Low-Voltage Bipolar-Type DC Microgrid for Super High Quality Distribution

Microgrid is one of the new conceptual power systems for smooth installation of many distributed generations (DGs). While most of the microgrids adopt ac distribution as well as conventional power systems, dc microgrids are proposed and researched for the good connection with dc output type sources such as photovoltaic (PV) system, fuel cell, and secondary battery. Moreover, if loads in the system are supplied with dc power, the conversion losses from sources to loads are reduced compared with ac microgrid. As one of the dc microgrids, we propose “low-voltage bipolar-type dc microgrid,” which can supply super high quality power with three-wire dc distribution line. In this paper, one system for a residential complex is presented as an instance of the dc microgrid. In this system, each house has a cogeneration system (CGS) such as gas engine and fuel cell. The output electric power is shared among the houses, and the total power can be controlled by changing the running number of CGSs. Super capacitors are chosen as main energy storage. To confirm the fundamental characteristics and system operations, we experimented with a laboratory scale system. The results showed that the proposed system could supply high-quality power under several conditions.

[1]  T.C. Green,et al.  Energy Management in Autonomous Microgrid Using Stability-Constrained Droop Control of Inverters , 2008, IEEE Transactions on Power Electronics.

[2]  Juan C. Vasquez,et al.  Adaptive Droop Control Applied to Voltage-Source Inverters Operating in Grid-Connected and Islanded Modes , 2009, IEEE Transactions on Industrial Electronics.

[3]  H. Nikkhajoei,et al.  Distributed Generation Interface to the CERTS Microgrid , 2009, IEEE Transactions on Power Delivery.

[4]  Hiroaki Kakigano,et al.  DC Micro-grid for Super High Quality Distribution — System Configuration and Control of Distributed Generations and Energy Storage Devices — , 2006 .

[5]  Timothy C. Green,et al.  Real-World MicroGrids-An Overview , 2007, 2007 IEEE International Conference on System of Systems Engineering.

[6]  J.M. Guerrero,et al.  Hierarchical control of droop-controlled DC and AC microgrids — a general approach towards standardization , 2009, 2009 35th Annual Conference of IEEE Industrial Electronics.

[7]  Philip T. Krein,et al.  Preventing instability in DC distribution systems by using power buffering , 2001, 2001 IEEE 32nd Annual Power Electronics Specialists Conference (IEEE Cat. No.01CH37230).

[8]  K. Hirose,et al.  Effect of breaking high voltage direct current (HVDC) circuit on demonstrative project on power supply systems by service level in Sendai , 2007, INTELEC 07 - 29th International Telecommunications Energy Conference.

[9]  K. Hirose,et al.  Study of AC/DC power supply system with DGs using parallel processing method , 2010, The 2010 International Power Electronics Conference - ECCE ASIA -.

[10]  Nikos D. Hatziargyriou,et al.  microgrids [guest editorial] , 2008 .

[11]  Y. Hayashi,et al.  Power and Heat Interchange System using Fuel Cells in Collective Housing , 2007, 2007 Power Conversion Conference - Nagoya.

[12]  H. Akagi,et al.  DC microgrid based distribution power generation system , 2004, The 4th International Power Electronics and Motion Control Conference, 2004. IPEMC 2004..

[13]  H. Kakigano,et al.  DC Voltage Control of the DC Micro-grid for Super High Quality Distribution , 2007, 2007 Power Conversion Conference - Nagoya.

[14]  Yun Wei Li,et al.  An Accurate Power Control Strategy for Power-Electronics-Interfaced Distributed Generation Units Operating in a Low-Voltage Multibus Microgrid , 2009, IEEE Transactions on Power Electronics.

[15]  S. Morozumi,et al.  Micro-grid Demonstration Projects in Japan , 2007, 2007 Power Conversion Conference - Nagoya.

[16]  Fred C. Lee,et al.  A method of defining the load impedance specification for a stable distributed power system , 1993 .

[17]  A. Sannino,et al.  An Adaptive Control System for a DC Microgrid for Data Centers , 2007, IEEE Transactions on Industry Applications.

[18]  Toshifumi Ise,et al.  DC loop type quality control center for FRIENDS-system configuration and circuits of power factor correctors , 2002, IEEE/PES Transmission and Distribution Conference and Exhibition.

[19]  E.F. El-Saadany,et al.  Adaptive Decentralized Droop Controller to Preserve Power Sharing Stability of Paralleled Inverters in Distributed Generation Microgrids , 2008, IEEE Transactions on Power Electronics.

[20]  H. Kakigano,et al.  Fundamental characteristics of DC microgrid for residential houses with cogeneration system in each house , 2008, 2008 IEEE Power and Energy Society General Meeting - Conversion and Delivery of Electrical Energy in the 21st Century.

[21]  Fred C. Lee,et al.  Impedance specifications for stable DC distributed power systems , 2002 .

[22]  H. Kakigano,et al.  Loss evaluation of DC distribution for residential houses compared with AC system , 2010, The 2010 International Power Electronics Conference - ECCE ASIA -.