Papers by Constantinos Sourkounis
Grid-supporting control structures with application in variable-speed wind turbines are in the fo... more Grid-supporting control structures with application in variable-speed wind turbines are in the focus of research to cope with the challenges that arise with the ever-growing integration of renewable energy sources in the electricity grid. Among others, the virtual synchronous machine has been pro-posed to emulate the behavior of conventional synchronous generators connected directly to the grid. Its application in variable-speed WTs requires an adaption of the overall control structure including also the controlled variable of the machine-side converter. Because of the growing nominal power, wind rotor dimensions and stochastic aerodynamic loads, the control of the assets also has to minimize the mechanical loads to attain a sufficient lifetime and to ensure an economic operation. Various control structures are proposed in research investigations for an active damping of torsional oscillations of the drive train, but they are mainly based on conventional control structures without grid-supporting methods such as the VSM. Therefore, in this paper a PID-shaft torque control is analyzed as additional controller of a variable-speed WT with a grid-side VSM and a cascaded machine-side control structure.
PCIM Europe 2014; International Exhibition and Conference for Power Electronics, Intelligent Motion, Renewable Energy and Energy Management; Proceedings of, May 20, 2014
This paper presents the effects of DC-Quick-Chargers (DCQC) for Electric Vehicles (EVs) on the gr... more This paper presents the effects of DC-Quick-Chargers (DCQC) for Electric Vehicles (EVs) on the grid connection, including assessments of the grid relevant harmonics as well as the high frequency behavior in both voltage and current. Furthermore, the behavior of DCQCs is evaluated at different short-circuit-line dimensioning. The efficiency and reactive power is also taken into account.
Modern, advanced digital control approaches for (multi-level) Voltage Source Converters (VSC) suc... more Modern, advanced digital control approaches for (multi-level) Voltage Source Converters (VSC) such as the Model Predictive Control (MPC) have been strongly investigated in the recent years. In this paper, we analyse a finite control set MPC approach, which has been implemented with an exhaustive search algorithm. Regarding the prediction model, a hybrid modelling approach is investigated, i. e. the complete plant model combines both, the discrete switching characteristics of the VSC as well as the DC-link, output filter and grid dynamics. To account for measurement and computational delays, a predictive compensation strategy is proposed. The overall control is implemented on an FPGA, taking advantage of its parallel processing capability. The major design philosophy of the VHDL implementation to face the high computational burden of the algorithm is discussed. Simulations and experimental studies have been carried out to benchmark various design parameters and validate the simulation.
IECON 2020 The 46th Annual Conference of the IEEE Industrial Electronics Society, Oct 18, 2020
Variable frequency drives in industrial speed-controlled applications with high reduction gear ra... more Variable frequency drives in industrial speed-controlled applications with high reduction gear ratios – which are often used in case the driven process demands for high torques – are prone to extensive and lightly damped mechanical oscillations. This is due to the low process-side inertia and notable gear play, which both encourage excitation of the lowest mechanical resonance frequency. Moreover, it is well known, that a significant active damping contribution is hardly realizable through tuning of a classical PI speed controller. Due to multifaceted requirements with respect to control objectives and mandatory robustness properties, ℋ∞ theory appears to be a promising instrument for the design of an advanced speed controller for such systems. Therefore, this paper presents a ℋ∞ theory-based speed control design methodology. A drive system example with very low load-side inertia is chosen in order to demonstrate the effectiveness of the presented control approach.
This paper presents a user-friendly solution for the generation of individually tailored intermod... more This paper presents a user-friendly solution for the generation of individually tailored intermodal mobility solutions involving various mobility providers. This consists of three essential elements. The users request the route planning via an interactive communication platform (smartphone- and web application), book one of the given solutions and pay for it as a bundle. Preferences or boundary conditions, such as the necessity of accessibility, can be specified by the users. A cloud-based data management system (CDMS) serves as a central interconnection and computing unit. Here, the offers of various mobility providers, including local public transport, car and bike sharing providers, as well as real-time data from various modes of transport are bundled and used to calculate reliable, tailor-made overall solutions for users. The real-time data also includes states of charge and the current charging power of electric vehicles as well as the utilisation of the charging infrastructure and the supply network. Thus, the CDMS also promotes smart charging and grid services with vehicle batteries. Users are guaranteed a sufficient state of charge at the start of the journey. For vehicle owners, vehicle parking also becomes a business model by permitting the distribution network operator to use the rechargeable battery. A mobility and energy module (MEMo) serves as an interface for providing the necessary data of the vehicles and the infrastructure to the CDMS and for transmitting the control signals from the CDMS.
Nowadays, adjustable speed drives are the driving force behind many technical advances in fields ... more Nowadays, adjustable speed drives are the driving force behind many technical advances in fields such as renewable energy or electric mobility. In many applications, flexible drivetrain structures and highest process demands encourage or even force the implementation of advanced motion control strategies. Highly accurate and yet low-order models of the mechanical drivetrain models are a key component of such control approaches. In this paper the two well-known concepts for the derivation of a mechanical minimum-order model are briefly presented and compared against the background of an application in state estimation for advanced motion control.
Electric vehicles (EVs) and their application raise new questions and pose many new demands. Acco... more Electric vehicles (EVs) and their application raise new questions and pose many new demands. Accordingly, the increasing amount of charging processes by EVs is a new and growing impact on the grid load. In order to deal with this impact and the resulting demands, load shifting allows the grid load to be adjusted. Taking this into consideration this paper initially analyzes, based on field test measurements, the EVs' occupation and extracts the times they are parked at a charging point. Combining this with the EVs' charging power, options for load shifting are discussed and emulated based on real data. The database includes charging processes of 500 people and a 785.000 km mileage of pure battery electric vehicles with a DC fast-charging option and extended range electric vehicles. The results indicate that EVs can partly be used as grid controlled load without changing the utilization.
Extended range electric vehicles offer the possibility to generate electrical energy with a setup... more Extended range electric vehicles offer the possibility to generate electrical energy with a setup of combustion engine and generator when the state of charge of the traction battery is low. As a result, the overall range can be extended to familiar values. The dimensioning of the purely electric range, i.e. the possible cruising range without use of the combustion engine, has much influence on the selling price and on the possible amortisation of the higher initial costs with respect to a comparable conventional car. In this paper, driven distances and consumptions of extended range electric vehicles which were measured during a field test are presented and discussed. The vehicles were used by private persons and by companies. A cost analysis is conducted to identify the necessary electric range for an early amortisation.
This paper presents a systematic evaluation of the impact of low power supply quality on electric... more This paper presents a systematic evaluation of the impact of low power supply quality on electric equipment in industrial production systems. Existing classifications of power supply quality are reviewed and compared. Phenomena of power supply quality relevant for industrial processes are deduced and examined in greater detail. The interaction process of distortions and electric equipment is presented and categories of susceptible equipment are proposed. Based on these selected groups of both, power supply quality phenomena and electric equipment, the individual influences on electric equipment in production systems are presented in matrix form. These matrix results serve as a crucial foundation for the in-depth investigation of the impact of low power supply quality and its propagation within individual production processes.
ATZ worldwide, Sep 29, 2017
The growing number of applications for battery systems requires, among others, more safety measur... more The growing number of applications for battery systems requires, among others, more safety measures, precision in detecting the current state of the cells and longevity. The growing number of requirements results in increasing complexity of the battery system. At the Ruhr University Bochum, a topology has now been developed that allows cell balancing and monitoring to occur simultaneously and therefore not only reduce the complexity but to achieve a better utilisation of the battery system with simultaneous cell loading through the active cell balancing concept.
Przegląd Elektrotechniczny, 2009
IEEE Transactions on Industry Applications, Jul 1, 2016
A space vector based bang-bang controller, driving a rotating target system (space vector bang-ba... more A space vector based bang-bang controller, driving a rotating target system (space vector bang-bang controller with flux aligned hysteresis shape SVBF) such as a machine or an acpower-supply is discussed in this paper. A two-level, three-phase conventional inverter is used as means of power conversion. The advantages such as a low switching frequency as well as further opportunities of the SVBF are specified. The results show the high degree of flexibility and potential for the SVBF in future applications.
IECON 2019 - 45th Annual Conference of the IEEE Industrial Electronics Society
This paper presents a relaying algorithm Based on Artificial Neural Network (ANN), and Adaptive N... more This paper presents a relaying algorithm Based on Artificial Neural Network (ANN), and Adaptive Neuro-Fuzzy Inference System (ANFIS) techniques for the protection of transmission lines. A feed-forward ANN with six inputs and eleven outputs has been developed for the detection and classification of faults. Data has been generated by simulating a 400kV, 50Hz, 100 km transmission line in PSCAD/EMTDC at a sampling frequency of 2kHz. ANN has been found with an accuracy of 100% for fault detection and classification in both training and testing phases with the relay operating time of 12.5ms. ANN has been further trained and tested using full data. Two-fold cross-verification was carried out. An accuracy of 100% was obtained on testing with a 12.5ms delay each time. In addition, the adaptive neuro-fuzzy Inference system with the same inputs and outputs with the ANN has been developed for the detection and classification of faults. The optimum number of epochs for both testing and training was found to be 5 with a training error of 0.0038754, and a testing error of 0.081. ANFIS has the least error, high accuracy, least number of epoch and faster than ANN.
2020 Fifteenth International Conference on Ecological Vehicles and Renewable Energies (EVER), 2020
In most of the purchasable electric vehicles a kind of drag torque emulation is implemented, i.e.... more In most of the purchasable electric vehicles a kind of drag torque emulation is implemented, i.e. the regenerative brake already works when the accelerator pedal is released and not only when the brake pedal is pressed. The effect of that drag torque on the energy consumption is analyzed for several cooperative braking systems with differently developed blending of the torque generated by the mechanical friction brakes and the torque generated by the electric drive train. By means of simulations, it is shown that the drag torque reduces energy consumption, mainly when using simple braking systems. With advanced systems, it can be counterproductive. The positive effect for an electric vehicle with a simple braking system is validated by means of measurements.
IECON 2019 - 45th Annual Conference of the IEEE Industrial Electronics Society, 2019
This paper presents a review based on Axial Induction Control (AIC), Wake Redirection Control (WR... more This paper presents a review based on Axial Induction Control (AIC), Wake Redirection Control (WRC) and artificial intelligence to support operation and optimal control of a wind farm. In addition to that, a simulation is carried out using Sim Windfarm in Matlab/Simulink, to generate a wind farm model with 8 wind turbines based on the NREL 5MW reference turbine. The data generated from the model consists of 24 measured values of wind speed and total power production by the wind farm. The main objective of the simulations is to generate data that can be used to predict the power output of the wind farm. The power prediction is done using nonlinear auto-regressive network with exogenous inputs (NARX) neural network, in which the measured wind speed is used as input to the NARX network, while power production is used as a target. The NARX configuration is based on a two-layer feed-forward network, with a sigmoid transfer function in the hidden layer and a linear transfer function in the output layer. The NARX network performs a one step ahead prediction for 1.25 seconds with small error. The prediction result indicates a good performance as confirmed by the error autocorrelation plot, regression graph and the response plot generated by the network. This prediction can be used to improve WRC, AIC, or turbines control in the range of seconds.
Przegląd Elektrotechniczny, 2009
Przegląd Elektrotechniczny, 2009
This paper contains a concept for a test bed of DC-Quick-Chargers (DCQC). The test bed is a speci... more This paper contains a concept for a test bed of DC-Quick-Chargers (DCQC). The test bed is a special build-on for DCQC to analyse the behavior of this kind of charger. It is possible to vary the output power by means of a controller. For this reason, it is an advantage to adjust different load rages up to 50kW.
Uploads
Papers by Constantinos Sourkounis