Jean-Régis Hadji-Minaglou

Design and simulation of a real-time implementable energy-efficient model-predictive cruise controller for electric vehicles

This paper presents the design of a novel energy-efficient model-predictive cruise controller for electric vehicles as well a simulation model of the longitudinal vehicle dynamics and its energy consumption. Both, the controller and the dynamic model are designed to meet the properties of a series-production electric vehicle whose characteristics are identified and verified by measurements. A predictive eco-cruise controller involves the minimisation of a compromise between terms related to driving speed and energy consumption which are in general both described by nonlinear differential equations. Considering the nonlinearities is essential for a proper prediction of the system states over the prediction horizon to achieve the desired energy-saving behaviour. In this work, the vehicle motion equation is reformulated in terms of the kinetic energy of the moving vehicle which leads to a linear differential equation without loss of information. The energy consumption is modeled implicitly by exploiting the special form of the optimisation problem. The reformulations finally lead to a model-predictive control approach with quadratic cost function, linear prediction model and linear constraints that corresponds to a piecewise linear system behaviour and allows a fast real-time implementation with guaranteed convergence. Simulation results of the MPC controller and the simulation model in closed-loop operation finally provide a proof of concept.

An efficient nonlinear model-predictive eco-cruise control for electric vehicles

A nonlinear problem formulation of an energy-saving model-predictive eco-cruise controller for electric vehicles is presented. With regard to the intended application in real-world tests, the model has to include the specific properties of a serial electric vehicle such as energy-recovery and a discontinuous accelerator input giving rise to a binary control variable. These specific features and the nonlinearity of the system dynamics make it a challenging task to formulate the optimisation problem in a way that allows a fast computation in real-time application. The challenges are addressed by using a model of the vehicle dynamics that is formulated in terms of the vehicle position instead of time and by considering the kinetic energy instead of the velocity. Furthermore, various constraints on the input and state variables are introduced for a realistic representation of the vehicle characteristics. A special focus is put on the treatment of a binary input variable in the optimisation. Here, in order to avoid a mixed-integer formulation of the problem, a continuous variable is introduced which is forced to take only discrete values by a penalty term. Finally, first simulation results underline the feasibility of this control approach.

Experimental studies on the development of a solar hybrid module with an aluminum microchannel evaporator

In recent years, the possibility to combine photovoltaics (PV) and solar thermal collectors into one hybrid module (PVT-module) has been increasingly investigated. PVT-modules produce thermal and electrical energy at the same time. As the efficiency of a photovoltaic module decreases with temperature, the temperature of the heat transfer media is often limited to about 30 °C and the PVT-module is combined with a heat pump, which increases the temperature on the “warm side”. This paper deals with a PVT-module, which combines a microchannel based evaporator of a CO2 (R744) heat pump with a PV panel (PVT-direct). The PVT-direct overall system is reduced to the refrigerant circuit due to the direct refrigerant expansion in the PVT-module. A conventional PVT heat pump system has an additional glycol-water circuit. Since a pump and an additional heat exchanger for the secondary cycle were omitted, the system has increased efficiency. Due to lower module temperatures, the increase of the photovoltaic efficiency is a further advantage of the PVT-direct-module. To prove the feasibility of the PVT-direct heat pump system, the Cologne Institute for Renewable Energy (CIRE) is developing and modeling a test facility for this purpose within the research project “PVT-direkt”. Furthermore, a functional PVT-direct-module with a microchannel based evaporator was designed and built. Much importance has been given to experimental studies under laboratory conditions in order to investigate (1) the adjustment of the functionality and layout of the PVT-direct-module for characterizing the joining of brazed joints in aluminum microchannel evaporators and (2) the influence of the backside aluminum plate of the PVT-direct-module regarding leakage currents and parasitic capacitances. The overall results obtained in these experimental studies are analyzed in this paper.

A novel model-predictive cruise controller for electric vehicles and energy-efficient driving

This paper presents a novel energy-efficient model-predictive cruise control formulation for electric vehicles. A predictive eco-cruise controller involves the minimisation of a compromise between terms related to driving speed and energy consumption which are in general both described by nonlinear differential equations. In this work, a coordinate transformation is used which leads to a linear differential motion equation without loss of information. The energy consumption is modeled by the maximum of a set of linear functions which is determined implicitly by the optimisation problem and thus leads to a piecewise linear model. The reformulations finally result in a model-predictive control approach with quadratic cost function, linear prediction model and linear constraints that corresponds to a piecewise linear system behaviour and allows a fast real-time implementation with guaranteed convergence. The controller and the underlying dynamic model are designed to meet the properties of a series-production electric vehicle whose characteristics are identified by measurements. Simulation results of the MPC controller and the simulation model in closed-loop operation finally provide a proof of concept.

Methodology for Optimally Sizing a Green Electric and Thermal Eco-Village

This paper presents an energy system for a future eco-village, situated in Luxembourg’s city center, whose thermal and electrical energy needs are covered by renewable resources. Specifically, electrical energy is provided by a biogas driven combined heat and power plant, and photovoltaic panels. Lithium-ion accumulators are used for storing the surplus of electrical energy production. Thermal energy needs are mainly covered by a dual source heat pump which draws environmental energy from an ice tank or solar air absorbers. A heat buffer stores heat produced by the combined heat and power plant, a power to heat module and the heat pump. This work focuses on optimally sizing, in terms of power rating, capacity or volume, the energy system components. To this end, a combinatorial simulation-based optimization approach has been developed using MATLAB. The optimal set-up is determined by minimizing the overall cost of the energy system with additional constraints to be respected. Annual needs in thermal and electrical energy, photovoltaic electricity production and the corresponding weather data are based on real data.

Phase-error correction by single-phase phase-locked loops based on transfer delay

A heterogeneous mix of recently installed and significant base of renewable energy resources in some countries combined with conventional power generation results in national and cross-border network instabilities. In fact, electricity from renewable energy resources is by nature intermittent and not steadily available locally and temporarily. This leads to a reduced functionality or life cycle of effected assets that shall be avoided. A decisive factor for network stability is the permanent balance between generation and load. The balance can be reached in an effective way if both energy generation and load sides are bundled to clusters on national, regional or even international levels. Examples of such clusters are virtual power plants or integrated markets. In addition, cultural differences in users’ behavior (e.g. electrical heating) or different time zones can be used to balance generation and loads if appropriately integrated. In order to fulfill this integration successfully, novel ready-tomarket distribution and transmission technologies play a crucial role as networks will be expanded and modernized towards smart grids in an intelligent, i.e., effective way to keep necessary investments under control, and to maintain public acceptance. Some examples of smart grid technologies will be outlined in the present paper/presentation, namely: HVDC technologies including a DC breaker for DC grid applications, developed by Alstom and its partners in the frame of the European FP7Program; Phase shifting and voltage control technologies, such as wide-area monitoring in possible combination with thyristor and transistor controlled dynamic VAR compensation (SVC/StatComs); and appropriate network management systems, i.e., market management systems that help manage the financial and physical flows of electricity, transmission and distribution management systems, as well as demand response management and energy market systems.Power monitoring of nuclear reactors is done by means of neutronic instruments, but its calibration is always done by thermal procedures. The reactor thermal power calibration is very important for precise neutron flux, fuel element burn up calculations, and mainly to electrical power. The burn up is linearly dependent on the reactor thermal power and its accuracy is important to the determination of the mass of burned U-235, fission products, fuel element activity, decay heat power generation and radiooxicity. Different methods for monitoring and controlling power in nuclear reactors are used.Comparative studies of different single-phase phase-locked loops (PLL) algorithms have been made. They show that the PLL based on sample delay (dPLL), presents the lowest computational load and is as robust as the three-phase synchronous reference frame PLL dqPLL by input signal amplitude and phase variations. Its weakness appears when the input signal frequency differs from its rated frequency: it depicts a steady error on the calculated signal phase-angle. After a brief review of the dqPLL which constitutes de base structure of the dPLL, the following work will present three methods that improves the phase detection accuracy of dPLL. It is shown that the modifications brought in the original structure do not influence the robustness and stability of the algorithm but reduce the phase angle offset error by input signal frequency variation. This is corroborated by tests including not only the fundamental input voltage disturbance like amplitude, phase and frequency variation but also harmonic voltage distortion.

Structured analysis of arbitrary island grids

This paper summarises an analytic control model for arbitrary island grids and presents findings on the dynamic behaviour of purely inverter driven island grids. Pole zero plots of different grid structures are presented and the influence of several inverter parameters on the grid stability is analysed. Findings show that for improved grid stability the inverters time constants should also relate to their rated power. Further it is shown how P-Q rotation in the droop control can improve the integration density of renewable power sources in the distribution grid.