| 1. |
- Chompoobutrgool, Yuwa, et al.
(author)
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A fundamental study on damping control design using PMU signals from dominant inter-area oscillation paths
- 2012
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In: North American Power Symposium (NAPS), 2012. - : IEEE. - 9781467323086 ; , s. 1-6
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Conference paper (peer-reviewed)abstract
- This article presents a fundamental study on feedback control using different types of signals available from a dominant inter-area oscillation path; the passageway containing the highest content of the inter-area oscillations. Results from the previous studies verify the persistence and robustness of dominant path signals and suggest that using such signals, effective damping control may be achieved. To corroborate the implication, signals available from phasor measurement units (PMU) e.g. voltage phasors (magnitude and angle) from the dominant path are used as feedback inputs for a power system stabilizer (PSS) control design for damping enhancement. The corresponding performance are compared with those using generator speed, which is a commonly used signal though not available from PMUs, as inputs. Contrary to expectations found in common practice, that of speed being the one of the most effective signal for damping control, it is demonstrated here that their corresponding damping performance is inferior to those using voltage phasors as feedback inputs. A conceptualized two-area system is used to analyze damping performance throughout this study.
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| 2. |
- Chompoobutrgool, Yuwa, 1984-
(author)
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Concepts for Power System Small Signal Stability Analysis and Feedback Control Design Considering Synchrophasor Measurements
- 2012
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Licentiate thesis (other academic/artistic)abstract
- In the Nordic power network, the existence of poorly damped low-frequency inter-area oscillations (LFIOs) has long affected stability constraints, and thereby, limited power transfer capacity. Adequate damping of inter-area modes is, thus, necessary to secure system operation and ensure system reliability while increasing power transfers. Power system stabilizers (PSS) is a prevalent means to enhance the damping of such modes. With the advent of phasor measurement units (PMUs), it is expected that wide-area damping control (WADC), that is, PSS control using wide-area measurements obtained from PMUs, would effectively improve damping performance in the Nordic grid, as well as other synchronous interconnected systems. Numerous research has investigated one ``branch'' of the problem, that is, PSS design using various control schemes. Before addressing the issue of controller design, it is important to focus on developing proper understanding of the ``root'' of the problem: system-wide oscillations, their nature, behavior and consequences. This understanding must provide new insight on the use of PMUs for feedback control of LFIOs. The aim of this thesis is, therefore, to lay important concepts necessary for the study of power system small signal stability analysis that considers the availability of synchrophasors as a solid foundation for further development and implementation of ideas and related applications. Particularly in this study, the focus is on the application addressed damping controller design and implementation. After a literature review on the important elements for wide-area damping control (WADC), the thesis continues with classical small signal stability analysis of an equivalent Nordic model; namely, the KTH-NORDIC32 which is used as a test system throughout the thesis. The system's inter-area oscillations are identified and a sensitivity analysis of the network variables directly measured by synchrophasors is evaluated. The concept of network modeshapes, which is used to relate the dynamical behavior of power systems to the features of inter-area modes, is elaborated. Furthermore, this network modeshape concept is used to determine dominant inter-area oscillation paths, the passageways containing the highest content of the inter-area oscillations. The dominant inter-area paths are illustrated with the test system. The degree of persistence of dominant paths in the study system is determined through contingency studies. The properties of the dominant paths are used to construct feedback signals as input to the PSS. Finally, to exemplify the use of the dominant inter-area path concept for damping control, the constructed feedback signals are implemented in a PSS modulating the AVR error signal of a generator on an equivalent two-area model, and compared with that of conventional speed signals.
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| 3. |
- Chompoobutrgool, Yuwa, et al.
(author)
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Development and Implementation of the Nordic Grid Model for Power System Small-Signal and Transient Stability Studies in a Free and Open Source Software
- 2012
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In: Power and Energy Society General Meeting, 2012 IEEE. - : IEEE. - 9781467327299 ; , s. 6344571-
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Conference paper (peer-reviewed)abstract
- This article presents an implementation of a Nordic grid model in Power System Analysis Toolbox (PSAT) -a free and open-source software. A newly developed hydro turbine and hydro governor (HTG) model is implemented with this grid model and compared with the currently available PSAT turbine and governor models. Small-signal and transient stability analyses of the system using the two models are carried out and compared to demonstrate the difference and necessity of accurate hydro turbine and governor model utilization. The paper ends with a validation of the linearized Nordic grid model generated by PSAT including the newly implemented HTG models. This validation is done through nonlinear time-domain simulation by applying both large and small disturbances.
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| 4. |
- Chompoobutrgool, Yuwa, et al.
(author)
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On the persistence of dominant inter-area oscillation paths in large-scale power networks
- 2012
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In: IFAC Proceedings Volumes (IFAC-PapersOnline) Volume 8, Issue PART 1, 2012. - : Elsevier BV. - 9783902823243 ; , s. 150-155
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Conference paper (peer-reviewed)abstract
- This article discusses the degree of persistence of dominant inter-area oscillation paths: the passageways containing the highest content of inter-area oscillations in large-scale power networks. To this aim, a number of contingency studies are carried out: faults being imposed on the lines connecting to the dominant inter-area path. The path persistence is then examined using the relationship between sensitivities of network variables (i.e. voltages and current, magnitude and angle), and mode shapes describing the contribution of the oscillations among the generators variables (e.g. speed and angle). This relationship is termed network modeshape. The larger in magnitude and the lesser the variation the network modeshape is, the more observable and the more robust the signals measured from the dominant path becomes. The outcome is a proposed signal combination to be used as inputs to the damping controller for mitigation of inter-area oscillations in large-scale power systems.
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| 5. |
- Chompoobutrgool, Yuwa, et al.
(author)
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Persistence of Multiple Interaction Paths for Individual Inter-Area Modes
- 2012
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In: IFAC Proceedings Volumes (IFAC-PapersOnline). - 9783902823243 ; , s. 14-19
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Conference paper (peer-reviewed)abstract
- Dominant interaction paths are the passageways containing the highest modal content of particular oscillations in interconnected power systems. For the case of inter-area modes, pinpointing the dominant path that corresponds to each mode may allow for the extraction of signals that bear a significant modal content at a particular inter-area frequency. Strong modal content for these inter-area modes may also be spread onto secondary paths. These secondary paths bear similar properties as those shown by dominant paths. The aim of this study is thus to demonstrate the persistence of both dominant and secondary paths by employing “network modeshape” properties. The existence of the paths is verified by nonlinear time-domain simulations where modal content at each inter-area frequency is extracted. The proper selection of feedback signals from the dominating paths may increase the flexibility of WAPODs by providing a number of signal choices to be used as backup in the presence of contingencies.
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| 6. |
- Li, Wei, et al.
(author)
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Development and implementation of hydro turbine and governor models in a free and open source software package
- 2012
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In: Simulation (San Diego, Calif.). - : Elsevier BV. - 1569-190X .- 1878-1462. ; 24, s. 84-102
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Journal article (peer-reviewed)abstract
- This article studies accurate and detailed hydro turbine and governor models, and implements these models in Power System Analysis Toolbox (PSAT)-a free and open source software. The implementation of these models in PSAT is approached using a general methodology, which is described in detail. To evaluate the performances of the developed hydro turbine and governor models, simulation studies are carried out on test systems of different scales, from a single-machine infinite-bus (SMIB) system to a larger system which includes 20 generators. Further more, transient stability analysis and small signal stability analysis are carried out to assess the performance of the implemented models.
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| 7. |
- Sturk, Christopher, et al.
(author)
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Structured Power System Model Reduction of Non-Coherent Areas
- 2012
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In: Power and Energy Society General Meeting, 2012 IEEE. - : IEEE. - 9781467327275 ; , s. 6344913-
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Conference paper (peer-reviewed)abstract
- This paper demonstrates how structured model reduction can be used to reduce the order of power systems without the need to identify coherent groups of generators. To this end the Klein-Rogers-Kundur 2-area system is studied in detail. It is shown how different modes of the system are captured as the model order is varied, which is of interest in e.g. distributed controller design, where the objective is to damp these oscillations. The power system is divided into a study area and an external area and the proposed algorithm is used to reduce the external area to a low order linear system, while retaining the nonlinear description of the study area. It is shown that this approach permits greater deviations from the steady-state than if a reduced system that is entirely linear is used, while still yielding accurate simulation results.
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