Ferroresonance is a non-linear and dangerous resonance phenomenon that can affect power networks ... more Ferroresonance is a non-linear and dangerous resonance phenomenon that can affect power networks and damage electrical equipment. The ferroresonance phenomenon is examined by dividing it into classes, with chaotic ferroresonance being the most dangerous type that causes overvoltage's. Detecting chaotic ferroresonance in a short period of time is of great importance in terms of taking measures and reducing equipment damage. In this study, we explored the application of deep convolutional neural networks (DCNNs) for the identification and classification of chaotic ferroresonance phenomena. Two pre-trained AlexNet models were adapted using transfer learning to perform these tasks. The first model was utilized to identify chaotic ferroresonance, while the second was employed to distinguish between different subtypes of chaotic ferroresonance by dividing voltage curve graphs into different periods and shapes. The training and testing of both DCNN models were conducted using snapshot images extracted from the voltage curves of all phase voltages. The results of the experiments showed high accuracy in both the identification and classification of chaotic ferroresonance phenomena.
In this article, a transformer model is presented that is applicable to low frequency electromagn... more In this article, a transformer model is presented that is applicable to low frequency electromagnetic transient phenomena of up to 1 kHz. An example of the energization of a no-load transformer is analyzed. A simplifed analytical approach is presented first. Due to the limitations of this approach, a numerical approach is introduced for the solution of the stiff differential equations that describe the transient phenomena. In both cases, algorithms have been developed for generating the waveforms of the state variables. The results of both algorithms are compared to the results of the MATLAB/Simulink/Power System Blockset for the analysis of electromagnetic transient phenomena in electrical energy systems. Developed algorithm with the introduced numerical approach can be used successfully in other low frequency transient phenomena where the main subject of analysis is the nonlinear character of the transformer: ferroresonance, load switch-off, transformer faults etc.
Transformer energization can produce a large nonsinuoidal inrush current which contains both odd ... more Transformer energization can produce a large nonsinuoidal inrush current which contains both odd and higher order harmonic components that can put transformer winding under mechanical stress. Additionally, they can cause irregular tripping of harmonic protection relays. Furthermore, in relatively weak power systems, such as is the Bosnian system, the superposition of harmonic components with system resonance frequencies may produce temporary overvoltages (TOV). Transformer winding failures and metal oxide surge arrester (MOA) energy stresses can occur due to TOV. The paper demonstrates a case study of an energization of a 220/110 kV transformer and power quality problems that can appear due to higher harmonics. Energy stresses of MOA provoked by transformer energization are considered in the paper.
The ferroresonant states associated with inductive voltage transformers may be generated by elimi... more The ferroresonant states associated with inductive voltage transformers may be generated by elimination of single-phase short-circuits in isolated distribution networks. The paper presents a qualitative analysis of causes of ferroresonance initiation, and significant parameters impacting ferroresonance, like zerosequence system capacitance and the number of connected voltage transformers. Using simulations, the causes of short-circuit occurrence for different system scenarios are investigated and damping devices for ferroresonance mitigations in a 35 kV isolated network are presented.
Pri određivanju nazivnog napona odvodnika prenapona posebnu pažnju treba obratiti na energetsko o... more Pri određivanju nazivnog napona odvodnika prenapona posebnu pažnju treba obratiti na energetsko opterećenje odvodnika kako pri privremenim, tako i pri atmosferskim te sklopnim prenaponima. Poznato je da visokonaponski odvodnici prenapona nižeg nazivnog napona pružaju bolju zaštitu i efikasnije štite opremu u rasklopnom postrojenju. S druge strane, odvodnici prenapona mogu biti energetski preopterećeni ukoliko je njihov nazivni napon prenizak. U ovom radu analizirana je prenaponska zaštita 110 kV postrojenja u hidroelektrani. Na osnovi provedenih simulacija i rezultata proračuna prenapona, predložena je optimalna prenaponska zaštita odvodnicima prenapona u postrojenju. Pri tome je posebna pažnja posvećena odabiru nazivnog napona odvodnika s ciljem efikasne zaštite komponenti visokonaponskog postrojenja. Analizirana je efikasnost zaštite postojećim odvodnicima prenapona i predložena su poboljšanja koja uključuju i mogućnost ugradnje odvodnika prenapona na dalekovodu.
The ferorresonance is a complicated and hard to predict phenomenon, and because of its harmful im... more The ferorresonance is a complicated and hard to predict phenomenon, and because of its harmful impact on the electrical equipment very interesting to be known in a greater detail. The ferroresonance occurs in several modes: fundamental, subharmonic, quasi-periodic and chaotic. This paper analyses the impact of the system parameters on obtaining the different ferroresonance modes. The analysis is carried out by simulating the behavior of one of the most common examples of the ferroresonance occurrence: unloaded single-phase transformer which is, when switched on, energized over the grading capacitor. The ferroresonant modes are indentified and represented by three different techniques: the spectral-density analysis, the phaseplane analysis and the Poincaré map.
Lightning is the main cause of faults on overhead lines thus having a major impact on the quality... more Lightning is the main cause of faults on overhead lines thus having a major impact on the quality of electricity supply. In order to improve the power quality, the correlation between lightning impacts measured by lightning location system (LLS) and events recorded by relay protection devices can be utilized. The paper describes examples of correlation that has been conducted for 110 kV overhead lines, with heightened number of power outages. The lightning density maps and other lightning data have been obtained for the area surrounding the overhead lines through a LLS that has been established in Croatia and Bosnia and Herzegovina, as part of the LINET network.
U ovom radu su predstavljene osnovne osobine LED sijalice kao izvora svjetlosti. Osnovni fokus ra... more U ovom radu su predstavljene osnovne osobine LED sijalice kao izvora svjetlosti. Osnovni fokus rada je istraživanje karakteristika LED sijalica u analizama visih harmonika u sistemu. U radu je istražen nelinearni karakter LED sijalica s obzirom na talasne oblike struja koje ove sijalice generiraju u distributivnu elektroenergetsku mrežu. Prikazani su rezultati mjerenja talasnih oblika struja tipicne LED sijalice, zajedno sa pripadnim harmonijskim karakteristikama (HD i THD) struje LED sijalice. U radu je realiziran pojednostavljeni elektricni model tipicne LED sijalice u aplikativan analizama visih harmonika u sistemu. Prikazana je komparativna analiza izmjerenih i simuliranih talasnih oblika struje LED sijalice, zajedno sa njihovim harmonijskim sadržajem.
Tokom 2009. godine je na podrucju Hrvatske uspostavljen sustav za lociranje munja (SLM, eng. Ligh... more Tokom 2009. godine je na podrucju Hrvatske uspostavljen sustav za lociranje munja (SLM, eng. Lightning Location System - LLS) kao dio Europskog sustava LINET. Sustav je razvijen na Sveucilistu u Munchenu u Njemackoj i danas broji preko 125 senzora diljem Europe. Sest senzora je instalirano na podrucju Hrvatske te dva na podrucju Bosne i Hercegovine. Prve analize podataka ukazuju na zadovoljavajucu ucinkovitost detekcije (eng. Detection Efficiency - DE) koja prelazi 90% za atmosferska pražnjenja oblak-zemlja i zadovoljavajucu tocnost lociranja (eng. Location Accuracy - LA) sa statistickom pogreskom ispod 300 m za podrucje Hrvatske. U razvoju je programska podrska za pracenje grmljavinske aktivnosti u realnom vremenu, analizu povijesnih grmljavinskih aktivnosti, statisticku obradu podataka, korelaciju podataka o grmljavinskim aktivnostima s položajem dalekovoda i izradu karata gustoce grmljavinske aktivnosti. U clanku je prikazana razvijena programska podrska za primjenu podataka o ud...
Correctly modelling the nonlinear saturation characteristics of the transformer iron core is of g... more Correctly modelling the nonlinear saturation characteristics of the transformer iron core is of great importance in steady-state calculations (harmonics and power quality) and calculations of the electromagnetic transients (inrush current, ferroresonance, temporary overvoltages). Thus, this paper presents an original estimation algorithm for determining the transformer nonlinear saturation characteristic from the measured inrush and steady-state current waveforms in entire windows of occurrences. The proposed algorithm is based on the minimization of a specifically defined cost function by applying the Nelder–Mead method, which was used to create a balance between the transformer steady-state current and the inrush current at zero residual flux. The algorithm uses the BDF numerical method in the background to solve the stiff differential equation system. By applying the appropriate indexes of quality estimation, it was demonstrated that, out of a total of twelve proposed analytical functions, the best optimization results were achieved with three proposed functions (the Frolich extended, three-term polynomial and special hyperbolic function). Detailed performances and accuracy suggested that the estimation algorithm has been verified by a very close agreement between the simulation results and measured transformer current waveforms in the steady-state and different inrush current scenarios.
Lightning discharge is a serious cause of damage to wind turbines. Because of their height, they ... more Lightning discharge is a serious cause of damage to wind turbines. Because of their height, they are exposed to direct lightning strikes which can damage the blades, mechanical parts or the electrical and control systems. According to the lightning protection zone concept, only the external parts are subjected to direct lightning strikes. The internal parts are subjected to indirect effects of lightning, but they are sensible because of their low insulation level. This paper elaborates the wind turbine exposure to lightning strikes and presents the EMTP-RV simulation of a direct strike to a wind turbine blade, identifying the overvoltages at the generator and the low voltage side of the step-up transformer, the ground potential rise and the energy absorbed by the surge protective devices, depending on the grounding resistance. Keywords—lightning location system, direct lightning strike, wind turbine, surge protective device
Ferroresonance is a nonlinear dynamic phenomenon that appears in the electric power system betwee... more Ferroresonance is a nonlinear dynamic phenomenon that appears in the electric power system between a non-linear inductances and system capacities excited by a sinusoidal voltage source. The most common non-linear elements of the electric power system are the iron core inductances of power and measuring transformers, reactors, etc. in which saturation of non-linear elements can occur. As a consequence of ferroresonance there may be a significant increase in the voltage value and under the certain conditions an excessive increase of the current value across the transformer terminals. This phenomenon can lead to damage of the measuring transformers and other equipment used in the network. Ferroresonance is one of the most common low-frequency electromagnetic transient phenomena that appear in the isolated power networks. Therefore, special attention must be on analyzing the probability of ferroresonance occurrence in electric power systems. In this paper, ferroresonance measurement results will be given. The waveform of the phase to ground voltage and wave form of the open delta voltage is obtained. Also, the Fourier transformation is performed on these signals. Proposed measurements are conducted in the real 35 kV distribution network with isolated neutral point. Also, efficiency of some experimentally tested mitigation measure will be presented within this paper.
... 1998. [12] M. Hanke, A New Implementation of a BDF Method Within the Method of Lines. Stockho... more ... 1998. [12] M. Hanke, A New Implementation of a BDF Method Within the Method of Lines. Stockholm, Sweden: Parallel and Scientific Computing In-stitute, 2001. [13] ME Hosea and LF Shampine, “Analysis and implementation of TR-BDF2,” Appl. Numer. Math., vol. 20, pp. ...
The paper analyzes laboratory ferroresonance measurements taken on an example of a three-phase th... more The paper analyzes laboratory ferroresonance measurements taken on an example of a three-phase three-legged power transformer. Ferroresonance occurrs due to a nonlinear inductance, capacitance and periodic voltage source in the network. A transformer becomes ferroresonant during an irregular circuit-breaker operation, when the interaction between the transformer nonlinear magnetizing inductances and phase-to-ground capacitances generate sustained distorted overvoltages. The measurement results and voltage waveforms show the presence of high and sustained ferroresonant overvoltages and a harmonic spectrum containing higher
The paper describes a simulation procedure which can be applied in order to analyse the preventio... more The paper describes a simulation procedure which can be applied in order to analyse the prevention of flashover near a substation by installing line surge arresters (LSAs). The demonstrated procedure includes the application of a three-dimensional electro-geometric model, description of modelling process, EMTP simulations and estimating the lightning performance of a high voltage substation. This is shown in the case study on the double-circuit line of 220 kV with one shield wire entering the substation. By locating LSA on a tower near a substation, the risk of backflashovers near the station is significantly reduced and the steepness and amplitude of incoming travelling waves are lowered, thus improving the protection performance of station arresters.
2006 IEEE PES Power Systems Conference and Exposition, 2006
This paper presents possibilities of linearly based interior point method in solving multiperiod ... more This paper presents possibilities of linearly based interior point method in solving multiperiod optimal power flows. LP model of interior point method for solving multiperiod optimal power flow and formulation multiperiod optimal power flows are presented. It has been shown that restarting from the optimal solution of one problem to find another optimal solution of the next perturbed problem, which has been known as hot start, under slow variable conditions, improve performance of the algorithm in respect to the flat start. There are problems of using optimal solution of original problem as starting point to the next perturbed problem, which is simulated as snap of the load. In this work authors suggest using starting point, which is not optimal one, but very close to optimal, and which is still far away from the boundary of feasible region. It has been shown that choosing that point is closely related with numerical problems. Algorithm, which can solve this problem, is tested on the standard IEEE 30 bus test system by applying classical Newton-Raphson method as a corrector
Ferroresonance is a non-linear and dangerous resonance phenomenon that can affect power networks ... more Ferroresonance is a non-linear and dangerous resonance phenomenon that can affect power networks and damage electrical equipment. The ferroresonance phenomenon is examined by dividing it into classes, with chaotic ferroresonance being the most dangerous type that causes overvoltage's. Detecting chaotic ferroresonance in a short period of time is of great importance in terms of taking measures and reducing equipment damage. In this study, we explored the application of deep convolutional neural networks (DCNNs) for the identification and classification of chaotic ferroresonance phenomena. Two pre-trained AlexNet models were adapted using transfer learning to perform these tasks. The first model was utilized to identify chaotic ferroresonance, while the second was employed to distinguish between different subtypes of chaotic ferroresonance by dividing voltage curve graphs into different periods and shapes. The training and testing of both DCNN models were conducted using snapshot images extracted from the voltage curves of all phase voltages. The results of the experiments showed high accuracy in both the identification and classification of chaotic ferroresonance phenomena.
In this article, a transformer model is presented that is applicable to low frequency electromagn... more In this article, a transformer model is presented that is applicable to low frequency electromagnetic transient phenomena of up to 1 kHz. An example of the energization of a no-load transformer is analyzed. A simplifed analytical approach is presented first. Due to the limitations of this approach, a numerical approach is introduced for the solution of the stiff differential equations that describe the transient phenomena. In both cases, algorithms have been developed for generating the waveforms of the state variables. The results of both algorithms are compared to the results of the MATLAB/Simulink/Power System Blockset for the analysis of electromagnetic transient phenomena in electrical energy systems. Developed algorithm with the introduced numerical approach can be used successfully in other low frequency transient phenomena where the main subject of analysis is the nonlinear character of the transformer: ferroresonance, load switch-off, transformer faults etc.
Transformer energization can produce a large nonsinuoidal inrush current which contains both odd ... more Transformer energization can produce a large nonsinuoidal inrush current which contains both odd and higher order harmonic components that can put transformer winding under mechanical stress. Additionally, they can cause irregular tripping of harmonic protection relays. Furthermore, in relatively weak power systems, such as is the Bosnian system, the superposition of harmonic components with system resonance frequencies may produce temporary overvoltages (TOV). Transformer winding failures and metal oxide surge arrester (MOA) energy stresses can occur due to TOV. The paper demonstrates a case study of an energization of a 220/110 kV transformer and power quality problems that can appear due to higher harmonics. Energy stresses of MOA provoked by transformer energization are considered in the paper.
The ferroresonant states associated with inductive voltage transformers may be generated by elimi... more The ferroresonant states associated with inductive voltage transformers may be generated by elimination of single-phase short-circuits in isolated distribution networks. The paper presents a qualitative analysis of causes of ferroresonance initiation, and significant parameters impacting ferroresonance, like zerosequence system capacitance and the number of connected voltage transformers. Using simulations, the causes of short-circuit occurrence for different system scenarios are investigated and damping devices for ferroresonance mitigations in a 35 kV isolated network are presented.
Pri određivanju nazivnog napona odvodnika prenapona posebnu pažnju treba obratiti na energetsko o... more Pri određivanju nazivnog napona odvodnika prenapona posebnu pažnju treba obratiti na energetsko opterećenje odvodnika kako pri privremenim, tako i pri atmosferskim te sklopnim prenaponima. Poznato je da visokonaponski odvodnici prenapona nižeg nazivnog napona pružaju bolju zaštitu i efikasnije štite opremu u rasklopnom postrojenju. S druge strane, odvodnici prenapona mogu biti energetski preopterećeni ukoliko je njihov nazivni napon prenizak. U ovom radu analizirana je prenaponska zaštita 110 kV postrojenja u hidroelektrani. Na osnovi provedenih simulacija i rezultata proračuna prenapona, predložena je optimalna prenaponska zaštita odvodnicima prenapona u postrojenju. Pri tome je posebna pažnja posvećena odabiru nazivnog napona odvodnika s ciljem efikasne zaštite komponenti visokonaponskog postrojenja. Analizirana je efikasnost zaštite postojećim odvodnicima prenapona i predložena su poboljšanja koja uključuju i mogućnost ugradnje odvodnika prenapona na dalekovodu.
The ferorresonance is a complicated and hard to predict phenomenon, and because of its harmful im... more The ferorresonance is a complicated and hard to predict phenomenon, and because of its harmful impact on the electrical equipment very interesting to be known in a greater detail. The ferroresonance occurs in several modes: fundamental, subharmonic, quasi-periodic and chaotic. This paper analyses the impact of the system parameters on obtaining the different ferroresonance modes. The analysis is carried out by simulating the behavior of one of the most common examples of the ferroresonance occurrence: unloaded single-phase transformer which is, when switched on, energized over the grading capacitor. The ferroresonant modes are indentified and represented by three different techniques: the spectral-density analysis, the phaseplane analysis and the Poincaré map.
Lightning is the main cause of faults on overhead lines thus having a major impact on the quality... more Lightning is the main cause of faults on overhead lines thus having a major impact on the quality of electricity supply. In order to improve the power quality, the correlation between lightning impacts measured by lightning location system (LLS) and events recorded by relay protection devices can be utilized. The paper describes examples of correlation that has been conducted for 110 kV overhead lines, with heightened number of power outages. The lightning density maps and other lightning data have been obtained for the area surrounding the overhead lines through a LLS that has been established in Croatia and Bosnia and Herzegovina, as part of the LINET network.
U ovom radu su predstavljene osnovne osobine LED sijalice kao izvora svjetlosti. Osnovni fokus ra... more U ovom radu su predstavljene osnovne osobine LED sijalice kao izvora svjetlosti. Osnovni fokus rada je istraživanje karakteristika LED sijalica u analizama visih harmonika u sistemu. U radu je istražen nelinearni karakter LED sijalica s obzirom na talasne oblike struja koje ove sijalice generiraju u distributivnu elektroenergetsku mrežu. Prikazani su rezultati mjerenja talasnih oblika struja tipicne LED sijalice, zajedno sa pripadnim harmonijskim karakteristikama (HD i THD) struje LED sijalice. U radu je realiziran pojednostavljeni elektricni model tipicne LED sijalice u aplikativan analizama visih harmonika u sistemu. Prikazana je komparativna analiza izmjerenih i simuliranih talasnih oblika struje LED sijalice, zajedno sa njihovim harmonijskim sadržajem.
Tokom 2009. godine je na podrucju Hrvatske uspostavljen sustav za lociranje munja (SLM, eng. Ligh... more Tokom 2009. godine je na podrucju Hrvatske uspostavljen sustav za lociranje munja (SLM, eng. Lightning Location System - LLS) kao dio Europskog sustava LINET. Sustav je razvijen na Sveucilistu u Munchenu u Njemackoj i danas broji preko 125 senzora diljem Europe. Sest senzora je instalirano na podrucju Hrvatske te dva na podrucju Bosne i Hercegovine. Prve analize podataka ukazuju na zadovoljavajucu ucinkovitost detekcije (eng. Detection Efficiency - DE) koja prelazi 90% za atmosferska pražnjenja oblak-zemlja i zadovoljavajucu tocnost lociranja (eng. Location Accuracy - LA) sa statistickom pogreskom ispod 300 m za podrucje Hrvatske. U razvoju je programska podrska za pracenje grmljavinske aktivnosti u realnom vremenu, analizu povijesnih grmljavinskih aktivnosti, statisticku obradu podataka, korelaciju podataka o grmljavinskim aktivnostima s položajem dalekovoda i izradu karata gustoce grmljavinske aktivnosti. U clanku je prikazana razvijena programska podrska za primjenu podataka o ud...
Correctly modelling the nonlinear saturation characteristics of the transformer iron core is of g... more Correctly modelling the nonlinear saturation characteristics of the transformer iron core is of great importance in steady-state calculations (harmonics and power quality) and calculations of the electromagnetic transients (inrush current, ferroresonance, temporary overvoltages). Thus, this paper presents an original estimation algorithm for determining the transformer nonlinear saturation characteristic from the measured inrush and steady-state current waveforms in entire windows of occurrences. The proposed algorithm is based on the minimization of a specifically defined cost function by applying the Nelder–Mead method, which was used to create a balance between the transformer steady-state current and the inrush current at zero residual flux. The algorithm uses the BDF numerical method in the background to solve the stiff differential equation system. By applying the appropriate indexes of quality estimation, it was demonstrated that, out of a total of twelve proposed analytical functions, the best optimization results were achieved with three proposed functions (the Frolich extended, three-term polynomial and special hyperbolic function). Detailed performances and accuracy suggested that the estimation algorithm has been verified by a very close agreement between the simulation results and measured transformer current waveforms in the steady-state and different inrush current scenarios.
Lightning discharge is a serious cause of damage to wind turbines. Because of their height, they ... more Lightning discharge is a serious cause of damage to wind turbines. Because of their height, they are exposed to direct lightning strikes which can damage the blades, mechanical parts or the electrical and control systems. According to the lightning protection zone concept, only the external parts are subjected to direct lightning strikes. The internal parts are subjected to indirect effects of lightning, but they are sensible because of their low insulation level. This paper elaborates the wind turbine exposure to lightning strikes and presents the EMTP-RV simulation of a direct strike to a wind turbine blade, identifying the overvoltages at the generator and the low voltage side of the step-up transformer, the ground potential rise and the energy absorbed by the surge protective devices, depending on the grounding resistance. Keywords—lightning location system, direct lightning strike, wind turbine, surge protective device
Ferroresonance is a nonlinear dynamic phenomenon that appears in the electric power system betwee... more Ferroresonance is a nonlinear dynamic phenomenon that appears in the electric power system between a non-linear inductances and system capacities excited by a sinusoidal voltage source. The most common non-linear elements of the electric power system are the iron core inductances of power and measuring transformers, reactors, etc. in which saturation of non-linear elements can occur. As a consequence of ferroresonance there may be a significant increase in the voltage value and under the certain conditions an excessive increase of the current value across the transformer terminals. This phenomenon can lead to damage of the measuring transformers and other equipment used in the network. Ferroresonance is one of the most common low-frequency electromagnetic transient phenomena that appear in the isolated power networks. Therefore, special attention must be on analyzing the probability of ferroresonance occurrence in electric power systems. In this paper, ferroresonance measurement results will be given. The waveform of the phase to ground voltage and wave form of the open delta voltage is obtained. Also, the Fourier transformation is performed on these signals. Proposed measurements are conducted in the real 35 kV distribution network with isolated neutral point. Also, efficiency of some experimentally tested mitigation measure will be presented within this paper.
... 1998. [12] M. Hanke, A New Implementation of a BDF Method Within the Method of Lines. Stockho... more ... 1998. [12] M. Hanke, A New Implementation of a BDF Method Within the Method of Lines. Stockholm, Sweden: Parallel and Scientific Computing In-stitute, 2001. [13] ME Hosea and LF Shampine, “Analysis and implementation of TR-BDF2,” Appl. Numer. Math., vol. 20, pp. ...
The paper analyzes laboratory ferroresonance measurements taken on an example of a three-phase th... more The paper analyzes laboratory ferroresonance measurements taken on an example of a three-phase three-legged power transformer. Ferroresonance occurrs due to a nonlinear inductance, capacitance and periodic voltage source in the network. A transformer becomes ferroresonant during an irregular circuit-breaker operation, when the interaction between the transformer nonlinear magnetizing inductances and phase-to-ground capacitances generate sustained distorted overvoltages. The measurement results and voltage waveforms show the presence of high and sustained ferroresonant overvoltages and a harmonic spectrum containing higher
The paper describes a simulation procedure which can be applied in order to analyse the preventio... more The paper describes a simulation procedure which can be applied in order to analyse the prevention of flashover near a substation by installing line surge arresters (LSAs). The demonstrated procedure includes the application of a three-dimensional electro-geometric model, description of modelling process, EMTP simulations and estimating the lightning performance of a high voltage substation. This is shown in the case study on the double-circuit line of 220 kV with one shield wire entering the substation. By locating LSA on a tower near a substation, the risk of backflashovers near the station is significantly reduced and the steepness and amplitude of incoming travelling waves are lowered, thus improving the protection performance of station arresters.
2006 IEEE PES Power Systems Conference and Exposition, 2006
This paper presents possibilities of linearly based interior point method in solving multiperiod ... more This paper presents possibilities of linearly based interior point method in solving multiperiod optimal power flows. LP model of interior point method for solving multiperiod optimal power flow and formulation multiperiod optimal power flows are presented. It has been shown that restarting from the optimal solution of one problem to find another optimal solution of the next perturbed problem, which has been known as hot start, under slow variable conditions, improve performance of the algorithm in respect to the flat start. There are problems of using optimal solution of original problem as starting point to the next perturbed problem, which is simulated as snap of the load. In this work authors suggest using starting point, which is not optimal one, but very close to optimal, and which is still far away from the boundary of feasible region. It has been shown that choosing that point is closely related with numerical problems. Algorithm, which can solve this problem, is tested on the standard IEEE 30 bus test system by applying classical Newton-Raphson method as a corrector
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Papers by Amir Tokic