Modelling and simulation of a power converter for variable speed hydrokinetic systems

Conference ProceedingsThis study presents the control scheme model of a micro-hydrokinetic turbine system equipped with a permanent magnet synchronous generator (PMSG). A power conversion system model is developed to allow a variable speed hydrokinetic turbine system to generate constant voltage and frequency at variable water speeds. A DC-DC boosting chopper is used to maintain constant DC link voltage. The DC current is regulated to follow the optimized reference current for maximum power point tracking (MPPT) operation of the turbine system. The DC link voltage is controlled to feed the current into the load through the line-side pulse width modulation (PWM) inverter. The proposed scheme is modelled and simulated using MATLAB/Simulink. The results show a high quality power conversion solution for a variable speed hydrokinetic river system

Flatness based control of a variable speed micro hydrokinetic generation system

Conference ProceedingsIn this paper, the concept of differential flatness is applied to a controller with the aim of producing constant voltage and frequency from a hydrokinetic with permanent synchronous generator submitted to variable water flow. The idea of this concept being to generate an imaginary trajectory that will take the system from an initial condition to a desired output generating power. The results show that, the generated output is dynamically adjusted during the voltage regulation process. The advantage of the proposed differential flatness based controller over the traditional proportional integral (PI) control is that decoupling is not necessary, as demonstrated by the modelling and simulation studies under different operating conditions, such as changes in water flow rate

A survey of differential flatness-based control applied to renewable energy sources

Conference ProceedingsThis paper presents an overview of various methods used to minimize the fluctuating impacts of power generated from renewable energy sources. Several sources are considered in the study (biomass, wind, solar, hydro and geothermal). Different control methods applied to their control are cited, alongside some previous applications. Hence, it further elaborates on the adoptive control principles, of which includes; Load ballast control, dummy load control, proportional integral and derivative (PID) control, proportional integral (PI) control, pulse-width modulation (PWM) control, buck converter control, boost converter control, pitch angle control, valve control, the rate of river flow at turbine, bidirectional diffuser-augmented control and differential flatnessbased controller. These control operations in renewable energy power generation are mainly based on a steady-state linear control approach. However, the flatness based control principle has the ability to resolve the complex control problem of renewable energy systems while exploiting their linear properties. Using their flatness properties, feedback control is easily achieved which allows for optimal/steady output of the system components. This review paper highlights the benefits that range from better control techniques for renewable energy systems to established robust grid (or standalone generations) connections that can bring immense benefits to their operation and maintenance costs