A. Cagnano

Online Optimal Reactive Power Control Strategy of PV Inverters

This paper proposes a decentralized nonlinear autoadaptive controller for reducing system losses by the optimal management of the reactive power supplied by the inverters of photovoltaic (PV) units. This ancillary service can be furnished on the base of standard needs or on voluntary basis. The control design is based on an optimization procedure involving the sensitivity theory in conjunction with the Lyapunov function and provides control laws acting as references of the PV inverter local controller. PV inverters must operate in a decoupled manner in order to provide the reactive power imposed by the control law and to transfer the active power produced by PV modules. The experiences and results conducted in an indoor laboratory as well as on an actual distribution network managed by ENEL Distribuzione S.p.A. demonstrate its effectiveness in reducing system losses.

PV plants for voltage regulation in distribution networks

This paper deals with the development of a centralized nonlinear auto-adaptive controller able to optimize the network voltage profile by managing the reactive power supplied by PV inverters. The control design is based on a realtime optimization procedure involving the sensitivity theory in conjunction with the Lyapunov function and produces the control laws that must be sent to local controllers of PV-inverters. The derived controller is implemented and tested on a MV distribution network.

Power System Stability Analysis in the Presence of Variable Speed Wind Generators

This paper aims to analyze Variable Speed Wind Turbine impact on transient behavior of a power system using time domain simulation. To this purpose, suitable mathematical models for Doubly Fed Induction Generators and Permanent Magnet Synchronous Generators with their control devices are considered. Simulations allow to assess the influence of VSWT on conventional synchronous generator dynamics after short-circuit fault occurrence.