Topics for Bachelor and Master Thesis Projects

You can pursue your Bachelor and/or Masther thesis project in the areas of Control Systems and Network Control Technology at our group. We appreciate your interest and can offer you the following current topics:

Adaptive observer design for distributed energy resources (B.Sc. or M.Sc.)
ContentResp.
The transient behavior of distributed energy resources (DERs), such as wind or photovoltaic parks, mayorly impacts the stability of the electric grid. Thus, the knowledge of the dynamics of the DERs is critical for the distribution system operator (DSO) for monitoring and reliable operation. Nevertheless, the dynamics are only verified once when the DERs are installed and inspected. Afterwards, changes of equipment, updates of the utilized software or aging can have a significant influence on the dynamic behavior and thus render the dynamics identified after the installation as infeasible.

This thesis aims at deriving a simplified model of DERs and designing an adaptive observer for this model to estimate the states and the unknown parameter of the DERs online. Using this adaptive observer, it should, thus. enable the DSO to update the dynamic models of the DERs continuously. The algorithm should be implemented and simulated in a case study.

If this topic is chosen for a bachelor thesis it should be assumed that voltage and current measurements are available at the terminal bus of the DER. If it is chosen as a master thesis it should be assumed that within the electric grid measurements are only available at some but not all of the buses. So, in an additionally first step these measurements should be used to estimate the voltages and currents at the terminal bus of the DER. For this an existing solution from the literature could be utilized. 
M.Sc. Nicolai Lorenz-Meyer
Design of observers for synchro-generators (M.Sc.)
ContentResp.
Observers of systems are used in several practical problems. For example, consider the theoretical state controllers with feedback: In the classical assumption, they are able to measure all system states needed to compute the corresponding control signal, so the implementation depends on them. In practice, however, this is not the case, as only a few states can be measured. This is due, for example, to the high cost of the necessary sensors or the lack of commercial sensors that can measure this variable. Therefore, an observer is needed that can implement the feedback state controllers. 

Another application of observers is the determination of faults in physical systems, where the observer simulates the expected behavior of the system. The objective of this project is to design an observer for synchronous generators of a nonlinear electromechanical system. The observer is simulated and analysed using Simulink/Matlab. Since generators are ubiquitous in electrical power systems, their study is essential in industry. 
Dr. José Ángel Mercado-Uribe
Comparison of local controllers for nonlinear electrical and mechanical system (B.Sc.)
ContentResp.
In general, non-linearity terms are widely used in mathematical models. Although some control theories deal with them, there is no extensive theory for coltroller design as in linear control theory. Therefore, one strategy to solve this problem is neglecting the presence of these terms so that the system is locally linearised by Taylor's series around the desired point, which allows designing the local controllers by using all well-known linear control theories. This thesis aims to compare two or three well-known linear controllers applied to electrical and mechanical systems. The controllers are going to be analysed and compared using Simulink/Matlab. Among the properties that will be considered are: the steady-state error, the velocity and region convergence, and the energy used by the controllers.  Dr. José Ángel Mercado-Uribe
Energy saving in multi-agent system in optimal coverage tasks (M.Sc.)
ContentResp.
UAVs (unmanned aerial vehicle) are increasingly being used in more and more areas. In surveillance or search activities they can be used to cover a specific area of a given terrain. There are some algorithms that allow to determine the optimal areas for each UAV, depending on the number of UAVs and the greater or lesser importance of the different points of the terrain. However, the way in which the UAVs must cover such areas based on energy autonomy has not yet been studied in depth. Within this project the different alternatives in which the energy autonomy is taken into account should be tested and analysed.Dr. Rolando Cortés Martínez
Leader-follower control of UAV under constrained scenarios (B.Sc.)
ContentResp.
In the leader-follower scheme a group of UAVs (unmanned aerial vehicle) must follow the leader in different formation schemes. However, if the environment in which they operate is constrained by walls and other obstacles, the followers must reconfigure the formation. The objective of this work is to analyse the various techniques to achieve this goal without compromising the following control task.Dr. Rolando Cortés Martínez
Modelling an islanded DC microgrid under a grid-aware energy management strategy (M. Sc.)
ContentResp.
With the growing awareness about environmental concerns, the use of renewable energy sources (RESs) as distributed generation units (DGUs) has significantly increased in recent years. The concept of microgrid (MG) represents a popular solution for integrating large shares of DGUs, energy storage systems (ESSs) and loads into a single controllable entity that can operate in a grid-connected or islanded mode with respect to a larger transmission network. DGUs are interfaced with the MG via power converters, which can adopt two different operation modes: namely grid-forming (voltage control) or grid-following (current control).

In the islanded case, a correct management of the MG energy resources is of high relevance due to the lack of a large power reserve provided by the transmission network. In this regard, employing a flexible and grid-aware control strategy for the MG represents an attractive solution. That is, a supervisor algorithm monitors relevant variables within the MG, e.g., power generated by RESs, state-of-charge of ESSs, voltage at the common bus, etc. in order to estimate the MG performance. Then, the performance is assessed by a set of logical rules which enable the DGUs to modify their operation mode in order to maintain a desired MG operation. The goal of the present project is to derive the dynamic model of an islanded DC MG composed of DGUs, ESSs and loads that operates under a grid-aware energy management strategy. Particular attention must be assigned to the grid-aware conditions which ensure the existence of equilibrium point(s). 
 
M. Sc. Ismael Jaramillo-Cajica
Development of a graphical user interface for the power-hardware-in-the-loop testbed facility at BTU (B.Sc.)
ContentResp.
With the goal of reducing the greenhouse emissions and fossil fuel consumption in the area of energy systems, the use of renewable energy sources (RESs) has remarkably increased in recent times. The physical properties of RES-based distributed generation units (DGUs) largely differ from those of conventional synchronous generators. Therefore, large scale power systems demand novel control techniques and operation strategies in order to ensure a stable operation. Moreover, the substantial changes in the system properties makes simulation-based analysis of DGU-based power systems become insufficient and thus, experimental validation through testbed facilities is required. 

Motivated by this, the Chair of Control Systems and Network Control Technology at BTU has designed and mounted a power-hardware-in-the-loop (PHIL) testbed laboratory for design, test and validation of control schemes in DGU-based power systems. As a key feature, the laboratory equipment is fully compatible with the Matlab/Simulink interface. In this regard, the goal of the present project is to design a graphical user interface (GUI) which enables the communication, display and control of the PHIL system through a Matlab/Simulink environment 
M. Sc. Ismael Jaramillo-Cajica
Non-linear control for drone in response of collision avoidance inputs (M.Sc.)
ContentResp.
One of the biggest challenges in controlling a drone is avoiding collisions with other UAVs (unmanned aerial vehicles) and obstacles. Currently there are many different methods to define a new direction. Most commonly, nonlinear controllers are used to generate a new drone-input. However, depending of the controller, the behaviour of the perturbation which is generated for the new direction have different effects on the flight of the drone. The objective of this project is to analyse different nonlinear methods for controlling drones when they are faced with obstacles.M.Sc. Oscar Fabian Archila Cruz
UAV control for problem of delay data communication and imprecision in sensor measurements (B.Sc.)
ContentResp.
Currently the use of UAV (unmanned aerial vehicle) is increasing in multiple applications. Thier use ranges from urban transport to agricultural activities. These new technologies introduce various challenges related to the capabilities of UAV technology.

In this case, we focus on the delay in data communication and the inaccuracy of sensor measurements. These problems can lead to path-planning-errors and collisions with another UAV depending on the application. The objective of this project is developing a method that decreases the control error related to the path planning and considering the inaccuracy of the current UAV-position and the delay in data transmission.
M.Sc. Oscar Fabian Archila Cruz
PLL-dependent stability of power inverters connected to voltage-weak grids (M.Sc.)
ContentResp.
To fulfil the goals of the energy transition, converter-based renewable energy sources must be integrated into the power grid to replace conventional energy generation. In order to keep a functioning grid, the converter-based energy generation sources must operate reliably and in a robust matter.

In this context, the objective of the thesis project is to investigate the stability of grid-connected inverters operating in grid-feeding mode which synchronization with the grid depends on phase-locked loops (PLL). As part of this, conditions over the inverter controllers and PLL-gains, that guarantee a stable operation, are obtained. Of special interest is the modelling of the inverter effect in the voltage at the connection point, since any fluctuation in this voltage will negatively affect the PLL performance, which in turn will result in poor inverter operation.
Dr. Juan G. Rueda-Escobedo
Versuchsstand: Mehrgrößen-Regelung (M.Sc.)
InhalteVerantw.
Für das Labor Regelungstechnik ist ein Beispielversuch zur Analyse und Synthese einer Mehrgrößen-Rege­lung zu entwickeln. Im Labor ist dazu ein Turmdrehkran-Modell vorhanden, dessen Bewegungen dreidimen­sional gesteuert werden können. Die Regelungsaufgabe könnte darin bestehen, mit einer Last jede mögliche Position im Bewegungsraum optimal anzufahren, im Sinne maximaler Geschwindigkeit der Bewegung bei minimaler Schwingungsneigung der Last.

Zunächst ist zu realen Kransteuerungen, dem typischen Verhalten und möglichen Regelstrategien zu recher­chieren. Die Ergebnisse sind in einem einführenden Kapitel zusammenzufassen.

Auf den vorhandenen Modellprozess sind geeignete Verfahren der Prozessanalyse und Modellierung anzu­wenden. Für Analysezwecke steht eine Signalerfassung über Personal-Computer in einer Matlab/Simu­link-Umgebung zur Verfügung.

Für die Regelung sind entsprechende Regelalgorithmen zu definieren, mit einem geeigneten Verfahren zu parametrieren und sowohl als Simulation, als auch am realen Versuchsstand zu testen. Dies sollte innerhalb der vorhandenen Matlab/Simulink-Umgebung erfolgen. Gegebenenfalls ist eigener Programmieraufwand notwendig. Bei erfolgreichem Test sind die einzelnen Schritte und Ergebnisse nachvollziehbar zu doku­men­tieren. Dies sollte den Hauptteil der Masterarbeit bilden.

In einem abschließenden Kapitel können Hinweise zur Einbindung in die Lehre und Vorschläge für Variationen der Versuchsdurchführung gegeben werden.

Anforderungen:
  • Grundlegende Kenntnisse aus den Modulen Regelungstechnik 1 und 2,
  • erweiterte Fähig­keiten im Umgang mit Matlab/Simulink
Angebot:
  • Arbeitsplatz und Betreuung am Fachgebiet, Hard- und Software bereits vorhanden.
   
Dr.-Ing. Uwe Rau
Versuchsstand: Kaskadenregelung (B.Sc.)
InhalteVerantw.
Für das Labor Regelungstechnik ist ein Beispielversuch zur Analyse und Synthese einer Kaskadenregelung zu entwickeln.

Zunächst ist zu praktischen Anwendungen, dem typischen Verhalten und den Vorteilen von kaskadierten Regelkreisen zu recherchieren. Anhand der Ergebnisse ist aus den im Labor vorhandenen Modell- und realen Regelstrecken ein geeigneter Prozess zusammenzustellen bzw. zu wählen.

Für diesen Prozess soll eine Kaskadenregelung entworfen und getestet werden. Dazu sind geeignete Verfahren zur Prozessanalyse und Modellierung anzuwenden. Für Simulationszwecke steht eine Matlab/Simulink-Umgebung zur Verfügung. Die Ergebnisse sind am realen Versuchsstand zu überprüfen.

Zur Regelung sind notwendige Reglertypen auszuwählen und mit einem geeigneten Verfahren zu parametrieren. Vor dem Test am realen Versuchsstand ist das Regelkreisverhalten durch eine Simulation zu überprüfen. Als Regler können sowohl Software-, Modell- als auch reale industrielle Regler verwendet werden.

Nach erfolgreichem Test sind die einzelnen Schritte und Ergebnisse nachvollziehbar zu dokumentieren. Hinweise zur Einbindung in die Lehre und Vorschläge für Variationen der Versuchsdurchführung sollen gegeben werden.

Angebot: Arbeitsplatz und Betreuung am Fachgebiet, Hard- und Software bereits vorhanden, Arbeitsaufwand kann über ein Semester gestreckt werden.
Dr.-Ing. Uwe Rau
Versuchsstand: Regelung technischer Strecken (Durchfluss, Füllstand, Luftstrom) (B.Sc.)
InhalteVerantw.
Für das Labor Regelungstechnik ist ein Beispielversuch zur Analyse und Synthese der Regelung einer realen technischen Regelstrecke zu entwickeln.

Zunächst ist zu praktischen Anwendungen und dem typischen Verhalten der Regelstrecke zu recherchieren. Anhand der Ergebnisse ist aus den im Labor vorhandenen technischen Möglichkeiten ein geeigneter Prozess zusammenzustellen.

Für diesen Prozess soll eine Regelung entworfen und getestet werden. Dazu sind geeignete Verfahren zur Prozessanalyse und Modellierung anzuwenden. Für Simulationszwecke steht eine Matlab/Simulink-Umgebung zur Verfügung. Die Ergebnisse sind am realen Versuchsstand zu überprüfen.

Zur Regelung sind notwendige Reglertypen auszuwählen und mit einem geeigneten Verfahren zu parametrieren. Vor dem Test am realen Versuchsstand ist das Regelkreisverhalten durch eine Simulation zu überprüfen. Als Regler können sowohl Software-, Modell- als auch industrielle Regler verwendet werden.

Nach erfolgreichem Test sind die einzelnen Schritte und Ergebnisse nachvollziehbar zu dokumentieren. Hinweise zur Einbindung in die Lehre und Vorschläge für Variationen der Versuchsdurchführung sollen gegeben werden.

Angebot: Arbeitsplatz und Betreuung am Fachgebiet, Hard- und Software bereits vorhanden,
Arbeitsaufwand kann über ein Semester gestreckt werden.
Dr.-Ing. Uwe Rau
Deep Reinforcement Learning in Active Distribution Grids (M.Sc.)
ContentResp.
This master thesis will be conducted in close cooperation with the Berlin-based Start-up Qantic (https://www.qantic.com/) and can be written either in English or German.

Motivation and background
In Germany, distribution grids play an important role in the integration of renewable energies. Originally designed as passive systems, they are developing into active energy grids in which not only many decentralized generation plants are connected, but also sector coupling, and other flexibility options will be implemented in the future. As a result, grid operation is becoming increasingly complex. In addition, there are often only a few measuring devices and sensors installed in low and medium-voltage grids that allow visibility of the condition of the current grid state. To be able to guarantee safe grid operation, in addition to the classic network expansion, a limitation of the feed-in power or a purchase of reactive power, among other things, are available. By means of a so-called Q/U control (Volt-Var-Control), node voltages can be influenced, e.g. in order to minimize network losses and to avoid voltage profile violations. The application of artificial neural networks (e.g. Deep Reinforcement Learning) to Q/U control is currently the subject of scientific work - in these publications the state of the network or its change of state as a result of actions (e.g. switching actions) is conceived as a sequential decision process (Markov Decision Process). The network state (e.g. the node voltages) can be changed here by actions that are clearly defined in advance (e.g., specification of a power factor). Furthermore, a metric is introduced to evaluate the quality of a respective action and the resulting network state (as a reward function). An algorithm now learns by interacting with the system to choose the actions that maximize the reward in the end. Previous work on the use of reinforcement learning in active distribution networks generally does not consider the technical and regulatory characteristics of German regulatory framework. Currently, the possibilities for active control of distribution grid operators in Germany still seem limited, as the installed resources are only capable of performing distributed Q-U control to a limited extent. On the other hand, German distribution system operators have specific instruments at their disposal to ensure grid stability (e.g. feed-in management and redispatch 2.0), which have national specificities. Accordingly, the research question of the final thesis could be: How can existing approaches in reinforcement learning be adapted to a distributed volt-var control in active distribution grids, which at the same time also comply with the German legislation.

Scope and working packages
A reinforcement learning algorithm is to be developed and implemented in the Python programming environment. Here, existing open-source implementations as well as models of Qantic GmbH can be built upon - basically, the following work steps are recommended:
  1. Familiarization with the current state of the art of volt-var control in distribution networks as well as a review of selected scientific publications.
  2. Development of a simulation of a distribution network using "Pandapower" to determine the nodal voltages; if necessary, existing topologies can be used here (https://pandapower.readthedocs.io/en/develop/networks.html).
  3. Explicit mapping of the possibilities to maintain a smooth voltage profile in German distribution grids (including specific measures such as feed-in management and redispatch).
  4. Transfer of the grid model into a simulation environment usable for reinforcement learning as a Markov Decision Process with defined state and action space as well as a reward function to evaluate voltage stability.
  5. Optimization of voltage stability with an existing open-source environment of a selected reinforcement learning algorithm 
Requirements and skillset
  1. Strong interest in machine learning topics and their application to power systems
  2. First experience in the programming language Python
  3. Basic knowledge of the structure and operation of electrical networks and their control concepts
References
[1] Gao, Y.; Yu, N.: Deep Reinforcement Learning in Power Distribution Systems: Overview, Challenge, and Opportunities, 2021, IEEE Power & Energy Society General Meeting
[2] Huang, B.; Wang, J.: Deep-Reinforcement-Learning-Based Capacity Scheduling for PV-Battery Storage System, 2021, IEEE Power & Energy Society General Meeting
[3] Gao, Y.: Safe and sample-efficient reinforcement learning for power distribution system controls, 2021, IEEE Power & Energy Society General Meeting
[4] Liu, H.; Wenchuan, W.: Robust Adversarial Reinforcement Learning for Inverter-based Volt-VAR Control in Active Distribution Networks, 2021, IEEE Power & Energy Society General Meeting
M.Sc. Nicolai Lorenz-Meyer
Matlab/Simulink toolbox for RMS simulations of power systems (B.Sc.)
ContentResp.
The current changes in power networks induced by the energy transition and the introduction of power electronic technologies had made necessary the study of such systems in a dynamical manner. Contrary to standard steady state and power flow analysis, now it is required to simulate the transient behavior of the networks with a particular interest on the response of the different elements’ controllers. One of the limitations in dynamic simulation of power systems is the lack of software tools specialized in both, power systems and automatic control. This is the case of PowerFactory, where the standard tools for power system analysis and simulation are available, but the incorporation of sophisticated control algorithms is rather difficult and obscure. On the other hand, one has Matlab/Simulink, designed to simulate complex control systems, but which lacks tools for simulation of large power networks.The purpose of the thesis is to dote Matlab/Simulink of elements for simulating transmission and distribution networks. These networks are usually simulated by neglecting the transient response of transmission lines and passive elements such as transformers, and only considering dynamical behavior in a time scale of tens of milliseconds or above. The process is usually referred as RMS-simulations. For that, the main tool would be Simscape, where the idea is to implement algebraic models of balanced and unbalanced three-phase impedances, admittances, transformers, ZIP loads, and compatible dynamical models of synchronous generators, induction motors and composite loads.Dr. Juan G. Rueda-Escobedo
Modeling and control of a bidirectional DC-DC converter for battery management (B.Sc.)
ContentDesp.
Nowadays we can find Li-ion batteries not only in a great variety of electronic devices, but also in vehicles, and soon in large scale power systems. This makes the understanding of the devices in charge of handling the charge and discharge of the batteries increasingly relevant. The goal of this work is to investigate the available technologies in bidirectional DC-DC converters for battery managements, and their implementation for dynamical simulation in Matlab/Simulink together with the associated controllers.Dr. Juan G. Rueda-Escobedo
Analysis of the algorithm to control a HV transformer tap changer in an utility scale PV plant (B.Sc. / M.Sc.)
ContentResp.
The monitoring data of a transformer tap changer, which is controlled by the power plant controller of a PV plant, shall be analyzed in Matlab in order to identify and estimate potential revenue losses. The analysis can be used to implement an improved control algorithm for the tap changer, which is then simulated and validated.Dipl.-Ing. Simo Kauth

The project work and thesis report can be done either in German or English.

For further information please get in touch with the indicated contact person. If you have an own topic proposal, we are happy to discuss this with you.