EPE Association: EPE 2020 - DS2k: Photovoltaics

EPE 2020 - DS2k: Photovoltaics
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2020 ECCE Europe - Conference > EPE 2020 - Topic 05: Renewable Energy Power Systems > EPE 2020 - DS2k: Photovoltaics

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   A Method to search Global Maxima by Permanent Monitoring of Voltage and Current of each PV Panel
By Shailendra RAJPUT [View]
[Download]

Abstract: An efficient MPPT system is needed for large solar plants including several serially and parallel-connected PV panels especially functioning in partial shading conditions. A proportional decrease in electrical power will be a result of inhomogeneous irradiation (partial shading), as well as multiple local maximums that may appear. The presence of multiple local maximums is the most difficult obstacle for traditional MPPT which is based on a sequential search of an optimum working point. The present article submits a new algorithm that can be corresponded to the mathematical modeling with elements of Artificial Intelligence (AI). A proposed method is to use permanent monitoring of a voltage, a current, and temperature of each PV panel placed in the string. An MPPT algorithm determines the position of a global maximum (GM) based on this information and in accordance with the previously obtained math model of individual PV panels. Owing principles of AI, math models should be periodically précised during the service life of the PV plant. Since none of the presented math algorithms can provide localization of GM with the accuracy, required for the modern MPPT, the proposed method desire to be complemented by a conventional approach, let say perturbation and observation or incremental conductance techniques. For example, an algorithm finding zero roots of a power derivative versus current change was used in our work. The proposed algorithm can achieve GM with relatively high speed that is only restricted by digital control ability. Currently, this task would take no more than 50-100 ms maximum. Therefore, the global maximum can be found for any rapidly changing solar irradiation.

   A New Dual-Mode MPPT Algorithm Applied to a Quadratic Converter in a Solar Energy System
By Jean-Paul GAUBERT [View]
[Download]

Abstract: The work on this paper aims to improve the efficiency of a photovoltaic energy system. Reducing the losses in the adaptation stage allows to improve this efficiency. For that, in this paper we will work on the adaptation stage between the solar panels and the loads to reduce the losses. As a first step, we will present a comparison between a conventional DC-DC boost converter usually used in solar system and a quadratic boost with a single switch. This comparison aims to show the advantage of using quadratic converters with high gain in solar systems. The results show that the quadratic converter has a higher efficiency compared to the conventional one, it allows also to reach higher values of gain for a practically acceptable values of duty cycle. This comparison justifies the choice of the quadratic converter. Then, a new dual-mode variable step-size maximum power point tracking (MPPT) algorithm is proposed. The proposed algorithm is used to control the quadratic converter. The proposed algorithm is based on the perturb and observe (P&O) algorithm. The P&O is one of the most known and used MPPT methods, its drawbacks appear during fast solar irradiance variation. The proposed control method is a double mode algorithm. The first mode is active when the operating point is near of the MPP. This mode allows to stabilize the operating point to reduce the steady-state oscillations that occur using the P&O. The second mode is activated when the operating point moves away from the MPP. This mode is a P&O with a large step size that allows tracking the MPP quickly which also reduces the losses. The proposed algorithm is tested through simulations using Simulink/MATLAB. Simulations results prove the efficiency of the proposed algorithm and its advantage compared to the P&O.

   Reduction of conduction losses in resonant converters by connecting three single-phase inverters to a common generator
By SERGIO TÁRRAGA [View]
[Download]

Abstract: This paper proposes the use of a resonant converter consisting of a high frequency bridge and three resonant circuits with their corresponding transformer and rectifier. This configuration eliminates the low frequency pulsating power in the oscillator and reduces the conduction losses compared to the use of three independent DC/DC converters considering unitary power factor. For situations when this conditions can't be fulfilled a method is proposed in order to obtain and calculate the filter capacitor, as well as a dynamic model that works for both situations. Finally, a scale prototype has been built, with experimental results.

   Validation of Thermal Stress Modeling in PV Inverters under Mission Profile Operation
By Ariya SANGWONGWANICH [View]
[Download]

Abstract: This paper quantifies the accuracy of thermal stress modeling in PV inverters under real mission profile operation. The estimated thermal stress profiles obtained from a lumped thermal network under one-day mission profiles are compared with the experimental measurement. According to the results, the average estimation error is well below 1.5 \% even under highly dynamics mission profile conditions.

EPE 2020 - DS2k: Photovoltaics
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2020 ECCE Europe - Conference > EPE 2020 - Topic 05: Renewable Energy Power Systems > EPE 2020 - DS2k: Photovoltaics
	[return to parent folder]

	A Method to search Global Maxima by Permanent Monitoring of Voltage and Current of each PV Panel By Shailendra RAJPUT	[View] [Download]
Abstract: An efficient MPPT system is needed for large solar plants including several serially and parallel-connected PV panels especially functioning in partial shading conditions. A proportional decrease in electrical power will be a result of inhomogeneous irradiation (partial shading), as well as multiple local maximums that may appear. The presence of multiple local maximums is the most difficult obstacle for traditional MPPT which is based on a sequential search of an optimum working point. The present article submits a new algorithm that can be corresponded to the mathematical modeling with elements of Artificial Intelligence (AI). A proposed method is to use permanent monitoring of a voltage, a current, and temperature of each PV panel placed in the string. An MPPT algorithm determines the position of a global maximum (GM) based on this information and in accordance with the previously obtained math model of individual PV panels. Owing principles of AI, math models should be periodically précised during the service life of the PV plant. Since none of the presented math algorithms can provide localization of GM with the accuracy, required for the modern MPPT, the proposed method desire to be complemented by a conventional approach, let say perturbation and observation or incremental conductance techniques. For example, an algorithm finding zero roots of a power derivative versus current change was used in our work. The proposed algorithm can achieve GM with relatively high speed that is only restricted by digital control ability. Currently, this task would take no more than 50-100 ms maximum. Therefore, the global maximum can be found for any rapidly changing solar irradiation.

	A New Dual-Mode MPPT Algorithm Applied to a Quadratic Converter in a Solar Energy System By Jean-Paul GAUBERT	[View] [Download]
Abstract: The work on this paper aims to improve the efficiency of a photovoltaic energy system. Reducing the losses in the adaptation stage allows to improve this efficiency. For that, in this paper we will work on the adaptation stage between the solar panels and the loads to reduce the losses. As a first step, we will present a comparison between a conventional DC-DC boost converter usually used in solar system and a quadratic boost with a single switch. This comparison aims to show the advantage of using quadratic converters with high gain in solar systems. The results show that the quadratic converter has a higher efficiency compared to the conventional one, it allows also to reach higher values of gain for a practically acceptable values of duty cycle. This comparison justifies the choice of the quadratic converter. Then, a new dual-mode variable step-size maximum power point tracking (MPPT) algorithm is proposed. The proposed algorithm is used to control the quadratic converter. The proposed algorithm is based on the perturb and observe (P&O) algorithm. The P&O is one of the most known and used MPPT methods, its drawbacks appear during fast solar irradiance variation. The proposed control method is a double mode algorithm. The first mode is active when the operating point is near of the MPP. This mode allows to stabilize the operating point to reduce the steady-state oscillations that occur using the P&O. The second mode is activated when the operating point moves away from the MPP. This mode is a P&O with a large step size that allows tracking the MPP quickly which also reduces the losses. The proposed algorithm is tested through simulations using Simulink/MATLAB. Simulations results prove the efficiency of the proposed algorithm and its advantage compared to the P&O.

	Reduction of conduction losses in resonant converters by connecting three single-phase inverters to a common generator By SERGIO TÁRRAGA	[View] [Download]
Abstract: This paper proposes the use of a resonant converter consisting of a high frequency bridge and three resonant circuits with their corresponding transformer and rectifier. This configuration eliminates the low frequency pulsating power in the oscillator and reduces the conduction losses compared to the use of three independent DC/DC converters considering unitary power factor. For situations when this conditions can't be fulfilled a method is proposed in order to obtain and calculate the filter capacitor, as well as a dynamic model that works for both situations. Finally, a scale prototype has been built, with experimental results.

	Validation of Thermal Stress Modeling in PV Inverters under Mission Profile Operation By Ariya SANGWONGWANICH	[View] [Download]
Abstract: This paper quantifies the accuracy of thermal stress modeling in PV inverters under real mission profile operation. The estimated thermal stress profiles obtained from a lumped thermal network under one-day mission profiles are compared with the experimental measurement. According to the results, the average estimation error is well below 1.5 \% even under highly dynamics mission profile conditions.