1,720,971 research outputs found
Application of Phasor Measurements for Online Monitoring and Adaptive Damping Control of Electromechanical Oscillations
Full text linkPower systems are large and complex systems consisting of thousands of components, like generators, transformers and transmission lines, which function together to ensure that the voltage and frequency are close to the nominal values. Traditionally, the major share of the electricity production was dominated by controllable sources like hydro, coal and nuclear power, where the production can be adjusted at will. To counteract climate change, production based on fossil fuels is phased out and replaced by renewable sources, among others solar and wind power. Since the production from these sources depends on the weather, this introduces larger and faster variations in the flow of electrical power from producer to consumer. Wind turbines and photovoltaics also affect and interact with the rest of the system in a significantly different way compared to conventional generators found in, e.g., hydro power plants. Adding that climate change brings increased frequency and intensity of extreme weather events, which often cause line outages or other disturbances to the grid, it must be expected that system operators are facing significant challenges in the future.
Motivated by this development, Statnett, and corresponding transmission system operators in other countries, are investing in new technology for monitoring of the system: Phasor Measurement Units provide voltage and current measurements with high resolution, allowing detailed dynamic transients to observed and analyzed. The measurement devices are deployed at strategic locations in the system, and continually stream measurements to the operators’ control center. The data stream can be analyzed continuously to extract information about the current state of the system, calculate stability indicators and margins, or propose remedial actions to mitigate incipient instability.
In this thesis, the focus is on investigating how increasing deployment of Phasor Measurement Units can be exploited to contribute to stable, secure and resilient operation of the system, subject to the mentioned expected challenges of the future. Specifically, a particular type of instability referred to as electromechanical oscillations or power oscillations in the literature is targeted. This type of oscillations is typically problematic when transferring large amounts of power between areas of generation via long transmission lines, and can be observed as power oscillations in power plants or grid frequency oscillations. The frequency is typically in the range 0.1 to 2 Hz and the damping is often satisfactory, but in some cases low damped or growing oscillations are experienced. The system is particularly vulnerable to this type of instability when it is in an unusual or unscheduled operating point, e.g., due to maintenance or outage of important components.
The three main contributions to this research field can be summarized as follows:
A method for estimation of frequency and observability of electromechanical oscillations based on phasor measurements. A prototype for online analysis of measurements and live visualization of oscillations is described.
Enhancements to a particular type of control algorithm for damping of electromechanical oscillations, referred to as the Phasor Power Oscillation Damper in the literature. Three distinct sub-contributions are described, where the most important is an adaptive variant of the algorithm, capable of adjusting internal parameters to changing operating conditions.
A power system simulation tool coded in Python. The tool was developed to support the development of the contributions in the previous point.
With these methods for monitoring and control, it is the aim of this thesis to contribute with increased situational awareness and new options for remedial action for handling instabilities, with the ultimate goal of facilitating stable, secure and resilient operation of the future power system.Joint degree between: NTNU Norwegian University of Science and Technology Faculty of Information Technology and Electrical Engineering Department of Electric Power Engineering DTU Technical University of Denmark Department of Electrical Engineering Center for Electric Power and Energ
Application of Phasor Measurements for Online Monitoring and Adaptive Damping Control of Electromechanical Oscillations
No full textPower systems are large and complex systems consisting of thousands of components, like generators, transformers and transmission lines, which function together to ensure that the voltage and frequency are close to the nominal values. Traditionally, the major share of the electricity production was dominated by controllable sources like hydro, coal and nuclear power, where the production can be adjusted at will. To counteract climate change, production based on fossil fuels is phased out and replaced by renewable sources, among others solar and wind power. Since the production from these sources depends on the weather, this introduces larger and faster variations in the flow of electrical power from producer to consumer. Wind turbines and photovoltaics also affect and interact with the rest of the system in a significantly different way compared to conventional generators found in, e.g., hydro power plants. Adding that climate change brings increased frequency and intensity of extreme weather events, which often cause line outages or other disturbances to the grid, it must be expected that system operators are facing significant challenges in the future.
Motivated by this development, Statnett, and corresponding transmission system operators in other countries, are investing in new technology for monitoring of the system: Phasor Measurement Units provide voltage and current measurements with high resolution, allowing detailed dynamic transients to observed and analyzed. The measurement devices are deployed at strategic locations in the system, and continually stream measurements to the operators’ control center. The data stream can be analyzed continuously to extract information about the current state of the system, calculate stability indicators and margins, or propose remedial actions to mitigate incipient instability.
In this thesis, the focus is on investigating how increasing deployment of Phasor Measurement Units can be exploited to contribute to stable, secure and resilient operation of the system, subject to the mentioned expected challenges of the future. Specifically, a particular type of instability referred to as electromechanical oscillations or power oscillations in the literature is targeted. This type of oscillations is typically problematic when transferring large amounts of power between areas of generation via long transmission lines, and can be observed as power oscillations in power plants or grid frequency oscillations. The frequency is typically in the range 0.1 to 2 Hz and the damping is often satisfactory, but in some cases low damped or growing oscillations are experienced. The system is particularly vulnerable to this type of instability when it is in an unusual or unscheduled operating point, e.g., due to maintenance or outage of important components.
The three main contributions to this research field can be summarized as follows:
A method for estimation of frequency and observability of electromechanical oscillations based on phasor measurements. A prototype for online analysis of measurements and live visualization of oscillations is described.
Enhancements to a particular type of control algorithm for damping of electromechanical oscillations, referred to as the Phasor Power Oscillation Damper in the literature. Three distinct sub-contributions are described, where the most important is an adaptive variant of the algorithm, capable of adjusting internal parameters to changing operating conditions.
A power system simulation tool coded in Python. The tool was developed to support the development of the contributions in the previous point.
With these methods for monitoring and control, it is the aim of this thesis to contribute with increased situational awareness and new options for remedial action for handling instabilities, with the ultimate goal of facilitating stable, secure and resilient operation of the future power system
Developing an Application for Simulating a Parametrized PM Machine by FEM
No full textA parametrized 2D model of a permanent magnet synchronous machine is developed in the finite elements method software COMSOL Multiphysics, along with a graphical user interface to control it. The GUI provides automatic construction of geometry based on specified input parameters, application of boundary conditions and equations, and post-processing of results. Algorithms are implemented to apply automatic periodicity settings and winding layouts for single layer and double layer integer and fractional slot windings. The output of the model is validated by comparing to analytical formulas and to other studies with known input parameters and results.
The purpose of developing the the application is educational, allowing simulations to be performed without requiring in-depth knowledge of FEM. A range of sample studies are presented in this respect, to indicate possible areas of application within the educational setting. It is found that simulations can be performed very efficiently, indicating that the application could provide a valuable tool for studying electrical machines. Depending on further development and implementation of additional functionality, the application could probably also be used in the process of designing machines
Developing an Application for Simulating a Parametrized PM Machine by FEM
Full text linkA parametrized 2D model of a permanent magnet synchronous machine is developed in the finite elements method software COMSOL Multiphysics, along with a graphical user interface to control it. The GUI provides automatic construction of geometry based on specified input parameters, application of boundary conditions and equations, and post-processing of results. Algorithms are implemented to apply automatic periodicity settings and winding layouts for single layer and double layer integer and fractional slot windings. The output of the model is validated by comparing to analytical formulas and to other studies with known input parameters and results.
The purpose of developing the the application is educational, allowing simulations to be performed without requiring in-depth knowledge of FEM. A range of sample studies are presented in this respect, to indicate possible areas of application within the educational setting. It is found that simulations can be performed very efficiently, indicating that the application could provide a valuable tool for studying electrical machines. Depending on further development and implementation of additional functionality, the application could probably also be used in the process of designing machines
Mode Shape Estimation using Complex Principal Component Analysis and k-Means Clustering
No full textWe propose an empirical method for identifying low damped modes and corresponding mode shapes using frequency measurements from a Wide Area Monitoring System. The method consists of two main steps: Firstly, Complex Principal Component Analysis is used in combination with the Hilbert Transform and Empirical Mode Decomposition to provide estimates of modes and mode shapes. The estimates are stored as multidimensional points. Secondly, the points are grouped using a clustering algorithm, and new averaged estimates of modes and mode shapes are computed as the centroids of the clusters. Applying the method on data resulting from a non-linear power system simulator yields estimates of dominant modes and corresponding mode shapes that are similar to those resulting from modal analysis of the linearized system model. Encouraged by the results, the method is further tested with real PMU data at transmission grid level. Initial results indicate that the performance of the proposed method is promising
Electric Field Simulations of High Voltage DC Extruded Cable Systems
No full textThe market for high voltage DC (HVDC) transmission systems has increased dramatically the last few decades. This is mainly due to the economic, electrical, and environmental advantages for bulk power transmission over long distances. Also, in some cases, such as for long subsea cable links, HVDC is the only option. HVDC cables have traditionally used oil-paper for insulation, with the most common type being the mass-impregnated, nondraining cable. The oil or mass-impregnated cables have for a century shown to have a very high reliability and are currently used for voltages and power ratings up to 525 kV and about 1 GW. Today, it is still the preferred technology for the highest voltage levels [1]. However, in the last two decades, extruded polymeric insulation has become more popular, and the highest voltage level currently installed is +320 kV used for grid interconnections and for offshore wind farms. HVDC cable systems using cross-linked polyethylene (XLPE) are available for voltages up to +600 kV and 3 GW and polypropylene based for +600 kV and 3.5 GW
Achieving Enhanced Phasor POD Performance by Introducing a Control-Input Model
Full text linkIn this paper, an enhancement to the well known Phasor Power Oscillation Damper is proposed, aiming to improve its performance. Fundamental to the functioning of this controller is the estimation of a phasor representing oscillations at a particular frequency in a measured signal. The phasor is transformed to time domain and applied as a setpoint signal to a controllable device. The contribution in this paper specifically targets the estimation algorithm of the controller: It is found that improved estimation accuracy and thereby enhanced damping performance can be achieved by introducing a prediction-correction scheme for the estimator, in the form of a Kalman Filter. The prediction of the phasor at the next step is performed based on the control signal that is applied at the current step. This enables more precise damping of the targeted mode. The presented results, which are obtained from simulations on a Single-Machine Infinite Bus system and the IEEE 39-Bus system, indicate that the proposed enhancement improves the performance of this type of controller.Achieving Enhanced Phasor POD Performance by Introducing a Control-Input ModelacceptedVersio
Achieving increased Phasor POD performance by introducing a Control-Input Model
No full textIn this paper, an enhancement to the well known Phasor Power Oscillation Damper is proposed, aiming to increase its performance. Fundamental to the functioning of this controller is the estimation of a phasor representing oscillatory behaviour at a particular frequency in a measured signal. The phasor is transformed to time domain and applied as a setpoint signal to a controllable device. The contribution in this paper specifically targets the estimation algorithm of the controller: It is found that increased estimation accuracy and thereby enhanced damping performance can be achieved by introducing a prediction- correction scheme for the estimator, in the form of a Kalman Filter. The prediction of the phasor at the next step is performed based on the control signal that is applied at the current step. This enables more precise damping of the targeted mode. The presented results, which are obtained from simulations on a Single-Machine Infinite Bus system and the IEEE 39-Bus system, indicate that the proposed enhancement improves the performance of this type of controller
A Platform for Development and Testing of WAMPAC Applications based on Kafka Streaming
Full text linkIn this paper a platform for developing and testing Wide Area Monitoring, Protection and Control (WAMPAC) applications is presented. The fundamental idea is that individual applications operate as microservices. Each application access and process data (e.g. data from Phasor Measurement Units) and produces results which can be further elaborated by other microservices, or directly presented to the operators. Streaming of data between microservices is handled by a Kafka streaming server which handles the complete information flow.The platform has been tested both on data streams from a lightweight real-time simulator (with hundreds of measurement channels), and on PMU streams generated from recorded data from the Nordic system (with thousands of measurement channels). The platform is characterized by low need of computational resources and easy installation (only requiring basic Python programming skills). Experience from this work indicates that the chosen approach is suitable for streamlining the process of development and testing of WAMPAC applications, with the aim of raising the technology readiness level of already existing applications in the literature or for future applications.A Platform for Development and Testing of WAMPAC Applications based on Kafka StreamingacceptedVersio
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