New nonlinear optimal controllers for a multimachine system are presented. Nonlinear field voltag... more New nonlinear optimal controllers for a multimachine system are presented. Nonlinear field voltage controllers (NFVC) are designed with the use of the feedback linearization approach to adjust generator state variables to external reference signals resulting from optimal power flow calculation in a stabilized power system. A nonlinear control law has been derived for the three-dimensional model of a generator. A new control strategy has been verified for a three machine power system. An extensive simulation study shows robustness of the nonlinear controllers and better performance than PSS-based classical controllers.
There are number of parameters and methods available for condition monitoring and diagnosis of po... more There are number of parameters and methods available for condition monitoring and diagnosis of power transformer insulation. We concentrate on a few of them. One of the parameters, which is becoming more and more vital for diagnostics of the integrity of a power transformer, is the moisture content of the insulation system. Migration of moisture between oil and paper insulation is a very complex, nonlinear process with many uncertainties. An adaptive neuro-fuzzy system identification is applied to predict the moisture content of solid insulation from on-line measurements of moisture characteristics of oil. The comparison of the measured and predicted values of the average moisture content in a paper-oil insulation system is presented. Development of a neuro-fuzzy thermal model of a power transformer, intelligent sensor technology, fuzzy signal conditioning and evaluation of partial discharges in power transformers are also discussed.
There are a number of parameters and methods available for condition monitoring and diagnostic of... more There are a number of parameters and methods available for condition monitoring and diagnostic of a power transformer insulation. In this paper we concentrate on a few of them. One of the parameters, which becomes more and more vital for diagnostics of the integrity of a power transformer, is the moisture content of insulation system. Migration of moisture from oil to paper insulation is a very complex, nonlinear with many uncertainties process. The adaptive neuro-fuzzy system identification is applied to predict moisture characteristics of oil. The comparison of the measured and predicted values of average moisture content in paper-oil insulation system is presented. The accurate evaluation of moisture content is extremely important when it is necessary to determine the dryness of the solid insulation during both the factory drying process and refurbishment of the transformer in field. The dry-out termination criteria based on the measurement of dielectric characteristics and classification of the dryness state by using the neuro-fuzzy pattern clustering is suggested for this purpose
In the operating transformer water is always in transition, either moving within cellulose insula... more In the operating transformer water is always in transition, either moving within cellulose insulation or migrating from paper to oil and versa visa. This article introduces a methodology where we use an equilibrium chart for an assessment of a dynamic process which may not reach an equilibrium and still give us a good sense of moisture state in the oil/paper system
In the operating transformer water is always in transition, either moving within cellulose insula... more In the operating transformer water is always in transition, either moving within cellulose insulation or migrating from paper to oil and versa visa. This article discusses the moisture cloud algorithm, which reveals the value water in oil measurement has in predicting the amount of water available for drying out, determining the safety margin of the insulation dielectric strength, assessing the residual water in new units undergoing temperature rise test, and in reliably ranking transformers across the fleet in terms of water state
The idea to write a Q&A column about water in transformers for this magazine came from various sp... more The idea to write a Q&A column about water in transformers for this magazine came from various speaking and consulting engagements. Very often during seminars, workshops or technical presentations I have been asked to explain and elaborate on ‘seems to be trivial’, but ‘appeared to be’ complex phenomena, statements or a fact related to presence and effects of water in transformers. Water in transformers is an intriguing topic and usually attracts an interest of large groups of professionals in the field of high-voltage electrical equipment operation and maintenance. From the onset of transformer manufacture, drying of solid and liquid insulation presents an operational and technical challenge, consuming a lot of effort and resources. Even after a thorough job on drying, water finds its way into a transformer taking every possible path during its transportation from factory floor to the final destination. Water is often labelled as the worst enemy of transformers and numerous researc...
This article attempts to explain not only how moisture affects the quality of the insulating liqu... more This article attempts to explain not only how moisture affects the quality of the insulating liquid, but also how online sensing of moisture parameters can be used in continuous monitoring of oil condition, rate of oil deterioration and aging of both oil and paper insulation, because, apart from being an insulator and a coolant, oil is also an information carrier
New nonlinear optimal controllers for a multimachine system are presented. Nonlinear field voltag... more New nonlinear optimal controllers for a multimachine system are presented. Nonlinear field voltage controllers (NFVC) are designed with the use of the feedback linearization approach to adjust generator state variables to external reference signals resulting from optimal power flow calculation in a stabilized power system. A nonlinear control law has been derived for the three-dimensional model of a generator. A new control strategy has been verified for a three machine power system. An extensive simulation study shows robustness of the nonlinear controllers and better performance than PSS-based classical controllers.
New nonlinear optimal controllers for a multimachine system are presented. Nonlinear field voltag... more New nonlinear optimal controllers for a multimachine system are presented. Nonlinear field voltage controllers (NFVC) are designed with the use of the feedback linearization approach to adjust generator state variables to external reference signals resulting from optimal power flow calculation in a stabilized power system. A nonlinear control law has been derived for the three-dimensional model of a generator. A new control strategy has been verified for a three machine power system. An extensive simulation study shows robustness of the nonlinear controllers and better performance than PSS-based classical controllers.
There are number of parameters and methods available for condition monitoring and diagnosis of po... more There are number of parameters and methods available for condition monitoring and diagnosis of power transformer insulation. We concentrate on a few of them. One of the parameters, which is becoming more and more vital for diagnostics of the integrity of a power transformer, is the moisture content of the insulation system. Migration of moisture between oil and paper insulation is a very complex, nonlinear process with many uncertainties. An adaptive neuro-fuzzy system identification is applied to predict the moisture content of solid insulation from on-line measurements of moisture characteristics of oil. The comparison of the measured and predicted values of the average moisture content in a paper-oil insulation system is presented. Development of a neuro-fuzzy thermal model of a power transformer, intelligent sensor technology, fuzzy signal conditioning and evaluation of partial discharges in power transformers are also discussed.
There are a number of parameters and methods available for condition monitoring and diagnostic of... more There are a number of parameters and methods available for condition monitoring and diagnostic of a power transformer insulation. In this paper we concentrate on a few of them. One of the parameters, which becomes more and more vital for diagnostics of the integrity of a power transformer, is the moisture content of insulation system. Migration of moisture from oil to paper insulation is a very complex, nonlinear with many uncertainties process. The adaptive neuro-fuzzy system identification is applied to predict moisture characteristics of oil. The comparison of the measured and predicted values of average moisture content in paper-oil insulation system is presented. The accurate evaluation of moisture content is extremely important when it is necessary to determine the dryness of the solid insulation during both the factory drying process and refurbishment of the transformer in field. The dry-out termination criteria based on the measurement of dielectric characteristics and classification of the dryness state by using the neuro-fuzzy pattern clustering is suggested for this purpose
In the operating transformer water is always in transition, either moving within cellulose insula... more In the operating transformer water is always in transition, either moving within cellulose insulation or migrating from paper to oil and versa visa. This article introduces a methodology where we use an equilibrium chart for an assessment of a dynamic process which may not reach an equilibrium and still give us a good sense of moisture state in the oil/paper system
In the operating transformer water is always in transition, either moving within cellulose insula... more In the operating transformer water is always in transition, either moving within cellulose insulation or migrating from paper to oil and versa visa. This article discusses the moisture cloud algorithm, which reveals the value water in oil measurement has in predicting the amount of water available for drying out, determining the safety margin of the insulation dielectric strength, assessing the residual water in new units undergoing temperature rise test, and in reliably ranking transformers across the fleet in terms of water state
The idea to write a Q&A column about water in transformers for this magazine came from various sp... more The idea to write a Q&A column about water in transformers for this magazine came from various speaking and consulting engagements. Very often during seminars, workshops or technical presentations I have been asked to explain and elaborate on ‘seems to be trivial’, but ‘appeared to be’ complex phenomena, statements or a fact related to presence and effects of water in transformers. Water in transformers is an intriguing topic and usually attracts an interest of large groups of professionals in the field of high-voltage electrical equipment operation and maintenance. From the onset of transformer manufacture, drying of solid and liquid insulation presents an operational and technical challenge, consuming a lot of effort and resources. Even after a thorough job on drying, water finds its way into a transformer taking every possible path during its transportation from factory floor to the final destination. Water is often labelled as the worst enemy of transformers and numerous researc...
This article attempts to explain not only how moisture affects the quality of the insulating liqu... more This article attempts to explain not only how moisture affects the quality of the insulating liquid, but also how online sensing of moisture parameters can be used in continuous monitoring of oil condition, rate of oil deterioration and aging of both oil and paper insulation, because, apart from being an insulator and a coolant, oil is also an information carrier
New nonlinear optimal controllers for a multimachine system are presented. Nonlinear field voltag... more New nonlinear optimal controllers for a multimachine system are presented. Nonlinear field voltage controllers (NFVC) are designed with the use of the feedback linearization approach to adjust generator state variables to external reference signals resulting from optimal power flow calculation in a stabilized power system. A nonlinear control law has been derived for the three-dimensional model of a generator. A new control strategy has been verified for a three machine power system. An extensive simulation study shows robustness of the nonlinear controllers and better performance than PSS-based classical controllers.
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