Low-cost power regulation scheme for grid-connected variable-speed wind turbine using TPPL lead-acid batteries

This paper presents a small-scale wind energy conversion system(WECS) with lead-acid batteries used for mitigating the resulting power fluctuations due to the wind speed variations. The low cost, high efficiency and great availability thin plates pure lead (TPPL) acid batteries are directly connected in series to the DC link to maintain the integrated wind power delivered to the grid constant using a simple control strategy. A maximum power point tracker (MPPT) of the variable-speed wind turbine is incorporated into the battery charging system by using a two-phase interleaved DC-DC converter. The proposed interleaved converter, designed for a MPPT of a 1.5 kW interior permanent magnet synchronous generator(IPMSG) driven by a wind turbine, is implemented in the lab. In addition, a three-level voltage source inverter is used for grid-integration of a variable-speed wind turbine instead of a two-level inverter in order to highly reduce switching ripple components of the grid-side current even at a low switching frequency and small filter size. The experimental results, described in this paper, validate the effectiveness of lead acid batteries, which makes the proposed system more reliable and attractive to both stand-alone and integrated system.