 as insufficient power ΔPU, and the target power setting APS shown in FIG. 2C is output to the system 7.

FIG. 3 is a control block for setting active power incorporated in the main controller 1 in FIG. 1, and FIG. 4 showing an enlarged part of FIG. 3 shows the storage amount (storage rate) of the storage battery 9. It is a power storage management table CT for management. The electricity storage management table CT is used when the main controller 1 manages the electricity storage amount. The storage battery 9 of this embodiment is, for example, a lithium storage battery (those having good characteristics for taking in and out high power), and has an upper limit (for example, 90%) and a lower limit (for example, 90%) of the maximum storage amount (100%). 20%) is set. If this range is exceeded, the storage battery 9 becomes unusable or unusable. Therefore, the range between the upper limit and the lower limit is defined as the range in which wave power can be generated. Further, since it is necessary to have a spare capacity for charging and discharging in order to be able to charge and discharge, the target storage amount (target storage amount) is set to, for example, 70%.

Here, when the active power setting APS (transmission power)> wave power generation power P1 (P2) in FIG. 1, that is, when the shortage ΔPU> surplus ΔPO in FIG. 2B, the difference is output from the storage battery 9 ( Since it continues to discharge), the amount of electricity stored in the storage battery 9 gradually decreases.

On the contrary, in the case of transmission power (active power setting) <wave power generation power in FIG. 1, that is, in the case of shortage ΔPU <surplus ΔPO in FIG. 2B, the difference is continuously input (charged) to the storage battery. The amount of electricity stored in the storage battery 9 gradually increases.

If the storage capacity of the storage battery 9 continues to decrease or increase, the storage capacity reaches the upper or lower limit or the lower limit, the power leveling role cannot be fulfilled, and the system must be shut down to protect the storage battery system. ..

Such a problem occurs because the active power setting APS is set to be constant regardless of the wave power generation power P1.

Therefore, in the present embodiment, the main controller 1 shown in FIG. 1 automatically changes the active power setting (grid interconnection output) APS to stabilize the discharge output of the storage battery 9. Here, the storage battery controller 9a monitors the storage amount (storage amount) of the storage battery module 9b and inputs it to the main controller 1. In the electricity storage management table CT of FIG. 4, the main controller 1 treats the period from that point to the upper limit of the electricity storage amount as "increase in power generation amount" except for the vicinity (± 5%) of the target electricity storage amount (for example, 70%), and from there. The period up to the lower limit of electricity storage is treated as "reduction of power generation".

FIG. 3 is a control block for the active power setting APS. It is determined whether or not the active power setting APS is changed periodically (for example, every minute). Specifically, a signal output from the determination unit C1 when the grid is connected and wave power is being generated, and a signal output from the storage battery controller 9a when the amount of power generation is increased (that is, the amount of electricity stored is increased). Enters the determination unit C2, the active power setting APS is incremented by a predetermined value α (for example, +2). On the contrary, the signal output from the determination unit C1 when the grid is connected and the wave power is being generated and the signal output from the storage battery controller 9a when the amount of power generation is reduced (that is, the amount of electricity stored is reduced) are determined. When entering the part C3, the active power setting APS is decremented by a predetermined value β (for example, -2). That is, in the present embodiment, the active power setting APS is changed stepwise at a predetermined timing.

This increase / decrease amount is adjusted by the active power setting unit C4 with respect to the immediately preceding active power setting APS, and then the gain is appropriately adjusted by the gain unit C5, and the command signal S10 is applied to the converter control board 10 of FIG. Sent as part.

The main controller 1 controls the DC / DC converter 8 for the storage battery through the converter control board 10 so that the power corresponding to the active power setting APS is secured on the DC bus 4, while the power corresponding to the active power setting APS is generated. The DC / AC converter 5 for grid interconnection is controlled so as to be output to the grid 7.

Assuming that the storage battery 9 is in the state of "increased storage capacity" as shown by the arrow a in FIG. 4 while the main controller 1 outputs the power set by the active power setting APS to the system 7 in this way, FIG. The active power setting APS in 1 changes in the increasing direction. That is, the state of "increased storage capacity" is derived from the fact that the wave power generation power P1 (P2) is larger than the active power setting ASP, and due to this, the active power setting APS is large in the control block of FIG. As the power changes in the above direction, the output to the system 9 increases with time, and the level of the active power setting ASP in FIG. 2 (b) rises, the charge ΔPO decreases, and the discharge ΔPU increases. The amount of electricity stored in No. 4 gradually decreases from the position of the arrow a in the figure and approaches the target amount of electricity stored.

On the other hand, assuming that the storage battery 9 is in the "reduced storage amount" state as shown by the arrow b in FIG. 4, the active power setting APS in FIG. 1 changes in a smaller direction. That is, the state of "reduced storage amount" is derived from the fact that the wave power generation power P1 (P2) is smaller than the active power setting ASP, but due to this, the active power setting APS is small in the control block of FIG. As a result, the output to the system 9 decreases with time, the level of the active power setting ASP in FIG. 2B decreases, the charge amount ΔPO increases, and the discharge amount ΔPU decreases. The amount of electricity stored in 4 gradually increases from the position of the arrow b in the figure and approaches the target amount of electricity stored.

That is, when the active power setting APS is larger than the wave power generation power P1 (P2), it changes in a smaller direction, and conversely, when it is smaller, it changes in a larger direction.

In FIG. 4, the range (70 ± 5%) around the target storage amount (70% in this embodiment) is not treated as an “increase in power generation” or “decrease in power generation” as an appropriate range, and the judgment unit C2, Since no output is made from any of C3, the switch SW is not turned on, and the active power setting APS is not updated.

In this way, the active power setting (transmission power) APS changes following the wave power generation power P1, so that the deviation for leveling the fluctuation in each cycle is compared with the case where the active power setting APS is constant. Is updated in the direction of becoming smaller. Therefore, the situation where the stored amount of the storage battery 9 reaches the upper limit or the lower limit is avoided, and the stored amount of the storage battery 9 is controlled within an appropriate range.

As a whole, in this wave power generation system WGS, all the power generated by the synchronous generators 1a and 1b is sent to the DC bus 4, and the main controller 1 sets the active power regardless of the amount of power generation P1 (P2). The power for ASP is passed through the system 7. Under that premise, the main controller 1 manages the charge / discharge of the storage battery 9 in cooperation with the storage battery controller 9a, and how much power is sent to the system 4 through the increase / decrease control of the active power setting ASP according to the amount of stored electricity. The charge amount is controlled within an appropriate range through how much electric power is charged and discharged to the storage battery 9.

To protect the storage battery, if the amount of electricity stored falls below the start of forced charging shown in FIG. 4, the main controller 1 stops wave power generation and grid interconnection operation, and the amount of electricity stored reaches the amount of forced charging by forced charging. It is configured to control recovery.

Similarly, in order to protect the storage battery, the main controller 1 is configured to control to stop wave power generation and grid interconnection operation when the amount of electricity stored is below the lower limit of power generation shown in FIG.

In addition, when the amount of electricity stored exceeds the upper limit of wave power generation shown in FIG. 4 due to periodic forced charging, etc., the main controller 1 stops wave power generation until it reaches the wave power generation possible range, and only discharges. It is configured to control the power transmission to the grid.

As described above, the wave power generation system WGS of the present embodiment has wave power generation power with respect to the active power setting APS to be transmitted when transmitting the power generation power P1 (P2) by the wave power generation unit 2 to the system 7. When P1 (P2) is small, the shortage is supplemented by discharging from the storage battery 9, and when the wave power generation power P1 (P2) is large with respect to the active power setting APS to be transmitted, the surplus is charged by charging the storage battery 9. In a system for leveling power fluctuations by collecting power, the active power setting APS is configured to change according to the wave power generation power P1 (P2).

In this way, the deviation between the active power setting APS and the wave power generation power P1 (P2) becomes smaller than when the active power setting APS is constant, so that the storage capacity of the storage battery 9 that compensates for the power fluctuation is the upper limit or It is possible to effectively avoid reaching the lower limit and stabilize the discharge output of the storage battery 9. Therefore, it is possible to avoid operating the storage battery 9 in an excessive charge / discharge pattern (charge / discharge frequency, depth), deteriorate the storage battery 9 and stabilize the transmitted power, and cause an abnormality in the wave power generation system WGS. It becomes possible to suppress it appropriately.

In this case, the storage amount of the storage battery is monitored, and the increase / decrease control of the active power setting according to the storage amount is performed. Specifically, the charge amount of the storage battery 9 is monitored, and if it exceeds the appropriate range, there is a tendency for power surplus, so the active power setting APS is increased, and if it falls below the appropriate range, there is a tendency for power shortage. Therefore, the active power setting APS is reduced. That is, since the wave power generation power P1 (P2) is irregular, it is not directly reflected in the active power setting APS, but is indirectly reflected in the active power setting APS through the charge amount of the storage battery 9, so that the storage battery 9 is reflected. It is possible to prevent the active power setting APS from fluctuating irregularly while protecting the power generation.

In particular, since the active power setting APS is increased or decreased stepwise at a predetermined timing, the change in the active power setting AP can be made to follow the global change in the wave power generation power P1 (P2). it can.

Further, since the change in the amount of electricity stored in the appropriate range is set as a dead zone that is not reflected in the active power setting, it is possible to prevent the active power setting APS from fluctuating in small steps and to perform stable power transmission.

Although one embodiment of the present invention has been described above, the specific configuration of each part is not limited to the above-described embodiment.

For example, in the above embodiment, the system for connecting the wave power generation power to the grid has been described, but even if the method is generalized as follows as a method rather than as a system and as a power supply method other than the grid connection, The same effect is achieved.

That is, in this wave power generation method, when the power generated by the wave power generation unit is supplied, when the wave power generation power is small with respect to the active power setting to be supplied, the shortage is supplemented and supplied by discharging from the storage battery. Wave power generation is a wave power generation method in which power fluctuations are leveled by recovering surplus electricity by charging a storage battery when the wave power generation power is larger than the effective power setting, and the active power setting is set to the wave power generation. It is characterized by changing according to electric power.

Also in this case, a method of monitoring the amount of electricity stored and changing the active power setting, a method of changing the active power setting stepwise, a method of providing a dead zone, and the like can be adopted in the same manner as in the above system.

Further, in the above embodiment, two generators are connected in parallel to the DC bus, but only one generator or three or more generators may of course be used.

In addition, various modifications can be made without departing from the spirit of the present invention, such as supplying electric power to a load of a pump hut or the like in parallel as needed.

2, 2a, 2b ... Wave power generation unit 7 ... System 9 ... Storage battery APS ... Active power setting P1 (P2) ... Wave power generation power WGS ... Wave power generation system

Claims (6)

When transmitting the power generated by the wave power generation unit to the grid, when the wave power generation power is small compared to the active power setting to be transmitted, the shortage is supplemented by discharging from the storage battery, and the active power setting to be transmitted is Wave power generation A wave power generation system that equalizes power fluctuations by recovering surplus power by charging the storage battery when the power is large.
A wave power generation system characterized in that the active power setting is configured to follow and change the wave power generation power. The wave power generation system according to claim 1, which is configured to monitor the amount of electricity stored in the storage battery and control the increase / decrease of the active power setting according to the amount of electricity stored. The wave power generation system according to claim 2, wherein the active power setting is increased when the stored amount exceeds the appropriate range, and the active power setting is decreased when the stored amount is below the appropriate range. The wave power generation system according to claim 2 or 3, wherein the active power setting is increased or decreased stepwise at a predetermined timing. The wave power generation system according to claim 3, wherein a change in the amount of electricity stored in an appropriate range is a dead zone that is not reflected in the active power setting. When supplying the generated power by the wave power generation unit, when the wave power generation power is small compared to the active power setting to be supplied, the shortage is supplemented by discharging from the storage battery, and the wave power is applied to the active power setting to be supplied. It is a wave power generation method that equalizes power fluctuations by recovering the surplus by charging the storage battery when the generated power is large.
A wave power generation method, characterized in that the active power setting is changed according to the wave power generation power.

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