Grid controller for use in smart grid system, smart grid system including the same, and method of controlling smart grid system

• US 9,659,332 B2
• Filed: 12/19/2012
• Issued: 05/23/2017
• Est. Priority Date: 12/27/2011
• Status: Active Grant

• Current Assignee: Kawasaki Jukogyo Kabushiki Kaisha
• Original Assignee: Kawasaki Jukogyo Kabushiki Kaisha
• Inventors: Tokuda, Noriaki, Yamaguchi, Yoshinari, Takebe, Tomoaki, Yamamoto, Yusuke, Takeda, Kenji
• Primary Examiner(s): Dao, Tuan
• Application Number:
  US14/369,244
• Publication Number:
  US 20140379151A1
• Time in Patent Office: 1,616 Days
• Field of Search: None
• CPC Class Codes: G05B 15/02 electric
• CPC Class Codes: G06Q 50/06 Energy or water supply
• CPC Class Codes: H02J 2300/20 The dispersed energy generation being of renewable origin
• CPC Class Codes: H02J 2300/22 The renewable source being solar energy
• CPC Class Codes: H02J 2300/28 The renewable source being wind energy wind motors F03D
• CPC Class Codes: H02J 2310/12 The local stationary network supplying a household or a building
• CPC Class Codes: H02J 3/32 using batteries with converting means
• CPC Class Codes: H02J 3/322 the battery being on-board an electric or hybrid vehicle, e.g. vehicle to grid arrangements [V2G], power aggregation, use of the battery for network load balancing, coordinated or cooperative battery charging
• CPC Class Codes: H02J 3/381 Dispersed generators
• CPC Class Codes: H02J 4/00 Circuit arrangements for mains or distribution networks not specified as ac or dc
• CPC Class Codes: Y02B 70/3225 Demand response systems, e.g. load shedding, peak shaving
• CPC Class Codes: Y02E 70/30 Systems combining energy storage with energy generation of non-fossil origin
• CPC Class Codes: Y04S 20/222 Demand response systems, e.g. load shedding, peak shaving

Abstract

A grid controller is communicably connected to controllers of a plurality of power storage units. The grid controller: obtains transmission power transmitted from the smart grid system to an external power system, the transmission power being a sum of electric power generated by power generating units, electric power consumed by loads in the smart grid system, and electric power charged into and discharged from the power storage units; calculates differential power between the transmission power and a smoothing operation output, the smoothing operation output being obtained by performing smoothing operation on the transmission power by using a smoothing filter; and performs control of smoothing the transmission power by performing allocation of the differential power of the transmission power in accordance with a charge-discharge state of each of power storage parts of the plurality of power storage units.

Claims

1. A grid controller having a hardware processor configured for use in a smart grid system in which at least one power generating unit and a plurality of power storage units are connected to each other and to an external power system in such a manner as to allow the power generating unit and the plurality of power storage units to transmit electric power to and receive electric power from each other and the external power system, each power storage unit including a power storage part storing electric power and a controller performing charge-discharge control of the power storage part, wherein

the grid controller is communicably connected to the controllers of the respective power storage units,

the grid controller:

obtains transmission power Pall transmitted from the smart grid system to the external power system, the transmission power Pall being a sum of electric power generated by the power generating unit, electric power consumed by loads in the smart grid system, and electric power charged into and discharged from the power storage units;

calculates differential power Δ

P between the transmission power Pall and a smoothing operation output Pall′

, the smoothing operation output Pall′

being obtained by performing smoothing operation on the transmission power Pall by using a smoothing filter; and

performs control of smoothing the transmission power Pall by performing allocation of the differential power Δ

P of the transmission power Pall in accordance with a charge-discharge state of each of the power storage parts of the plurality of power storage units.

2. The grid controller according to claim 1, wherein

in a case where there are a plurality of power storage units to which the differential power Δ

P is to be allocated, the grid controller determines allocation amounts in accordance with magnitudes of charge-discharge command values, the values being set in advance by the controllers corresponding to the power storage parts of the power storage units, in order to adjust an amount of electric power stored in each of the power storage parts of the power storage units to a predetermined charge-discharge target value.

3. The grid controller according to claim 1, wherein

the grid controller is configured such that:

in a case where the transmission power Pall is less than the smoothing operation output Pall′

, the grid controller transmits such a control command value as to reduce a charge amount per unit time of a power storage unit whose power storage part is in a charging state among the plurality of power storage units, the grid controller transmitting the control command value to the controller corresponding to the power storage part in a charging state; and

in a case where the transmission power Pall is less than the smoothing operation output Pall′

even if the charge amount per unit time of the power storage unit whose power storage part is in a charging state among the plurality of power storage units is set to 0, the grid controller transmits such a control command value as to cause electric power stored in the power storage unit whose power storage part is in a charging state to be discharged, the grid controller transmitting the control command value to the controller corresponding to the power storage part in a charging state.

4. The grid controller according to claim 3, wherein

the grid controller is configured such that

in a case where the transmission power Pall is less than the smoothing operation output Pall′

even if a discharge amount per unit time of the power storage unit whose power storage part is in a charging state among the plurality of power storage units is increased, the grid controller transmits such a control command value as to increase a discharge amount per unit time of a power storage unit whose power storage part is in a discharging state among the plurality of power storage units, the grid controller transmitting the control command value to the controller corresponding to the power storage part in a discharging state.

5. The grid controller according to claim 1, wherein

the grid controller is configured such that:

in a case where the transmission power Pall is greater than the smoothing operation output Pall′

, the grid controller transmits such a control command value as to reduce a discharge amount per unit time of a power storage unit whose power storage part is in a discharging state among the plurality of power storage units, the grid controller transmitting the control command value to the controller corresponding to the power storage part in a discharging state; and

in a case where the transmission power Pall is greater than the smoothing operation output Pall′

even if the discharge amount per unit time of the power storage unit whose power storage part is in a discharging state among the plurality of power storage units is set to 0, the grid controller transmits such a control command value as to cause the power storage unit whose power storage part is in a discharging state to be charged with electric power, the grid controller transmitting the control command value to the controller corresponding to the power storage part in a discharging state.

6. The grid controller according to claim 5, wherein

the grid controller is configured such that

in a case where the transmission power Pall is greater than the smoothing operation output Pall′

even if a charge amount per unit time of the power storage unit whose power storage part is in a discharging state among the plurality of power storage units is increased, the grid controller transmits such a control command value as to increase a charge amount per unit time of a power storage unit whose power storage part is in a charging state among the plurality of power storage units, the grid controller transmitting the control command value to the controller corresponding to the power storage part in a charging state.

7. The grid controller according to claim 1, wherein

the grid controller:

separates the plurality of power storage units into a plurality of groups in accordance with usage of each of the power storage units;

performs predetermined weighting on the plurality of groups and on a time constant of the smoothing filter;

sets an evaluation function, in which differences between target values of control command values of the respective groups and control command values to be calculated by the grid controller, and a difference between a target value of the time constant of the smoothing filter and a setting value of the time constant to be calculated by the grid controller, are weighted and averaged based on the predetermined weighting; and

calculates the control command values of the respective groups and the setting value of the time constant of the smoothing filter, such that the evaluation function becomes minimum.

8. The grid controller according to claim 1, wherein

the grid controller:

obtains electric power generated by the power generating unit, electric power consumed by the loads in the smart grid system, and electric power charged into and discharged from the power storage units; and

calculates the transmission power Pall based on the generated electric power, the consumed electric power, and the charged and discharged electric power, which are obtained.

9. A smart grid system comprising:

at least one power generating unit connected to an external power system in such a manner as to allow the power generating unit to transmit electric power to and receive electric power from the external power system;

a plurality of power storage units connected to the power generating unit and the external power system in such a manner as to allow the plurality of power storage units to transmit electric power to and receive electric power from the power generating unit and the external power system, each of the power storage units including a power storage part storing electric power and a controller performing charge-discharge control of the power storage part; and

the grid controller according to claim 1.

10. A method of controlling a smart grid system in which at least one power generating unit and a plurality of power storage units are connected to each other and to an external power system in such a manner as to allow the power generating unit and the plurality of power storage units to transmit electric power to and receive electric power from each other and the external power system, each power storage unit including a power storage part storing electric power and a controller performing charge-discharge control of the power storage part, wherein

the method comprising:

obtaining transmission power Pall transmitted from the smart grid system to the external power system, the transmission power Pall being a sum of electric power generated by the power generating unit, electric power consumed by loads in the smart grid system, and electric power charged into and discharged from the power storage units;

calculating differential power Δ

P between the transmission power Pall and a smoothing operation output Pall′

, the smoothing operation output Pall′

being obtained by performing smoothing operation on the transmission power Pall by using a smoothing filter; and

performing control of smoothing the transmission power Pall by performing allocation of the differential power Δ

P of the transmission power Pall in accordance with a charge-discharge state of each of the power storage parts of the plurality of power storage units.