Pub Date : 2008-06-10DOI: 10.1109/ISNCC.2008.4627508
A. Wetula
The paper presents an algorithm for detection of a complex envelope of power grid signals. The algorithm is based on a Hilbert transform. It was prepared for an analysis of a low-frequency disturbances, but can also be used as a compex envelope source for other applications. An implementation of the algorithm in a digital signal processor was made to proof an ability of a real-time operation. Analyses with various numerical representations and input signal quantization were done. Execution times on a DSP were measured. Tests proved that the presented algorithm is able to analyze power grid signals in a real-time with satisfying performance and uncertainty.
{"title":"A Hilbert transform based algorithm for detection of a complex envelope of a power grid signals - an implementation","authors":"A. Wetula","doi":"10.1109/ISNCC.2008.4627508","DOIUrl":"https://doi.org/10.1109/ISNCC.2008.4627508","url":null,"abstract":"The paper presents an algorithm for detection of a complex envelope of power grid signals. The algorithm is based on a Hilbert transform. It was prepared for an analysis of a low-frequency disturbances, but can also be used as a compex envelope source for other applications. An implementation of the algorithm in a digital signal processor was made to proof an ability of a real-time operation. Analyses with various numerical representations and input signal quantization were done. Execution times on a DSP were measured. Tests proved that the presented algorithm is able to analyze power grid signals in a real-time with satisfying performance and uncertainty.","PeriodicalId":143815,"journal":{"name":"2008 International School on Nonsinusoidal Currents and Compensation","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122785448","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2008-06-10DOI: 10.1109/ISNCC.2008.4627490
M. Castilla, J. Bravo, M. Ordóñez, J. Montaño, A. López, D. Borrás, J. Gutierrez
In this paper, a multivectorial decomposition of power equation in single-phase circuits for periodic n-sinusoidal /linear and nonlinear conditions is presented. It is based on a frequency-domain Clifford vector space approach. By using a new generalized complex geometric algebra (GCGA), we define the voltage and current complex-vector and apparent power multivector concepts. First, the apparent power multivector is defined as geometric product of vector-phasors (complex-vectors). This new expression result in a novel representation and generalization of the apparent power similar to complex-power in single-frequency sinusoidal conditions. Second, in order to obtain a multivectorial representation of any proposed power equation, the current vector-phasor is decomposed into orthogonal components. The power multivector concept, consisting of complex-scalar and complex-bivector parts with magnitude, direction and sense, obeys the apparent power conservation law and it handles different practical electric problems where direction and sense are necessary. The results of numerical examples are presented to illustrate the proposed approach to power theory analysis.
{"title":"The geometric algebra as a power theory analysis tool","authors":"M. Castilla, J. Bravo, M. Ordóñez, J. Montaño, A. López, D. Borrás, J. Gutierrez","doi":"10.1109/ISNCC.2008.4627490","DOIUrl":"https://doi.org/10.1109/ISNCC.2008.4627490","url":null,"abstract":"In this paper, a multivectorial decomposition of power equation in single-phase circuits for periodic n-sinusoidal /linear and nonlinear conditions is presented. It is based on a frequency-domain Clifford vector space approach. By using a new generalized complex geometric algebra (GCGA), we define the voltage and current complex-vector and apparent power multivector concepts. First, the apparent power multivector is defined as geometric product of vector-phasors (complex-vectors). This new expression result in a novel representation and generalization of the apparent power similar to complex-power in single-frequency sinusoidal conditions. Second, in order to obtain a multivectorial representation of any proposed power equation, the current vector-phasor is decomposed into orthogonal components. The power multivector concept, consisting of complex-scalar and complex-bivector parts with magnitude, direction and sense, obeys the apparent power conservation law and it handles different practical electric problems where direction and sense are necessary. The results of numerical examples are presented to illustrate the proposed approach to power theory analysis.","PeriodicalId":143815,"journal":{"name":"2008 International School on Nonsinusoidal Currents and Compensation","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125624472","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2008-06-10DOI: 10.1109/ISNCC.2008.4627514
J. Montaño, M. Castilla, A. López, J. Bravo, D. Borrás, J. Gutierrez
(N-1)-phase N-wire systems are analyzed into an orthonormal-coordinate system using the fundamental laws of polyphase systems and the condition of zero neutral-current. N-dimension voltage vectors are referenced to a virtual star-point and the current vectors are decomposed into three mutually orthogonal components, two of them are responsible of the active power. Without the condition of zero neutral-current, results are modified: the current vector is decomposed into a power-current vector and a complementary current vector. Only the first component transports the instantaneous collective power, the other is useless. The analysis is valid for a general situation and shows the condition of line losses minimization after compensation with active power filters.
{"title":"Analysis of instantaneous NSV&C in polyphase systems","authors":"J. Montaño, M. Castilla, A. López, J. Bravo, D. Borrás, J. Gutierrez","doi":"10.1109/ISNCC.2008.4627514","DOIUrl":"https://doi.org/10.1109/ISNCC.2008.4627514","url":null,"abstract":"(N-1)-phase N-wire systems are analyzed into an orthonormal-coordinate system using the fundamental laws of polyphase systems and the condition of zero neutral-current. N-dimension voltage vectors are referenced to a virtual star-point and the current vectors are decomposed into three mutually orthogonal components, two of them are responsible of the active power. Without the condition of zero neutral-current, results are modified: the current vector is decomposed into a power-current vector and a complementary current vector. Only the first component transports the instantaneous collective power, the other is useless. The analysis is valid for a general situation and shows the condition of line losses minimization after compensation with active power filters.","PeriodicalId":143815,"journal":{"name":"2008 International School on Nonsinusoidal Currents and Compensation","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132947869","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2008-06-10DOI: 10.1109/ISNCC.2008.4627498
H. V. Haghi, M. Bina
Power systems use STATCOM for compensating purposes that is subjected to the high switching frequencies. Various PWM techniques make selective harmonic elimination possible, which effectively control the harmonic content of voltage source inverters. On the other hand, distribution systems have to supply unbalanced nonlinear loads, transferring oscillations to the DC-side of the converter in a realistic operating condition. Thus, additional uncharacteristic harmonics are modulated through the STATCOM at the point of common coupling (PCC). This requires more attention when switching angles are calculated offline using the optimal-PWM technique. This paper suggests a harmonic-domain model in order to realistically evaluate the injected harmonics at the PCC. This model properly takes into account the DC capacitor effect, effects of other possible varying parameters such as voltage unbalance as well as network harmonics, and effects of operating conditions on the STATCOM harmonic performance. The model is programmed, and can be easily run with other algorithms such as Monte Carlo simulation. Further, a semi-stochastic method is proposed to predict and simulate the three-phase voltage unbalance, leading to an analytical tool for prediction of harmonic performance of STATCOM. The predictive method is developed based on the measured data obtained from a low-voltage distribution network. Finally, the modeled STATCOM is linked with the distribution substation, applying the proposed voltage unbalance modeling to evaluate aggregate harmonics of the load.
{"title":"Complete harmonic-domain modeling and performance evaluation of an optimal-PWM-modulated STATCOM in a realistic distribution network","authors":"H. V. Haghi, M. Bina","doi":"10.1109/ISNCC.2008.4627498","DOIUrl":"https://doi.org/10.1109/ISNCC.2008.4627498","url":null,"abstract":"Power systems use STATCOM for compensating purposes that is subjected to the high switching frequencies. Various PWM techniques make selective harmonic elimination possible, which effectively control the harmonic content of voltage source inverters. On the other hand, distribution systems have to supply unbalanced nonlinear loads, transferring oscillations to the DC-side of the converter in a realistic operating condition. Thus, additional uncharacteristic harmonics are modulated through the STATCOM at the point of common coupling (PCC). This requires more attention when switching angles are calculated offline using the optimal-PWM technique. This paper suggests a harmonic-domain model in order to realistically evaluate the injected harmonics at the PCC. This model properly takes into account the DC capacitor effect, effects of other possible varying parameters such as voltage unbalance as well as network harmonics, and effects of operating conditions on the STATCOM harmonic performance. The model is programmed, and can be easily run with other algorithms such as Monte Carlo simulation. Further, a semi-stochastic method is proposed to predict and simulate the three-phase voltage unbalance, leading to an analytical tool for prediction of harmonic performance of STATCOM. The predictive method is developed based on the measured data obtained from a low-voltage distribution network. Finally, the modeled STATCOM is linked with the distribution substation, applying the proposed voltage unbalance modeling to evaluate aggregate harmonics of the load.","PeriodicalId":143815,"journal":{"name":"2008 International School on Nonsinusoidal Currents and Compensation","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126078203","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2008-06-10DOI: 10.1109/ISNCC.2008.4627487
M. Hartman, M. Hashad
The analysis of energy transfer in the circuits is based on the instantaneous power p(t), which is the product of the two waveforms u(t),i(t) . An interesting thing is the search for mutual relations between these two waveforms. In the paper the authors made an attempt to describe power states in electrical circuits with periodic waveforms with the help of the correlation of the two functions. In mathematics correlation is the measure of similarity or mutual dependence between the two functions. Electrical energy is a simultaneous and mutual cooperation of voltage and current waveforms - therefore, the authors defined and examined the correlation function Psi(t) of these waveforms. On the basis of the defined correlation function between the voltage and the current, the authors introduced two new powers: the sine power function Psis t and the cosine power function Psic t.
{"title":"The correlation functions of power as a new proposition to describe power states in circuits with periodical voltage and current waveforms","authors":"M. Hartman, M. Hashad","doi":"10.1109/ISNCC.2008.4627487","DOIUrl":"https://doi.org/10.1109/ISNCC.2008.4627487","url":null,"abstract":"The analysis of energy transfer in the circuits is based on the instantaneous power p(t), which is the product of the two waveforms u(t),i(t) . An interesting thing is the search for mutual relations between these two waveforms. In the paper the authors made an attempt to describe power states in electrical circuits with periodic waveforms with the help of the correlation of the two functions. In mathematics correlation is the measure of similarity or mutual dependence between the two functions. Electrical energy is a simultaneous and mutual cooperation of voltage and current waveforms - therefore, the authors defined and examined the correlation function Psi(t) of these waveforms. On the basis of the defined correlation function between the voltage and the current, the authors introduced two new powers: the sine power function Psis t and the cosine power function Psic t.","PeriodicalId":143815,"journal":{"name":"2008 International School on Nonsinusoidal Currents and Compensation","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129773653","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2008-06-10DOI: 10.1109/ISNCC.2008.4627502
M. Pasko, M. Maciążek, D. Buła
The comparison of performance and accuracy of the active power filter control algorithm realizations has been presented in the paper. The worked out algorithms are based on dq synchronous frame control strategy. The following Texas Instruments digital signal controllers were used for the realization: fixed-point TMS320F2812 and floating-point TMS320F28335. The TMS320F28335 digital signal controller is the first floating-point controller in the C2000 family. It combines flexible control-specific interfaces and ease of use of an industrial microcontroller(MCU) with the processing power of DSP technology (up to 300 MFLOPS). Using of the floating-point digital signal processor allows improving accuracy of the computation, particularly in digital filtering (IIR low-pass filter) which has a direct influence on the quality of the generated current waveforms. The worked out algorithms have been practically verified on APF prototype which was built in the Institute of Industrial Electrical Engineering and Computer Science. The presented problems have been illustrated by laboratory results.
{"title":"Performance and accuracy comparison of fixed and floating-point realizations of the Active Power Filter control algorithm","authors":"M. Pasko, M. Maciążek, D. Buła","doi":"10.1109/ISNCC.2008.4627502","DOIUrl":"https://doi.org/10.1109/ISNCC.2008.4627502","url":null,"abstract":"The comparison of performance and accuracy of the active power filter control algorithm realizations has been presented in the paper. The worked out algorithms are based on dq synchronous frame control strategy. The following Texas Instruments digital signal controllers were used for the realization: fixed-point TMS320F2812 and floating-point TMS320F28335. The TMS320F28335 digital signal controller is the first floating-point controller in the C2000 family. It combines flexible control-specific interfaces and ease of use of an industrial microcontroller(MCU) with the processing power of DSP technology (up to 300 MFLOPS). Using of the floating-point digital signal processor allows improving accuracy of the computation, particularly in digital filtering (IIR low-pass filter) which has a direct influence on the quality of the generated current waveforms. The worked out algorithms have been practically verified on APF prototype which was built in the Institute of Industrial Electrical Engineering and Computer Science. The presented problems have been illustrated by laboratory results.","PeriodicalId":143815,"journal":{"name":"2008 International School on Nonsinusoidal Currents and Compensation","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125741124","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2008-06-10DOI: 10.1109/ISNCC.2008.4627513
K. Sozański
This paper describes a shunt active power filters (APF) with improved dynamic performance. When the value of load current changes rapidly, the APF transient response is too slow, the line current suffers from dynamic distortion. This distortion causes an increase of harmonic content in the line current, which is dependent on a time constant. The APF control current dynamics is dependent on the inverter output time constant consisting of APF output inductance and resultant impedance of load and mains. In the proposed circuit transient performance of APF is improved using non-causal predictive current compensation. In the second solution modified output inverter is used. According to this modification the APF dynamics are improved. The Matlab simulation results of the modified APF are also presented in the paper. As an example a control circuit for a three-phase 75 kVA parallel active power filter (APF) is used.
{"title":"Improved shunt active power filters","authors":"K. Sozański","doi":"10.1109/ISNCC.2008.4627513","DOIUrl":"https://doi.org/10.1109/ISNCC.2008.4627513","url":null,"abstract":"This paper describes a shunt active power filters (APF) with improved dynamic performance. When the value of load current changes rapidly, the APF transient response is too slow, the line current suffers from dynamic distortion. This distortion causes an increase of harmonic content in the line current, which is dependent on a time constant. The APF control current dynamics is dependent on the inverter output time constant consisting of APF output inductance and resultant impedance of load and mains. In the proposed circuit transient performance of APF is improved using non-causal predictive current compensation. In the second solution modified output inverter is used. According to this modification the APF dynamics are improved. The Matlab simulation results of the modified APF are also presented in the paper. As an example a control circuit for a three-phase 75 kVA parallel active power filter (APF) is used.","PeriodicalId":143815,"journal":{"name":"2008 International School on Nonsinusoidal Currents and Compensation","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132596064","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2008-06-10DOI: 10.1109/ISNCC.2008.4627492
M. Dumitrescu, T. Munteanu, G. Gurguiatu, C. Vlad, D. Floricau
The paper proposes to analyze a real case study from Galati town power delivery system. The study will consider a technical solution to save power losses using an adequate harmonics filter together with a reactive power correction system. The solution conducts calculations with the objective to minimize the total power losses. On this purpose we use an important data base obtained by local power delivery system monitoring. The paper uses also the results of EDSA professional power system analysis software performing active and reactive power flow calculations for the analyzed power delivery system.
{"title":"Power delivery system nonsinusoidal regime analysis","authors":"M. Dumitrescu, T. Munteanu, G. Gurguiatu, C. Vlad, D. Floricau","doi":"10.1109/ISNCC.2008.4627492","DOIUrl":"https://doi.org/10.1109/ISNCC.2008.4627492","url":null,"abstract":"The paper proposes to analyze a real case study from Galati town power delivery system. The study will consider a technical solution to save power losses using an adequate harmonics filter together with a reactive power correction system. The solution conducts calculations with the objective to minimize the total power losses. On this purpose we use an important data base obtained by local power delivery system monitoring. The paper uses also the results of EDSA professional power system analysis software performing active and reactive power flow calculations for the analyzed power delivery system.","PeriodicalId":143815,"journal":{"name":"2008 International School on Nonsinusoidal Currents and Compensation","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132841449","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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