JP4064334B2 - Energy system control device and control method - Google Patents

Description

  The present invention relates to a control device and a control method for an energy system having a distributed power supply device including a storage battery and connected to a power system and a power load.

  As a method of creating a power generation plan for performing low-cost operation control of an energy system having a plurality of distributed power supply devices, as described in Patent Document 1, a metaheuristic method such as tabu search or genetic algorithm is used. There is a method using In recent years, with the spread of distributed power sources, etc., the need to consider nonlinear and discontinuous characteristics and constraints has increased, and the metaheuristic method is a high-speed approximate solution of the global optimal solution at a relatively high speed regardless of the function form. Therefore, it has come to be used for power generation planning.

In addition, as a method for controlling in real time, there is a method for controlling the energy cost to be minimized in consideration of the power generation cost and the discharge cost of the storage battery, as in the fuel cell system control method described in Patent Document 2. is there.
JP 2001-258157 A JP 2003-163013 A

  When performing optimal control such as cost reduction for an energy system including a storage battery, it is necessary to consider the charge / discharge balance of the storage battery, and for example, it is necessary to create and control an optimal operation plan for one day. However, when there is a large amount of time fluctuation and high-precision demand forecasting is difficult, such as household power demand, simply creating an optimal plan as in the past will enable operation planning corresponding to actual power demand fluctuations. There is a problem that it is difficult to correct low-cost control in real time. The above-described real-time control method simply evaluates whether or not the cost can be temporarily reduced, so there is no guarantee that the operation will be optimal for the entire day.

  In addition, when the cost reduction is evaluated only by running cost as in the conventional control method, there is a case where the operation / control does not result in a total cost reduction due to renewal due to the life of the equipment.

  The objective of this invention is providing the control apparatus and control method of an energy system which can perform low-cost control rather than control by only an optimal operation plan.

In order to achieve the above object, a control device for an energy system of the present invention comprises:
An optimum operation plan creation means for creating an optimum operation plan for the distributed power supply;
Storage and storage costs obtained by measuring and integrating storage battery charge and discharge amounts and charge costs, and storing and receiving power to and from the power system through simulations that increase or decrease storage battery charge and discharge amounts The amount of charge / discharge of the storage battery in the optimal operation plan when it is determined that the sum of the change in the electricity sales / purchase cost due to the charge / discharge of the storage battery is negative (the cost is reduced). Control command value determining means for changing the control command value and transmitting it to the distributed power supply device.

  According to the present invention, in response to temporary fluctuations in natural energy power generation or power demand, it is repeatedly determined by simulation calculation whether the energy cost can be reduced by changing the charge / discharge amount of the storage battery, and the control command value is corrected. By doing so, it is possible to perform control at a lower cost than control based only on the optimum operation plan.

  In addition, since the cost for which the life of the apparatus has been shortened by the operation is taken into consideration in the control, even near-optimal operation control is possible even in the long term until the renewal of the storage battery or the like.

  Next, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a configuration diagram of an energy system according to an embodiment of the present invention.

  The energy system includes a distributed power supply device 1, a power system 2, and a control device 3.

  The distributed power supply device 1 includes a solar cell 11, a fuel cell 13, and a storage battery 12.

  The control device 3 includes a communication unit 31, an optimum operation plan creation unit 32, and a control command value determination unit 33. The communication unit 31 connects the control device 3 to the Internet or the like to obtain information related to weather forecasts and the like. The optimum operation plan creation unit 32 predicts the generated power load demand and hot water supply demand of the solar cell 11 using the weather forecast information, and creates the optimum operation plan of the fuel cell 13 and the storage battery 12 using the prediction result. The command value determination unit 33 determines control command values for the fuel cell 13 and the storage battery 12 based on the optimum operation plan, and transmits them to the distributed power supply device 1.

  FIG. 2 is a schematic diagram showing the flow of processing of the control device 3.

  First, the optimum operation plan creation unit 32 is a distributed power source that can be controlled using the price of purchased / sold power received and transmitted to / from the power system 2, the daily power / heat load demand forecast, and the power generation forecast of the solar cell 11. An operation plan for power generation of a certain fuel cell 13 and charge / discharge of the storage battery 12 is created (step 101). In creating an operation plan, for example, the objective function is minimized with the cost obtained by adding / subtracting the power cost of power transmission / reception with the power grid 2 to / from the energy cost of the day, that is, the fuel cost used for power generation or the like. Search for driving patterns. The fuel cost is calculated from the fuel flow rate with respect to the generated power in the generated power target pattern by modeling the efficiency characteristics, start-up characteristics, response characteristics, etc. of the fuel cell 13. The storage battery 12 and hot water storage tank are modeled in consideration of charging / discharging loss, heat dissipation loss, etc., and the remaining capacity is calculated, and in order to balance the storage battery and hot water tank in one day, the charging cost and the hot water storage cost are reduced. The difference in days is added to the objective function as a penalty function. Further, overcharge, overdischarge, etc. of the storage battery 12 may be handled as a constraint condition or added as a penalty function in the same manner. Various optimal algorithms can be applied as search methods. By using metaheuristic techniques such as tabu search and genetic algorithm, a highly accurate approximate solution of the global optimal solution can be obtained within a realistic time. be able to. This operation plan is created, for example, on a daily basis or 24 hours ahead of the current time, and is updated as needed by correcting the forecast data.

  Next, the command value creation unit 33 calculates the storage amount and the storage cost of the storage battery 12 from the measurement data such as the charge / discharge current of the storage battery 12 (step 102). FIG. 3 shows an example of this calculation flow. In the case of charging, the measured charging current is integrated and added to the stored power storage amount (step 201). When the battery is fully charged, the charged amount is set to the rated value (steps 202 and 203). At this time, the error due to self-discharge in the storage battery 12 and the accumulated error of the measured value can be corrected. The storage cost is calculated from the grid power price, charge amount, charging efficiency, etc. at that time, and added to the stored storage cost (step 204). In the case of power generation, the power generation cost may be used instead of the grid power price, or the average cost may be calculated. In the case of discharging, the measured discharge current is integrated and subtracted from the stored power storage amount (step 205). If it is determined from the storage battery voltage that the storage amount is the lower limit, the storage amount and storage cost are reset (steps 206 and 207). The storage cost is calculated by multiplying the storage unit price by the integrated value of the discharge current (step 208), and subtracted from the stored storage cost (step 209). Here, the power storage unit price is calculated from the power storage cost per unit power storage amount.

  Next, it is determined whether or not it is necessary to perform calculation by simulation for changing the command value according to the optimum operation plan (step 103). For example, when the error between the predicted value and the measured value of the power generation amount or demand of the solar battery 11 is greater than or equal to a predetermined value, it is determined that there is a possibility of change, and the charge / discharge amount of the storage battery 12 is increased or decreased by one step. Is calculated (step 104). You may judge by the measured value which deducted the solar cell power generation amount from the electric power demand whether it became larger than the predicted value more than the predetermined value. In other words, when it is necessary to supply more power than expected, temporarily, it is cheaper to increase the amount of discharge from the storage battery 12 than to receive the power from the power system 2. Make a decision. On the other hand, when the power supply less than the predicted value is temporarily sufficient, it is determined whether it is better to reduce the discharge amount of the storage battery 12 than to reduce the power reception of the power system 2.

  FIG. 4 shows an example of a process (step 104) for performing simulation calculation when the charge / discharge amount of the storage battery 12 in the flow of FIG. This one stage is determined according to the responsiveness of the storage battery 12, the calculation speed in the control device 3, and the like. The simulation calculation is performed using the modeling of the fuel cell 13 and the storage battery 12 described above.

  In the case of charging, it is first determined whether or not a constraint condition such as the maximum charging current in the storage battery 12 is satisfied when the amount of charge is increased by one step (step 301). Only when this constraint condition is satisfied, simulation calculation in this case is performed (step 302). Cost reduction when charging amount is increased by one step from the increase in storage cost, which is assumed to be charged at the storage unit price calculated from the stored storage amount / storage cost. Calculate as minutes. Next, when the charge amount is decreased by one step, it is determined whether or not a constraint condition such as a minimum charging current in the storage battery is satisfied (step 303). The simulation calculation in this case is performed only when this constraint condition is satisfied. A value obtained by subtracting the decrease in the power storage cost that is charged at the power storage unit price from the decrease in the buying and selling power cost is calculated as the cost decrease when the charge amount is decreased by one step (step 304).

  In the case of discharging, it is first determined whether or not a constraint condition such as the maximum discharge amount in the storage battery 12 is satisfied when the discharge amount is increased by one step (step 305). The simulation calculation in this case is performed only when this constraint condition is satisfied. A value obtained by subtracting the decrease in the power storage cost that was discharged at the power storage unit price from the decrease in the buying and selling power cost is calculated as the cost decrease when the discharge amount is increased by one step (step 305). Furthermore, when considering the shortening of the life of the storage battery 12 due to cycle charge / discharge, the increase in the storage battery life cost due to the increase in the discharge amount is subtracted from the decrease in the cost (step 307). The storage battery life cost is obtained by dividing the initial cost per unit discharge amount of the storage battery by (cycle life × discharge depth) and multiplying by the discharge amount. Here, in the case of a lead storage battery, since the cycle life and the depth of discharge are inversely proportional, (cycle life × discharge depth) can be treated as a constant value (Japanese Patent Laid-Open No. 2003-161768). Next, when the discharge amount is decreased by one step, it is determined whether or not a constraint condition such as the minimum discharge current in the storage battery 12 is satisfied (step 308). The simulation calculation in this case is performed only when this constraint condition is satisfied. A value obtained by subtracting the increase in the power purchase cost from the increase in the power storage cost assumed to have been discharged at the power storage unit price is calculated as the cost decrease when the discharge amount is reduced by one step (step 309). Further, when considering the shortening of the life due to the cycle charge / discharge of the storage battery, the decrease in the storage battery life cost due to the decrease in the discharge amount is added from the decrease in the cost (step 310).

  The command value of the charge / discharge amount of the storage battery 12 is changed if the constraint condition of the storage battery 12 is satisfied by increasing / decreasing the charge / discharge amount by one step and the cost reduction is equal to or greater than a predetermined value. (Steps 106 and 107).

  Such calculation for changing the command value of the storage battery 12 is continuously performed at regular time intervals. When updating the optimal operation plan including the power generation plan at the timing when the forecast data such as power generation / demand is corrected, etc., after updating the operation plan such as minimizing the energy cost, the command of the storage battery 12 Calculate the value change.

It is a block diagram of the energy system of one Embodiment of this invention. 3 is a flowchart showing a flow of processing of a control device 3. It is a flowchart of the calculation process of the electrical storage amount and electrical storage cost in FIG. It is a flowchart of the simulation calculation at the time of increasing / decreasing the charging / discharging amount of the storage battery 12 in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Distributed power supply device 2 Electric power system 3 Control apparatus 11 Solar cell 12 Storage battery 13 Fuel cell 31 Communication part 32 Optimal operation plan preparation part 33 Command value preparation part 101-107, 201-209, 301-310 Step

Claims (6)

A control device of an energy system having a distributed power supply device including a storage battery and connected to a power system and a power load,
An optimum operation plan creating means for creating an optimum operation plan of the distributed power supply device;
By storing and storing the storage amount and storage cost obtained by measuring and integrating the charge / discharge amount and charge cost of the storage battery, and by calculating the simulation when the charge / discharge amount of the storage battery is increased or decreased, When it is determined that the sum of fluctuations in the buying and selling power costs due to power transmission and reception and the fluctuations in the power storage costs due to the charge / discharge amount of the storage battery is negative, the charge / discharge amount of the storage battery in the optimum operation plan A control device for an energy system, comprising control command value determination means for changing a control command value and transmitting the control command value to the distributed power supply device.   The control command value determining means is configured such that a difference between a predicted value and a measured value of the power load demand and, if the distributed power supply includes a natural energy source, a difference between the predicted value and the measured value of the power generation are not less than a predetermined value. When it becomes, the control apparatus of the energy system of Claim 1 which performs calculation by the simulation for the said control command value change.   A value obtained by adding an increase in a value obtained by multiplying an initial cost of the storage battery by a life reduction rate of the storage battery due to the discharge amount to the increase in the storage cost due to the charge / discharge amount of the storage battery is defined as a change in the storage cost. Item 4. The energy system control device according to Item 1. A method for controlling an energy system having a distributed power supply including a storage battery and connected to a power system and a power load,
Creating an optimal operation plan that minimizes the energy cost of the energy system;
Calculating a storage amount and a storage cost from measurement data obtained by measuring a charge / discharge amount and a charge cost of the storage battery;
Determining whether the difference between the predicted value of power generation / demand and the measured value is greater than or equal to a predetermined value;
When the difference between the predicted value and the measured value is equal to or greater than a predetermined value, calculating a cost reduction amount when the charge / discharge amount of the storage battery is increased or decreased by one step; and
Determining whether the cost reduction is greater than or equal to a predetermined value;
When the said cost reduction part is more than predetermined value, it has the step which changes the command value of the charging / discharging amount of the said storage battery in the said optimal operation plan, The control method of an energy system. The step of calculating the storage amount / storage cost includes
If the storage battery is being charged, the integrated value of charging current is added to the amount of electricity stored.If the battery is fully charged, the amount of electricity stored is set to the rated value, the charge cost is calculated from the power cost, and the storage cost is calculated. Add,
If the storage battery is discharging, the accumulated value of the discharge current is subtracted from the storage amount, and if it is a discharge limit, the storage amount and storage cost are reset, and the storage unit price is calculated from the storage amount and storage cost. The energy system control method according to claim 4, comprising subtracting a value obtained by multiplying a unit price of power storage by an integrated value of discharge current from the power storage cost. The step of calculating the cost reduction is as follows:
If the storage battery is being charged, if the charge amount of the storage battery is increased by one step, if the charge amount is less than or equal to the maximum charge amount, (the increase in the storage cost that is charged at the storage unit price)-(buying and selling When the charge amount of the storage battery is decreased by one step, if the charge amount is equal to or greater than the minimum charge amount, (the decrease in the power purchase cost)-(the unit price of electricity storage) Calculated as a reduction in storage cost)
If the storage battery is being discharged, when the discharge amount of the storage battery is increased by one step, if the charge amount is equal to or less than the maximum discharge amount, it is assumed that (the decrease in the power purchase cost)-(discharged at the unit price of electricity storage) If the storage battery discharge amount is reduced by one step, then the discharge amount is the minimum discharge amount. If it is above, calculate (increased storage cost that was discharged at the unit price of storage)-(increased trading power cost), and add (reduced battery life cost due to reduced discharge amount) to this The control method of the energy system of Claim 4 or 5.

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