Large-capacity battery energy storage in wind power (1)

1 Introduction
    The power system is a dynamic equilibrium system, power transmission and distribution of electricity must always maintain a balance. Wind energy is an intermittent energy, and wind speed forecasts there is a certain error, wind farms can not provide a steady power, power stability and continuity is poor. In traditional power system, any small perturbation caused by dynamic imbalance in power will result in oscillation unit, large-capacity energy storage systems and wind turbine combination, can effectively suppress or mitigate the volatility of wind power to reduce the wind power the grid. As long as the energy storage capacity is large enough and fast enough response speed, you can achieve complete balance of power in any case, this is an active stability caused by the idea of ​​the power system [1]. The stability control device and energy storage technologies do not have to work together and the generator excitation system, therefore, can be easily used in the system for the suppression of the oscillation is the most effective parts. Control the amount of such a stability control device can act directly on the source of the cause system oscillation accurate compensation of the imbalance in power, can be less or even without considering the system running status change on the control device to control the effect of The device parameters tuning is very easy for the robustness of the system running status change is also very good.
    2 battery energy storage technology development in the world
    In recent years, developed countries such as Japan, the United States and the European battery energy storage technology into a larger, leading technology. Japan to lead the world in research and application of the sodium sulfur battery, Japan insulators (NGK INSULATORS) 300 MW NAS battery systems and central monitoring system order from the Abu Dhabi Electricity and Water Authority. Panasonic and Matsushita Electric Works, and the Danish power companies the SEAS-NVE 'jointly launched in 2009 aimed at smart grid demonstration experiments. Toshiba announced in 2010, received orders for Okinawa Electric Power in the autumn of 2010 in the Miyakojima Islands microgrid empirical test "equipment, will build a new generation of apple laptop battery balance of power changes taking renewable energy load power system . Sanyo Electric is also Western Canada Green Energy Park "into the 1.5 MW; h lithium-ion battery, the other manufacturers are also actively involved in battery energy storage projects. Aspects of Europe and the United States, 2001, Canada, VRB Power Systems Inc. in South Africa built a 250 kW vanadium flow battery energy storage demonstration system to achieve the commercial operation of the vanadium redox flow battery energy storage. VRB Power Systems Inc. of Australia Hydro Tasmania on KingIsland company to build wind power supporting all vanadium flow storage hp laptop batteries was completed in November 2003, the system storage capacity of 800 kW ·; h, the output power of 250 kW. In February 2004, VRB Power Systems, Inc. has built a castle Valley, Utah Pacific Corp output power of 250 kW, the energy storage capacity of 2 MW; h vanadium redox flow battery energy storage system. The end of 2006 the company began the international so far for the Irish construction of the maximum rated output power of 2 MW (pulse output power of 3 MW), energy storage capacity of 12 MW; h vanadium redox flow acer laptop battery energy storage system. U.S. Japan's Sumitomo Electric Industries and VRB Power Systems Inc. technology, namely the establishment of demonstration runs of 2 MW and 6 MW of all vanadium flow storage batteries.
    Innogy, the UK in August 2000 to build the first commercial-scale energy storage peaking demonstration power plant with a 680 MW gas turbine power generation field supporting the energy storage system storage capacity of 120 MW; h, to meet 10 000 families a day of electricity demand.
    German the EVONIK industrial shares announced joint Daimler Motor Company R & D institutions to jointly develop a large capacity for wind and solar power, low-cost lithium-ion laptop battery stored power plant, the initial plan to build a power in Saarland, western Germany for 1 MW of energy storage devices. In large-scale battery energy storage technologies, we started late, with the developed countries there is a large gap: First, the equipment capacity is still small; short life of the equipment, inefficient use of; is the weak level of intelligent devices. China from the foreign advanced level gap in the energy storage applications is also a great abroad have been dozens of sets of energy storage power station put into operation, there are no large-capacity battery energy storage demonstration projects put into operation.
    At present, the application of the scale of China's replacement battery energy storage is very small, but with the gradual implementation of the adjustment of the national energy policy and energy conservation and environmental protection policy, the scale of its application is also expected to gradually expand. The Shanghai Municipal Electric Power Company has been building, including the the Caoxi station, avant-garde station, the silver station three energy storage demonstration power plant, electricity dispatch center directly through the power grid energy storage management system implemented on the storage station distribution around the unified control and remote monitoring. BYD in Shenzhen Longgang, a 1 MW (4 MW; h), energy storage power station.
    The national grid belongs to a new source Holdings Ltd of Zhangjiakou City Zhangbei development and construction of the nation's first scenery storage demonstration projects, the total size of the project for wind power of 500 MW, photoelectric 100 MW, 70 MW of energy storage. The Zhangbei optical storage project is the world's largest demonstration project of scenery storage Trinity, but have not yet entered into operation, has completed a project design, a construction work is in progress.
    The rapid development of wind power energy storage technologies
    Wind energy as a clean, renewable energy, more and more world attention. China's wind energy reserves are large, wide distribution, the only land-based wind energy reserves, about 253 million kW. In recent years, grid-connected wind power in China's rapid development. As of the end of 2007, total installed capacity of about 600 million kW. In December 2008, China's total installed capacity of wind power has more than 1000 million kW, ranking fifth in the world, as of mid-March 2011, China's total wind power installed capacity of 4450 million kW, wind power the construction of the largest global the first place. This also means that China has entered the renewable energy superpower ranks. Very broad prospects for the development of Chinese wind energy generation industry, is expected for a long time in the future will maintain rapid development, and profitability will increase steadily as the technology mature.
    To build the world's highest in China's wind power, wind power has always restricts the healthy development of China's wind power. Data show that China's wind power capacity is cumulative and net 3107 million kW, still refrain wind power grid This is due to the characteristics of wind power random and intermittent, resulting in frequent fluctuations of the output of the wind turbine, which wind power the output reliability is poor, the proportion of wind power is too large, make the grid frequency modulation, peaking increasing pressure, as well as the grid long-distance transmission of technical requirements and operating costs increase sharply. Therefore, large-scale wind farms and network access operation of the power system has also brought some new problems:
    1) the randomness of the wind power and uncontrollability to power system planning and stable operation has brought new challenges;
    2) the wave characteristics of the wind power and the volatility characteristics of the grid load is difficult to more prominent peak load regulation and a higher demand for peaking capacity and speed of response;
    3) Due to the change of wind speed, the wind turbine is easy to cause the grid voltage and power fluctuation, as well as by reactive power and voltage control and power quality problems.
    Wind power has the conflict between the intermittent and volatility of the power system needs real-time balance, the grid-connected wind power fluctuations need to balance through the regulation of conventional power and energy storage system, as long plagued the main problems of wind power. Impoundment storage power station due to geographical limitations, does not have universal availability, therefore, the introduction of large-capacity camera battery energy storage device can be universally applied to compensate for fluctuations in wind power to the grid to bring all kinds of wind farm The effect is an appropriate choice of technology [8]. Through the coordination of energy storage systems and wind power systems, not only effectively reduce the impact and influence of the wind power system, improve the consistency of the wind power output forecast, protect the credibility of the power of electricity supply, but also to reduce the reserve capacity of the power system and improve the economy of power system operation, while improving the power system the ability to accept wind power.
    4 requirements for wind power at home and abroad
    More and more large and medium-sized wind farms have been built and put into operation, Wind Power gradually increasing proportion of wind farm power fluctuations will affect the local grid power quality, voltage fluctuation and flicker. Will have a significant impact on the local grid, in severe cases can lead to serious accidents [9,10]. The wind farm grid technical requirements of the wind farm active power change requirements, such as:
    1) Eltra and Eltra & Elkraft requirements and wind farms l min, the output power change is less than 5% of the maximum power equal to the wind farm. The wind farm control system to ensure that within 2 s down to less than 20% of the rated power Eltra & Elkraf, requires per minute rate of power change of the wind farm within 10% to 100% adjustable;
    2) E.ON and ESBNG requires wind farm output power at any time less than its registered capacity. E.ON per minute power requirements reduce at least 10% of the rated capacity, ESBNG requirements related to the 15 min power variation of the wind farm the size per minute power change is less than 100 MW wind farm is less than 5%, less than 200 MW wind farm power changes of less than 4% of the rated capacity per minute, less than 2% of the rated capacity greater than 200 MW wind farm power change per minute;
    3) Scottish grid technology requirements can exceed the rated power wind farm output power within a reasonable period of time;
    4) China State Grid Corporation of the provisions of the Wind Farm 1 min and 10 min, the rate of power change, the rate of change of the installed capacity of wind farms, such as less than 30 MW wind farm 10 min, the maximum variation is 20 MW, 1 min, the biggest change is 6 MW;
    5) the requirements of Scottish wind farm starts and stops to meet the requirements of the voltage quality of Scottish also asked to stop to meet the changing requirements of the maximum power from wind farms, and not more than 25% of the rated capacity can jump, and points within 30 min The stage gradually exit.
    Five large-capacity camcorder battery energy storage technologies for wind power steady
    Apparently active power of the most important means of regulation is energy storage, high-power, high-capacity storage system to stabilize the wind power fluctuations and intermittent. Energy storage capacity of the system reaches a certain size, the energy storage system and wind turbine combination, can effectively inhibit or mitigate the volatility of wind power, to reduce the impact of wind power on the grid [11,12]. Large-capacity battery energy storage technologies in wind power to achieve the following functions:
    1) smooth unit output: the combination of the battery charger energy storage system with wind turbine wind farm output, smooth perturbations of the fast wind speed, reducing the impact of wind farm output fluctuations on the grid, reducing the impact of wind power fluctuations on the grid.
    2) improve the consistency of the wind power output forecasts: Energy Storage as a tie to adjust the output prediction based on the wind farm output curve to optimize the output, improve the credibility of the wind power output.
    3) improve the ability of scheduling: energy storage system, you can control the active and reactive power of the wind power output for power peaking, wind power units to run as a scheduling unit cell, with the power system frequency control, fast the ability of the power response and other ancillary services.
    4) the peak transfer: high-power high-capacity energy storage system to the instability of wind power can be collected at the appropriate time to smooth the release, transfer peak, reducing the impact on the grid;
    5) ensure that the wind power generation system is a continuous and reliable power supply: when the environmental factors or external conditions change rapidly, the wind power generation system can not stabilize the output power of the stored energy in the energy storage system can produce a certain amount of energy and power supporting role, to ensure load sustained, stable power supply.
    6) system reliability and redundancy is greatly improved: multiple smaller capacity grid-connected inverters in parallel control run, making the system according to the characteristics of a variety of new energy power generation, and start a different number of grid-connected inverter control, the power generation efficiency of the system so that you can achieve optimal to further improve system reliability and redundancy will be greatly enhanced.
    7) so that the wind power generation has a greater impact on the schedulability: a simple new energy power generation system by environmental factors, therefore, unable to formulate a specific generation planning. If the configuration energy storage devices, can provide the necessary electricity at a particular time, without regard to the power generation unit power generation, new energy power generation system and grid connection, and fed to the grid, and can provide clipping emergency power support services. Just follow the pre-established power generation planning for power generation. The greater the capacity of energy storage devices, the scheduling of the system is free, you can get more economic benefits, but the greater the investment required, the key is to find the best economic balance point.
    6 Conclusion
    This paper reviews the development status of energy storage technology at home and abroad, the problems faced by wind power in the rapid development of the proposed high-capacity compaq laptop battery energy storage technology in the wind power system. Domestic and foreign research results show that the large capacity battery energy storage technology provides a wide range of storage features to solve the wind power, to improve power system stability, improve the quality of power supply of new ideas and effective technical support. Therefore, countries in the world, especially developed countries, are actively carrying out research in this area. We should take full advantage of the good opportunity of China's rich wind resources and power sector reform. Actively carry out research in this area, to provide new technology to support the efficient operation of the safety of China's electric power system. Large-capacity toshiba laptop battery energy storage technologies play an increasingly important role in the clean energy generation. The market potential is huge, has an increasingly important economic and social values.