Integrated energy systems are considered as an indispensable part of the pathway towards a low-carbon sustainable future, as well as secure and reliable systems, characterised with a high level of flexibility and resilience. Increased penetration of renewable energy sources into energy systems is contributing to the reduction of carbon emission, thereby reducing the level or air pollution, climate changes and supporting the quality of life on the Earth. In this context, energy conversion systems realized by wind turbine generators have been and are still in the focus of extensive research on different system aspects, from planning, exploitation, monitoring, control, or protection perspective. To maximize the utilisation of available wind energy, modern wind turbine generators are connected to the main grid over power electronics (e.g. Type-3, or Type-4 wind generators). Consequently, they are electromagnetically disconnected from the rest of the power system and they provide little or no inertia, contrary to conventional synchronous generators, synchronously connected to the grid and synchronously operated to each other. This synchronism is necessary to ensure a stable system operation. The reduction of the system inertia imposes serious technical challenges on preserving system frequency stability. As it is known, inertia is one of key factors determining the robustness of power systems against sudden active power imbalances caused by different types of frequency events (generator disconnection, or load connection). The reduction of synchronous power reserves further intensifies this problem by reducing the system ability to maintain frequency within a permissible range following frequency events. Consequently, grid operators demand renewable energy sources, which are also referred to as nonsynchronous generators, to emulate the behaviour of synchronous generators to some extent and to participate in (fast) frequency control upon need. In general, countermeasures applied to these sources to contribute to frequency support are classified into two main categories: a) temporary and b) persistent energy reserve-based approaches. This paper presents a review on latest research findings and developed mechanisms for frequency control using wind energy conversion systems as the most frequently deployed renewable energy sources in modern power systems. Relying on lessons learned from the past two decades, in this paper current and future challenges, feasible solutions and subsequent research prospects are detailed. Some key principles that should underlie future changes of wind integrated energy systems are suggested and further research directions are addressed.

综合能源系统被认为是通向低碳可持续未来的必不可少的部分，也是具有高度灵活性和弹性的安全可靠的系统。可再生能源越来越多地渗透到能源系统中，这有助于减少碳排放，从而减少了水平或空气污染，气候变化并改善了地球的生活质量。在这种情况下，从计划，开发，监视，控制或保护的角度出发，风力涡轮发电机实现的能量转换系统一直是并且仍然是针对不同系统方面的广泛研究的重点。为了最大程度地利用可用的风能，现代风力发电机通过电力电子设备（例如3型，或4型风力发电机）。因此，它们与电力系统的其余部分电磁断开连接，与传统的同步发电机相反，它们提供的惯性很小或没有惯性，与发电机同步连接到电网并彼此同步运行。这种同步对于确保系统稳定运行是必需的。系统惯性的减小对保持系统频率稳定性提出了严峻的技术挑战。众所周知，惯性是确定电力系统抵抗由不同类型的频率事件（发电机断开或负载连接）引起的突然有功功率不平衡的鲁棒性的关键因素之一。同步功率储备的减少通过降低系统在发生频率事件后将频率保持在允许范围内的能力，进一步加剧了这个问题。因此，电网运营商需要可再生能源（也称为非同步发电机）在一定程度上模拟同步发电机的行为并根据需要参与（快速）频率控制。一般而言，应用于这些资源以有助于频率支持的对策可分为两大类：a）临时方法和b）基于持久能量储备的方法。本文对使用风能转换系统作为现代电力系统中最常使用的可再生能源的最新研究成果和已开发的频率控制机制进行了综述。根据过去二十年的经验教训，本文详细介绍了当前和未来的挑战，可行的解决方案以及后续的研究前景。建议了风能集成能源系统未来变化的一些关键原则，并提出了进一步的研究方向。