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International audience; The growing intelligence of the nowadays distribution grids is due to the integration of Information and Communication Technologies (ICTs). Such a development is converting the traditional grid into the smart grid concept. Communicating over a reliable ICT infrastructure, distributed Intelligent Electronic Devices (IEDs) perform supervision, protection, and control of the smart grid. The communication network is not errorless, and any error of the underlying communication network can degrade the power grid performance or even cause instability in it. Hence, there is a necessity to obtain a modeling method to analyze its Quality of Service (QoS). One of the most important quality measures of the Substation Communication Network (SCN) traffic is the message transmission delay. Thus, this paper proposes a methodology to evaluate the message transmission delay through an analytical model. To estimate the transmission delay, a port connection model represents the message distribution model. Then a traffic-flow-source model, and a traffic-flow-service model are applied to characterize each flow while it is served through different ports. Finally, delay is calculated based on the corresponding flow and service information. The estimation model is applied on an IEC-61850-MMS (Manufacturing Message Specification)-based communication scenario for a load-shedding goal that is considered over a real reduced-scale HV/MV smart substation test bench. The estimated results are compared to the measured values by the Wireshark network analyzer that indicates an estimation error of less than 10%.

International audience; Vast integration of new technologies to enable smart control of the power grid requires a reliable, efficient and resilient communication infrastructure. Today, many communication protocols (e.g., IEC 61850, OPC UA, Modbus, Internet, WiMAX, 4G, Wi-Fi, etc.) and technologies (e.g., PLC, GSM, Optic fiber, RF radio mesh, Cellular, etc.) are established for the smart grid applications. In case of the stability guarantee of smart grid, the Quality of Service (QoS) is a challenge to be considered. One of the major concerns in data delivery over the network is a low latency message transmission to ensure the time critical tasks, e.g., control and protection tasks. In this context, the main contribution of this paper is to propose a model methodology for the communication network delay in smart grid applications. To be compatible with the further goal of delay predictive compensation method, the present paper proposes a message transmission delay estimation method using Long Short-Term Memory (LSTM) neural network. To this end, Python is the chosen programming language, including its required libraries for the considered application. Delay values measured on a real-time HV/MV substation application are used as input data for validation purpose.

This paper proposes a state-feedback control of both grid and circulating current in modular multilevel converters (MMCs), which ensures that the input-coupled dynamics of the two currents to be controlled within a multi-input–multi-output (MIMO) approach. A systematic design procedure is detailed and the strategy is validated on a comprehensive MATLAB®/Simulink® model of a three-phase MMC. Simulation results show that, compared with the conventional control featuring two separate control loops, the proposed control shows better performance under unbalanced grid conditions. This paper proposes a state-feedback control of both grid and circulating current in modular multilevel converters (MMCs), which ensures that the input-coupled dynamics of the two currents to be controlled within a multi-input-multi-output (MIMO) approach. A systematic design procedure is detailed and the strategy is validated on a comprehensive MATLAB®/Simulink® model of a three-phase MMC. Simulation results show that, compared with the conventional control featuring two separate control loops, the proposed control shows better performance under unbalanced grid conditions.

International audience; This paper reports on the operation assessment of an electrical power generation system based upon cross-flow water turbines. The specific power take-off system has been tested in real-world conditions in a variety of scenarios and the experimental results have confirmed previous modeling assessments. Dynamical proprieties have been precisely identified and stable system operation over the entire operating range has been achieved. Steady-state characterization in terms of power coefficient has also been done, allowing the assessment of power generation system global efficiency and enabling the building of more precise models to be used in further simulations and assessments for power grid integration. Maximum power point tracking and other specific operation regimes such as angular position synchronization have also been validated.

International audience; Prosumers are households that are both producers and consumers of electricity. In this paper, an Energy Management System (EMS) for a DC-microgrid-based prosumer is designed and simulated, whose aim is to coordinate operation of a photovoltaic (PV) system and a battery for supplying a DC load; interaction with the utility grid – modelled as an infinite-power source – is minimized, such that power is either injected or drawn only when strictly necessary. The PV system and the battery are paralleled on a common DC-link by means of a boost converter and a synchronous buck converter, respectively, while an inverter ensures connection to the utility grid. In order to design and simulate the individual components of the microgrid, MATLAB®/Simulink® tools were used. During the study, different operating scenarios were created with respect to the PV power, load and the state of charge (SoC) of the battery. Thus, the following operation modes were identified: following mode, discharge mode, charging mode – referring to the battery operating modes that depend of its SoC. The aim of the EMS is to ensure the requirements of a prosumer application and switch between these different modes. Simulation results have shown that the developed EMS can achieve effective coordination within the microgrid, and all goals are reached.

In this study, 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 multiple-input multiple-output linear parameter-varying (LPV)/ H ∞; 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 optimisation criterion expresses the frequency separation requirements. A reduced-order version of the LPV / H ∞ controller is also proposed to handle an embedded implementation with limited computational burden. The non-linear multi-source system is simulated in MATLAB ®/Simulink ® using two different types of driving cycles: the driving cycle of IFSTTAR (Institut Francais des Sciences et Technologies des Transports, de l'Amenagement et des Reseaux) 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-proportional–integral-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.

Nowadays power grids are intelligent since their protection, supervision and control are held by a communication network through which different Intelligent Electronic Devices (IEDs) are interoperating. To design and maintain an efficient Substation Communication Network (SCN) with high transmission quality, developing a unitary mathematical model of the SCN data traffic as underlying paradigm of any control design approach is an important issue. In this paper, a stochastic representation of data traffic is derived, and a parametric analysis over the communication channel characteristics is presented. The identification method is illustrated on an electrical distribution grid containing two renewable sources which are exchanging information by means of IEC 61850 GOOSE (Generic Object-Oriented Substation Event) communication protocol in the context of a simple distributed reactive power control. The co-simulation and code process of both electrical and communication configurations are performed in MATLAB®/Simulink® environment.

This paper presents a robust H ∞ control design approach for primary frequency regulation in isolated microgrids (MGs). MGs consisting of diesel generators, photovoltaic (PV) panels, and storage units are here considered. Starting from given desired design specifications, a multi-variable H ∞ controller is designed via the linear matrix inequalities (LMI) method. In the second step, uncertainty in the storage device state of charge (SoC) is considered and a robustness analysis using µ–analysis is carried out in order to determine its maximum variation range for which the control performances imposed are respected for the considered operating point. MATLAB ® /Simulink ® time-domain simulations validate the controller’s robustness and performance in the presence of various load disturbances and SoC uncertainty.

International audience; This paper deals with an adaptive frequency-based power sharing method between batteries and ultracapacitors (UC) as power sources within an electric vehicle. An adaptive frequency splitter is used for routing the low-frequency content of power demand into the battery and its high-frequency content into the UC system, taking profit from the UC as a peak power unit. Autonomy may thus be increased while preserving battery state of health and ensuring that UC voltage variations remain confined within certain desired range. Results obtained by real-time experiments on a dedicated test rig validate the proposed energy management approach and recommend it to be applied as power source coordination method to microgrids in general.

This paper proposes a robust H ∞ control design approach for primary frequency regulation in a diesel-photovoltaic (PV)-storage hybrid power generation system operating in stand-alone mode. Based on real-time digital simulators, namely RT-LAB® and dSPACE®, a rapid-prototyping test bench composed of a real supercapacitor-based energy storage system (ESS) and an emulated diesel-PV-load grid is developed in order to experimentally validate this frequency control strategy under realistic operating conditions. Starting from given desired dynamic specifications, a multi-variable H ∞ controller is designed via the linear matrix inequalities (LMI) method. In the second step, uncertainty in the steady-state value of the supercapacitor state of charge (SoC) is considered and a robustness analysis using μ –analysis is performed in order to determine its maximum variation range for which the imposed closed-loop performances are respected for the considered operating point. MATLAB®/Simulink® time-domain simulations and real-time experiments show the effectiveness of the proposed robust control approach. Then, a series of real-time experiments are performed to validate the controller’s robustness and performance in the presence of various load disturbances and SoC uncertainty.

This 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 Francais des Sciences et Technologies des Transports, de l'Amenagement et des Reseaux), and this approach is assessed against another optimal strategy that uses LQR as control design.

International audience; Smart 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.

This paper focuses on exploring a new method of real-time replication of the dynamic behaviour of prime movers that drive rotating generators involved in energy conversion chains. Their behaviour depends on the mover’s mechanical characteristics and dynamical properties, such as inertia or friction coefficient, which are seldom known precisely. Being also dependent on the variations of the primary energy resource, not always controllable in its natural environment, this behaviour must be simulated by using a smaller and cheaper mover, whose model is sufficiently known such that to render it fully controllable. This paper explores the possibility that the desired real-time replication be achieved by means of a new method of tracking the mover’s rotational speed. To this end, various controllers, both linear and nonlinear can be employed. The design steps are provided for a PI controller, as well as for two nonlinear controllers, while focusing on the practical aspects of controller implementation. Their performance results are assessed comparatively on an experimental rig for two types of prime movers: one whose mechanical torque-speed characteristic is linear and a cross-flow water turbine, having a nonlinear torque-speed characteristic.

This paper focuses on the design, building, error evaluation, and performance assessment of a physical simulator for a variable-speed wind energy conversion system (WECS). Such simulator, dedicated to control algorithms validation, must replicate the dynamical behavior of the WECS physically in real time. To this end, software parts, which model subsystems of the plant, and hardware parts, taken as they are from the plant, are closed-loop connected, thus implementing a hardware-in-the-loop (HIL) simulator. The simulator interacts with a software-simulated environment-in this case, the wind velocity-in order to run experiments under controllable conditions. Controllers to be tested interact directly with the hardware part of the simulator, thus better approaching the behavior of the real-world WECS. A complete grid-connected generation chain employing a horizontal-axis fixed-pitch three-bladed rotor permanent-magnet-synchronous-generator-based WECS is chosen as example for the design and performance assessment of an HIL simulator, both in frequency and time domain.

International audience; The control problem associated to a class of horizontal-axis fixed-pitch variable-speed low-power wind energy conversion systems, working in the partial load region, consisting in the energy conversion maximization, is approached here under the assumption that the wind turbine model and its parameters are poorly known. Using a new approach derived from the optimum seeking methods category, genericall called Maximum Power Point Tracking (MPPT), the proposed control solution aims at driving the average position of the operating point near to optimality. Instead of inducing sinusoidal search signals, the wind turbulence is here used as search disturbance. The high-speed shaft's average rotational speed is slowly adjusted using the Fast Fourier Transform processing of some available measures from the system as an estimate of the operating point's position/distance to optimality. Numerical simulations are used for preliminary checking the control law based on this estimation.

The bucket brigades are self-balancing production lines where each human operator can move from one station to the next to continue working on a given part. When workers finish their job, they walk back to take over the ongoing work of their predecessor. For the bucket brigades, the line balancing emerges spontaneously. Several mathematical models have been proposed in literature for the analysis of bucket brigades, often where the basic assumptions seem to be too constraining. This paper analyses the behaviour of these lines when relaxing some of the usual restrictive assumptions. Two approaches are developed: analysis and simulation. An original analytical model is suggested and using this model, the sufficient condition of self-balancing for a finite backward velocity is studied. Then, a novel technique for the simulation of bucket brigades is proposed. This model uses the software Matlab/Simulink™. The results of simulation study are reported and analysed. The simulation model is flexible and easily e...

The bucket brigades are self-balancing production lines: each operator works on many adjacent workstations, such that the balancing emerges spontaneously, due to a decentralized control strategy (the TSS Rule). In the theoretical model - the Normative Model - it is assumed that the work on the next item is restarted instantaneously and simultaneously for all the operators. In this paper the behavior of these lines when relaxing this assumption is analyzed and a sufficient self-balancing condition for this new model is provided.

International audience; This paper deals with control of a kVA-rated power conversion system containing energy storage devices used for three-phase applications. Two main operating modes are possible: grid-feeding, when system operates as a power source connected to the grid, and grid-forming (standalone), when system operates as a voltage source supplying an islanded load. A two-level global control architecture is employed for both cases, which relies on three-phase current control in the alpha-beta frame as inner loops. Proportional-resonant (PR) controllers are used to this end. This paper discusses PR controllers design and numerical implementation and proposes a solution to deal with the parameter-varying nature of plant, exhibited especially in the off-grid case. Opportunity of using Smith predictor schemes for compensate pure delay due to digital pulse-width modulation (PWM) is also analyzed. MATLAB®/Simulink® simulation results illustrate the proposed control approach effectiveness.

In this paper an order-reduction approach for multi-variable LPV/Hinf controller ispresented and applied to design a power source coordination strategy within a multi-sourceenergy system. The energy system has three different kinds of power sources – fuel cell, batteryand supercapacitor – which compose the power supply system of an electric vehicle. All sourcesare paralleled together with their associated DC-DC converters on a common DC-link coupledto vehicle’s electrical motor and its converter. DC-link voltage must be regulated in spite ofload power variations corresponding the driving cycle. The reduced controller is found to havea special form that is consistent with the physical properties of the studied system. The ISTIAmethod (Poussot-Vassal and Vuillemin [2012]) is used here to reduce the order of the LPVcontroller. The MIMO LPV reduced controller is proved to ensure quadratic stability of theclosed-loop system. Besides, this controller could be implemented with smaller computationalburden. The nonlinear multi-source system is simulated in MATLAB/Simulink usingthe Normalized European Driving Cycle (NEDC) as load profile. Simulation shows goodperformance of the reduced-order LPV/Hinf controller to be used in power sharing strategy.

International audience; Plug-in electric vehicles (PEVs) under the vehicle-to-grid (V2G) concept, providing ancillary services such asregulation, spinning reserves and peak shaving have been subjectof many research works. However, power quality issues, such ascurrent unbalance and voltage unbalance have had less receptionamong researchers in recent years. In order to draw attention onthis matter, the purpose of this paper is to assess the economicprofit of current-unbalance-minimization strategy as a new V2Gapplication, from the point of view of PEV owners connected at acommon-connection-point (CCP) in a low voltage (LV) network.To do so, the economic profit formulation is included in a PEVsmart charging strategy for current unbalance minimization andthe new strategy is tested on LV network environment, whosespecifications are taken from French energy and distributionsystems. Results show that uncoordinated charging causes a PEVuser an average negative profit of -40 Eurocents over a day, whereasusing the CUF minimization strategy with V2G capabilities,the negative average profit, over a day, is reduced to -2 Eurocents.Moreover, positive average profit per hour is registered throughthe afternoon and evening, leaving negative average profit perhour (necessary to charge the PEV’s battery) for late night andearly morning hours when energy prices are the lowest.

This article proposes a supervisor synthesis for a two level hierarchical control structure of a grid connected wind power system to ensure its safe and optimal operation. The global hybrid dynamics may roughly be captured into a hybrid automaton. The optimization tasks, specific to different operating regimes, are performed by the low level continuous controllers. A supervisor placed on a higher level must guarantee the safe transition from an operating regime to another, triggered by some discrete events. The interest is focused on the design problem on the higher level: the discrete event modelling and the supervisor design in the supervisory control framework.

This paper focuses on a control application of optimization in wind power systems. An optimal control structure for variable speed fixed pitch wind turbines is presented. The optimality of the whole system is defined by the trade-off between the energy conversion maximization and the control input minimization that determines the mechanical stress of the drive train. The frequency separation of the short-term and the long-term variations, adopted in the wind modelling, has resulted in a two-loop control structure. The optimal problem is treated within a complete linear quadratic stochastic approach, whose effectiveness was tested on an electromechanical wind turbine simulator.

This paper presents a two loop optimal control structure for variable speed fixed pitch horizontal axis wind turbines (HAWT) having flexible drive trains. That structure, formed by a low frequency loop and a high frequency loop, is the result of the frequency separation principle adopted in the wind modelling. The optimality of the whole system is expressed by the trade-off between the energy conversion maximization and the minimization of the total load excitation that induces the drive train's mechanical stress. This optimal problem is treated within a complete linear quadratic stochastic approach, whose effectiveness was proved by numerical simulation.

The behaviour of a variable speed wind power system (WPS) has two simultaneous aspects: a stationary one, due to the seasonal (low frequency) component of the wind speed, and a dynamic one, in response to the turbulence (high frequency) component. In this paper, a nonlinear controller to optimize the stationary behaviour of a variable speed WPS is designed, which is based on the onoff control advantages. This optimization aims at maximizing the power harvested from the seasonal wind speed. The closed loop system is analysed by using the describing function method along with a linearized model of the nonlinear plant. An improved control law is proposed to robustify the system to parametric uncertainties. Both numerical and real time simulations have been performed to show the effectiveness of the proposed approach.

International audience; This paper deals with an Extremum Seeking Control MPPT algorithm for grid-connected PV systems without intermediary DC–DC converter stage. The method uses the DC-link voltage ripple as dithering signal, which “naturally” results from the grid inverter operation. A thorough analysis emphasizes the significant variation of system behaviour with the irradiance. Relevant control design guidelines and necessity of an adaptive control approach for fast-changing irradiance tracking emerge from this analysis. MATLAB/Simulink numerical simulations are presented in order to illustrate the closed-loop dynamic performance under various scenarios, which also allows for assessing advantages and limitations of the proposed method.

The problem of optimal design of the assembly lines is considered. The paper is especially focused on the line balancing and resource planning step for the preliminary design stage. A survey of existing methods is given.

This paper deals with a particular class of manufacturing lines governed by some typical rules so that they balance themselves. Such lines are also called "bucket brigades". The self-balancing means the autonomous functioning at a steady production rate, that is called stationary behavior. Their state trajectories are piecewise continuous in between occurrences of certain discrete events. That is why such manufacturing lines may be modeled as hybrid dynamic systems with autonomous switching and autonomous impulses (jumps)- The hybrid model allows that a stability analysis be approached. A sufficient condition to reach the stationary periodical behavior is proved.

This paper proposes a discrete-event based approach of modeling and control for continuous processes. The main idea consists in obtaining a discrete-event model for a continuous plant which is to be controlled by an event based supervisor. The process has to be handled by means of discrete event systems theory and, in order to achieve that, the discrete event modeling (DEM) formalism is proposed. Once the closed-loop system is designed, it is necessary for its structural properties being proved. One example is provided: a supervisory control strategy for a refrigerating plant. Some simulation results are also presented.

International audience; This paper provides adequate information about the problem of real-time replicating in laboratory conditions. The dynamic behavior of stand-alone low-power wind energy conversion systems (WECS) in response to the wind speed variations and also to the electrical load variations is replicated. The investigated system consists of a variable-speed wind turbine based on a permanent-magnet synchronous generator (PMSG), a diode bridge rectifier, a DC-DC step-down converter and a wide range DC load. Because of reduced noise level and better steady-state accuracy, a speed-driven hardware-in-the-loop physical WECS simulator has been used to accomplish this task. Its significant drawback - that is, a reduced bandwidth - has been significantly alleviated by using an enhanced software simulator structure which uses a feed-forward compensation of the inherent physical disturbance produced by the generator torque variations. Both time-domain experimental results and a thorough frequency-domain error analysis show good replication performance in the frequency range of variation of both wind speed and electrical load.

International audience; Circuit breakers are ubiquitous elements used for ensuring safe operation of low-voltage power systems. Nowadays the loads supplied by the power systems migrate towards exhibiting significant strong nonlinear behavior accompanied by inrush currents or high-order harmonics that can cause a false tripping of circuit breakers. It is thus necessary to study the interaction between these new loads and the protection devices in order to fully assess their compatibility. Following this context, this paper deals with a new test rig dedicated to protection switching devices, which is based on the hardware-in-the-loop real-time simulation concept. The proposed approach is focused on replicating the tripping conditions of a real circuit breaker coupled to a power system emulated by means of a real-time simulator. The software part of this simulator adds flexibility to the test rig as the circuit configurations and the operating scenarios may conveniently be adapted at lowest cost. The control of the interface between the software simulator and the hardware under test, as well as the closed-loop stability issues, has been thoroughly approached. Experiments carried out on this test rig show the effectiveness of this new test prototyping concept in characterizing real circuit breakers behavior when they protect lighting circuits.

International audience; This chapter focuses on the formulation and solving of the main control problems specific to low-power wind energy conversion systems (WECS) depending on their use either for grid-connected or for stand-alone application systems. This chapter approaches three classes of problems - namely, the low-power WECS specificity, operation of low-power WECS within grid-connected applications and use of low-power WECS as parts of stand-alone multi-source systems supplying isolated loads - with special focus on the associated control problems. A comprehensive synthesis of main results from the literature is aimed at, also giving the opportunity of presenting some results obtained by the authors.

International audience; This 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).

International audience; This 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.