MIMO Hinf control for power source coordination - application to energy management systems of electric vehicles

International audienceThis paper deals with a control strategy used for designing energy management systems within average-power electric vehicles. The power supply system is composed of three sources, namely a fuel cell, a battery and an ultracapacitor - specialized within distinct frequency ranges - which must be coordinated in order to satisfy power demand of the vehicle's electrical motor. The three sources with their associated DC-DC converters are paralleled on a common DC-bus supplying the electrical motor. The DC-bus is required to be constant regardless of the load state thanks to the fuel cell which provides the mean power and to the other two sources - auxiliary sources - which are controlled to supply the high-frequency variations of power demand according to an H1 optimization strategy. MATLAB/ Simulink numerical simulation is used to validate the proposed strategy under real driving cycle condition proposed by IFSTTAR (Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux), and this approach is assessed against another optimal strategy that uses LQR as control design

Extremum seeking control techniques applied to photovoltaic systems with multimodal power curves

International audienceThis paper proposes a modified Perturb and Observe (P&O) Extremum Seeking Control (ESC) technique in presence of multiple maxima. ESC is applied to single-phased grid-connected photovoltaic (PV) arrays which have to provide maximum power irrespective of solar irradiance conditions. In particular, partially shadow conditions may lead to steady-state power curves exhibiting multiple maxima. The power harvested from the PV generator is injected in the single-phased power grid by using two power converter stages: step-up DC-DC converter and DC-AC inverter. When multiple power maxima exist, the amplitude of the perturbation signal plays an important role in successfully tracking the global maximum. Two amplitude modulation strategies are analyzed for the same case study: amplitude modulation by using a first-order-system-response signal and amplitude modulation by using small duty ratio square-wave signal, respectively. MATLAB®/Simulink® numerical simulations are presented in order to assess the two approaches comparatively

LPV control for power source coordination - application to electric vehicles energy management systems

International audienceThis paper presents an LPV/Hinf control strategy applied to power source coordination on board of average power electric vehicles. The proposed approach concerns separation in frequency responses between three power sources in order to satisfy power demand of the vehicle's electrical motor, taking into account that sources are devoted to work within distinct frequency ranges. The three sources - fuel cell, battery and ultracapacitor - are connected in parallel to a common DC-bus which supplies the electrical motor. The idea is to use the weighting function associated to the LPV/Hinf controller to determine the auxiliary power source behaviors - battery and ultracapacitor - and to minimize the variation in fuel cell current and the DC-bus voltage. As a result, DC-bus voltage is regulated to 150 V, while the fuel cell provides mean power to the electrical motor. The proposed approach is validated by MATLAB/Simulink numerical simulation by using two driving scenarios, namely Normalized European Driving Cycle (NEDC) and the driving cycle proposed by IFSTTAR (Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux)

Power sources coordination through multivariable LPV/Hinf control with application to multi-source electric vehicles

International audienceIn this paper the problem of multi-source power sharing strategy within electric vehicles is considered. Three different kinds of power sources - fuel cell, battery and supercapacitor - compose the power supply system, where all sources are current-controlled and paralleled together with their associated DC-DC converters on a common DC-link. The DC-link voltage must be regulated regardless of load variations corresponding to the driving cycle. The proposed strategy is a robust control solution using a MIMO LPV/H-inf controller which provides the three current references with respect to source frequency characteristics. The selection of the weighting functions is guided by a genetic algorithm whose optimization criterion expresses the frequency separation requirements. A reduced-order version of the LPV/H-inf controller is also proposed to handle an embedded implementation with limited computational burden. The nonlinear multi-source system is simulated in MATLAB® / Simulink® using two different types of driving cycles: the driving cycle of IFSTTAR (Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux) and a constant load profile used in order to illustrate system steady-state behaviour. Simulation results show good performance in supplying the load at constant DC-link voltage according to user-configured frequency-separation power sharing strategy. When assessed against the classical-PI-based filtering strategy taken as base-line, the proposed strategy offers the possibility of integrating a variety of constraints into a systematic design procedure, whose result guarantees stability and performance robustness

Reduced-order LPV controller for coordination of power sources within multi-source energy systems

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Impact of IEC 61850 GOOSE Communication Quality on Decentralized Reactive Power Control in Smart Distribution Grids – a Co-simulation Study

International audienceSmart grids are expected to increase efficiency, reliability and sustainability of future energy usage. Employing state-of-the-art information and communication technologies, within power grids, is defining for smart grids; therefore interaction between energy grids and communication networks requires thorough study. Combined simulation of the behaviour of the electrical and communication network would allow to analyse their influences on one each other.In this paper, the results of a MATLAB® /Simulink® cosimulation of an electrical distribution grid containing two renewable sources in interaction with its communication network are presented. Communication between different nodes is based on the IEC 61850 GOOSE protocol, whose simulation model incorporates its different efficiency and reliability features. Communication network and electrical grid are modelled using SimEvents® blocks and SimPowerSystems® blocks, respectively. The effect of perturbations on the reliability of the data transfer links, while information to perform decentralised reactive power control is flowing on them, is examined

Optimal frequency separation of power sources by multivariable LPV/Hinf control: application to on-board energy management systems of electric vehicles

International audienceIn this paper a multi-variable LPV/Hinf control approach is applied to design a strategy for power source coordination within a multi-source energy system. Three different kinds of power sources - fuel cell, battery and ultracapacitor - compose the power supply system of an electric vehicle. All sources are current-controlled and paralleled together with their associated DC-DC converters on a common DClink coupled to vehicle's electrical motor and its converter. DC-link voltage must be regulated in spite of load power variations representing the driving cycle image. To this end, a MIMO LPV/Hinf provides the three current references so that each source operates in its most suitable frequency range as either high-energy-density or high-power-density source: lowfrequency, mean power is provided by fuel cell, ultracapacitor supplies/absorbs the instantaneous variations of power demand and battery operates in between the two other sources. Selection of Hinf weighting functions is guided by a genetic algorithm whose optimization criterion expresses the frequency separation requirements. The nonlinear multi-source system is simulated in MATLAB®/Simulink® using the driving cycle of IFSTTAR (Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux) as load profile, whose frequency content is richer than that of Normalized European Driving Cycle (NEDC). Simulation results show good performance in supplying the load at constant DC-link voltage according to user-configured frequency-separation power sharing strategy

Frequency robust control in stand-alone microgrids with PV sources : design and sensitivity analysis

International audienceIn this paper, a robust H-infinity control strategy for frequency regulation is proposed in isolated microgrids (MGs) composed of diesel engine generators, photovoltaic (PV) sources, and storage units. First, the linear matrix inequalities (LMI) method is adopted to design a multi-variable H-infinity controller which ensures given specifications. In a second step, uncertainties in the storage device state of charge (SoC) are considered and a sensitivity analysis is carried out in order to determine the maximum variation range of SoC for which the dynamic performances are respected. The controller's robustness and performance in the presence of various load disturbances, PV output power variations, and the SoC uncertainty are validated through a series of nonlinear time-domain simulations performed with MATLAB/Simulink.</p

Co-simulation of a Low-Voltage Utility Grid Controlled over IEC 61850 protocol

International audienceThis paper presents a co-simulation model using MATLAB® toolboxes to illustrate an interaction between the communication system and the energy grid, coherent with the concept of smart grid that employs IEC 61850 communication standard. The MMS (Manufacturing Message Specification) protocol supported by IEC 61850, based on TCP/IP is used for the vertical communication between the Supervisory and Data Acquisition (SCADA) system and Intelligent Electronic Devices (IEDs) embedding the local control of different parts of the smart grid. In this paper an IED supporting the power control of a photovoltaic (PV) plant connected to a low-voltage (LV) utility grid is considered. Communication system consisting of the transport layer and a router placed on the network layer is modeled as an event driven system using SimEvents® toolbox and energy grid is modeled as a time-driven system using SimPowerSystems® toolbox. Co-simulation results are obtained by combining different communication scenarios and time-varying irradiance scenarios for thee PV plant when the PV plant is required to provide a certain power in response to a power reference received from SCADA over the communication network. The analysis aims at illustrating the impact that stochastic behavior and delays due to network communication have on the global system behavior