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.

Variable-speed microhydropower energy systems have recently received significant attention in the renewable energy field, due to its overall efficiency and great potential available worldwide. This emergent technology combined with maximum power point tracking (MPPT) techniques allows us to replace the burden classical governing mechanical systems, being a very effective way of ensuring high energy efficiency when operating in free water flows. In this paper, a variable-speed microhydropower plant based on a semi-Kaplan turbine is employed and a novel adaptive high-performance MPPT technique is proposed. This allows high tracking quality due to superior dynamic response and high output power quality due to steady-state oscillations cancellation. This approach has been experimentally validated by using a dedicated test rig.

Variable speed micro-hydropower energy systems have recently received significant attention in the renewable energy field, due to its overall efficiency and great potential available worldwide. This emergent technology combined with direct power control allows simplifying the burden classical governing mechanical systems, and avoiding the speed control loop. In this paper, a “run of river” variable speed micro-hydropower plant (MHPP) based on a semi-Kaplan turbine is employed and a direct power control combined to a MPPT technique is proposed. This allows high tracking quality due to superior dynamic response. This approach has been experimentally validated by using a dedicated benchmark.

This paper deals with a renewable energy conversion system based on cross-flow water turbines operating in a river stream. Two twin vertical towers, each of which is composed of four such turbines, need to meet an imposed restriction between their angular positions (synchronization) in order to achieve improved hydrodynamic performances. The synchronization is achieved by a control approach, without using any power coupling (mechanical or electrical) between the two towers. As each tower is equipped with a permanent-magnet synchronous generator which delivers electrical power to the grid through a back-to-back power electronics converter, their rotational speeds can be controlled such that to achieve angular position synchronization. Being similar to the phase-locked loop devices used in electronics, the proposed method has been tested on a power hardware-in-the-loop simulator dedicated to cross-flow water turbines and proved good potential for being easily and effectively used in practice due to its simplicity and reliability.

This paper proposes a new method of controlling cross-flow-water-turbine (CFWT)-based generation systems, having fixed pitch, by power regulation. The method consists of directly controlling the electrical generator power, as imposed by a dispatcher, without employing an inner rotational speed control loop. The proposed control approach represents the base for the operation framework (i.e., output power and rotational speed limitations, start-up, and stopping) for the entire operating range up to the cut-out water flow speed. A permanent-magnet synchronous generator is used in this paper. The system is operated at low rotational speed values, i.e., in the so-called hydrodynamic stall region, where mechanical and hydrodynamic stresses are lower. Given that this region corresponds to an unstable dynamic behavior, the power regulation relies upon an inner loop of rotational-speed stabilization. Consequently, the innermost (electrical machine current) control loop is fed by a reference having two components, namely, the driving and stabilization currents. The embodied control laws and the output power and rotational speed limitation sequences have been experimentally validated on a real-time simulator of CFWT-based generation systems.

Wind Farm -Impact in Power System and Alternatives to Improve the Integration 110 work considers optimal operation of wind storage system as an optimization problem that deals with primary sources, storage capacity as well as demand.The main objective is to meet grid requirements in term of limiting the fluctuations and providing possible ancillary services.The intermittency management will be assessed into two steps: anticipation phase and reactivity phase.The first one, which will generally be done at Month-1, Week-1 or Day-1, consists in using forecast information (weather, network demand …) to define the optimal operation schedule for wind -storage system.On real time operation, the system has to deal with possible vagaries and take the right adjustment control with actual capacity.The problem is complex with numerous discrete control variables and continuous ones.A mixed-integer linear programming (MILP) is used to efficiency solve the problem.An example is given to illustrate the proposed method.Results indicate that wind power with storage can meet the network requirements while best ensure its profits.Results also show that the proposed optimal operation strategy which limits considerably the fluctuations on power system will facilitate the integration of more wind power.In this chapter, we deal with a wind system combined with a hydraulic storage (we name the system W+S since now) where the input is the network demand power and the output is the provided wind power.This system has to response to the management requirements in taking into account the wind vagaries, the storage and de-storage capacity, the energetic cost of the flux transfer and highlighting economical efficiency.

This paper deals with a generation system based on cross-flow water turbines (CFWTs) operating in a river stream. It is equipped with a permanent-magnet synchronous generator and can feed a power grid or an insulated load through a back-to-back power electronics converter. This paper concerns the control of these two operating regimes with focus on the manner of achieving a soft switching between them, in order to ensure the balance between the generated and the provided power and to alleviate transients. The control laws and the switching sequences have been experimentally validated on a real-time CFWT simulator equipped with the same type of generator and power electronics converter. This paper aims at offering a synthetic vision of how the CFWT-based generation system should be controlled across the main operating regimes in order to preserve its continuity of service.

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.

The paper investigates the performance of variable speed wind turbine (VSWT) configuration with DC-DC converter under restricted output power conditions. The considered regimes of turbine operation are: at maximum available aerodynamic power and at limited output electric power. The wind turbine system consist of synchronous generator (SG) connected to diode rectifier, DC chopper and load. Two different control methods are used: with predefined turbine characteristics and with fuzzy logic controller. The turbine controllers combine the maximum power point tracking (MPPT) and limited power point tracking (LPPT) algorithms. The performance of the dynamic models and the control loops are tested under various wind conditions. The simulation results are shown. The results prove the strategy and models reliability.

The paper studies the performance of variable speed wind turbine (VSWT) configuration with non-inverting buck-boost converter. The wind turbine systems consist of permanent magnet synchronous generator (PMSG) connected to diode rectifier, DC chopper and load. New control strategy, based on the maximum power point tracking (MPPT) and limited power point tracking (LPPT) algorithms is used to improve the system operation. When necessary to limit the power injected to the grid, due to system operator demands, a control unit is implementing to switch between two regimes of wind turbine operation: at maximum power and at limited power. The MPP tracker is simple perturb and observation (P&O) controller in combination with two optimum wind turbines power/torque versus speed characteristics. Two control loops: inner feed forward current control loop and outer voltage control closed loop are applied for the non-inverting buck-boost converter. The performance of the dynamic models and the control loops is tested under various wind conditions. The simulation results are shown. The results prove the strategy and models reliability.

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.

The real-time wind turbine simulators are enabling the testing of wind energy conversion systems’ (WECS) control units and of the associated control algorithms in a controlled environment. It is known that a simulator can predict the behaviour of an industrial system subjected to certain operating conditions before its real-world implementation. But, the main motivation of using physical simulators for wind energy applications, resides within another argument. It is about the fact that a dedicated laboratory setup can provide something that does not exist in real-world applications: controllable wind velocity. So, a wind turbine physical simulator offers a prime mover which behaves as a “wind-turbinepowered-like shaft” (Nichita et al., 2002), allowing the static and dynamic characteristics replication of a mathematically-modelled wind turbine. This is the great advantage of such simulator as it replaces very expensive parts – such as the turbine rotor and the drive train – operating in a stochastic environment by conveniently-controlled electrical motors, operating in a controlled environment. This allows the repetitive experiments being carried out independently from wind and meteorological conditions in a most safe laboratory environment. Besides its prime mover, all of the physical WECS elements are present in the physical simulator as they are in the real-world application. Therefore, the electromechanical part of the generation chain exhibits the real phenomena presented in a wind power system. In this way the above-listed advantages are not faded by replicating a simplified electrical behaviour and a WECS-dedicated control unit will interact with a genuine wind power system. When analyzing the concerned literature, one can note that the preliminary experimental validation of WECS control laws is always performed on wind turbine simulators. This is a reason for quite rich literature being dedicated to this subject. One can find two types of papers dealing with small-scale WECS simulators for different generation configurations. The first category is composed of works focusing on test rig building aspects (Leithead et al., 1994; Battaioto et al., 1996; Rodriguez-Amenedo et al., 1998; Diop et al., 1999a; Akhmatov et

Power systems today are undergoing a full mutation, primarily due to the opening of power markets, evolution of technology, exhaustion of natural resources, and dramatic changes in climate. In order to respond to these challenges, countermeasures that leverage power electronic converter technology must be taken at all the levels of the power system: generation, transport and distribution. Due to their innovative character, these solutions require powerful analysis tools, well adapted to the multitude of involved dynamics. The current paper proposes and analyzes the use of a real-time Power Hardware-in-the-Loop (PHIL) simulator for a wind park generation power system, in order to face these complex requirements.