Stable Supply

TEPCO undertakes power system reforms

The Tokyo Electric Power Company (TEPCO) is a leading power utility in Japan, serving one-third of the country’s total electricity demand. The company has a strong financial position and has played a significant role in shaping the electricity market in Japan, creating a robust infrastructure. However, frequent natural disasters in the country and nuclear power generation risks have adversely affected TEPCO’s electricity supply.

To address these challenges, the company has implemented measures aimed at securing stability on both the electricity supply and demand sides, and decided to change its organisational structure. One of the key initiatives has been the adoption of smart grid measures to strengthen the network infrastructure, improve operational efficiency and minimise costs.

The company has adopted several smart grid initiatives such as the upgradation of the distribution network with sensors and modern communication technologies, wind power generation enhancement through wide area coordination, and deployment of battery supervisory control and data acquisition (SCADA) and communication systems. It has implemented a power system reform roadmap, laying out a comprehensive plan for smart meter roll-out. The implementation of these measures has led to a strong operational performance by the company. As per the latest data available, the system average interruption frequency index was 0.07 and the system average interruption duration index was four minutes in 2013-14. The company’s transmission and distribution (T&D) system losses have largely remained below 5 per cent owing to its smart initiatives. In anticipation of full liberalisation of the electric power industry in Japan, the company has decided to adopt a holding company structure, with effect from April 2016, with three operating subsidiaries – TEPCO Fuel and Power incorporated for the fuel and thermal power generation business, TEPCO Power Grid for the T&D business and TEPCO Energy Partner for the retail electricity business.

Power system reform roadmap

In 2013, TEPCO formulated a roadmap for power system reforms to transform Japan’s power network. This roadmap has been divided into three phases. Phase I focused on the implementation of wide area grid operation,  scheduled to be completed by 2015. Phase II was aimed at achieving complete retail liberalisation and is expected to be completed in 2016. Phase III, which is expected to be completed by 2020, is aimed at legal unbundling of the T&D segment.

Under Phase I, TEPCO undertook detailed planning for the implementation of wide-area grid operation with a focus on wide-area power supply and demand balancing, planning interconnecting and trunk transmission lines, and setting up emergency control for demand-supply balancing. Phase II aims to achieve complete retail liberalisation through the abolition of tariff regulations. Meanwhile, Phase III aims to set new rules to promote grid stabilisation in a neutral manner and build a capacity market and bidding system for power plants in order to create a competitive market.

Reform initiatives

TEPCO has adopted several reform initiatives in its power generation, T&D, and retail business. In the generation businesses, the company has formed an alliance with Chubu Electric Power Company to expand its fuel procurement and power generation business. In the T&D business, it has taken several steps to reduce energy wheeling costs, ensure stable electric supply, and launch smart meters services on a large scale.

In order to enhance productivity, it has refurbished ageing facilities and implemented initiatives such as reducing prices and stepping up power procurement through competitive bidding.

Smart grid initiatives

TEPCO has undertaken several smart grid initiatives to upgrade its power system infrastructure such as upgradation of the distribution system network, wind power generation enhancement through an increase in east-west interconnection capacity, and the development of integrated battery systems and advanced communication systems.

Upgradation of distribution network: TEPCO has taken a number of steps to optimise distribution network operations, which include a monitoring and control system with built-in sensor switches. These will help secure the power quality using measurement data, ensure quick fault detection and prompt restoration to prevent faults, and improve efficiency using remote control methods. The adoption of strategies such as conducting a prompt system impact study for interconnection, remote setting for control devices, fault point detection monitoring and switching based on phase angle measurement are a part of the smart initiatives taken by TEPCO to modernise the distribution system.

Wind power generation enhancement: Another smart grid initiative is the expansion of wind power generation capacity with wide area coordination. TEPCO receives power from wind farms in Hokkaido and Tohoku. To regulate this power, the company has installed remote control systems, which also help reduce fluctuations. TEPCO is connected to the east-west interconnection, which has a capacity of 1,200 MW. To increase this interconnection capacity, TEPCO will install an additional 900 MW high voltage direct current link by 2020.

Battery SCADA system: A key initiative adopted by TEPCO is the deployment of battery SCADA systems for integrated control of battery storage systems. The battery SCADA system enables the system operator to control multiple dispersed batteries as a large virtual battery. The main functions of a battery SCADA system are controlling load frequency, balancing daily demand-supply and maintaining spinning reserves. The central load despatch centre is connected to the power plants and the battery SCADA system, which controls multiple battery systems at the distribution end through a well-developed information collection and distribution system. In order to minimise costs, TEPCO has conducted island field tests wherein smart technology is deployed to control both power plants and energy storage facilities.

Communication system configuration: TEPCO has deployed an advanced communication system configuration, which is a combination of wireless mesh, power line communication (PLC) and a cellular network. In this system, the consumer data is collected through a home energy management system (HEMS), which is connected to the wireless mesh network and the cellular network. These networks transmit the data to a base station, which is connected to the retailer through an optic fibre network. This system has several advantages such as low costs and better power availability. The wireless mesh network comprising meters helps minimise costs and is suitable for high-density areas. The PLC network is suitable for complex buildings where radio signals are likely to be blocked. Cellular services are suitable for low-density areas. A highly reliable optic fibre network will also be employed in the trunk line of the smart grid in the coming years. The company will deploy a combination of various telecommunication technologies for the last mile to improve investment efficiency.

Smart meters

The company has undertaken large-scale smart meter installation in its distribution area. Under this, it has connected the battery systems of households to HEMS, which transmits electricity usage information to retailers through smart meters. In addition, the company had already installed smart meters at the 20 kV voltage level for 3,000 consumers and the 6 kV voltage level for a consumption load of more than 500 kW for 12,000 consumers by 2014. Around 230,000 smart meters at the 6 kV voltage level for a consumption load of less than 500 kW will be installed by end-2016. Meanwhile, around 27 million smart meters at the below 6 kV voltage level are planned to be installed by 2020.  Another important application of smart meters is improved demand response. The smart meters will help analyse the power demand pattern and introduce dynamic pricing for residential consumers. The company will undertake critical peak pricing and provide rebates to consumers who reduce consumption during peak hours.

The way forward

TEPCO has secured stable power supply utilising its large-capacity and robust power transmission network. The smart grid platform will play an important role in achieving energy efficiency and optimisation. The company will take further steps to leverage this platform through smart meters, and new services and business models based on the liberalised market. It will also make significant investments in research and development, and new technologies.

With inputs from a presentation by Takashi Ohara, Deputy Manager, Power System Engineering Center, TEPCO

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