Abstract
The intermittent power generation of a wave energy converter (WEC) is a critical factor affecting the safe and stable operation of island microgrids. However, the sea trials data of the 500 kW “Chang Shan Hao” WEC indicated that the intermittent power generation was pronounced under low wave energy density in China. Most of methods used to reduce intermittency rely on energy storage systems resulting in high costs. The cost-effective alternative technologies can promote wave energy commercialization. Thus, an improved power tracking control strategy for hydraulic energy storage WECs without additional hardware cost is proposed. Two power tracking schemes, a primary tracking scheme and a secondary tracking scheme (STS), are used to improve the output characteristics of a WEC. The power output range of the STS improves by 75% compared to the conventional control strategy. The intermittency of the WEC is investigated with a fully coupled wave-to-grid model. Results demonstrate that STS improves wave-to-wire efficiency by 48.5% in specific low sea states compared to the conventional control strategy. The schemes achieve continuous power generation in a larger range of sea states, effectively mitigating the intermittency of the WEC, thereby facilitating the integration of large-scale WECs into island microgrids.