As offshore wind power scales up globally, maintaining grid stability is becoming a more complex challenge. Among the innovative technologies addressing these hurdles, the Static Synchronous Compensator (STATCOM) stands out for its ability to manage power quality in dynamic and unpredictable wind environments.
How STATCOM Supports Offshore Wind: In offshore wind farms, where voltage fluctuations, reactive power imbalances, and frequency variations can pose significant issues, STATCOM provides real-time voltage regulation and reactive power support. This is essential for mitigating power oscillations and enhancing dynamic grid performance, especially in weak grid scenarios or remote offshore installations. It also plays a key role in power oscillation damping (POD), preventing the system from experiencing harmful oscillations that could destabilize the grid.
However, one of the biggest challenges offshore wind faces is the intermittency and variability of wind generation. Integrating battery energy storage systems (BESS) with STATCOM offers a powerful solution to these challenges.
Benefits of Combining STATCOM with Battery Energy Storage:
- Enhanced Power Oscillation Damping: BESS can absorb or inject power in real-time, working alongside STATCOM to dampen oscillations and smooth out transient events, which is crucial for ensuring grid stability.
- Improved Voltage and Frequency Control: Batteries provide additional reactive power support, helping maintain voltage and frequency even under fluctuating wind conditions.
- Increased System Resilience: By storing excess wind power during high-generation periods and dispatching it during low-wind scenarios, BESS minimizes the impact of wind variability on grid stability.
- Reduced Curtailment: With BESS, excess wind energy that would otherwise be curtailed can be stored and used later, maximizing the efficiency and profitability of wind farms.
- Smoothing Power Output: STATCOM and BESS together help mitigate the intermittency of wind generation, providing a more consistent and reliable power flow to the grid.
Integrating STATCOM with energy storage can be a game-changer, especially in tackling the power oscillation damping and voltage stability challenges faced in offshore wind. Together, these technologies not only boost the operational reliability of offshore wind farms but also help make the entire energy system more resilient and flexible.
In light of the above, we would like to present a published paper by Dr Sohal Mian (Power Systems Director). The paper proposes a delta-connected Modular Multilevel STATCOM with partially rated storage (PRS-STATCOM), capable of providing both reactive, and active power support. The purpose is to provide short-term energy storage enabled grid support services such as inertial, and frequency response, either alongside or temporarily instead of standard STATCOM voltage support. The topology proposed here contains two types of sub-modules (SM) in each phase-leg: standard sub-modules (STD-SMs), and energy storage element sub-modules (ESE-SMs) with a DC-DC interface converter between the SM capacitor, and the ESE. A control structure has been developed that allows energy transfer between the SM capacitor, and the ESE resulting in active power exchange between the converter, and the grid. Injecting a 3rd harmonic current into the converter waveforms can be used to increase the amount of power that can be extracted from the ESE-SMs, and so reduce the required ESE-SMs fraction in each phase-leg. Simulation results demonstrate that for three selected active power ratings, 1 p.u., 2/3 p.u., and 1/3 p.u., the fraction of SMs that need be converted to ESE-SMs are only 69%, 59% & 38%. Thus, the proposed topology is effective in adding real power capability to a STATCOM without a large increase in equipment cost.
The paper signifies the verticality and flexibility of the STATCOM topology and the added benefits towards grid stability. The paper can be accessed here:
https://ieeexplore.ieee.org/document/9216022
