Miguel Angel Guerrero-Martinez

Three-phase bidirectional battery charger for smart electric vehicles

A three-phase battery charger for electric vehicles is proposed in this paper. The charger is bidirectional, allowing the Charging and Vehicle to Grid operation modes. A novel Balanced Sinusoidal Source Current control strategy is proposed so that the charger demands or injects into the grid a perfect sinusoidal and balanced source current in phase with the positive sequence fundamental component of the phase-to-neutral grid voltage, achieving a unity displacement power factor. In this way, the charger turns the car into a smart vehicle, reducing the existing problem of harmonic current demand by electric and hybrid vehicles and improving the power quality of the electric power system. The topology and control stage of the charger are shown. Simulation tests are conducted to validate the proper operation of the charger under sinusoidal, distorted and unbalanced source voltages.

Three-phase single stage photovoltaic inverter with active filtering capabilities

This paper presents a study about the power injection of grid connected photovoltaic plants when there are non-linear loads connected to the point of common coupling. The smart grid scenario suggests that the photovoltaic energy should take care not only about the active power, but also about the reactive power. The study compares the last years criteria of injecting the maximum active power, with the expected tendency of providing reactive power in an active filter way for avoiding currents harmonics in the grid. The topology used is a traditional three-phase inverter controlled by a power balance technique through a synchronous hysteresis band. First of all, a power injection system that do not care about the loads connected into the grid is developed, then the loads are taken into account to improve the grid operation by supplying them. Both configurations are implemented in a prototype to compare the results via experimental tests.

A new criterion for selecting the inductors of an Active Power Line Conditioner

This paper analyzes the inductances used at the terminals of an Active Power Line Conditioner (APLC) based on a voltage source inverter (VSI) in some current correction topologies. The criteria to select the optimal inductances values are determined and a novel design criterion, named “control criterion”, is proposed. This novel method is applied to situations where there are sharp current variations as the case of a three phase rectifier feeding a resistive load. A parametrical analysis of the expressions obtained for the inductors is performed, obtaining the intervals of possible values of inductance that can meet the initial specifications. Finally a simulation is carried out to verify how the method presented reaches these specifications.

A Grid Connected Photovoltaic Inverter with Battery-Supercapacitor Hybrid Energy Storage

The power generation from renewable power sources is variable in nature, and may contain unacceptable fluctuations, which can be alleviated by using energy storage systems. However, the cost of batteries and their limited lifetime are serious disadvantages. To solve these problems, an improvement consisting in the collaborative association of batteries and supercapacitors has been studied. Nevertheless, these studies don’t address in detail the case of residential and large-scale photovoltaic systems. In this paper, a selected combined topology and a new control scheme are proposed to control the power sharing between batteries and supercapacitors. Also, a method for sizing the energy storage system together with the hybrid distribution based on the photovoltaic power curves is introduced. This innovative contribution not only reduces the stress levels on the battery, and hence increases its life span, but also provides constant power injection to the grid during a defined time interval. The proposed scheme is validated through detailed simulation and experimental tests.

Point of common coupling voltage regulation with photovoltaic power plant infrastructures

This paper presents a point of common coupling voltage regulation technique by using a photovoltaic power plants generation system for controlling not only the injection active power but also the balance reactive power. The need of this functionality becomes true when some countries propose the use of renewable energy to help the grid when a sag is detected as a new standard. However, the idea is extensible to Smart-Grids where the power balance must be provided by the distributed generation. Active power injection is developed by a reference power point tracking and reactive power regulation by controlling the node voltage, both with dq current control with the different power priority possibilities. The studied topology is based on a single-stage traditional inverter but the control algorithm philosophy is valid for any topology. The whole system has been simulated in order to validate the control algorithm and tune the controller for obtaining the best transient response with zero steady state.

A Smart Power Electronic Multiconverter for the Residential Sector

The future of the grid includes distributed generation and smart grid technologies. Demand Side Management (DSM) systems will also be essential to achieve a high level of reliability and robustness in power systems. To do that, expanding the Advanced Metering Infrastructure (AMI) and Energy Management Systems (EMS) are necessary. The trend direction is towards the creation of energy resource hubs, such as the smart community concept. This paper presents a smart multiconverter system for residential/housing sector with a Hybrid Energy Storage System (HESS) consisting of supercapacitor and battery, and with local photovoltaic (PV) energy source integration. The device works as a distributed energy unit located in each house of the community, receiving active power set-points provided by a smart community EMS. This central EMS is responsible for managing the active energy flows between the electricity grid, renewable energy sources, storage equipment and loads existing in the community. The proposed multiconverter is responsible for complying with the reference active power set-points with proper power quality; guaranteeing that the local PV modules operate with a Maximum Power Point Tracking (MPPT) algorithm; and extending the lifetime of the battery thanks to a cooperative operation of the HESS. A simulation model has been developed in order to show the detailed operation of the system. Finally, a prototype of the multiconverter platform has been implemented and some experimental tests have been carried out to validate it.

Development of a Photovoltaic Array Emulator in a Real Time Control Environment Using xPC Target

This paper is devoted to the design and construction of a photovoltaic array emulator for high power applications in order to test all kind of photovoltaic inverters. To develop such device, a rapid prototyping tool based on xPC Target of Matlab/Simulink has been used, providing a real-time testing environment. PV array emulator can be used to evaluate the performance of photovoltaic inverters as any test conditions can be programmed. The proposed emulator operates as a distributed control system taking advantage of the TCP/IP protocol features.

Active power injection control of a photovoltaic system through ultracapacitor storage

This document presents a three-phase grid-connected power injection system for a photovoltaic power source with control of the injected active power through an energy storage system based on ultracapacitors. The ultracapacitor technology offers high power density that matches properly in a Smart-Grid scenario with the need of active power regulation for quasi-manageable energy ability. A voltage source inverter injects the power into the grid, while a bidirectional direct current converter regulates the charge of the ultracapacitor. In this way, the ultracapacitor could be charged when the active power needed in the grid is below the photovoltaic power, it could be discharged in the opposite case, and, if the ultracapacitor is saturated the power point tracked depends on the reference, injecting the desired active power in every assumption. The system has been implemented in a prototype through a FPGA/processor controller, so the hardware/software co-design is detailed. Finally, the performance of the configuration is exposed via experimental tests.

Power injection system for photovoltaic plants based on a multiconverter topology with DC-link capacitor voltage balancing

This paper presents the simulation of a new topology for the power injection system of a single-phase grid connected photovoltaic generation system that is based on the parallel association of two voltage source inverters: one is a 3 level neutral point clamped operated using a low switching frequency strategy and the other is a 2 level inverter which operates with a pulse width modulation based strategy. The aim of this topology is that multilevel inverter injects the power and the other inverter controls the current quality. The DC-link capacitor voltage balancing is solved by using the redundant states of the multilevel inverter. The proposal optimizes the system design, allowing high power injection, permitting reduction of system losses and an increase of the energy injected into the grid.

Issues and improvements of hardware/software co-design sensorless implementation in a permanent magnet synchronous motor using Veristand

This paper is focused on the implementation of a field oriented control of a permanent magnet synchronous in the emerging rapid control prototyping tool Veristand through a National Instruments PXI device. The device is composed of a FPGA and a controller so the hardware/software co-design is discussed in order to optimize the control system. The algorithm is solved by calculating the position of the rotor in two ways: firstly with the resolver sensor and secondly with a signal injection sensorless method to compare the position results. Both configurations are simulated to tune the system properly, and finally they are tested experimentally with the mentioned control platform. Taking advantage of the Veristand hardware/software co-design flexibility, the sensorless method was implemented in two ways in order to demonstrate the flexibility of the control system and compare the results of both solutions.