@inproceedings{HahnBurkhardtSemerowetal., author = {Hahn, Christoph and Burkhardt, Matthias and Semerow, Anatoli and Luther, Matthias and Ruhle, Olaf}, title = {Generic modeling of a self-commutated multilevel VSC HVDC system for power system stability studies}, series = {2015 IEEE Applied Power Electronics Conference and Exposition}, booktitle = {2015 IEEE Applied Power Electronics Conference and Exposition}, publisher = {IEEE Computer Society Press}, isbn = {978-1-4799-6735-3}, doi = {10.1109/apec.2015.7104728}, abstract = {This paper provides a generic stability model of a self-commutated multilevel VSC (Voltage Source Converter) HVDC (High Voltage Direct Current) and its appropriate control. At first the approach of modeling depicts the independence of the AC and DC quantities and therefore two separate models - one for the AC and one for the DC side - can be figured out. The AC side model is developed in the dq frame out of the according differential equations. For the DC side no further transformation is required. Regarding the fact of balanced energy terms the two models can be merged. The consolidation of both models reveals a comprehensive large signal model of a multilevel based HVDC system which can be used for detailed analyses in power system stability studies. Due to the comparison of the generic stability model with an EMT (Electro-Magnetic Transient) HVDC model the consistence of the dynamic behavior is shown.}, language = {en} } @inproceedings{RaabFrauenknechtWellhoeferetal., author = {Raab, Alexander and Frauenknecht, Dominik and Wellh{\"o}fer, Anatoli and Luther, Matthias and Kuri, Ananya}, title = {Hybrid EMT and Phasor based MMC-HVDC Model for Advanced Power System Simulation}, publisher = {IEEE}, abstract = {The objective of this paper is the implementation and comparison of a hybrid phasor-based (RMS) and electromagnetic transient (EMT) modular multilevel converter high voltage direct current (MMC-HVDC) model for advanced and detailed studies of large power systems. The general modeling approach for hybrid simulation of modular multilevel converters for HVDC applications with the corresponding control concepts is described. The HVDC model can be divided into AC and DC components with different simulation time steps and representation using network partitioning. The connected AC grids and converter models are considered in the phasor-based time domain, while the DC connection is simulated in the electromagnetic-transient time domain. The coupling of the models is established by the total energy control of the MMC. The hybrid approach is evaluated in comparison to an average MMC HVDC model in an EMT simulation. The results show the advantages of the hybrid model. The model can be simulated with comparatively low computational effort, while the DC transients can be represented in detail during disturbances.}, language = {en} } @inproceedings{ScheibeSemerowMenkeetal., author = {Scheibe, Christian and Semerow, Anatoli and Menke, Jasmin and La Seta, Piergiovanni and Raab, Alexander and Mehlmann, Gert and Luther, Matthias}, title = {A Novel Co-Simulation Concept using Interprocess Communication in Shared Memory}, series = {2019 IEEE Power and Energy Society General Meeting}, booktitle = {2019 IEEE Power and Energy Society General Meeting}, publisher = {IEEE Computer Society Press}, isbn = {978-1-7281-1981-6}, issn = {1944-9925}, doi = {10.1109/PESGM40551.2019.8973964}, abstract = {The paper describes a novel co-simulation concept for power system analysis using interprocess communication via shared memory. This innovative approach enables manufacturers, utilities and other parties a continuous and efficient use of simulation models within the phases of preliminary investigations, planning, design and operation. It paves the way for the practical implementation of the concept of a digital twin. Besides the technical specification of the process communication, the realization of process synchronization and the model interfaces are comprehensively discussed. Performance topics are practically treated. Finally, as an application of the novel concept, a successfully implemented study in a power system simulation tool is demonstrated in order to prove its practical feasibility.}, language = {en} } @inproceedings{SemerowWolfWellhoeferetal., author = {Semerow, Anatoli and Wolf, Thomas and Wellh{\"o}fer, Sabine and Luther, Matthias}, title = {Power system model order reduction based on dominant modes in modal analysis}, series = {2017 IEEE Power \& Energy Society General Meeting}, booktitle = {2017 IEEE Power \& Energy Society General Meeting}, publisher = {IEEE Computer Society Press}, issn = {1944-9933}, doi = {10.1109/pesgm.2017.8274669}, pages = {1 -- 5}, abstract = {Investigations of small-signal stability of electrical power systems are usually performed by modal and time-domain analysis using descriptive differential equations of machines. Thereby, the modal analysis enables the identification of all dominant states of the linearized power system model, which are associated with electromechanical interactions and power oscillations. For reasons of simplification and due to computation capabilities, a reduction of the model order is often advantageous. This can be done by neglecting different physical effects within the machines, retaining the topology and the modal characteristics of the power system regarding its electromechanical behavior. This paper presents a modal analysis based approach for power system model order reduction. In order to reproduce the small-signal behavior of power systems accurately, damping and synchronizing parameters are introduced within the reduced-order model. Subsequently, each coefficient is determined analytically for a single machine infinite bus system and using the particle swarm optimization method for a multi-machine system. The deviation to the electromechanical reference modes of the higherorder power system model constitutes the objective function to be minimized. The results confirm that the approach is suitable for the aspired goals and fulfills the accuracy requirements.}, language = {en} } @inproceedings{SemerowMiltnerHornetal., author = {Semerow, Anatoli and Miltner, Andreas and Horn, Stefan and Dimitrovski, Robert and Luther, Matthias}, title = {Analysis of a disturbance localization method for incidents in continental Europe}, series = {2016 IEEE PES Innovative Smart Grid Technologies Conference Europe}, booktitle = {2016 IEEE PES Innovative Smart Grid Technologies Conference Europe}, publisher = {IEEE Computer Society Press}, isbn = {978-1-5090-3358-4}, doi = {10.1109/isgteurope.2016.7856312}, abstract = {To localize incidents such as generator trips or load shedding, which cause transients in power systems, a technique from seismology is used in this paper: triangulation by means of information from Phasor Measurement Units (PMU). The synchronized observation of frequency change arrival times, which represent an electromechanical disturbance propagation, allows to approximate the disturbance location and thereby to support a reliable power system operation. For the verification and further development of this method a post analysis of three incidents of last years in the Continental Europe synchronous area (CESA) power system is done using two different numerical methods to solve the set of triangulation equations. The calculated deviations of estimated to real locations show on the one hand a relative good approximation to the real incident locations, but also a high dependency on the assumed electromechanical disturbance propagation speed and the chosen parameters of signal processing. Nevertheless, the method seems to be promising for future applications and is worth to be further developed.}, language = {en} } @inproceedings{SemerowHornSchwarzetal., author = {Semerow, Anatoli and Horn, Stefan and Schwarz, Bianca and Luther, Matthias}, title = {Disturbance localization in power systems using wide area measurement systems}, series = {2016 IEEE International Conference on Power System Technology}, booktitle = {2016 IEEE International Conference on Power System Technology}, publisher = {IEEE Computer Society Press}, isbn = {978-1-4673-8848-1}, doi = {10.1109/powercon.2016.7753872}, abstract = {There are different innovative concepts to localize disturbances with an electromechanical impact in power systems using synchronized frequency measurements from Wide Area Measurement Systems. This paper investigates five approaches, of which four are mainly discussed and one is novel: Gradient Search, Triangulation, Parzen Windows, Probability Circles and Time Distance Ratios. The similarities and differences of the methods are described and analyzed within a case study using publicly available frequency measurements and a dynamic study model. The cases are selected with the aim to point out the limits of the methods and to derive recommendations for improvements to be further developed. The study explicitly shows the challenges of the application and provides suggestions how to meet them.}, language = {en} } @article{GlasSemerowLuther, author = {Glas, J. and Semerow, Anatoli and Luther, Matthias}, title = {General analysis of frequency containment and restoration reserves of wind power plants in power systems}, series = {Renewable Energy and Power Quality Journal}, volume = {1}, journal = {Renewable Energy and Power Quality Journal}, number = {14}, publisher = {European Association for the Development of Renewable Energy, Environment and Power Quality (EA4EPQ)}, issn = {2172-038X}, doi = {10.24084/repqj14.237}, pages = {96 -- 101}, abstract = {The increasing share of renewable energies, such as photovoltaics and wind power, lead to an all new situation in power systems over the past years. It changes the demand and possibilities of providing ancillary services like frequency containment (FCR) and restoration reserves (FRR). To cover the reduction of conventional generation units, which are usually used to provide those services, new possibilities have to be analysed. The aim of this paper is to show the possibilities of providing FCR and FRR by pitch-controlled wind power plants, regarding the overall dynamic system behaviour. Hence, a basic grid model with an integrated wind park, using pitch-control to adjust its power output, is being introduced and described. The simulation results of different wind situations during a power loss in the grid are then presented in order to assert the practicability of wind power plants providing FCR and FRR. As a conclusion, it is to ascertain that, pitch-control can be a way to support conventional units in providing ancillary services, but can't be a stand-alone solution. © 2016, European Association for the Development of Renewable Energy, Environment and Power Quality.}, language = {en} } @inproceedings{KreplinHoehnSemerowetal., author = {Kreplin, Sarina and H{\"o}hn, Sebastian and Semerow, Anatoli and Luther, Matthias}, title = {Generator modeling in the context of small-signal stability}, series = {2016 IEEE Power and Energy Society General Meeting}, booktitle = {2016 IEEE Power and Energy Society General Meeting}, issn = {1944-9933}, doi = {10.1109/pesgm.2016.7741598}, abstract = {Modal analysis is the well-established method for investigating small-signal stability. Dominant states of a particular oscillatory or monotonous mode can be identified by linearizing the system's differential equations. Since generator oscillation is predominantly influenced by the speed deviation and the rotor angle, whereas other state variables play a minor role, an approach to reduce a generator's state matrix to a lower order is presented in this paper. Fundamental, analytical investigations concerning generator modeling of synchronous generators connected to an infinite bus ensure the correct reproduction of the generator's electromechanical behavior without losing accuracy compared to higher-order models.}, language = {en} } @inproceedings{SemerowMuthLuther, author = {Semerow, Anatoli and Muth, Lukas and Luther, Matthias}, title = {Investigation of impacts on the disturbance propagation in power systems}, series = {2016 IEEE International Conference on Power System Technology}, booktitle = {2016 IEEE International Conference on Power System Technology}, publisher = {IEEE Computer Society Press}, doi = {10.1109/POWERCON.2016.7754061}, abstract = {Disturbances as generation trips, load shedding or other switching events propagate measurably throughout power systems as electromechanical interactions and may cause undesirable phenomena as power oscillations. Therefore, it is essential to have a deeper understanding of the electromechanical phenomenon to improve current countermeasures. For this reason, the present study analyzes the impacts on the disturbance propagation speed as line, generator and operating parameters, by means of an exemplary power system model and numerical simulation. The used conventional speed determination method is presented and discussed with regard to further development. By varying each of the selected system parameters, the sensitive influence on the propagation speed is studied and compared to the theoretical expectations. Additionally, the impact of different incident locations in a power system is investigated to determine the influence of system structure on the propagation.}, language = {en} } @inproceedings{SemerowHoehnBaueretal., author = {Semerow, Anatoli and H{\"o}hn, Sebastian and Bauer, Benedikt and Luther, Matthias}, title = {An innovative method to develop power system equivalents with focus on inter-area oscillations and primary control representation}, series = {2015 IEEE Eindhoven PowerTech}, booktitle = {2015 IEEE Eindhoven PowerTech}, publisher = {IEEE Computer Society Press}, doi = {10.1109/PTC.2015.7232581}, abstract = {An innovative method to develop power system equivalents is presented in this paper. The purpose is the representation of system inertia, inter-area oscillations and primary control of large interconnected power systems by means of publicly available information. The approach to reach this target is based on a systematically developed load-flow model and the representation of system dynamics by means of standard dynamic models for generation units, their appropriate control and loads. The initial parameters of the standard dynamic models are tuned with regard to frequency measurements and published power system characteristics. The developed method allows general analysis of extensive influences on the dynamic behavior of a particular power system. Conceivable applications of the developed method are proposed for further system analysis. Finally an employment of the method is shown for the Continental Europe synchronous area (CESA).}, language = {en} }