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Environmental Technology R&D Achievements

Smart Grid Demonstration Project

Mitsubishi Electric Has Set Up Experimental Equipment to Conduct Test Trials of Smart Grid Technologies, and Has Begun Partial Verification Testing

A smart grid is a form of electricity transmission and distribution network that, in utilizing information technology to address fluctuations in both supply and demand, helps realize the stable flow of electricity. Changes in supply reflect the increased use of such natural sources of energy as wind and solar power, while changes in the demand for electricity in this instance refer to the ongoing market acceptance of electric vehicles (EVs) as well as the trend toward all-electric-powered housing. (Source: The Conference on Next-Generation Energy and Social Systems; The Ministry of Economy, Trade and Industry of Japan).

Renewable energies such as solar and wind power are viewed with promise in the quest to create a low-carbon society. These forms of electric power generation, on the other hand, are subject to the elements. The volume of power generated fluctuates according to changes in the weather and other conditions. Accordingly, these methods pose considerable difficulties in controlling output. The development of exhaustive element technologies that optimally balance electric power generation, distribution and consumption is considered critical to addressing this issue through the practical application of smart grids.

Mitsubishi Electric has implemented a smart grid experiment at three of its sites in Japan: Amagasaki, Ofuna and Wakayama. The objective of this experiment is to operate a real system, in the field, to log data and to validate fundamental technologies. Partial system operations began in fiscal 2011.


Fiscal 2011 Research and Development Results

Mitsubishi Electric boasts technologies in each of the three core fields of electricity generation, distribution and consumption. Harnessing this collective strength, the Company is engaging in a variety of smart grid technology development activities aimed at realizing stable electricity supply. The following is a selection of Mitsubishi Electric's key development achievements in fiscal year 2011.

1. Generating Electricity: Optimizing Supply-Demand Balance

Electric power companies are obligated to maintain constant frequency levels and the instantaneous balance between demand and supply by adjusting output through the use of thermoelectric and pumped storage generation. With the expected increase in photovoltaic power generation the supply power may fluctuate considerably due to changes in the weather. Imbalance between demand and supply cause fluctuation in the system frequency, that may, in turn, affect negatively user appliances and, in a worst case, lead to a power outage.

In order to resolve this issue, Mitsubishi Electric developed optimal demand/supply control technologies able to control not only conventional generators but also batteries and other storage devices. By implementing and operating Mitsubishi Electric's planning and control system, electric power companies can ensure stable operation of the power system and high quality power to customers.


2. Distributing Electricity: Monitoring and Controlling Voltage Levels

In a conventional power system, electricity is distributed from the power plants through the transmission and distribution networks to final consumers. Transmission and distribution networks are designed to deliver the electricity at the consumer side at a predefined voltage level (in Japan, residential load is supplied at 101V+/- 6V). Photovoltaic power generation is in general connected at the distribution level of the power system. For this reason, it is possible for the power produced by the PV to cause a 'counter' power flow from the consumer side to be delivered to other consumers through the distribution network. This phenomenon may present two challenges: an increase of the voltage in areas with high PV production; and voltage fluctuation throughout the system due to the intermittency characteristics of the PV production.

Taking these issues into consideration, Mitsubishi Electric developed a voltage control system that incorporates optimal power flow computation software. This system has been designed to rapidly analyze power flow to forecast the voltage profile on the distribution network, and, in in some cases, control voltage regulation equipment to ensure the appropriate voltage. The optimal control signal is developed through optimal power flow calculation.


3. Consuming Electricity: Developing Advanced Metering Infrastructure with Wireless Mesh Network Technology

Electric companies are accelerating efforts to develop an advanced meter infrastructure (AMI) to improve customer services and reduce meter reading costs. An essential element in this AMI is the smart meter. A smart meter is a device that not only measures the electricity consumption but is also able to communicate with a center. Developing the communication network between the meter and the center present several challenges, including costs and reliability. Mitsubishi Electric has developed AMI technologies and systems that ensure reliability and flexibility in measuring and controlling electricity meters through next generation wireless mesh networks.

Wireless mesh networks provide a transmission method that links electric meters to relay data by each meter through other meters, using a multi-hop network scheme. This network has helped reduce the time required to acquire data while at the same time curtailing costs.

While wireless mesh networks present cost benefits, some challenges have to be overcome to ensure practical application. Simultaneous transfer of data between meters at the same frequency can cause signal collision, preventing reliable data collection. Mitsubishi Electric has developed a technology that controls the timing of transmission to reduce the probability of signal collision.

Mitsubishi Electric's AMI system enables stable operation and real time reading of the power consumption of 500 next-generation electronic meters at 30 minute intervals for residential and industrial smart meters.

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Commenced Smart Grid Demonstration Experiments at Ofuna Smart House from May 2011

Mitsubishi Electric constructed a demonstration facility, Ofuna Smart House, located in Ofuna City, Kanagawa Prefecture. The Company launched demonstration experiments of its smart grid compatible Home Energy Management System (HEMS) from May 2011. In response to a growing awareness of energy efficiency, these experiments help realize energy savings and shifts in peak loads while at the same time demonstrating the support that these systems provide in enhancing resident safety and security. Furthermore, experiments at this facility are connected to backbone and power distribution system demonstrations at facilities in Amagasaki and Wakayama. Steps will be taken to verify the practical reality of zero emission homes as a part of efforts to create a low-carbon society.