The increasing penetration of renewable generation has led to a massive decrease of system inertia, which brings significant challenges for frequency control because less time is available to take control actions before the frequency deviates to an unacceptable level. As a result, network operators need to procure more reserve power to contain the frequency deviation, which will lead a significant increase of operational cost. Furthermore, renewable generation is often un-uniformly distributed in the system, so there are also differences in the inertia level in different parts of the network, resulting in regional variations of frequency during frequency disturbances. Therefore, future frequency response schemes not only need to be faster, but also need to consider the regional impact of frequency disturbances to avoid the response deployed from jeopardising the overall system stability.
This paper presents a novel wide-area monitoring and control scheme that is capable of dispatching fast and coordinated frequency response from a variety of distributed resources (e.g. wind, PV, energy storage, etc.). The proposed system, termed “Enhanced Frequency Control Capability (EFCC)”, fully considers the regional impact of frequency disturbances and is capable of deploying much faster response compared with conventional primary response schemes (from a few seconds to within one second), thus enhancing the frequency control in future power systems with low inertia. The EFCC system has been developed under an innovation project via the UK’s Network Innovation Competition framework. This paper presents the overall architecture of the EFCC system and the design of the key components within EFCC to realise the enhanced frequency control objectives. Case studies are presented, which demonstrate that the EFCC system is effective in containing the frequency deviation in a low inertia system while considering the regional impact; it can correctly distinguish frequency events from pure electrical faults to avoid unnecessary operation; and it is capable of effectively handling communication degradation to correctly provide frequency response when required.
- fast frequency control
- low inertia system
- wide-area monitoring and control systems