• 전기학회논문지
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• 제59권12호
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• pp.2165-2172
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• 2010

This paper presents the operation algorithm of microgrid on the Real Time Pricing(RTP) for building the smart grid. RTP is higher power price variability than flat rate and time of use. However it has an effect on peak clipping and peak load shifting due to the increased price on peak time power demand. When the RTP are applied to the microgrid system, the proposed algorithm is able to be effective and economic operation. The implemented system is operated for the economic operation in microgrid connected with the power system. On the other hand, when the microgrid is operated on isolation mode, it focus on the improvement of stability and the power supply reliability of the sensitive loads. The test system are implemented and calculated on various operation modes based on non-dispachable generator output and RTP data for validating the proposed operation algorithm. The calculated results are compared to the implemented results using real-time simulator. It can be confirmed that the proposed operation system are identical results to the calculated one. When the proposed operation algorithm is applied to the system, it can be show the effectiveness of the peak clipping and peak load shifting and the improvement of economic feasibility.

• 전기학회논문지
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• 제60권8호
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• pp.1467-1472
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• 2011

This paper presents an optimal operation of microgrid systems and considering a tie-lines capacities that concerned each grid. The microgrid system consists of a wind turbine, a diesel generator, and a fuel cell. An one day load profile and wind resource for wind turbine generator were used for the study. For the grid interconnection, tie-line capacities were applied as constraints. The capacity constraints of tie-lines in production cost analysis are very important issues in the operation and planning of microgrid. In optimization, the Harmony Search (HS) algorithm is used for solving the problem of microgrid system operation which a various generation resources are available to meet the customer load demand with minimum operating cost. The application of HS algorithm to optimal operation of microgrid proves its effectiveness to determine optimally the generating resources without any differences of load mismatch.

• Journal of Electrical Engineering and Technology
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• 제10권2호
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• pp.452-464
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• 2015

This paper proposes a DC microgrid operational strategy and control method for improved service reliability. The objective is to supply power to as many non-critical loads as possible, while providing an uninterrupted power supply to critical loads. The DC bus signaling method, in which DC voltage is an information carrier, is employed to implement the operational strategy in a decentralized manner. During grid-connected operation, a grid-tied converter balances the power of the microgrid by controlling the DC voltage. All loads are connected to the microgrid, and operate normally. During islanded operation, distributed generators (DGs), a backup generator, or an energy storage system balances the power. However, some non-critical loads may be disconnected from the microgrid to ensure the uninterrupted power supply to critical loads. For enhanced service reliability, disconnected loads can be automatically reconnected if certain conditions are satisfied. Control rules are proposed for all devices, and detailed microgrid operational modes and transition conditions are then discussed. Additionally, methods to determine control parameter settings are proposed. PSCAD/EMTDC simulation results demonstrate the performance and effectiveness of the proposed operational strategy and control method.

• 전기학회논문지P
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• 제66권4호
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• pp.169-176
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• 2017

This paper presents research on low-voltage microgrids to maintain a continuous power supply to critical loads on grid-connected islands in Korea. The low-voltage microgrids of this paper focused on that changes public office buildings into uninterrupted microgrids by autonomous operation. For this, a microgrid controller (MGC) and a power conditioning system (PCS) that allow a seamless transfer between grid-connected and grid-isolated operation are proposed. The proposed PCS operates with a silicon controlled rectifier (SCR) switch and employs a simple structure. It supplies power continuously without operators through a coordinated operation between MGC and PCS. In addition, proposed MG has a schedule operation for minimizing electricity charges and provides ancillary services that enable the utilization of resources according to the operation purpose of utility distribution networks. To demonstrate the uninterrupted low-voltage microgrid proposed in this study, a microgrid was implemented and tested in a public office building in Anjwa Island, Jeollanam-do in Korea. A seamless, autonomous operation history, despite system disturbances, was obtained through a long-term demonstration of operation. The results showed that the proposed microgrid technology can be used to achieve energy resilience in grid-connected island areas.

• 전기학회논문지
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• 제60권12호
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• pp.2190-2195
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• 2011

Due to enhanced demands on quality, security and reliability of the electric power energy system, a microgrid has become a subject of special interest. In this paper, output characteristics of energy storage system (ESS) with an electric double layer capacitor (EDLC) and battery energy storage system (BESS) of a renewable energy based microgrid were analyzed under grid-connected and islanded operation modes. The microgrid which consists of photovoltaic and wind power turbine generators, diesel generator, ESS with an EDLC, BESS and loads was modeled using real time digital simulator. The results present the effective control patterns of the microgrid system.

• KEPCO Journal on Electric Power and Energy
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• 제2권2호
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• pp.269-272
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• 2016

Distribution management system or microgrid energy management system plays an important role in monitoring, operation and control of electrical distribution systems by utilizing IT infrastructure. Nowadays, the rapid increase of the distributed resources makes the conventional management system have some additional functionality for the reliable operation due to intermittent renewables and the efficient operation on the economical purpose. In this paper, the brief standard software functional requirements of microgrid energy management system are provided through survey of the recent commercial products of the major vendors, and furthermore the architectures of microgrid energy management system are provided in comparison with major suppliers' microgrid energy management system. The summary of investigation will be able to make the developers and researchers focus on the specific functionality in the real world.

• 전기학회논문지
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• 제61권10호
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• pp.1548-1553
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• 2012

The important requirement for microgrid operation is to meet the balance between supply and demand. To meet, Combined Heat and Power (CHP) generation should be considered in microgrid scheduling. CHP generation is economical on the side of a consumer because it products heat and power. Therefore, it is high efficient. This paper presents a mathematical model for optimal microgrid operation including CHP generation using the optimal ratio of heat and power due to demand. The objective function and constraints are modeled by linear program (LP). Through the case study, the validation of the proposed model is shown.

• 전기학회논문지
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• 제63권1호
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• pp.18-26
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• 2014

A microgrid can play a significant role for enlargement of renewable energy sources and emission reduction because it is a network of small, distributed electrical power generators operated as a collective unit. In this paper, an application of optimization method to economical operation of a microgrid is studied. The microgrid to be studied here is composed of distributed generation system(DGS), battery systems and loads. The distributed generation systems include combined heat and power(CHP) and small generators such as diesel generators and the renewable energy generators such as photovoltaic(PV) systems, wind power systems. Both of thermal loads and electrical loads are included here as loads. Also the emissions trading scheme to be applied in near future, the cost of unit start-up and the operational characteristics of battery systems are considered as well as the probabilistic characteristics of the renewable energy generation and load. A mathematical equation for optimal operation of this system is modeled based on the mixed integer programming. It is shown that this optimization methodology can be effectively used for economical operation of a microgrid by the case studies.

• 전기학회논문지
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• 제60권1호
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• pp.1-7
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• 2011

Active power control scheme for distributed generation in microgrid consists of feeder flow control and unit power control. Feeder flow control is more useful than the unit power control for demand-side management, because microgrid can be treated as a dispatchable load at the point of common coupling(PCC). This paper presents detailed descriptions of the feeder flow control scheme for the hybrid system in microgrid. It is divided into three parts, namely, the setting of feeder flow reference range for stable hybrid system operation, feeder flow control algorithm depending on load change in microgrid and hysteresis control. Simulation results using the PSCAD/EMTDC are presented to validate the inverter control method for a feeder flow control mode. As a result, the feeder flow control algorithm for the hybrid system in microgrid is efficient for supplying continuously active power to customers without interruption.

• International Journal of Computer Science & Network Security
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• 제22권3호
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• pp.355-363
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• 2022

This paper presents the modeling for islanded hybrid AC/DC microgrid and the verification of the proposed supervisory controller for energy management for this microgrid. The supervisory controller allows the microgrid system to operate in different power flows through the proposed control algorithm, it has several roles in the management of the energy flow between the different components of the microgrid for reliable operation. The proposed microgrid has both essential objectives such as the maximum use of renewable energies resources and the reduction of multiple conversion processes in an individual AC or DC microgrids. The microgrid system considered for this study has a solar photovoltaic (PV), a wind turbine (WT), a battery (BT), and a AC/DC loads. A small islanded hybrid AC/DC microgrid has been modeled and simulated using the MATLAB-Simulink. The simulation results show that the system can maintain stable operation under the proposed supervisory controller when the microgrid is switched from one operating mode of energy flow to another.