Hybrid STATCOM–Capacitor–DER Framework for Advanced Power Factor Correction and Efficiency Enhancement in 33 kV Distribution Networks

Power factor correction (PFC) remains a critical requirement in medium-voltage (MV) distribution networks, particularly at the 33 kV level, where high reactive power demand and increased integration of distributed energy resources (DERs) lead to elevated losses, poor voltage regulation, and reduced overall efficiency. Conventional solutions, such as fixed or switched capacitor banks, provide cost-effective reactive power support but lack the flexibility to handle dynamic load variations and are prone to resonance issues. Similarly, advanced devices such as Static Synchronous Compensators (STATCOMs) deliver fast dynamic compensation but entail high investment costs when deployed as standalone solutions. In parallel, inverter-interfaced DERs have emerged as potential providers of reactive support, though their contribution is often underutilized due to fragmented control strategies. This paper proposes a novel hybrid STATCOM–Capacitor–DER framework for advanced power factor correction and enhancement of distribution efficiency in 33 kV networks. The framework employs optimally placed switched capacitor banks to provide economical bulk reactive power, a substation-level STATCOM for fast dynamic compensation and power factor trimming, and DER inverters configured with Volt-VAR droop control to deliver distributed support at feeder ends. A coordinated control hierarchy, supported by predictive Volt-VAR optimization, ensures synergy among the three elements. Simulation studies on a representative 33 kV feeder demonstrate significant improvements, including a correction of the power factor correction to ≥ 0.99, a reduction in feeder loss of up to 20% and improved voltage stability under variable load and renewable conditions. The proposed framework offers a scalable and practical way for utilities to achieve advanced PFC while using existing DER assets.