Antonio Zecchino

Enhancing the Role of Electric Vehicles in the Power Grid: Field Validation of Multiple Ancillary Services

With increased penetration of distributed energy resources and electric vehicles (EVs), different EV integration strategies can be used for mitigating various adverse effects, and supporting the grid. However, the research regarding EV smart charging has mostly remained on simulations, whereas the experimental validation has rarely been touched upon. This paper focuses mainly on evaluating the technical feasibility of a series-produced EV to provide flexibility in real distribution grids. The implemented controller uses contemporary and widely supported standards for limiting the EV charging rate, which essentially means that it is applicable to any EV complying with IEC 61851 and SAE J1772 standards. The field test validation is conducted in a real Danish distribution grid with a Nissan Leaf providing three ancillary services through unidirectional ac charging, namely, congestion management, local voltage support, and primary frequency regulation. Several performance parameters, such as EV response time and accuracy, are assessed and benchmarked with current requirements. Ultimately, this paper aims to strengthen the applied research within the EV integration domain through validating smart grid concepts on original standard-compliant equipment.

Voltage control for unbalanced low voltage grids using a decoupled-phase on-load tap-changer transformer and photovoltaic inverters

This paper presents modeling and analysis of the potential benefits of joint actions of a MV/LV three-phase power distribution transformer with independent on-load tap-changer control on each phase and photovoltaic inverters provided with reactive power control capability, in terms of accommodating more renewable generations in the LV grid. The potential benefits are investigated in terms of voltage unbalance reduction and local voltage regulation. 24-hours root-mean-square dynamics simulation studies have been carried out with time-step of 1 second using 10-mins resolution consumption and production profiles. A totally passive real Danish low voltage distribution network is used for the grid topology as well as for the characterization of loads profiles, while the production ones are empirically defined under assumptions in scenarios with different level of photovoltaic penetration and grade of unbalance.

Grid frequency support by single-phase electric vehicles employing an innovative virtual inertia controller

The displacement of conventional generation by converter connected resources reduces the available rotational inertia in the power system, which leads to faster frequency dynamics and consequently a less stable frequency behavior. Virtual inertia, employing energy storage systems, could be used to limit the rate of change of frequency of power systems, thus, improving frequency dynamics. Electric vehicles (EVs) can represent a reliable solution to enhance frequency stability due to their fast response and capability to provide a large amount of aggregated power. On one hand, EVs are capable of adjusting the battery charging process (i.e., power flow) according to pre-defined algorithms. On the other hand, in case of islanded operation (i.e., low inertia), some of the EVs technical constraints might cause oscillations. This study presents two control algorithms which show that the EVs are capable of providing virtual inertia support. The first controller employs a traditional droop control, while the second one is equipped with an innovative control algorithm to eliminate likely oscillations. It is shown that, the proposed innovative control algorithm compared to the traditional droop control, assures same effects in terms of frequency but reducing significantly the number of variation of the EVs current set-point.

Grid frequency support by single-phase electric vehicles: Fast primary control enhanced by a stabilizer algorithm

Electric vehicles are growing in popularity as a zero emission and efficient mode of transport against traditional internal combustion engine-based vehicles. Considerable as flexible distributed energy storage systems, by adjusting the battery charging process they can potentially provide different ancillary services for supporting the power grid. This paper presents modeling and analysis of the benefits of primary frequency regulation by electric vehicles in a microgrid. An innovative control logic algorithm is introduced, with the purpose of curtailing the number of current set-point variations that the battery needs to perform during the regulation process. It is shown that, compared to traditional droop-control approaches, the proposed solution assures same effects in terms of frequency containment, by employing a considerably lower number of variations of battery current set-point. The modeled low voltage microgrid is built to reproduce a real configuration of the experimental facility SYSLAB-PowerLabDK. Root-mean-square simulation studies have been carried out in DIgSILENT PowerFactory environment for the validation of the controller.

Investigation of phase-wise voltage regulator control logics for compensating voltage deviations in an experimental low voltage network

Abstract This article investigates the control logics of an on-load tap-changer transformer by means of experimental system validation. The experimental low-voltage unbalanced system consists of a decoupled single-phase on-load tap-changer transformer, a 75-m 16-mm2 cable, a controllable single-phase resistive load, and an electric vehicle that has the vehicle-to-grid function. Three control logics of the on-load tap-changer transformer are described in the study. The three control logics are classified based on their control objectives and control inputs, which include network currents and voltages, and can be measured either locally or remotely. To evaluate and compare the control performances of the three control logics, all of the tests use the same loading profiles. The experimental results indicate the modified line compensation control can regulate voltage in a safe band in the case of various load and generation conditions.