This paper presents a combination system of wind energy conversion and hydrogen production. Hydrogen is expected as an alternative energy source in the future, and this is the best way to produce it from renewable energy like wind energy. On the other hand, the output of a wind generator, in general, fluctuates greatly due to wind speed variations, and thus the output fluctuations can have a serious influence on the power system operation. In the proposed system, a variable speed wind generator is adopted, and an electrolyzer is installed in parallel with it for hydrogen production. Output power from the wind generator is smoothed and supplied to the power system as well as to the electrolyzer based on the cooperative control method. The performance of the proposed system is evaluated by simulation analyses, in which simulations are performed by using PSCAD/EMTDC. Index Terms-Hydrogen production, power smoothing, variable speed wind generator, wind energy conversion.

Recently, wind energy conversion system using a Doubly-Fed Synchronous Generator (DFSG) has attracted an interest. This system can control rapidly real and reactive power output independently by secondary AC excitation. Furthermore, since wind turbine can be operated in variable speed, fluctuations of the output due to changing wind speed in short period can be reduced. This paper proposes a new control method for this system to enhance the transient stability of neighboring induction generators in the same wind farm.

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The spread of wind power generation is progressed hugely in recent year from viewpoint of environmental problems including global warming. Though wind power is considered as a very prospective energy source, wind power fluctuation due to the random fluctuation of wind speed has still created some problems. Therefore, research is going on how to smooth this wind power fluctuation. This paper presents energy capacitor system (ECS) which consists of electric double-layer capacitor (EDLC) and power electronics devices and works as an electric power storage system for generated output leveling the output power. Moreover, hydrogen is paid to attention in recent year from viewpoint of exhaustion problem of fossil fuel. Therefore the hydrogen generator (HHOG) is also installed at the wind farm to generate hydrogen. In this paper, the effectiveness of the proposed system is verified by the simulation analyses using PSCAD/EMTDC. Figure 1 shows the model system used for the simulation analyses of the proposed system. The output of the squirrel-cage induction generator, which works as wind generator (50 [MVA] power rating) is smoothed with ECS (20 [MVA] power rating), and hydrogen gas is produced constantly from the hydrogen generator(10 [MVA] power rating). In this paper, to verify the effectiveness of the proposed system, the real wind speed data is used which was obtained Fig. 1. Model system in Hokkaido Island, JAPAN. As rigid conditions, −4 [m/s] and +4 [m/s]of real wind speed was used as Case 1 and Case 2.The simulation result is shown in Fig. 2. In a low wind speed of Fig. 2(a), it is clear that when ECS is used, the line power can be smoothed well. In a high wind speed of Fig. 2(b), since the pitch controller is used to maintain the IG real power at the rated level, the fluctuation of the line power is small. In this case, when ECS is used the line power can be smoothed. In hydrogen generator, it can be confirmed the constant hydrogen generation by constant power consumption as shown in Fig. 2(c). The amount of the hydrogen gas generation is 254 [Nm 3 ] in 600 sec simulation time. From these results, it can be concluded that the proposed system can operate effectively in power systems to generate constant hydrogen as well as generate high quality electrical power from the natural fluctuating wind. (a) Line Power (Case 1 [low wind speed]) (b) Line power (Case 2 [high wind speed]) (c) Amount of hydrogen gas generation Fig. 2. Simulation result -2 -