Estimation-Based Extremum-Seeking Control: A Real-Time Approach for Improving Energy Efficiency in Photovoltaic Systems

Ehsan Moshksar; Teymoor Ghanbari; Haidar Samet; Martin Guay

doi:10.1109/JSYST.2018.2868125

Estimation-Based Extremum-Seeking Control: A Real-Time Approach for Improving Energy Efficiency in Photovoltaic Systems

Ehsan Moshksar, Teymoor Ghanbari, Haidar Samet, Martin Guay

Research output: Contribution to journal › Article › Academic › peer-review

8 Citations (Scopus)

Abstract

This paper presents a novel real-time algorithm to find unknown maximum power of photovoltaic (PV) systems. The maximum power of a typical PV system is continuously changing with variations in solar irradiance and PV module temperature. There is no precise mathematical equation to show relation between PV output power and environmental variables. Since power of a PV cell/module is unknown nonlinear and time-varying function of irradiance and temperature, real-time approaches are required to find maximum power values through time. Based on strong concavity feature of PV output power, one can consider this measurable signal as an unknown objective function that needs to be maximized. Hence, an estimation-based extremum-seeking control algorithm is proposed to solve this nonlinear and uncertain optimization problem. First, gradient of the objective function with respect to the PV voltage is treated as an unknown time-varying parameter. An adaptive estimation technique is utilized to identify this parameter. Then, a direct gradient-based adaptive controller is designed to find optimum voltage value and the corresponding maximum power point at uniform and uncertain weather condition in real time. Unlike most model-free approaches, the proposed algorithm has proof of convergence with precise steady-state and fast-transient performance.

Original language	English
Article number	8488688
Pages (from-to)	3141-3152
Number of pages	12
Journal	IEEE Systems Journal
Volume	13
Issue number	3
DOIs	https://doi.org/10.1109/JSYST.2018.2868125
Publication status	Published - Sept 2019
Externally published	Yes

Bibliographical note

Funding Information:
Manuscript received January 6, 2018; revised May 19, 2018; accepted August 8, 2018. Date of publication October 10, 2018; date of current version August 23, 2019. This work was supported by the National Elites Foundation of Iran. (Corresponding author: Ehsan Moshksar.) E. Moshksar and T. Ghanbari are with the School of Advanced Technologies, Shiraz University, Shiraz 71946-84560, Iran (e-mail:,[email protected]; [email protected]). H. Samet is with the School of Electrical and Computer Engineering, Shiraz University, Shiraz 71946-84636, Iran (e-mail:,[email protected]). M. Guay is with the Department of Chemical Engineering, Queen’s University, Kingston, ON K7L 3N6, Canada (e-mail:,[email protected]). Digital Object Identifier 10.1109/JSYST.2018.2868125

Keywords

Extremum-seeking control (ESC)
photovoltaic (PV) systems
real-time optimization
stability analysis
time-varying environment
uncertain systems

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

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10.1109/JSYST.2018.2868125

Cite this

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title = "Estimation-Based Extremum-Seeking Control: A Real-Time Approach for Improving Energy Efficiency in Photovoltaic Systems",

abstract = "This paper presents a novel real-time algorithm to find unknown maximum power of photovoltaic (PV) systems. The maximum power of a typical PV system is continuously changing with variations in solar irradiance and PV module temperature. There is no precise mathematical equation to show relation between PV output power and environmental variables. Since power of a PV cell/module is unknown nonlinear and time-varying function of irradiance and temperature, real-time approaches are required to find maximum power values through time. Based on strong concavity feature of PV output power, one can consider this measurable signal as an unknown objective function that needs to be maximized. Hence, an estimation-based extremum-seeking control algorithm is proposed to solve this nonlinear and uncertain optimization problem. First, gradient of the objective function with respect to the PV voltage is treated as an unknown time-varying parameter. An adaptive estimation technique is utilized to identify this parameter. Then, a direct gradient-based adaptive controller is designed to find optimum voltage value and the corresponding maximum power point at uniform and uncertain weather condition in real time. Unlike most model-free approaches, the proposed algorithm has proof of convergence with precise steady-state and fast-transient performance.",

keywords = "Extremum-seeking control (ESC), photovoltaic (PV) systems, real-time optimization, stability analysis, time-varying environment, uncertain systems",

author = "Ehsan Moshksar and Teymoor Ghanbari and Haidar Samet and Martin Guay",

note = "Funding Information: Manuscript received January 6, 2018; revised May 19, 2018; accepted August 8, 2018. Date of publication October 10, 2018; date of current version August 23, 2019. This work was supported by the National Elites Foundation of Iran. (Corresponding author: Ehsan Moshksar.) E. Moshksar and T. Ghanbari are with the School of Advanced Technologies, Shiraz University, Shiraz 71946-84560, Iran (e-mail:,[email protected]; [email protected]). H. Samet is with the School of Electrical and Computer Engineering, Shiraz University, Shiraz 71946-84636, Iran (e-mail:,[email protected]). M. Guay is with the Department of Chemical Engineering, Queen{\textquoteright}s University, Kingston, ON K7L 3N6, Canada (e-mail:,[email protected]). Digital Object Identifier 10.1109/JSYST.2018.2868125 ",

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AU - Guay, Martin

N1 - Funding Information: Manuscript received January 6, 2018; revised May 19, 2018; accepted August 8, 2018. Date of publication October 10, 2018; date of current version August 23, 2019. This work was supported by the National Elites Foundation of Iran. (Corresponding author: Ehsan Moshksar.) E. Moshksar and T. Ghanbari are with the School of Advanced Technologies, Shiraz University, Shiraz 71946-84560, Iran (e-mail:,[email protected]; [email protected]). H. Samet is with the School of Electrical and Computer Engineering, Shiraz University, Shiraz 71946-84636, Iran (e-mail:,[email protected]). M. Guay is with the Department of Chemical Engineering, Queen’s University, Kingston, ON K7L 3N6, Canada (e-mail:,[email protected]). Digital Object Identifier 10.1109/JSYST.2018.2868125

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N2 - This paper presents a novel real-time algorithm to find unknown maximum power of photovoltaic (PV) systems. The maximum power of a typical PV system is continuously changing with variations in solar irradiance and PV module temperature. There is no precise mathematical equation to show relation between PV output power and environmental variables. Since power of a PV cell/module is unknown nonlinear and time-varying function of irradiance and temperature, real-time approaches are required to find maximum power values through time. Based on strong concavity feature of PV output power, one can consider this measurable signal as an unknown objective function that needs to be maximized. Hence, an estimation-based extremum-seeking control algorithm is proposed to solve this nonlinear and uncertain optimization problem. First, gradient of the objective function with respect to the PV voltage is treated as an unknown time-varying parameter. An adaptive estimation technique is utilized to identify this parameter. Then, a direct gradient-based adaptive controller is designed to find optimum voltage value and the corresponding maximum power point at uniform and uncertain weather condition in real time. Unlike most model-free approaches, the proposed algorithm has proof of convergence with precise steady-state and fast-transient performance.

AB - This paper presents a novel real-time algorithm to find unknown maximum power of photovoltaic (PV) systems. The maximum power of a typical PV system is continuously changing with variations in solar irradiance and PV module temperature. There is no precise mathematical equation to show relation between PV output power and environmental variables. Since power of a PV cell/module is unknown nonlinear and time-varying function of irradiance and temperature, real-time approaches are required to find maximum power values through time. Based on strong concavity feature of PV output power, one can consider this measurable signal as an unknown objective function that needs to be maximized. Hence, an estimation-based extremum-seeking control algorithm is proposed to solve this nonlinear and uncertain optimization problem. First, gradient of the objective function with respect to the PV voltage is treated as an unknown time-varying parameter. An adaptive estimation technique is utilized to identify this parameter. Then, a direct gradient-based adaptive controller is designed to find optimum voltage value and the corresponding maximum power point at uniform and uncertain weather condition in real time. Unlike most model-free approaches, the proposed algorithm has proof of convergence with precise steady-state and fast-transient performance.

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ER -

Estimation-Based Extremum-Seeking Control: A Real-Time Approach for Improving Energy Efficiency in Photovoltaic Systems

Abstract

Bibliographical note

Keywords

UN SDGs

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