Over the last few decades, the consolidated goal of reducing greenhouse gasses has increased the relevance of renewable energy research, electromobility, energy storage, and distributed generation, micro-grids, among others. Micro-grids, systems working in islanding mode, are particular cases where some disadvantages are present due to the wide variations which may appear across their electrical quantities. Variations on the voltage amplitude and the frequency are intrinsic in the operation of weak grids, because they have low inertia and therefore the load must be able to cope with these variations, otherwise loads may trip electrical system protection. Particularly, on power electronic drives, these frequency deviations will lead to increased system nonlinearities, entailing a more critical controller design. To overcome these issues, this paper presents an implementation of a resonant controller with self-tuned gains. The strategy imposes a constant sampling time which allows these controllers to be used in variable frequency environments. In addition, the computational capacity required for the digital board is also considered. The simulated and experimental results provided demonstrate the good performance of this proposal.

Power converters have turned into a critical and every-day solution for electric power systems. In fact, the incorporation of renewable energies has led towards the constant improvement of power converter topologies and their controls. In this context, over the last 10 years, model predictive control (MPC) is positioned as one the most studied and promising alternatives for power converter control. In voltage source inverters (VSI), MPC has only been applied in the inner current control loop, accelerating and improving its dynamic response, but as mentioned, has been limited only to the current control loop. The fastest of the MPC techniques is the Deadbeat (DB) control, and in this paper, it is proposed to employ DB control on the entire system, therefore accelerating the time response not only for the current loops, but also for voltage loops. At the same time, this avoids overshoots and overpower in order to protect the power converter, leading to the fastest dynamic response according to VSI capabilities. For renewable energies, fast-dynamics entails fast maximum power tracking and therefore, maximizes energy harvesting, or in other words, reduces the losses due to the control dynamics. Thus, this paper gives a clear procedure and key points for designing a DB control for all the variables based on a mathematical model, which is corroborated by simulations and the experimental results.

This article presents a systematic control design procedure for an active front-end (AFE) converter connected to a power electronics embedded grid. A parametric model of the grid is first identified using the AFE itself to excite the system. This model is then integrated with the AFE one in order to obtain a global system representation. Subsequently, a globally optimized local controller is synthesized for the AFE keeping in consideration the interaction between the converter and the grid. The proposed method is finally tested experimentally, and its performance is compared with a traditional proportional–integral controller in a $dq$ synchronous reference frame.

Embedded electrical grids are comprised of multiple interconnected power converters, and have been recently adopted widely into applications such as micro-grids, electrical ships and More Electric Aircraft (MEA). Key aims of MEA research include reducing the overall size and weight of the electrical system without compromise to performance. H ₂ control optimization have been gaining large attention in the development of controllers for such systems. In this paper, a comparative review between decentralised optimal H ₂ controllers, and more traditional PI control method for a three-phase embedded grid in MEA shall be undertaken. The comparison involves investigating the tuning process, the implementation, the performance and the capability of reducing the overall size and weight of the system. H ₂ controls are being designed with full knowledge of the system dynamics and interactions, and is expected in theory to deliver greater capability to meet MEA core research objectives, in contrast to traditional PI methods.

This paper deals with the impact of harmonic filters interactions in the aircraft grid, in particular, their influence on the control performance of each subsystem. The study has been carried out on a notional electrical system composed by two three-phase power converters a Voltage Source Inverter (VSI) and an Active Front End (AFE). The beginning of the paper presents the origin of the issue trend of reducing the filter size and weight, which is especially true in aircraft industry. Then, roles of the filter and their design challenges are discussed. Next part of the paper describes the controller constraints, its design and the control system modelling approach including specially developed simulation tool used for the interactions analysis. Simulation results with the experimental verification are presented showing the interactions impact on the system dynamics. Finally, optimization of the filters under dynamic control constraints considering systems components interaction presented as the simulation tool application.

Electrification of non-propulsive aircraft systems has resulted in the increased proliferation of power electronics embedded grids on aircraft. Typically, power converters on these networks are optimised locally without consideration to the wider grid dynamics, which as a result increases the interactive effect between sub-systems. Filters are typically used to decouple these interactive effects, however since weight is a key design factor for aircraft, filters are typically reduced in size, further increasing interactive effects. Recent studies into H $_2$ control, due to its ability to develop decentralised controls whilst considering the global grid dynamic model, have shown to reduce these interactive effects, however studies concentrate only on fixed frequency systems, atypical to modern variable frequency grids on modern aircraft today. In this paper, H $_2$ optimisation is used to optimise a target converter to a pre-designed converter generating the variable frequency AC bus. The proposed method shows that not only are interactions reduced on the target converter for all frequencies but allows the pre-designed system to run as designed without detrimental performance, even during large power transients for full range of frequencies. This paper includes mathematical derivations, key design points, and has been validated and compared against other popular controls by experiment.