JP6338009B1 - Power stabilization system and control device using power storage device - Google Patents

Abstract

A power stabilization system using a power storage device capable of effectively suppressing the required capacity of the power storage device is provided. A control device of a power stabilization system includes a long-cycle fluctuation relaxation control unit for relaxing long-period fluctuations of a composite output, and a composite output that is a control point at the start of a long-period fluctuation relaxation designated time zone. A composite output preparation value calculation unit that calculates a preparation value; and a composite output preparation value setting unit that reflects the composite output preparation value in the composite output target value. [Selection] Figure 1

Description

  The present invention relates to a power stabilization system and a control device using a power storage device that suppresses power fluctuations in a power system.

  In recent years, the interconnection of variable power sources using renewable energy such as solar power generation and wind power generation to the power system has increased. An output fluctuation mitigation control method has been proposed in which a power storage device composed of a storage battery or flywheel is installed at a solar power plant or wind power plant to compensate for minute fluctuation components or short-period fluctuation components of the output of the power generation equipment. (For example, refer to Patent Document 1).

  The power stabilization system described in Patent Document 1 generates power generated by a variable power source in order to reduce the influence on the system frequency when a variable power source such as a solar power plant or a wind power plant is connected to the power system. The power is combined with the charge / discharge power of the power storage device and smoothed. In such a power stabilization system, when the stored power amount of the power storage device reaches the upper limit or the lower limit, further power compensation cannot be performed. Therefore, in addition to charge / discharge control for stabilizing power fluctuations, an appropriate storage can be performed. Correction control for ensuring the amount of electric power is performed.

JP 2007-318883 A

  By the way, the fluctuation components of variable power sources such as solar power generation and wind power generation whose output fluctuates depending on weather conditions, etc., are short-period fluctuations that are output fluctuation components up to several tens of minutes and tens of minutes to several hours Are mixed with long-period fluctuations, which are output fluctuation components.

  As a background that is expected to mitigate long-term fluctuations of variable power sources, there is a lack of ability to adjust long-term fluctuations of existing power generation facilities. In the power system, the supply and demand balance is generally maintained by adjusting the output of existing power generation facilities such as thermal power generators and hydroelectric power generators in response to fluctuations in power demand and variable power sources. In particular, when the power demand of the customer greatly changes depending on the time of day or season, the output is adjusted with the change in the number of operating units for such a long-term fluctuation. However, in the time zone when the change in power demand is large and the time zone where the number of units in operation is small, the ability to adjust long-period fluctuations by the existing power generation facilities decreases. Therefore, in the time zone when the adjustment capability of the existing power generation facilities is reduced, long-term fluctuations are expected to be mitigated for the variable power source that uses renewable energy and the power storage device for the variable power source.

  In such a situation, if there is a limit to the decrease or increase in the combined output (the combined power generated by the variable power supply and the charge / discharge power of the power storage device) for the purpose of stable power supply, the power storage device is applied. There is a concern that the load will increase. For example, the power storage device needs to be discharged when the amount of power generation decreases in a time zone in which the reduction of the combined output is prohibited. In order to sufficiently cope with the request for the reduction of the composite output, it is necessary to secure the expected discharge power and the maximum value of the discharge power amount as the necessary capacity of the power storage device. Assuming that the expected discharge power and the maximum value taking into account all weather fluctuations are expected, the required capacity of the power storage device increases and the equipment cost increases.

  This invention is made | formed in view of this point, and it is set as one of the objectives to provide the power stabilization system and control apparatus using the power storage device which can suppress the required capacity | capacitance of a power storage device effectively.

A power stabilization system according to an aspect of the present invention includes a power storage device that performs charging and discharging, and a power converter that mutually converts input and output due to charging and discharging of the power storage device between a power system and the power storage device. A control device that controls a conversion operation of the power converter, and controls a combined output of the variable power source and the power storage device linked to the power system based on a combined output target value. Is a composite output preparation value for calculating a composite output preparation value that is a control point at the start of at least the long-period fluctuation relaxation specified time zone, and a long-period fluctuation relaxation control unit for relaxing the long-period fluctuation of the composite output A calculation unit, and a combined output preparation value setting unit that reflects the combined output preparation value in the combined output target value , wherein the combined output preparation value calculation unit is a preparation time before the long-period fluctuation relaxation designated time zone Only the remaining time of the belt Or by using the long period change mitigation remaining time of the specified time period before the preparation time period and the remaining time of the long period change mitigation specified time period, and calculates the combined output preparation value.

  ADVANTAGE OF THE INVENTION According to this invention, the power stabilization system and control apparatus using the electric power storage apparatus which can suppress the required capacity | capacitance of an electric power storage apparatus effectively can be provided.

It is a figure which shows the structural example of the electric power stabilization system which concerns on the 1st Embodiment of this invention. It is a figure showing the three Examples which concern on a synthetic | combination output preparation value setting part. It is a figure which shows the effect acquired by the 1st Embodiment of this invention. 4A is a waveform diagram showing a problem when the combined output is greatly increased in the non-decreasing designated time zone, FIG. 4B is a waveform diagram showing a problem when the synthesized output is kept constant in the non-decreasing designated time zone, and FIG. 4C. These are waveform diagrams showing an example of a desirable method of increasing the composite output in the non-decreasing designated time zone. It is a control block diagram which shows the structural example of the power stabilization system which concerns on the 3rd Embodiment of this invention. It is a figure which shows the effect acquired by the 3rd Embodiment of this invention. It is a figure explaining a long-period fluctuation relaxation designated time zone. It is a figure explaining the characteristic of this invention, and its positioning. It is a figure which shows the required charging power when a fluctuation | variation power supply output falls in step shape. FIG. 10A is a diagram showing the maximum required charging power in each time zone, FIG. 10A shows a case where the composite output can be zero before the start of the specified time zone, and FIG. 10B cannot be zero before the start of the specified time zone 10C shows a case where the current time is within the specified time zone, and FIG. 10D shows a case where the current time is outside the specified time zone. It is a figure which shows a synthetic | combination output preparation function. It is a block diagram which shows the processing content in a synthetic | combination output preparation value calculation part. It is a figure which shows the maximum required charge electric power in each time slot | zone, FIG. 13A is an example in the 1st case where the start time of the designated time slot is later than the current time, and FIG. 13B is the start time of the designated time slot. FIG. 13C shows an example in which the start time of the specified time zone is the current time. It is a figure which shows the simulation result at the time of reducing a power station synthetic | combination output to a synthetic | combination output preparation value, FIG. 14A is a figure which shows SOC value (%) of an electric power storage apparatus, FIG. 14B is an output change rate (% / min). 14C is a diagram showing a combined power plant output, a variable power output, and a storage battery output.

  An object of the present invention is to alleviate long-period fluctuations by combined output control of a variable power source and a power storage device. Three patterns shown in FIG. 7 can be considered as the time period in which the combined output control is restricted for long period fluctuation relaxation (hereinafter referred to as the long period fluctuation relaxation designated time period). First, in the time zone when demand increases, the variable power source is imposed with a “non-decreasing” constraint. This is because if the variable power supply decreases in a time zone where demand is expected to increase, the balance between demand and supply will be disrupted, causing problems such as power outages. Secondly, in a time zone in which demand is expected to be constant, the restriction of “increase / decrease” is imposed on the variable power source. Third, in the time zone when demand is expected to decrease, the constraint of “unincreaseable” is imposed on the variable power supply. The time zones in which the decrease cannot be increased, the increase cannot be made, and the increase and decrease cannot be made are collectively defined as a long-period fluctuation relaxation designated time zone (sometimes abbreviated as a designated time zone). The present inventors have developed how to control the combined output of the variable power source and the power storage device in the long-period fluctuation relaxation designated time zone. The details of the control have been filed in Japanese Patent Application No. 2006-167802.

  During the long-period fluctuation relaxation designated time zone, the reduction or increase in the combined output of the fluctuation power supply and the power storage device is limited, so the degree of freedom in control is small. For this reason, we have developed the system so that it is in an optimal state of control before or after entering the long-period fluctuation relaxation designated time zone. FIG. 8 shows four technical features of the present invention. The first point is that the control point when entering the long period fluctuation relaxation designated time zone is set to an optimum value called a preparation value. The second point is how to calculate the preparation value, the third point is how to shift the control point to the preparation value, and the fourth point is the control in the long period fluctuation relaxation designated time zone. It is a device. Details are described below.

(First embodiment)
First, the configuration of the power stabilization system according to the first embodiment will be described with reference to FIG.
The power stabilization system 10 according to the present embodiment includes a power storage device 11, a power converter 12, and a control device 13. The power converter 12 is connected to the power system 15 via the transformer 14. A wind power generator 16 is connected to the power system 15 via the transformer 17. The control device 13 has either a configuration in which the active power PG that is the output of the wind power generator 16 is input or a configuration in which a combined output obtained by combining the power plant output and the charge / discharge power of the power storage device 11 is input. good. In the following description, a configuration for inputting a power plant output that is an output of the wind power generator 16 will be described.

  The power storage device 11 is configured by, for example, a flywheel, a secondary battery, or a capacitor. The power converter 12 is connected to the power system 15 and the power based on the power converter output command value PO given from the control device 13 (here, the direction in which power is discharged from the power storage device 11 is “positive”). Power is exchanged with the storage device 11. When the power storage device 11 is a flywheel, the AC power on the flywheel side and the AC power on the power system 15 side are converted in both directions. When the power storage device 11 is a secondary battery or a capacitor, the DC power on the secondary battery or capacitor side and the AC power on the power system 15 side are converted bidirectionally.

  The control device 13 includes outputs from the active power detection unit 21, the power generation amount prediction unit 45, the combined output preparation value calculation unit 24, the combined output preparation value setting unit 22, the long cycle fluctuation relaxation control unit 23, and the long cycle fluctuation relaxation control unit 23. A subtracting element 44 for subtracting the active power PG from the combined output target value PA and outputting an output command of the power storage device 11, and a power converter control unit 27.

  The active power detection unit 21 detects the active power PG of the wind power generator 21 serving as a power plant output based on the voltage and current value at the output end of the wind power generator 16. When there are a plurality of wind power generators, the effective power PG of the entire wind power generation is detected based on the voltage and current values of the electric wires output from the plurality of wind power generators. Alternatively, the sum may be calculated after detecting the effective power of each wind power generator.

  The power generation amount prediction unit 45 is a calculation unit that predicts the future power generation amount of the power plant. For example, general weather forecast data acquired from the outside and power generation data of other nearby power plants are used as inputs, and predicted values are calculated using a numerical weather model or a statistical model. The power generation amount predicted value PG-q to be calculated is a predicted value related to the power generation amount in the specified time zone, such as the power generation amount (kWh) during the specified time zone and the time average value (kWh / h). The predicted power generation amount PG-q may be a predicted value of the generated power (kW) after a certain time has elapsed from a certain time or the present. When specifying the time, for example, it may be the end time of a specified time zone in which relaxation of long-period fluctuations is required, or may be intermediate between the start and end of the specified time zone. Select based on the restrictions on the format of available weather forecast data.

  Further, when calculating the power generation amount predicted value PG-q, a prediction method for correcting the power generation amount predicted value by further using a measured value such as an output of the wind power generator or an anemometer installed in the wind power generator may be used. good.

  The composite output preparation value calculation unit 24 calculates a composite output preparation value PG-p as an appropriate composite output value at the start time of the long period fluctuation relaxation designated time zone. The second technical feature of the present invention shown in FIG. 8 is roughly divided into two calculation methods. Further, a method of calculating the composite output preparation value PG-p different from that of the present embodiment will be described in detail in the fourth embodiment.

The first is a method of using the current active power PG. As a method of calculating a composite output preparation value for reducing the required capacity of the power storage device 11 as much as possible, there is a method based on the current power generation output (for example, the active power PG). The composite output preparation value PG-p can be determined by subtracting the positive value ΔP.
PG-p = PG-ΔP

Alternatively, the composite output preparation value PG-p can be determined by multiplying the active power PG by a coefficient M smaller than 1 (for example, 0.5 to 0.9).
PG-p = PG × M

Thereby, the composite output preparation value PG-p is determined so as to be always smaller than the power generation output (for example, the active power PG).
However, in the method using the first power plant output, if the coefficient M multiplied by the power plant output (for example, active power PG) is decreased, the combined output becomes too small and the charging power increases, and the power storage device 11 There is a possibility that electric power that cannot be fully charged is generated, or that the amount of electric power stored in the power storage device 11 reaches the upper limit. As a result, there is a demerit that an opportunity loss of generated power (hereinafter referred to as lost power) is increased by reducing the output of the wind power generator 16.

  Therefore, as a second method, instead of always multiplying the power plant output by a coefficient to make the composite output ready value smaller than the current value of the power plant output (for example, active power PG), A method for appropriately determining the composite output ready value in accordance with the quantity prediction value) was considered.

That is, in the second method using the predicted power generation amount, the composite output preparation value is determined by the power generation amount prediction value PG-q calculated by the power generation amount prediction unit 45. For example, the composite output preparation value PG-p is determined to be equal to the power generation amount prediction value PG-q. According to this calculation method, when the predicted power generation amount after a predetermined period of time is smaller than the current power plant output and a discharge of a predetermined amount or more is predicted, the combined output decreases as in the first method, Acts in a direction to suppress discharge. The first method is to determine the combined output preparation value in accordance with the power generation amount predicted value when the power generation amount predicted value after the lapse of the predetermined period is larger than the current power plant output and charging of a predetermined amount or more is predicted. Unlike the above, the combined output increases and acts to suppress charging. In the first method using the power plant output, only a composite output preparation value that is smaller than the current value can be set, but in the method using the power generation amount prediction value, a composite output preparation that is larger than the current value is possible. A value can also be set. This is because when it is predicted that the amount of power generation will increase, there is no need to discharge, so there is no need to suppress the combined output, which can reduce lost power.
In the second method, in order to appropriately determine the combined output preparation value in accordance with future output fluctuations, the necessary capacity is suppressed while suppressing excessive charging of the power storage device 11 and accompanying increase in lost power. be able to. For example, when the power generation amount predicted value after a predetermined period of time is smaller than the current power plant output, the combined output is reduced in the same manner as the first method, and acts to suppress discharge. When the power generation amount predicted value after the lapse of the predetermined period is larger than the current power plant output, the combined output increases unlike the first method, and acts to suppress charging.

  In the second method, the combined output preparation value PG-p is determined to be equal to the power generation amount predicted value PG-q. However, the composite output preparation value PG-p is determined to be the active power PG and the power generation amount prediction value PG-. It may be the smaller of q and one. In this case, even if the power generation amount predicted value PG-q is larger than the actual power generation amount, the combined output preparation value uses the active power PG which is the current power generation output, so that the generated power is temporarily reduced. However, it is easy to avoid the shortage of the stored power amount of the power storage device 11 due to the increase in the discharge amount, and even if the generated power increases, the combined output can be suppressed by suppressing the generated power.

  The power generation amount prediction may be estimated in the confidence interval, and a value smaller than the median value of the estimated power generation amount prediction may be adopted as the composite output preparation value. In general, there is an error between the predicted value and the true value, and the distribution of the error does not follow the normal distribution. For example, although the power generation amount prediction value per hour is 1 MWh / h, it is assumed that a section from 0.5 MWh / h to 1.2 MWh / h can be taken. In that case, if 0.5 MWh / h is employed as the combined output preparation value, the capacity of the power storage device 11 is not likely to be insufficient even if there is a prediction error. On the other hand, when the combined output preparation value is set to a small value of 0.5 MWh / h and the power generation amount is actually set to a large value of 1.2 MWh / h, there is a concern that the lost power of the wind power generator 16 may increase. When priority is given to the reduction of lost power, a value larger than the median value of power generation prediction may be adopted as the composite output preparation value.

  The combined output preparation value setting unit 22 processes the active power PG of the variable power source using the combined output preparation value calculated by the combined output preparation value calculation unit 24. This is a characteristic part of the third invention in FIG. 8 and relates to how the composite output target value is transferred to the composite output preparation value. Details will be described later with reference to FIG.

  The long cycle fluctuation relaxation control unit 23 receives the output of the composite output preparation value setting unit 22 and outputs a composite output target value for performing long cycle fluctuation relaxation control. In order to realize the three patterns that the long cycle fluctuation relaxation specified time cannot be decreased, cannot be increased, and cannot be increased or decreased, it is configured by a limiter. In the case where the reduction cannot be performed, it is possible to realize a control that does not reduce the combined output by setting a set value that is the lower limit value of the limiter. In the case where the increase cannot be made, it is possible to realize a control that does not increase the combined output by setting a set value that is the upper limit value of the limiter. When the increase / decrease is not possible, a control that does not increase / decrease the combined output can be realized by setting a value that is the upper and lower limit values of the limiter.

  In order to realize only when the increase / decrease is not possible, the composite output target value may be held at a certain value by using a hold circuit.

  The power converter control unit 27 generates a power converter output command value PO according to the difference between the combined output target value PA output from the long-period fluctuation relaxation control unit 23 and the active power PG, and the power converter output command The power converter 12 is controlled based on the value PO, and the power storage device 11 is charged and discharged with power.

  Next, the composite output preparation setting unit 22 that reflects the composite output preparation value in the calculation of the composite output target value will be described with reference to FIG.

  FIG. 2A, which is one of the variations of the composite output preparation value setting unit 22, is configured by a switch, and the composite output preparation value PG-p is replaced with the generated active power PG at the start time of the long-period fluctuation relaxation designated time zone. Switched to As a result, it is possible to start the control with the synthesized output preparation value, which is the best control point, from the start time of the long period fluctuation relaxation designated time zone. Thereafter, in order to realize normal long-period fluctuation relaxation control, the switch reenters the original active power PG within a short time.

  FIG. 2B, which is one of the variations of the composite output preparation value setting unit 22, is configured by a limiter, and the composite output preparation value PG-p is set as the upper limit value of the limiter at the start time of the long period fluctuation relaxation designated time zone. The composite output target value is limited so as not to be larger than the composite output preparation value PG-p. Alternatively, the combined output preparation value PG-p is set as the lower limit value of the limiter in FIG. 2B, and the combined output target value is limited so as not to be smaller than the combined output preparation value PG-p. The aim of setting the former composite output preparation value to the upper limit value is to prevent the discharge power and the discharge power amount from being exceeded in the long-period fluctuation relaxation designated time zone. That is, when the output of the wind power generator 16 greatly decreases in the long-period fluctuation relaxation designated time zone, the discharge power / discharge power amount of the power storage device increases in order to maintain the combined output appropriately. As a result, the stored power amount of the power storage device is insufficient or the capacity of the power storage device needs to be increased at the start time of the long-period fluctuation relaxation designated time zone. In order to avoid this, the combined output at the start time of the long period fluctuation relaxation designated time zone is limited in advance to a combined output preparation value or less. On the other hand, the purpose of setting the latter composite output preparation value to the lower limit is to prevent the charging power and the amount of charging power from being exceeded in the long-period fluctuation relaxation designated time zone. In other words, when the output of the wind power generator 16 greatly increases in the long period fluctuation relaxation designated time zone, the charging power / charging power amount of the power storage device increases in order to maintain the combined output appropriately. As a result, it is necessary to reduce the output of the wind power generator or increase the capacity of the power storage device because the stored power amount of the power storage device reaches the upper limit at the start time of the long period fluctuation relaxation designated time zone. In order to avoid this, the combined output at the start time of the long period fluctuation relaxation designated time zone is limited in advance to the combined output preparation value or more. The limiter of FIG. 2B has a higher degree of freedom in control design than that of FIG. 2A. In other words, it is not a method of strictly controlling the combined output to the combined output ready value, but there is room for utilizing other functions (for example, storage battery charging power control) that reflect, for example, correction of the stored power amount within the range allowed by the limiter. Is leaving. The limiter shown in FIG. 2B is also released in a short time like the switch shown in FIG. 2A, and thereafter normal long-period fluctuation relaxation control is realized.

  FIG. 2C, which is one of the variations of the composite output preparation value setting unit 22, is configured by P control as an example of feedback control. The difference from FIG. 2A and FIG. 2B is the composite output target value PA (or the composite output target value PA). Output measurement value) as an input. P control is performed so that the composite output target value PA becomes the composite output preparation value. The synthesized output preparation value setting unit 22 synthesizes the synthesized output while continuously changing the synthesized output target value to some extent by using feedback control (P control may be used as another example) such as P control in FIG. 2C. A factor that hinders adjustment to the output preparation value can be corrected to a certain extent. Examples of the obstruction factor include factors caused by the outside of the control device such as fluctuations in the load on the premises of the power plant and control inside the wind power generator, and factors caused by the inside of the control device such as the protection control function of the power storage device or power converter. . When the combined output or the combined output target value does not match the combined output preparation value due to these factors, the control in FIG. 2C has an effect of adjusting the deviation between the combined output target value and the combined output preparation value to zero. On the other hand, in the control of FIG. 2C, it takes time until the combined output target value PA reaches the combined output preparation value and becomes a steady state. Therefore, the time required for the feedback control to reach the steady state is secured in advance before the start time of the long period fluctuation relaxation designated time zone. The gain of the P control is set to 0 in the time before the time when the feedback control is started, and the gain of the P control is set to a predetermined value during the time from the time to the start time of the long period fluctuation relaxation designated time zone. Switch to the value. As a result, the output signal of the composite output preparation value setting unit outputs the input signal PG as it is before the feedback control start time, and according to the difference between the composite output preparation value setting unit and the composite output target value during the feedback control. By adjusting the composite output target value PA, an effect is obtained in which the composite output target value PA reaches the composite output preparation value continuously and stably before the start time of the long period fluctuation relaxation designated time zone.

Next, the effect of the first embodiment of the present invention will be described with reference to FIG.
FIG. 3A illustrates the discharge power (required capacity) when the control device 13 does not have the combined output preparation value setting unit 22 and performs only the long-period fluctuation mitigation control. As shown by a broken line in FIG. 3A, the output power of the wind power generator 16 is assumed to fluctuate up and down, and the time period from time T1 to T2 is set to the long-period fluctuation relaxation designated time (cannot be reduced). To do. The output power is in the vicinity of the peak at time T1, which is the start time of the long-period fluctuation relaxation designated time zone. The output is kept constant. Since the output power decreases from the maximum value to the minimum value from time T1 to time T2, during that time, the power storage device 11 is discharged and the combined output is maintained at the value at time T1. For this reason, a large discharge power (required capacity) is required as indicated by hatching in FIG. 3A.

  On the other hand, FIG. 3B illustrates discharge power (necessary capacity) required when the control by the control device 13 is performed. As in FIG. 3A, the output power (broken line) of the wind power generator 16 fluctuates up and down, and the time period from the time T1 to the time T2 is set to the long-period fluctuation relaxation designated time (cannot be reduced).

  The power generation amount prediction unit 45 (see FIG. 1) predicts the power plant output in the long period fluctuation relaxation designated time zone. When it can be predicted that the power plant output will decrease as shown in FIG. 3B, an appropriate combined output preparation value PG-p is determined using the power generation amount prediction value PG-q. For example, as shown in FIG. 3B, if the predicted power generation value PG-p at the time T3 near the middle in the designated time zone (cannot be reduced) is used as the composite output preparation value PG-p, the discharge in the long-period fluctuation relaxation designated time zone. It can be seen that power (required capacity) can be greatly reduced. Assume that the power generation amount predicted value PG-q at time T3 is set as the combined output preparation value PG-p in the limiter of the combined output preparation value setting unit 22 in FIG. As a result, the combined output target value is limited so as not to exceed the combined output preparation value PG-p in the limiter of the combined output preparation value setting unit 22. In the example shown in FIG. 3B, the upper limit of the composite output is changed to the composite output preparation value PG-p at the start time T1 of the designated time zone. Until time T3 when the power plant output falls below the combined output preparation value PG-p, the power storage device 11 performs a charging operation to absorb the power generation output. The power exceeding the charging capacity of the power storage device 11 may be discarded. From time T3 when the power plant output falls below the combined output to time T2, in order to keep the combined output from falling, the power storage device 11 performs a discharging operation for discharging power. When the end time T2 of the instruction time zone is reached, the long-cycle fluctuation relaxation control limiter is canceled and the limiter is not activated. As a result, the combined output changes from the combined output preparation value PG-p to the power generation output.

  Further, according to the present embodiment, the composite output preparation value setting unit 22 shifts the composite output target value to the composite output preparation value PG-p, so that the composite output is restricted in the long period fluctuation relaxation designated time zone. Even if this happens, it is possible to achieve control while suppressing the required capacity of the storage battery.

(Second Embodiment)
The second embodiment relates to long-period fluctuation relaxation control within a long-period fluctuation relaxation designated time zone, which is a characteristic part of the fourth invention in FIG.

  In the long-period fluctuation relaxation designated time zone, in the non-decreasing time zone where the reduction of the composite output is prohibited, the composite output is allowed to increase. Two control cases where the problem occurs are shown. The first case will be described with reference to FIG. 4A. The designated time zone from time T1 to time T2 indicated by the dotted line in FIG. 4A is designated as the non-decreasing designated time zone. 4A shows a state where the power storage device 11 is fully charged and can no longer be charged. In this state, lost power is generated, so control is performed to increase the combined output target value and increase the combined output. If the wind power generation output subsequently decreases, the combined output cannot be reduced because it is in the designated time zone that is subject to the restriction that cannot be reduced. Therefore, since the power storage device 11 is discharged and maintains the combined output, the discharge amount (required capacity) of the power storage device 11 is increased. If the capacity of the power storage device 11 is small, there arises a problem that the restriction that cannot be reduced cannot be observed.

  In the second case (FIG. 4B), the designated time zone from time T1 to time T2 is designated as the non-decreasing designated time zone as in case 1, and charging of the power storage device 11 is fully charged at time T4. In such a situation, control is performed so as not to increase the composite output target value. In this case, the non-decreasing constraint can be observed, but the lost power is greatly generated.

  In order to avoid the above case, an upper limit is set to the composite output target value when it is assumed that the power generation output decreases during the designated time zone in which reduction is impossible. The upper limit value is appropriately set by considering the capacity of the power storage device 11 and the predicted power generation amount of wind power generation. The power generation amount prediction value calculated by the power generation amount prediction unit 45 is analyzed, and the presence or absence of a decrease in the power generation output in the non-decreasing designated time zone is grasped. In the example shown in FIG. 4C, the output decrease of the power plant output after time T4 is predicted after the power plant output increases in the non-decreasing designated time zone. In such a case, a value (kW) obtained by dividing the predicted power generation amount (kWh) in the time zone from the current time to the specified time zone end time by the time (h) from the current time to the specified time zone end time is the upper limit of the composite output. Set as value. Alternatively, the power amount of lost power shown in FIG. 4C may be subtracted from the predicted power generation amount (kWh), or the amount of discharge power that can be discharged by the power storage device may be added. There are several ways to determine the upper limit value of the composite output, but a limiter is set to either the input / output of the composite output preparation value setting unit 22 or the input / output of the long-period fluctuation relaxation control unit 23. This can be achieved. Alternatively, an internal limiter may be limited.

  As described above, in the second embodiment, when a decrease in the power generation amount of the variable power source is predicted in the instruction time zone in which the decrease in the composite output is prohibited, by limiting the increase in the composite output in the instruction time zone, The required capacity of the power storage device can be effectively suppressed.

(Third embodiment)
In the third embodiment, short period fluctuation relaxation control is added to the first embodiment.
The configuration of the power stabilization system according to the third embodiment will be described with reference to FIG. The difference from the first embodiment is that a short period fluctuation relaxation control unit 25 is added to the control device 50.

  The short cycle fluctuation mitigation control unit 25 receives the output of the combined output preparation value setting unit 22 and performs short cycle fluctuation mitigation control by the smoothing filter 46 and the limiter 47. Short-cycle fluctuation mitigation control is a technique that suppresses short-cycle fluctuation components superimposed on long-period fluctuation components included in the output of a variable power source such as wind power generation, and suppresses fluctuations in the combined output within a certain range. Control.

Since other configurations are the same as those of the first embodiment, description thereof is omitted.
Next, the composite output preparation setting unit 22 that reflects the composite output preparation value in the calculation of the composite output target value will be described with reference to FIG. Since short cycle fluctuation relaxation control cannot change the composite output suddenly, it is necessary to gradually change the control.Prepare time zone is set before long cycle fluctuation relaxation designated time zone, and the control point is shifted gradually. Some ideas are needed. This point relates to how to shift to the preparation value, which is the third feature of the present invention in FIG.

  FIG. 2A, which is one of the variations of the composite output preparation value setting unit 22, includes a switch. The composite output preparation value setting unit 22 switches the switch during the preparation time period, and generates the composite output preparation value PG-p. Output instead of the active power PG. Further, the output signal of the short cycle fluctuation mitigation control unit 25 is limited by the short cycle fluctuation mitigation control unit 25 to limit the rate of change, and a signal from which the short cycle fluctuation component is removed is output as a composite output target value PA. As a result, it is possible to gradually shift from the start time of the preparation time zone to control at the composite output preparation value, which is the best control point. Thereafter, when the long period fluctuation relaxation designated time zone is entered, the switch reenters the original active power PG in order to realize the long period fluctuation relaxation control.

  FIG. 2B, which is one of the variations of the composite output preparation value setting unit 22, is configured by a limiter. At the start time of the preparation time zone, the composite output preparation value PG-p is set as the upper limit value of the limiter, and the short The output signal of the period fluctuation relaxation control unit 25 is limited so as not to exceed the combined output preparation value PG-p. Further, by limiting the rate of change of the output signal of the short cycle fluctuation relaxation control unit 25 by the short cycle fluctuation relaxation control unit 25, the combined output target value is gradually controlled to a value smaller than the output preparation value PG-p over the preparation time period. It can be performed. In addition, when a designated time zone incapable of increasing is set, the composite output preparation value PG-p is set as the lower limit value of the limiter in FIG. 2B. The limiter shown in FIG. 2B is also released at the same time as the preparation period is over, like the switch shown in FIG. 2A, and thereafter normal short-cycle fluctuation relaxation control and long-cycle fluctuation relaxation control are realized.

  The same applies to FIG. 2C, which is one of the variations of the composite output preparation value setting unit 22, but since it is configured by a feedback control system such as P control / PI control, it takes time to reach a steady state. It is necessary to adjust the control gain and the time constant so that the required time is sufficiently shorter than the period of the preparation time zone.

Next, the effect of the third embodiment of the present invention will be described with reference to FIG.
FIG. 6A illustrates the discharge power (required capacity) when the control device 50 does not have the combined output preparation value setting unit 22 and only the long-period fluctuation relaxation control and the short-period fluctuation relaxation control are performed. As shown by a broken line in FIG. 6A, the output power of the wind power generator 16 is assumed to fluctuate up and down, and the time period from the time T1 to the time T2 is set to the long-period fluctuation relaxation designated time (cannot be reduced). To do. The output power is in the vicinity of the peak at time T1, which is the start time of the long-period fluctuation relaxation designated time zone. Since this is the non-decreasing designated time zone, the synthesis is mainly performed by the action of the limiter of the long-cycle fluctuation relaxation control unit 23. The output is kept constant. Since the output power decreases from the maximum value to the minimum value from time T1 to time T2, during that time, the power storage device 11 is discharged and the combined output is maintained at the value at time T1. For this reason, a large discharge power (necessary capacity) is required as shown by hatching in FIG. 6A. When the end time T2 of the instruction time zone is reached, the lower limit value of the limiter of the long cycle fluctuation relaxation control unit 23 is released, and the limiter is not applied. As a result, the combined output changes to the power generation output at a speed at which the short period fluctuation is suppressed by the action of the limiter 47 of the short period fluctuation relaxation control unit.

  On the other hand, FIG. 6B illustrates discharge power (necessary capacity) required when the control by the control device 50 is performed. Similarly to FIG. 6A, the output power (broken line) of the wind power generator 16 fluctuates up and down, and the time period from the time T1 to the time T2 is set to the long-period fluctuation relaxation designated time (cannot be reduced). The power generation amount prediction unit 45 (see FIG. 1) predicts the power plant output in the long period fluctuation relaxation designated time zone. When it can be predicted that the power plant output will decrease as shown in FIG. 6B, an appropriate combined output preparation value PG-p is determined using the power generation amount prediction value PG-q. For example, as shown in FIG. 6B, a combined output value is obtained such that the charge amount and the discharge amount of the power storage device 11 are equal in the designated time zone (non-decreasing designated time zone), and the composite output value is prepared as a composite output preparation. It can be seen that the discharge power (required capacity) in the long period fluctuation relaxation designated time zone can be significantly suppressed by controlling the value. Assume that the composite output value obtained earlier by the limiter of the composite output preparation value setting unit 22 in FIG. 2B is set as the composite output preparation value PG-p at the start time T0 of the preparation period of the long period fluctuation relaxation designated time period. Over time, the combined output gradually decreases to the combined output ready value. At the start time T1 of the designated time, the control point has moved to the set composite output preparation value. In the example shown in FIG. 6B, the power storage device 11 performs a charging operation to absorb the power generation output until time T3 when the power plant output falls below the combined output preparation value PG-p. From time T3 when the power plant output falls below the combined output to time T2, in order to keep the combined output from falling, the power storage device 11 performs a discharging operation for discharging power. When the end time T2 of the instruction time zone is reached, the limiter of the long-period fluctuation relaxation control 23 is released and the limiter is not applied. As a result, the combined output changes from the combined output preparation value PG-p to the power generation output at a speed at which the short period variation is suppressed by the action of the limiter 47 of the short period variation mitigation control unit.

  By providing the preparation time zone according to the above embodiment, the composite output preparation value can be reflected in the composite output within the range of short cycle fluctuation mitigation control. As a result, the required capacity of the power storage device 11 can be reduced. Suppressed long-cycle fluctuation relaxation control and short-cycle fluctuation relaxation control can be realized.

  In this example, the power generation amount prediction unit 45 is disposed inside the control device 13, but the power generation amount prediction unit 45 may be disposed outside the control device 13. In this case, the power generation amount predicted value PG-q or the combined output preparation value PG-p is supplied to the control device 13 from the outside.

(Fourth embodiment)
The power stabilization system according to the fourth embodiment has the same basic configuration as that of the first to third embodiments, but the method for calculating the composite output preparation value and the preparation value in the composite output preparation value calculation unit. This is an example in which the transition operation is different. Even if the power generation output of the wind power generator 16 suddenly decreases, the combined output preparation value calculation unit in the fourth embodiment is in the power storage device 11 if the combined power plant output is less than this value. A composite output ready value is calculated that the technical requirement failure due to insufficient charging power can be avoided. Hereinafter, a method for calculating the composite output preparation value will be described in detail.

  It is necessary to cope with the sudden decrease in the power generation output of the wind power generator 16 by the discharge of the power storage device 11. The amount of charging power of the power storage device 11 needs to be large enough to ensure the amount of discharging power that can be handled when the output of the wind power generator 16 suddenly decreases. Here, the amount of discharge power that can maintain the required combined power output even if the output of the wind power generator 16 is reduced is defined as the required charge power.

  Moreover, the case of the fluctuation | variation power supply output fall in which the maximum amount of discharge electric power is required theoretically is when the output of the wind power generator 16 falls to 0 instantly in steps. In order to control the discharge power amount to the minimum with respect to the step-like fluctuation power supply output decrease, it is desirable to decrease the combined output as quickly as possible. This is because the difference between the combined output and the variable power supply output is reduced. However, since the combined output is restricted by short-cycle fluctuation and long-cycle fluctuation, the rate of change and the fluctuation direction are limited. A case is assumed in which the combined output is brought close to the fluctuation power supply output (= 0) in the shortest time while satisfying the constraints of short cycle fluctuation and long cycle fluctuation. The decrease in the output of the wind power generator 16 immediately decreases from the current fluctuation power supply output level to the output 0 (step-like decrease), and at the same time, the combined output is rapidly decreased while satisfying the constraints of the short cycle variation and the long cycle variation. The amount of discharge power required when conditions are assumed is defined as the maximum required charge power.

  FIG. 9 exemplifies necessary charging power when the variable power supply output decreases stepwise. Region A (shaded portion + filled portion) is the required charging power when the variable power output decreases stepwise, and region B is the expected power generation at that time. Here, the output of the wind power generator 16 does not necessarily suddenly decrease to 0, but the output of the wind power generator 16 gradually decreases to a certain level, and an output corresponding to the area B can be expected. A power generation amount (corresponding to the above-described region B) in which the output of the wind power generator 16 can be reliably expected in the designated time zone is defined as “expected power generation amount”.

For example, the current time is the start time of the specified time zone, the variable power output at the current time is 100 MW, the expected power generation amount B is (variable power output at the current time −70 MW) × the remaining time of the specified time zone, It is assumed that the limitation of short-cycle fluctuation is that the output change rate is within 60 MW / h. In this case, the required charging energy A is as follows.
A = maximum required charging power-expected power generation amount = (100 MW × 3h + 100 MW × 100 MW / 2/60 MW / h) − (100 MW−70 MW) × 3 h
= 293MWh

  When the capacity of the power storage device 11 is small, there is a high possibility that the amount of electric power that can be discharged at the current time point is less than the amount of the required charging electric energy A.

  Therefore, in the present embodiment, a combined output target value that limits the combined power plant output is calculated in accordance with the dischargeable power amount (necessary charging power amount) of the power storage device 11 at the current time point. When the combined power output of the power plant is limited, the required charging power is changed from the region A shown in FIG. 9 to a small region A ′, and can withstand the sudden decrease of the wind power generator 16. Thereby, it is possible to avoid the technical requirement from being unsatisfactory due to a shortage of necessary charging power.

For example, as illustrated in FIG. 9, if the combined power output of the power plant is suppressed to 50%, the required amount of charge power (region A ′ in FIG. 9) is as follows.
A ′ = maximum required charging power−expected power generation amount = (50 MW × 3h + 50 MW × 50 MW / 2/60 MW% / h) − (100 MW−70 MW) × 3 h
= 81MWh

  Here, even when the output level of the wind power generator 16 and the combined power output of the power plant are the same, the maximum required charging electric energy varies depending on the remaining time in the preparation time zone and the remaining time in the designated time zone. Therefore, in order to calculate an appropriate composite output preparation value, it is desirable to consider the remaining time in the preparation time zone and / or the remaining time in the designated time zone. Hereinafter, a calculation method for optimizing the composite output preparation value using the remaining time in the preparation time zone and the remaining time in the designated time zone will be described in detail.

10A to 10D show the maximum required charging power amount in each time zone.
FIG. 10A shows the maximum required charging power when the operation (output) of the wind power generator 16 stops in the preparation time period (decrease prohibition preparation time) and the combined output can be zero before the start of the specified time period (cannot decrease). The quantity Esmax is shown. The composite output must be changed so as to satisfy the short cycle fluctuation criterion (for example, the output change speed is within 1% / min) and the long cycle fluctuation criterion (decrease prohibited in the specified time zone (cannot be reduced)). The required charging power Esmax cannot be made zero. In the example of FIG. 10A, the required power amount (the gray area of the triangle in the preparation time zone), which is the combined output when reduced at a predetermined output change rate, corresponds to the maximum required charging power Esmax. Note that the larger the output when the wind power generator 16 is stopped, the larger the triangle of FIG. 10A becomes similar, and thus the maximum required charging energy Esmax increases exponentially.

  FIG. 10B shows the maximum required charging power Esmax when the operation (output) of the wind power generator 16 stops in the preparation time zone and the combined output cannot be made zero before the start of the designated time zone (cannot be reduced). In this case, after the composite output decreases at a predetermined output change rate using the preparation time zone, the composite output must be constant in the specified time zone (cannot be reduced), and the specified time zone (cannot be reduced) ends. Using the subsequent decrease prohibition opening time, the combined output is further reduced at a predetermined output change rate. In the example of FIG. 10B, the necessary power (the trapezoidal gray area in the preparation time zone and the triangular gray area in the reduction prohibition opening time) and the composite output when maintaining at a predetermined output change rate and the composite output are kept constant. The sum of the power (rectangular gray area in the specified time zone) corresponds to the maximum required charge power amount Esmax.

  FIG. 10C shows the maximum required charging power Esmax when the operation (output) of the wind power generator 16 is stopped in the designated time zone (cannot be reduced). In this case, it is necessary to make the composite output constant in the specified time zone (cannot be reduced), and the composite output is output at a predetermined output change rate using the decrease prohibition release time after the end of the specified time zone (cannot be reduced). It goes down. In the example of FIG. 10C, the required power when the composite output is kept constant (rectangular gray area in the specified time zone (non-decreasing)) and the required power when decreasing at a predetermined output change rate (decreasing prohibition opening time) The total sum of the triangular gray areas) corresponds to the maximum required charge power amount Esmax.

  FIG. 10D shows the maximum required charging energy Esmax when the operation (output) of the wind power generator 16 is stopped at the end of the designated time period (cannot be reduced) (at the start of the reduction prohibition opening time). In this case, the combined output decreases at a predetermined output change rate using the decrease prohibition release time after the end of the designated time period (cannot be decreased). In the example of FIG. 10D, the required charging power (the gray area in the triangle of the reduction prohibition opening time) when it is reduced at a predetermined output change speed corresponds to the maximum required charging power amount Esmax. 10A and 10D do not include the designated time zone (cannot be reduced) in the predetermined time after the operation (output) of the wind power generator 16 is stopped, so that the combined output can be brought close to zero earliest (that is, maximum) The required charge power amount Esmax is the smallest).

  Next, a method for calculating the composite output preparation value Pp will be described. If the combined output preparation value Pp is set to a very small value, the required charging power is naturally reduced, and deviation of the output fluctuation standard due to insufficient charging power can be avoided. On the other hand, when the combined power output of the power plant becomes smaller than the variable power output, it is necessary to charge until the amount of charged power reaches the upper limit of charge power operation, and it is necessary to throw away the power that can not be charged by the variable power output limit, If the composite output preparation value Pp is excessively reduced, the profit of the operator is deteriorated. Therefore, it is necessary to appropriately set the composite output preparation value Pp.

  In the present embodiment, the composite output preparation value Pp is appropriately set using a composite output preparation function that receives the dischargeable electric energy and outputs the composite output preparation value. The composite output preparation function is a function having a characteristic that the composite output preparation value changes depending on the time zone even if the dischargeable power amount (≈charge power amount) is the same.

  FIG. 11 shows a composite output preparation function. The vertical axis is the composite output preparation value, and the horizontal axis is the dischargeable electric energy corresponding to the function input. Even if the variable power output suddenly drops, the combined output preparation value can avoid the technical requirement from being unsatisfactory due to a shortage of charging power if the combined output of the power plant is below this value. It is a value. The dischargeable electric energy is a value obtained by adding the charged electric energy of the power storage device 11 and the expected electric energy of the wind power generator 16. If the expected electric energy is taken into consideration, the composite output ready value can be calculated with higher accuracy, but it is not essential. For example, the combined output preparation value may be calculated using only the amount of charging power of the power storage device 11.

  As shown in FIG. 11, the composite output preparation function in normal time (preparation time zone, normal operation time zone other than the specified time zone) is set to a function that can maintain the power plant composite output high with low charge power. The slope of the function is maximized (maximum slope). On the other hand, the combined output preparation function at the specified time zone start time is set to a function that cannot maintain the combined power plant output high unless the amount of charging power is high, and the function slope is minimized (minimum slope). The slope of the composite output preparation function is adjusted between the maximum slope and the minimum slope according to the remaining time in the preparation time zone and the remaining time in the designated time zone. Specifically, the slope of the composite output preparation function is gradually adjusted from the maximum slope to the minimum slope from the start time of the preparation time period to the start time of the specified time period. The gradient of the composite output preparation function is gradually adjusted from the minimum gradient to the maximum gradient over the end time. As shown in FIG. 10A to FIG. 10D, the remaining time of the preparation time zone (remaining time from the current time to the specified time zone start time) and the remaining time of the designated time zone change according to the current time. This corresponds to the change in the maximum required charging power corresponding to the remaining time. Therefore, by adjusting the slope of the composite output preparation function according to the remaining time of the preparation time zone determined by the relationship with the current time and the remaining time of the specified time zone, the optimum composite output preparation according to the change of the current time The value can be calculated.

  Note that the composite output preparation function may add constraints such as the power plant capacity. For example, in the case of the slope of the composite output preparation function at the normal time in FIG. 11, the composite output preparation value reaches the rated output of the wind power generator 16 when the dischargeable power amount is around 50%, and thus the dischargeable power amount is 50. If it is higher than around%, it can be flattened at the value of the rated output of the wind power generator 16, and the combined power output of the power plant can be made lower than the rated output of the wind power generator 16.

  The composite output preparation function shown in FIG. 11 can gradually adjust the slope of the composite output preparation function according to the change of the current time, and calculate the composite output preparation value suitable for the current time state.

  By using such a composite output preparation function, it is possible to smoothly perform the preparation value transition operation (transition to the composite output preparation value and cancellation of the composite output preparation value) shown in FIG. Hereinafter, a specific method of shifting to the composite output preparation value and canceling the composite output preparation value will be described with reference to FIG.

  The configuration of FIG. 2A, which is one of the variations of the composite output ready value setting unit 22, that is, a method for realizing the operation of shifting the ready value by switching the switch will be described. The composite output preparation value setting unit 22 is configured to be able to input the generated power generation power PG as shown in FIG. 1 (FIG. 5).

  First, at the time sufficiently earlier than the specified time zone start time, the generated power PG is selected for the switch in FIG. 2A. The combined output preparation value calculation unit 100 is not limited to the designated time zone start time, and always calculates an optimal combined output preparation value at any time.

  The timing for switching to the combined output ready value by switching the switch is the time when the current time is within the preparation time zone and the combined output ready value falls below the generated power PG or the combined output target value PA. This is because if the generation effective power PG or the combined output target value PA further increases, the combined output preparation value is exceeded, and the necessary charge power amount cannot be secured.

  The timing at which the switch is returned to the original state and the combined output preparation value is released is the time when the combined output preparation value at the current time exceeds the generated power PG or the combined output target value PA. This is because the required amount of charging power can be secured with the current amount of electric power that can be discharged. By switching at these timings, the output signal of the composite output preparation value setting unit 22 does not change suddenly before and after the switch switching, and the adjustment of the long cycle fluctuation relaxation control unit 23 and the short cycle fluctuation relaxation control unit 25 is facilitated. .

  The configuration of FIG. 2B, which is one of the variations of the composite output preparation value setting unit 22, that is, a method for realizing the operation of preparation value transition by setting the composite output preparation value to the upper limit value of the limiter will be described. As shown in FIG. 11, if the method of continuously calculating the composite output preparation value is used, the upper limit value of the limiter of the composite output preparation value setting unit 22 may be always set as the output signal of the composite output preparation function, and the special switching is performed. No action is necessary. This is because whether the output signal of the composite output preparation value setting unit 22 is equal to the generated active power PG or the composite output preparation value is automatically switched at an appropriate timing. Hereinafter, a specific example of the switching procedure will be shown.

  First, if the current time is sufficiently earlier than the designated time zone start time, the composite output preparation function has a large slope and the composite output preparation value increases as shown in FIG. As a result, the upper limit value of the limiter becomes larger than the generated power active power PG, and the output signal of the combined output preparation value setting unit 22 becomes equal to the generated power active power PG.

  Next, as time passes and the current time approaches the designated time zone start time, the slope of the composite output preparation function decreases. As a result, the composite output preparation value is also reduced. When the combined output preparation value becomes smaller than the generated power generation power PG, the output signal of the combined output preparation value setting unit 22 becomes equal to the combined output preparation value that is the upper limit value of the limiter, so that the transition to the preparation value is performed.

  Thereafter, when the current time falls within the designated time zone, the slope of the composite output preparation function increases as the current time approaches the designated time zone end time. The upper limit value of the limiter becomes larger than the power generation active power PG at the timing when the power generation active power PG exceeds the combined output preparation value corresponding to the dischargeable power at the current time. As a result, the output signal of the combined output preparation value setting unit 22 becomes equal to the generated power generation power PG, and the preparation value is released.

  By these operations, the output signal of the combined output preparation value setting unit 22 does not change suddenly before and after the switch is switched, and the adjustment of the long cycle variation relaxation control unit 23 and the short cycle variation relaxation control unit 25 is facilitated.

  If the generated active power PG is a sufficiently small value, the transition to the composite output ready value does not occur. However, in this case, the necessary charging power amount is small and the charging power amount is not insufficient, which hinders control. There is no.

  The configuration of FIG. 2C, which is one of the variations of the composite output ready value setting unit 22, that is, a method for realizing the operation of shifting the ready value by switching the gain in the feedback control system such as P control / PI control will be described.

  First, at a time sufficiently earlier than the designated time zone start time, the gain in FIG. 2C is set to 0, and the output signal of the combined output preparation value setting unit 22 is the generated active power PA. The combined output preparation value calculation unit 100 is not limited to the designated time zone start time, and always calculates an optimal combined output preparation value at any time.

  Next, when the current time is within the preparation time zone, it is determined when the combined output ready value falls below the combined output target value PA, and the gain is set to a certain specified value at the determination time. This is because if the generation effective power PG or the combined output target value PA further increases, the combined output preparation value is exceeded, and the necessary charge power amount cannot be secured.

  Thereafter, when the current time is within the specified time zone, the timing at which the combined output preparation value exceeds the combined output target value PA is determined, and the gain is returned to 0 at the determination time. This is because the required amount of charging power can be secured with the current amount of electric power that can be discharged.

  At these timings, the deviation between the composite output target value and the composite output preparation value becomes 0. Therefore, even if the gain setting is switched, the output signal of the composite output preparation value setting unit 22 does not change suddenly, and long-period fluctuation relaxation control is performed. Adjustment of the unit 23 and the short cycle fluctuation relaxation control unit 25 is facilitated.

  FIG. 12 is a block diagram showing the processing contents in the composite output preparation value calculation unit. In the present embodiment, time t, which is the current time, is input to composite output preparation value calculation unit 100, and the measured value (ES) of charge energy of power storage device 11 is input. In the first to third embodiments, the active power PG and the power generation amount prediction value are input to the combined output preparation value calculation unit 24. In the present embodiment, these pieces of information are not used. A composite output ready value can be calculated.

The combined output preparation value calculation unit 100 includes a remaining time calculation unit 101, a dischargeable electric energy calculation unit 102, and a combined output preparation function calculation unit 103. The remaining time calculation unit 101 calculates the remaining time Tp in the preparation time zone and the remaining time _TL in the designated time zone from the time t indicating the current time. The dischargeable power amount calculation unit 102 includes a dischargeable power amount calculation unit 102 that outputs a dischargeable power amount EC by a unit conversion calculation from a measured charge power amount (or SOC value) of the power storage device 11, and a dischargeable power amount. and a power amount correcting unit 105 outputs the corrected dischargeable power amount Ed by adding the estimated power generation amount E _BL to the amount EC. In this example, since the dischargeable electric energy EC is calculated on the assumption that the power generation output of the wind power generator 16 has decreased in a stepped manner, the expected power generation _EBL is added to the dischargeable electric energy. . If the specification does not take into account the expected power generation amount _EBL to the dischargeable power amount, the power amount correction unit 105 is unnecessary. The composite output preparation function calculation unit 103 receives the dischargeable electric energy Ed as an input, and calculates the optimal composite output preparation value Pp in consideration of the remaining time Tp in the preparation time zone and / or the remaining time _TL in the designated time zone. .

Specifically, the composite output preparation value Pp is determined so as to satisfy the following expression (1).
In this example, as Ed = Es _{+ E BL,} discharge will be adding an amount of power Ed prospective power generation amount _{E BL,} the combined output preparation value Pp calculated without taking into account the estimated power generation amount _{E BL} to discharge electric energy Ed May be.
The dischargeable electric energy Ed can be expressed by Expression (1).

The above equation (1) is a quadratic equation relating to the composite output preparation value Pp. Therefore, Pp can be calculated by the solution formula shown in the following equation (2).

In the above formula (2), terms of ^RTP 2/2 corresponds to the maximum required charging power shown in FIG. 10A (triangular area). The Ed ≦ rTp ^2/2 of the case, a case where a power station combined output until the start time of the specified time zone (reduction not) can migrate to 0. In this case, the composite output preparation value Pp is adjusted to a small value calculated by Expression (2). On the other hand, Ed> rTp The ^2/2 of the case, which is when it is not possible to migrate the power plant combined output until the start time of the specified time zone (decrease is impossible) to 0. In this case, since the charging power remains even after the designated time zone (cannot be reduced), it can be increased to the composite output preparation value Pp calculated by the equation (2).

As described above, the optimum combined output preparation value Pp is calculated from the current dischargeable electric energy, the remaining time Tp of the preparation time zone, and the remaining time _TL of the designated time zone based on the expression (2). Can do.

In the above description, the case where the composite output preparation value calculation unit 100 calculates the composite output preparation value Pp using both the remaining time Tp in the preparation time zone and the remaining time _{TL in} the designated time zone is described as an example. did. However, the composite output preparation value calculation unit 100 can calculate the composite output preparation value Pp using only one of the remaining time Tp in the preparation time zone and the remaining time _{TL in} the designated time zone. That is, the composite output preparation value calculation unit 100 can calculate the composite output preparation value Pp based on the remaining time of the preparation time zone and / or the designated time zone.

In the above-described embodiment, in the calculation of the composite output preparation value Pp, the composite that has the minimum discharge power amount with respect to the theoretical worst condition that the power generation output of the wind power generator 16 rapidly decreases stepwise to zero. Assume output control. For this purpose, the remaining time Tp in the preparation time zone and the remaining time _TL in the designated time zone are used to calculate how much the combined output can be reduced by the start time of the designated time zone.

If the remaining time Tp of the preparation time zone is unknown, it is impossible to grasp to what extent the combined output can be reduced. As a result, the amount of discharge power required to satisfy both the short cycle fluctuation and long cycle fluctuation constraints is increased. Here, “when the remaining time Tp of the preparation time zone is unknown” can be rephrased as “when the start time (start time) of the designated time zone is unknown”, and is classified into the following two cases. .
・ The length of the specified time zone is known, but the start time (start time) of the specified time zone is unknown.
-The end time (end time) of the specified time zone is known, but the start time (start time) of the specified time zone is unknown.

On the other hand, when the remaining time _TL of the specified time zone is unknown, for example, the start time (start time) of the specified time zone is known, but the end time (end time) of the specified time zone is unknown. . Hereinafter, the control method (computation output preparation value Pp calculation method) for each of these cases will be described.

<When the length of the specified time zone is known, but the start time (start time) of the specified time zone is unknown>
This corresponds to the case where the remaining time Tp of the preparation time zone is unknown in the above-described equation (1). Assuming the theoretical worst condition that the generated power of the wind power generator 16 suddenly decreases to 0 in steps, the combined output preparation value Pp becomes the largest because the remaining time Tp = 0 in the preparation time zone In other words, this is a case where the start time (start time) of the specified time zone is now.

  FIG. 13A, FIG. 13B, and FIG. 13C show the second case where the start time (start time) of the designated time zone is later than the current time (the time until the designated time zone is relatively long), which is later than the current time. In this case (time until the designated time zone is relatively short), an example of the maximum required charging power in the present case is shown. 13A to 13C, the maximum required charging power is the largest in FIG. 13C. This is because the amount of discharge power from the current time to the start time (start time) of the specified time zone (the trapezoid on the left side of FIGS. 13A and 13B) and the amount of discharge power after the end of the specified time zone (of FIGS. 13A to 13C). This is because the total area with the triangle portion on the right side is the same, and the area of the discharge power amount (rectangular portion in the middle of FIGS. 13A to 13C) in the designated time zone is compared.

From the above, the maximum required charging power Esmax can be calculated by the following equation (3) with Tp = 0 if Pp is replaced by Pg in the above equation (1). Note that when calculating the maximum required charging power Esmax, the efficiency of the power storage device 11 (efficiency during discharging) may be further considered, or the charging power amount corresponding to the charging power operation lower limit value may be considered. good.
However,
Pg: Current output of the variable power supply (kW)
r: Output change speed setting value (kW / h)
T _L : Remaining time in the specified time zone (h)
It is.

The same applies to the composite output preparation value Pp. The worst condition is when Tp = 0, that is, when the designated time zone start time is the same as the current time. Substituting into Equation (1) and Equation (2) is as follows.

<When the end time (end time) of the specified time zone is known, but the start time (start time) of the specified time zone is unknown>
This corresponds to the case where the total time of the remaining time Tp in the preparation time zone and the remaining time _{TL in the} designated time zone (which is defined as T _L ′) is determined, but the breakdown is unknown. Assuming the theoretical worst condition that the generated power of the wind power generator 16 suddenly decreases stepwise to zero, the maximum required charging power becomes the largest when Tp = 0 and T _L = T _L ' In other words, this is a case where the start time (start time) of the specified time zone is now. That is, the maximum required charging power Esmax can be calculated by the following equation (5) where Tp = 0 and T _L = _TL ′ if Pp is replaced by Pg in the above equation (1). In calculating the maximum required charging power, the efficiency of the power storage device 11 (efficiency at the time of discharging) may be further considered, or the charging power amount corresponding to the charging power operation lower limit value may be considered. .
However,
Pg: Current output of the variable power supply (kW)
r: Output change speed setting value (kW / h)
TL ': Maximum remaining time in the specified time zone (the time from the present to the end time of the specified time zone) (h)
It is.

The composite output preparation value Pp is as follows, by substituting Tp = 0 and T _L = T _L ′ into the equations (1) and (2).

<If the start time (start time) of the specified time zone is known, but the end time (end time) of the specified time zone is unknown>
This corresponds to the case where the remaining time Tp of the preparation time zone is determined, but it is only known that the remaining time _TL of the designated time zone is greater than zero. The worst condition in this case is that the remaining time T _L = ∞ in the designated time zone. If the discharge is continued for a long time in the designated time zone, the charging power will eventually become insufficient, so the combined output must be made zero by the start time (start time) of the designated time zone. In the above-described equation (1), when Pp is replaced with Pg and T _L = ∞, the maximum required charge energy Esmax can be calculated by the following equation (7). However, since it is actually impossible to set the required charging power = ∞, the upper limit value of the maximum required charging power calculated by Pg ² / 2r is employed in Equation (7).
However,
Pg: Current output of the variable power supply (kW)
r: Output change speed setting value (kW / h)
It is.

Assuming that T _L = ∞ in equation (1), the equation for the composite output preparation value Pp is as follows.

Actually, the dischargeable electric energy Ed cannot be made infinite, so Pp ≦ rTp is a constraint condition. In other words, the composite output preparation value Pp is the smaller of (2rEd) ^1/2 and rTp.

  Next, simulation results when the combined output is lowered to the combined output preparation value in the power stabilization system according to the fourth embodiment will be described.

  14A to 14C show simulation results when the power plant combined output is lowered to the combined output ready value. 14A is the SOC value (%) of the power storage device 11, FIG. 14B is the output change rate (% / min), FIG. 14C is the combined power output of the power plant, the variable power output (generated power of the wind power generator 16), and the storage battery output ( The charging / discharging electric power of the electric power storage apparatus 11 is shown.

  In the simulation, the designated time for the first non-decreasing time zone is set from 7:00 to 10:00, and the designated time for the second non-decreasing time zone is set from 16:00 to 19:00. ing. Also, a designated time zone that is an increase / decrease impossible time zone is set from 11:30 to 13:30, and a specified time zone that is an increase impossible time zone is set from 20:00 to 23:00. Yes. A preparation time zone is set about one hour before each designated time zone.

  Focusing on time zone A shown in FIG. 14C, a high composite output (maximum value) is maintained until the preparation time zone of the first non-decreasing time zone (designated time) is entered (the composite output at the normal time in FIG. 11). Preparation function). When entering the preparation time zone of the first non-decreasing time zone (designated time), the slope of the composite output preparation function becomes small, so even if the variable power output is 100%, the composite output preparation value is lowered and the composite output preparation value is lowered. Output decreases. The composite output preparation value decreases until the disclosure time of the first non-decreasing time zone (designated time), and the slope of the composite output preparation function at this time is minimized. After that, the variable power output remains at 100% even when the first non-decreasing time zone is entered, while the remaining time of the first non-decreasing time zone (designated time) decreases, so even if the combined output is increased It will be in a situation where necessary charging power can be secured. Therefore, the slope of the composite output preparation function increases again and the composite output preparation value is increased, so that the composite output is restored to 100%.

  Next, attention is focused on the time zone B shown in FIG. 14C. When entering the preparation time zone of the non-increasable time zone (specified time), the slope of the composite output preparation function becomes smaller again, the composite output preparation value is lowered until the start time of the non-increasable time zone, and then remains constant To be controlled. In the simulation, the variable power output (power generated by the wind power generator 16) decreases when entering the preparation time zone of the non-increasing time zone (designated time). For this reason, in order to maintain the combined output, the storage battery output (discharge power of the power storage device 11) gradually increases from zero. The SOC value starts to decrease in response to the increase in the storage battery output (FIG. 14A). Since the variable power supply output has not recovered during the non-increasing time zone (specified time), the combined output is maintained at the storage battery output (discharge power of the power storage device 11). The SOC continuously decreases during the non-increasing time zone (designated time), but the non-increasing time zone (designated time) has passed without causing SOC shortage.

  Then, after the non-increasing time zone (designated time) has elapsed, control is performed so that the combined output is lowered until the combined output matches the variable power output. Control for limiting the combined output is not performed after the start time (16:00) of the second non-decreasing time zone.

  In addition, the control device 13 described above includes a CPU and a memory (storage device such as a hard disk) not shown, and various correction calculation processing, compensation power calculation processing, control processing of the power converter 12, and the like are as follows. It may be realized by hardware, or may be realized by the CPU reading and executing a predetermined application program stored in the storage device. Further, when realized by hardware, it may be controlled using a digital circuit such as a programmable controller, or may be realized by an analog control circuit such as an operational amplifier.

  In the above description, the wind power generator is exemplified as the variable power source linked to the power system, but the present invention is not limited to the wind power generator. For example, the variable power source may be solar power generation or the like. The present embodiment is directed to a variable power source that collects renewable energy and generates power, but is not necessarily limited to renewable energy.

DESCRIPTION OF SYMBOLS 10 Power stabilization system 11 Power storage apparatus 12 Power converter 13, 50 Control apparatus 15 Electric power system 16 Wind generator 21 Active power detection part 22 Synthetic output preparation value setting part 23 Long period fluctuation relaxation control part 24, 100 Synthetic output preparation Value calculation unit 25 Short cycle fluctuation mitigation control unit 27 Power converter control unit 44 Subtraction element 45 Power generation amount prediction unit 46 Smoothing filter 47 Limiter 101 Remaining time calculation unit 102 Dischargeable power amount calculation unit 103 Synthetic output preparation function calculation unit

Claims (10)

A power storage device that performs charging and discharging, a power converter that mutually converts input and output by charging and discharging of the power storage device between a power system and the power storage device, and controls a conversion operation of the power converter, A control device that controls a combined output of the variable power source and the power storage device linked to the power system based on a combined output target value, and a power stabilization system using the power storage device,
The control device includes a long-cycle fluctuation mitigation control unit for mitigating long-period fluctuations of the synthesized output, and a synthesis that calculates a composite output preparation value that serves as a control point at least at the start of the long-period fluctuation mitigation designated time zone An output preparation value calculation unit, and a composite output preparation value setting unit that reflects the composite output preparation value in the composite output target value ,
The composite output preparation value calculation unit includes only the remaining time of the preparation time zone before the long-period fluctuation relaxation designated time zone, or the remaining time of the preparation time zone before the long-cycle fluctuation relaxation designated time zone and the long-cycle fluctuation relaxation. The power stabilization system characterized in that the composite output preparation value is calculated using a remaining time in a designated time zone . The combined output preparation value calculation unit inputs the dischargeable electric energy of the power storage device and outputs the combined output preparation value, and only the remaining time of the preparation time zone, or the remaining time of the preparation time zone and the length 2. The power stabilization system according to claim 1, wherein an optimum combined output preparation value is calculated using a combined output preparation function whose characteristics change corresponding to the remaining time of the period fluctuation relaxation designated time zone. The composite output preparation value calculation unit is characterized in that a change in the characteristic of the composite output preparation function is represented by a slope, and the composite output preparation function is used in a normal operation time zone other than the preparation time zone and the long-period fluctuation relaxation designated time zone. And the slope of the composite output preparation function is minimum at the start time of the long cycle fluctuation relaxation specified time zone, and from the start time of the preparation time zone to the start time of the long cycle fluctuation relaxation specified time zone. The characteristic of the composite output preparation function is shifted in a direction in which the slope decreases, and the characteristic of the composite output preparation function is shifted in a direction in which the slope increases from the start time to the end time of the long period fluctuation relaxation specified time zone. The power stabilization system according to claim 2, wherein: The composite output preparation value calculation unit adds a value obtained by adding a predicted power generation amount that can be expected even when the output of the variable power source is reduced in a stepped manner to the charging power amount of the power storage device. The power stabilization system according to claim 2 , wherein the power stabilization system is used as a power stabilization system. The composite output preparation value calculating section, the power stabilizing system according to any of claims 1 to 4, characterized in that calculating the composite output preparation value based on the following equation.
The composite output preparation value calculating section, the power stabilizing system according to any of claims 1 to 5, characterized in that to calculate the composite output preparation value using the power generation amount prediction value of the fluctuation power.   2. The composite output preparation value setting unit shifts the composite output target value to the composite output preparation value by switching between the generated power of the variable power source and the composite output target value with a switch. The described power stabilization system.   The composite output preparation value setting unit shifts the composite output target value to the composite output preparation value by applying a limiter that sets the composite output preparation value to an upper limit and / or a lower limit to the power generation active power of the variable power source. The power stabilization system according to claim 1, wherein:   The composite output preparation value setting unit feedback-controls a difference between the composite output target value and the composite output preparation value, and shifts the composite output target value to the composite output preparation value. The described power stabilization system. In a power stabilization system using a power storage device, a power converter that mutually converts input / output by charging / discharging of the power storage device between the power system and the power storage device is controlled to connect to the power system. A control device that controls a combined output of a variable power supply and the power storage device based on a combined output target value;
The control device includes a long cycle fluctuation relaxation control unit for relaxing long cycle fluctuations of the composite output, and a composite output for calculating a composite output preparation value that is a control point at the start of the long cycle fluctuation relaxation designated time zone a preparation value calculating unit, and said composite output preparation value the combined output preparation value setting unit to be reflected on the composite output target value possess,
The composite output preparation value calculation unit includes only the remaining time of the preparation time zone before the long-period fluctuation relaxation designated time zone, or the remaining time of the preparation time zone before the long-cycle fluctuation relaxation designated time zone and the long-cycle fluctuation relaxation. A control device that calculates the composite output preparation value using a remaining time in a specified time zone .