This paper presents a comparison of a variety of control strategies for the primary frequency control of wind power plants. These strategies include inertial as well as pitch angle regulators. The inertial control is sensitive to both the frequency variation through a standard droop control, and the rate of change of frequency. Since these controllers tend to counteract the operation of the Maximum Power Point Tracking (MPPT), the paper also investigates the effect of blocking the MPPT whenever the inertial control is enabled. The pitch angle control allows for a power reserve and prevents the rotor speed from exceeding the nominal value. A modified version of the WSCC 9-bus, 3-machine system with a 30% of wind penetration and a type 3 wind turbine model is considered in the case study. The behavior of these controllers are first analyzed separately. Then a compound controller, which merges together all strategies above, is proposed and discussed.
8 April 2025 in Transportation Research Part A: Policy and Practice
In a context of environmental and socio-economic challenges, metropolitan areas represent a fundamental territorial scale for addressing cohesion, competitiveness, and sustainability, key priorities in European territorial development. Accessibility to services is crucial, as it reflects the right to full citizenship, particularly in territories where attractive urban centres coexist with peripheral areas. Balancing these dynamics is a major challenge for metropolitan governance and planning, especially in Italy, where Metropolitan Cities (MCs) have been institutionalised for over a decade. This paper examines spatial structure, accessibility, and governance through a comparative analysis of three Italian MCs in the Po Valley macro-region, a polycentric system along the Mediterranean Corridor of the Trans-European Transport Network. Despite overall interconnections, the MCs display different settlement and accessibility patterns. The Metropolitan City of Turin is selected as a case study for its territorial diversity, metropolitan-mountainous character, misalignment between administrative and functional boundaries, and accessibility limitations. The research examines current planning instruments and governance-government arrangements of the case study in addressing these challenges. Findings, framed within the decadal review of Italian MCs, emphasise the need for greater coordination between plans, policies and programmes, combined with strengthened inter-municipal collaboration and territorial representation, to support a multi-level governance framework capable of coherent, effective, and balanced metropolitan development.