{'fraction_non_alphanumeric': 0.02040816326530612, 'fraction_numerical': 0.0012368583797155227, 'mean_word_length': 5.271317829457364, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Enhancing frequency response of wind farms using hybrid energy storage systems

The decarbonisation of electricity networks has led to increasing numbers of renewables in the energy mix. Besides energy generation, large-scale wind generators are now called to provide mandatory frequency response according to several grid regulations. This, however, could impose significant constraints on their operation, reducing the capabilities in power and energy delivery and resulting in loss of profits. Energy storage systems (ESSs) can act as a means to limit these losses and ensure that services are delivered according to network regulations. However, there are many occasions where a single energy storage (ES) technology would fail to be economically viable for this purpose. This paper builds on established techniques for sizing ES to complement wind generators in providing frequency support and introduces considerations for hybrid ES systems (HESSs) comprised of more than one technology. The methodology was applied for a 60 MW wind farm complemented by a Vanadium Redox flow battery (VRFB) and supercapacitors for the provision of Primary, Secondary and High frequency response as defined in United Kingdom (UK) Grid Code, however it is technology-independent and could be used to support various cases. Linear Programming is used for sizing the system and maximizing revenues and three cases are compared i.e. using no storage, using a single ESS and using a HESS respectively. The results confirm that, under certain conditions, the use of a HESS can provide increased revenues for this type of applications.