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    A modelling case study of an island mode solar power plant
    (Institute of Electrical and Electronics Engineers Inc., 2015) Kabalci, Ersan; Gorgun, Alper; Kabalci, Yasin; Gokkus, Goksel
    The solar panel model is designed according to equation of a solar cell, and all the required parameters such as open circuit voltage, short circuit current etc are considered in order to modify the output power regarding to a commercial photovoltaic (PV) panel. The dc-dc conversion is performed with a buck converter where the optimal duty cycle is dynamically updated by a proportional-integral (PI) controlled generator. The settling time and dc voltage ripples are minimized to increase the efficiency of the dc-dc converter. On the other hand, the single-phase inverter is constructed with an H-bridge that is the most basic multilevel topology known ever. The main intention during the inverter operation was decreasing the total harmonic distortion (THD) ratios as much as possible. Therefore, the modulation scheme is particularly applied to decrease THD by eliminating side band harmonics. The line voltage is properly fixed to 220V/50Hz that is common in northern and central Europe. The THD ratio of the line voltage is measured at 0.03%, while the THD of the current is 0.82%. The power factor of the entire system is measured as 0.99 considering the 8.1° phase displacement between current and voltage waveforms. The analysis results verify the efficiency of the proposed solar power plant and its components.; This paper deals with efficiency analysis of a solar power plant that is considered to be installed in island mode with 2 kWp rated power. The test bed designed in Simulink © 2015 IEEE.
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    A Modelling Case Study of an Island Mode Solar Power Plant
    (IEEE, 2015) Kabalci, Ersan; Kabalci, Yasin; Gorgun, Alper; Gokkus, Goksel
    This paper deals with efficiency analysis of a solar power plant that is considered to be installed in island mode with 2 kWp rated power. The test bed designed in Simulink c consists of solar panel, buck converter, and H-bridge inverter models all based to analytical concepts. The solar panel model is designed according to equation of a solar cell, and all the required parameters such as open circuit voltage, short circuit current etc are considered in order to modify the output power regarding to a commercial photovoltaic (PV) panel. The dc-dc conversion is performed with a buck converter where the optimal duty cycle is dynamically updated by a proportional-integral (PI) controlled generator. The settling time and dc voltage ripples are minimized to increase the efficiency of the dc-dc converter. On the other hand, the single-phase inverter is constructed with an H-bridge that is the most basic multilevel topology known ever. The main intention during the inverter operation was decreasing the total harmonic distortion (THD) ratios as much as possible. Therefore, the modulation scheme is particularly applied to decrease THD by eliminating side band harmonics. The line voltage is properly fixed to 220V/50Hz that is common in northern and central Europe. The THD ratio of the line voltage is measured at 0.03%, while the THD of the current is 0.82%. The power factor of the entire system is measured as 0.99 considering the 8.1 phase displacement between current and voltage waveforms. The analysis results verify the efficiency of the proposed solar power plant and its components.
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    Dual DC-DC converter and monitoring interface for asymmetrical string inverters
    (Institute of Electrical and Electronics Engineers Inc., 2015) Kabalci, Ersan; Bayindir, Ramazan; Gokkus, Goksel; Kabalci, Yasin
    This paper proposes monitoring of the dual DC-DC converters that independently operate of each other in the same topology (Buck-Boost). The dual converter structure is proposed to implement asymmetrical string inverter that is intended to be used variously arranged PV strings. The converters are operated by independently running MPPT algorithms. The converters are supplied by programmed dc sources emulating freely arranged solar arrays, and different loads are connected to each converter output. The converters allow using independent power sources like hybrid power techniques owing to these features. Current and voltage sensors measure the output powers of each converter, where the obtained values are evaluated by P&O algorithm on MCU and the PWM signals are generated. At the same time, obtained values are transmitted to computer by a microcontroller on optically isolated UART to USB unit. The received values are saved in a database to enable historical and instant analyse capability of the converters. © 2015 IEEE.
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    Dual DC-DC Converter and Monitoring Interface for Asymmetrical String Inverters
    (IEEE, 2015) Kabalci, Ersan; Bayindir, Ramazan; Gokkus, Goksel; Kabalci, Yasin
    This paper proposes monitoring of the dual dc-dc converters that independently operate of each other in the same topology (Buck-Boost). The dual converter structure is proposed to implement asymmetrical string inverter that is intended to be used variously arranged PV strings. The converters are operated by independently running MPPT algorithms. The converters are supplied by programmed dc sources emulating freely arranged solar arrays, and different loads are connected to each converter output. The converters allow using independent power sources like hybrid power techniques owing to these features. Current and voltage sensors measure the output powers of each converter, where the obtained values are evaluated by P&O algorithm on MCU and the PWM signals are generated. At the same time, obtained values are transmitted to computer by a microcontroller on optically isolated UART to USB unit. The received values are saved in a database to enable historical and instant analyse capability of the converters.
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    Dual DC-DC converter design for string inverters used in solar plants
    (Institute of Electrical and Electronics Engineers Inc., 2015) Kabalci, Ersan; Kabalci, Yasin; Gokkus, Goksel
    This study deals with the design of a dual buck converter where both of them are simultaneously operated to regulate photovoltaic (PV) string inputs. The proposed control and converter structure is intended to improve the dc-bus interface for solar arrays and to control the dc bus voltage of a commercial grid-tie inverter that is generated by four PV arrays. The control algorithm is improved by including PI control to the regular perturb-and-observe algorithm. Regarding to the international standards on single-phase commercial string inverters such as AS4777-2013, IEC62109, and IEC61727, the maximum power of each solar array is allowed to be 1.2 kWp while the maximum total input power is limited to 4.8 kWp. Individual MPPT controllers that are improved in this study control each one of the dc converters handling dual solar arrays at the input connection. The dc interface voltages regulated by converters are coupled on a unique dc bus to generate the supply voltage of inverter section. The controllers perform a robust operation against the freely fluctuating irradiation values of each solar arrays. © 2015 IEEE.
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    Dual DC-DC Converter Design for String Inverters Used in Solar Plants
    (IEEE, 2015) Kabalci, Ersan; Kabalci, Yasm; Gokkus, Goksel
    This study deals with the design of a dual buck converter where both of them are simultaneously operated to regulate photovoltaic (PV) string inputs. The proposed control and converter structure is intended to improve the dc-bus interface for solar arrays and to control the dc bus voltage of a commercial grid-tie inverter that is generated by four PV arrays. The control algorithm is improved by including PI control to the regular perturb-and-observe algorithm. Regarding to the international standards on single-phase commercial string inverters such as AS4777-2013, IEC62109, and IEC61727, the maximum power of each solar array is allowed to be 1.2 kWp while the maximum total input power is limited to 4.8 kWp. Individual MPPT controllers that are improved in this study control each one of the dc converters handling dual solar arrays at the input connection. The dc interface voltages regulated by converters are coupled on a unique dc bus to generate the supply voltage of inverter section. The controllers perform a robust operation against the freely fluctuating irradiation values of each solar arrays.
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    Single phase multilevel string inverter for solar applications
    (Institute of Electrical and Electronics Engineers Inc., 2015) Kabalci, Ersan; Kabalci, Yasin; Canbaz, Ridvan; Gokkus, Goksel
    The proposed study deals with modeling and implementation of a multilevel string inverter with non-isolated DC-DC converter design. The modeled system is intended to be used for solar applications that the photovoltaic panels are connected in string structure. However, the DC-DC converter and multilevel inverter are capable to be used in distributed energy generation applications owing to the proposed control infrastructure. The entire design includes dual buck converter at the dc coupling input where both of the converters simultaneously operate to regulate photovoltaic string voltages. Each dc converter is capable to manage a string comprised of two photovoltaic arrays at the input. The maximum power of each solar array is allowed to be 1.2 kWp while the maximum value of total input power is limited to 4.8 kWp regarding to the related international standards such as AS4777-2013, IEC62109, and IEC61727. The output voltages of dc converters are set to 120V by the proportional-integral controller and are coupled over dc busbar to supply 9-level string inverter. The multilevel string inverter is comprised of two H-bridges in symmetrical topology where it is arranged according to regular 5-level symmetrical inverter. Furthermore, the regular sinusoidal pulse width modulator is enhanced to increase voltage level of inverter to nine instead of regular 5-level output. The inverter provides unity power factor with 0.63% total harmonic distortion ratio. © 2015 IEEE.