Monica Aguado

Power hardware-in-the-loop technique applied to a LV network for integrating a supercapacitor with an average model of STATCOM

This paper investigates the effects on voltage stability of a converter based STATCOM integrated with a Supercapacitor into a low voltage (LV) distribution network. An Average Model of a STATCOM was simulated, where the IGBT Voltage-Source Converter was represented by equivalent controlled voltage sources. The STATCOM was modeled in the Real Time Digital Simulators (RTDS®) dedicated software RSCAD. Subsequently, Power Hardware- in- the -Loop (PHIL) tests were executed with an impedance load as Hardware under Test (HuT) in order to validate the systems performance. Simulations and PHIL experimental results are outlined to demonstrate the STATCOMs contribution on nodal voltage regulation, whereas the integration and control of an energy storage system (ESS) such as a Supercapacitor is further discussed throughout this paper.

Implementation of a fuzzy logic controller for virtual inertia emulation

Any inequality in the overall systems power balance causes a variation in the kinetic energy of the rotating masses and thus a change in frequency. The inertia stored in all the rotational parts of the system is defined as a resistance to change and impedes sudden frequency variations. In general, synchronous machines consist of large and heavy rotating parts which serve as an obstacle against abrupt frequency deviations. This paper investigates the application of various designs of frequency control that support frequency stability. At a second phase, for improving the performance of frequency control, an additional controller is implemented, employing a fuzzy structure controller with virtual inertia response. It is shown that during step load changes and after the implementation of a continuous fluctuation in the system, the lower the total systems rotational inertia is, the more the frequency stabilization deteriorates. Nevertheless, through the aforementioned control strategies, frequency stability is enhanced. This study presents the results from the Researcher Exchange Program within the FP7 ELECTRA IRP European project.

Implementation of a microgrid model for DER integration in real-time simulation platform

Comprehensive analysis of Distributed Energy Resources (DER) integration requires tools that provide computational power and flexibility. In this context, throughout this paper PHIL simulations are performed to emulate the energy management system of a real microgrid including a diesel synchronous machine and inverter-based sources. Moreover, conventional frequency and voltage droops were incorporated into the respective inverters. The results were verified at the real microgrid installation in CRES premises. This research work is divided into two steps: A) Real time in RSCAD/RTDS and PHIL simulations where the diesel generators active power droop control is evaluated, the battery inverters droop curves are simulated and the load sharing for parallel operation of the systems generation units is examined. B) microgrid experiments during which various tests were executed concerning the diesel generator and the battery inverters in order to examine their dynamic operation within the LV islanded power system.

A Modified Control Scheme of Droop-Based Converters for Power Stability Analysis in Microgrids

Microgrid is principally an active distribution network since it aggregates numerous DG systems through their interface converters and different loads at distribution level. This paper discusses the power sharing in autonomous AC-microgrid infrastructure by common - and - droop control schemes on parallel-connected converters. Moreover, this research work proposes a frequency and voltage restoration mechanism through the utilization of secondary control. Experimental results are presented for a two-50 kVA parallel-connected converter-based system, demonstrating the necessity for the proper operation of the secondary control in order to monitor the system’s capability to withstand any perturbations that may occur and to ensure the system’s security.