1 Descriptions of Function

Transcription

1 NEDO Local Level Use Case #A2 Autonomous decentralized control of microgrid which consists only of generating equipments with grid-connected inverters, under the islanding operation. 1 Descriptions of Function 1.1 Function Name Version 3.0 Nov 7, 2011 Autonomous decentralized control of microgrid which consists only of generating equipments with grid-connected inverters, under the islanding operation 1.2 Function ID Local Level Use Case A2 1.3 Brief Description This use case describes control function of microgrid system, which is comprised only of generating equipments with grid-connected inverters, under islanding operation. This microgrid system is characteristic of the point that each generating equipment implements autonomous control without transferring signals among the paralleled inverters. Local Level Use Case _A2 Aichi Microgrid -islanding mode- rev4.doc 1 11/7/20

2 Fig.1 Configuration of microgrid system under islanding operation Note: The use case is described based on the results of NEDO s demonstration project conducted at Chubu Rinku Toshi in Tokoname city, Aichi prefecture. System voltage and frequency is determined by PAFC inverter. A sodium sulfur (NaS) battery is used for storage within the system. 1.4 Narrative The microgrid in this use case consists of generating equipment with grid-connected inverters and load, conducts islanding from commercial power grid. Islanding operation is activated with black start to ensure a stable power supply to customer s power receiving facility in the microgrid in case of power grid failure. Using PAFC operated as Grid Independent (GI) mode for reference source of voltage and frequency, the microgrid has an autonomous decentralized control function while aligning with other generating equipment such as battery and PAFC operated as Grid Connected (GC) mode. In this use case, voltage and frequency control that is necessary to realize the islanding operation is described in three Steps: Step 1: Implementation of power drooping characteristic in multiple inverters Step 2: Power compensation control to eliminate steady-state deviation of voltage and frequency; and Step 3: AC voltage control. Local Level Use Case _A2 Aichi Microgrid -islanding mode- rev4.doc 2 11/7/20

3 Step 1: Implementation of power drooping characteristic in multiple inverters This Step ensures stability of voltage and frequency of the microgrid under the islanding operation by implementing: - a control circuit with reactive power output that has a slope characteristic according to the change in voltage of the grid, and - control circuit with active power output that has a slope characteristic according to the change in frequency of the grid to PAFC. 1.1: Voltage & frequency fluctuation GI_PAFC & GI_PAFC 1.2: Active and reactive power dispatch Fig.2 Diagram of Step1 f V Rated Frequency Reference Value P Q Fig.3 Slope Characteristic Local Level Use Case _A2 Aichi Microgrid -islanding mode- rev4.doc 3 11/7/20

4 Step 2: Power compensation control to eliminate steady-state deviation of voltage and frequency With the function described in Step 1, there remains a steady-state deviation from reference voltage and frequency due to a lack of an integral control function. In Step 2, the voltage and frequency are kept to the reference value by adjusting the output of the NaS battery so as to maintain a constant output level of PAFC. 2.1: PAFC net output 2.2: power dispatch SENSOR & Fig.4 Diagram of Step2 Step 3: AC voltage control (Automatic Voltage Regulator (AVR) operation) In Step 3, PAFC (which is not the reference source for voltage and frequency) conducts reactive power control by comparing the voltage at the grid-connecting point and the reference voltage to reduce voltage fluctuation of an isolated grid. 3.1: PAFC sending-end voltage & 3.2: Reactive power dispatch Fig.5 Diagram of Step3 Local Level Use Case _A2 Aichi Microgrid -islanding mode- rev4.doc 4 11/7/20

5 <Acronyms> AVR EMS GC GI PAFC Automatic Voltage Regulator Energy Management System Grid Connected Grid Independent Phosphoric Acid Fuel Cell Power Conditioning System 1.5 Actor (Stakeholder) Roles Grouping (Community) Group Description Actor Name GI_PAFC & GI_PAFC & Actor Type (person, organization, device, system, or subsystem) Device System Device Actor Description PAFC and that serve as reference source of voltage and frequency of islanding grid. for GI_PAFC &. Generates dispatch of GI_PAFC &. PAFC and that serves as the supply source of reactive power for isolated grid, aside from GI_PAFC &. Local Level Use Case _A2 Aichi Microgrid -islanding mode- rev4.doc 5 11/7/20

6 Grouping (Community) Group Description Actor Name Actor Type (person, organization, device, system, or subsystem) System Actor Description for &. Generates dispatch of &. SENSOR Device Sensor that measures net output of PAFC. & Device System Battery and. of &. Generates power dispatch for &. 1.6 exchanged Object Name Voltage & frequency fluctuation Active power dispatch Reactive power dispatch PAFC net output PAFC sending-end voltage Power dispatch Object Description Fluctuation value of voltage & frequency in an islanding grid. Active power dispatch value for GI_PAFC & generated by GI_PAFC. Reactive power dispatch value for GI_PAFC & generated by GI_PAFC. Net output of GI_PAFC & and &. Sending-end voltage of GI_PAFC & and &. Power dispatch value for battery generated by. Local Level Use Case _A2 Aichi Microgrid -islanding mode- rev4.doc 6 11/7/20

7 Object Name Reactive power dispatch Object Description Reactive power dispatch value for & generated by. 1.7 Activities/Services Activity/Service Name Activities/Services Provided N/A 1.8 Contracts/Regulations Contract/Regulation Impact of Contract/Regulation on Function N/A Policy From Actor May Shall Not Shall Description (verb) To Actor N/A Constraint Type Description Applies to N/A Local Level Use Case _A2 Aichi Microgrid -islanding mode- rev4.doc 7 11/7/20

8 2 Step by Step Analysis of Function 2.1 Steps to implement function Autonomous decentralized control of microgrid under the islanding operation Preconditions and Assumptions Actor/System//Contract Drooping characteristic of GI_PAFC & Generators in islanding grid Reference voltage at PAFC terminal Preconditions or Assumptions Slope characteristic of active power and frequency and that of reactive power and AC voltage are preset. Generators have already started-up by black start operation. Reference voltage at PAFC terminal is preset. (440V for NEDO demonstration project.) Steps # Event Primary Actor Name of Description of Producer Receiver Name of Info Exchanged Additional Notes IECSA Environment Step 1: Implementation of power drooping characteristic in multiple inverters 1.1 On-going monitoring by GI_PAFC GI_PAFC Detection of voltage & frequency fluctuation GI_PAFC detects local frequency and voltage fluctuations associated with load fluctuation. GI_PAFC & GI_PAFC Voltage & frequency fluctuation Local Level Use Case _A2 Aichi Microgrid -islanding mode- rev4.doc 8 11/7/20

9 # Event Primary Actor Name of Description of Producer Receiver Name of Info Exchanged Additional Notes IECSA Environment 1.2 GI_PAFC Dispatch GI_PAFC provides active and reactive power dispatch based on the slope characteristic. GI_PAFC Step 2: Power compensation control to eliminate steady-state deviation of voltage and frequency 2.1 On-going monitoring by Acquisition of PAFC net output acquires PAFC net output. SENSOR 2.2 Step 3: AC voltage control (AVR operation) 3.1 On-going monitoring by Power dispatch Acquisition of PAFC sending-end voltage provides power dispatch for & so that the PAFC net output is maintained at the reference output. acquires PAFC sending-end (local) voltage. & GI_PAFC & & Active and reactive power dispatch PAFC net output Power dispatch PAFC sendingend voltage Local Level Use Case _A2 Aichi Microgrid -islanding mode- rev4.doc 9 11/7/20

10 # Event Primary Actor Name of Description of Producer Receiver Name of Info Exchanged Additional Notes IECSA Environment 3.2 Reactive power dispatch provides reactive power dispatch for & so that the PAFC sending-end voltage is maintained at the reference voltage. & Reactive power dispatch Post-conditions and Significant Results Actor/Activity Islanding grid Post-conditions Description and Results Stabilizes voltage & frequency of islanding grid. 2.2 Architectural Issues in Interactions FUTURE USE 2.3 Diagram FUTURE USE Local Level Use Case _A2 Aichi Microgrid -islanding mode- rev4.doc 10 11/7/20

11 3 Auxiliary Issues 3.1 References and contacts ID Title or contact Reference or contact information [1] A Verification Test Result of Islanding Operation of a Microgrid Configured with New Energy Generators and a Study of Improvement of Voltage Control Electrical Engineering in Japan, Vol. 176, No. 2, 2011 Translated from Denki Gakkai Ronbunshi, Vol. 129-B, No. 1, January 2009, pp (in Japanese) 3.2 Action Item List ID Description Status N/A 3.3 Revision History No Date Author Description H. Iwasaki H. Maejima Draft for Review H. Iwasaki Draft for Review Oct H. Iwasaki H. Maejima 3.0 Nov T. Shimakage J. Sumita K. Nishioka H. Iwasaki H. Maejima J. Reilly Draft for review 3 Final Version Local Level Use Case _A2 Aichi Microgrid -islanding mode- rev4.doc 11 11/7/20