Microcomputer Control of a Residential Photovoltaic Power Conditioning System
TL;DR: In this paper, a microcomputer-based control of a residential photovoltaic power conditioning system is described, which is responsible for array current feedback control, maximum power tracking control, array safe zone steering control, phase-locked reference wave synthesis, sequencing control, and some diagnostics.
Abstract: Microcomputer-based control of a residential photovoltaic power conditioning system is described. The microcomputer is responsible for array current feedback control, maximum power tracking control, array safe zone steering control, phase-locked reference wave synthesis, sequencing control, and some diagnostics. The control functions are implemented using Intel 8751 single-chip microcomputer-based hardware and software. The controller has been tested in the laboratory with the prototype power conditioner and shows excellent performance.
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TL;DR: In this paper, a buck-type DC/DC converter is used to maximize the photovoltaic array output power, irrespective of the temperature and irradiation conditions and of the load electrical characteristics.
Abstract: Maximum power point tracking (MPPT) is used in photovoltaic (PV) systems to maximize the photovoltaic array output power, irrespective of the temperature and irradiation conditions and of the load electrical characteristics. A new MPPT system has been developed, consisting of a buck-type DC/DC converter, which is controlled by a microcontroller-based unit. The main difference between the method used in the proposed MPPT system and other techniques used in the past is that the PV array output power is used to directly control the DC/DC converter, thus reducing the complexity of the system. The resulting system has high-efficiency, lower-cost and can be easily modified to handle more energy sources (e.g., wind-generators). The experimental results show that the use of the proposed MPPT control increases the PV output power by as much as 15% compared to the case where the DC/DC converter duty cycle is set such that the PV array produces the maximum power at 1 kW/m/sup 2/ and 25/spl deg/C.
1,309 citations
TL;DR: In this paper, an overview of single-phase inverters developed for small distributed power generators is presented, compared, and evaluated against the requirements of power decoupling and dual-grounding, the capabilities for grid-connected or/and stand-alone operations, and specific DG applications.
Abstract: This paper presents an overview of single-phase inverters developed for small distributed power generators. The functions of inverters in distributed power generation (DG) systems include dc-ac conversion, output power quality assurance, various protection mechanisms, and system controls. Unique requirements for small distributed power generation systems include low cost, high efficiency and tolerance for an extremely wide range of input voltage variations. These requirements have driven the inverter development toward simpler topologies and structures, lower component counts, and tighter modular design. Both single-stage and multiple-stage inverters have been developed for power conversion in DG systems. Single-stage inverters offer simple structure and low cost, but suffer from a limited range of input voltage variations and are often characterized by compromised system performance. On the other hand, multiple-stage inverters accept a wide range of input voltage variations, but suffer from high cost, complicated structure and low efficiency. Various circuit topologies are presented, compared, and evaluated against the requirements of power decoupling and dual-grounding, the capabilities for grid-connected or/and stand-alone operations, and specific DG applications in this paper, along with the identification of recent development trends of single-phase inverters for distributed power generators.
899 citations
Cites background from "Microcomputer Control of a Resident..."
...Multiple-stage boost inverter by GEC [13]....
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...17 shows a multiple-stage boost inverter [13] with a current source inverter in the last power stage....
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...This configuration was commercially developed by General Electric Company (GEC) for 10-kW grid-connected photovoltaic systems [24]....
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TL;DR: A simple method of tracking the maximum power points (MPPs) and forcing the system to operate close to these points is presented, and the principle of energy conservation is used to derive the large- and small-signal model and transfer function.
Abstract: Photovoltaic systems normally use a maximum power point tracking (MPPT) technique to continuously deliver the highest possible power to the load when variations in the insulation and temperature occur. It overcomes the problem of mismatch between the solar arrays and the given load. A simple method of tracking the maximum power points (MPPs) and forcing the system to operate close to these points is presented. The principle of energy conservation is used to derive the large- and small-signal model and transfer function. By using the proposed model, the drawbacks of the state-space-averaging method can be overcome. The TI320C25 digital signal processor (DSP) was used to implement the proposed MPPT controller, which controls the DC/DC converter in the photovoltaic system. Simulations and experimental results show excellent performance.
746 citations
Cites background from "Microcomputer Control of a Resident..."
...The traditional – characteristics of a solar array, when neglecting the internal shunt resistance, is given by the following equation [2]:...
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...The saturation current ( ) of the solar array varies with temperature according to the following equation [2]:...
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TL;DR: A novel maximum-power-point-tracking (MPPT) controller for a photovoltaic (PV) energy conversion system is presented, and a single-stage configuration is implemented, resulting in size and weight reduction and increased efficiency.
Abstract: A novel maximum-power-point-tracking (MPPT) controller for a photovoltaic (PV) energy conversion system is presented. Using the slope of power versus voltage of a PV array, the proposed MPPT controller allows the conversion system to track the maximum power point very rapidly. As opposed to conventional two-stage designs, a single-stage configuration is implemented, resulting in size and weight reduction and increased efficiency. The proposed system acts as a solar generator on sunny days, in addition to working as an active power line conditioner on rainy days. Finally, computer simulations and experimental results demonstrate the superior performance of the proposed technique.
714 citations
Cites background or methods from "Microcomputer Control of a Resident..."
...If the internal shunt resistance is neglected, the characteristic of a PV array can be given as [8], [9]...
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...Generally speaking, the frequency of the inverter input current is twice the fundamental frequency of the inverter output current [8]....
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...An MPPT method often used is the perturbation and observation method [8], [9], because the method is easy to implement....
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TL;DR: In this article, the authors proposed a high performance single-stage inverter topology for grid connected PV systems, which can not only boost the usually low photovoltaic (PV) array voltage, but can also convert the solar dc power into high quality ac power for feeding into the grid, while tracking the maximum power from the PV array.
Abstract: This paper proposes a high performance, single-stage inverter topology for grid connected PV systems. The proposed configuration can not only boost the usually low photovoltaic (PV) array voltage, but can also convert the solar dc power into high quality ac power for feeding into the grid, while tracking the maximum power from the PV array. Total harmonic distortion of the current, fed into the grid, is restricted as per the IEEE-519 standard. The proposed topology has several desirable features such as better utilization of the PV array, higher efficiency, low cost and compact size. Further, due to the very nature of the proposed topology, the PV array appears as a floating source to the grid, thereby enhancing the overall safety of the system. A survey of the existing topologies, suitable for single-stage, grid connected PV applications, is carried out and a detailed comparison with the proposed topology is presented. A complete steady-state analysis, including the design procedure and expressions for peak device stresses, is included. Necessary condition on the modulation index "M" for sinusoidal pulsewidth modulated control of the proposed inverter topology has also been derived for discontinuous conduction mode operation. All the analytical, simulation and experimental results are presented.
636 citations
Cites background or methods from "Microcomputer Control of a Resident..."
...“Hill climbing” or the “perturb and observe method” [ 1 ] has been used to track the maximum power point (MPP) of the PV source....
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...Though, multistage systems [ 1 ] have been reported for certain applications, grid connected PV systems usually employ two stages [Fig. 1(a)] [3]–[7] to appropriately condition the available solar power for feeding into the grid....
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...The nonlinear i–v characteristics of the PV array [ 1 ] and the rotation and revolution of the earth around the sun, further necessitate the application of maximum power point tracking (MPPT) [2] to the system....
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References
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01 Jan 1980
TL;DR: This two-volume compilation of solar cell design data is written from industrial, university, and governmental sources and contains tutorial descriptions of analytical methods, solar-cell characteristics, and cell material properties widely used in specifying solar- cell array performance and hardware design.
Abstract: Twelve-chapter two-volume compilation of solar cell design data is written from industrial, university, and governmental sources. Volumes contain tutorial descriptions of analytical methods, solar-cell characteristics, and cell material properties widely used in specifying solar-cell array performance and hardware design, as well as analysis, fabrication, and test methods.
459 citations
TL;DR: In this article, a trade-off study was performed for many transistor and thyristor circuits and configurations and the weighting criteria included full and part load efficiency, size, weight, reliability, ease of control, injected harmonics, reactive power requirements, and parts cost.
Abstract: An investigation into power conditioners that interface with photovoltaic arrays and utilities has been recently completed. The ratings for this investigation include residential systems (5-30 kW) that interface with a 240-V single-phase utility connection and intermediate systems (30-200 kW) that interface with a 480-V three- phase utility connection. Both systems mandated that an isolation transformer be provided between the array and the utility interface. A trade-off study was performed for many transistor and thyristor circuits and configurations. The weighting criteria included full- and part-load efficiency, size, weight, reliability, ease of control, injected harmonics, reactive power requirements, and parts cost. As the result of this study, a 10-kW high-frequency PWM transistor inverter feeding a high-frequency isolation transformer with a sinusoidally shaped current wave was selected. The output of the transformer is rectified with a diode bridge rectifier. Four thyristors, used as 60-Hz switches, reverse the polarity of the rectified current on every other half-cycle of the utility voltage. This reversal is accomplished slightly before the natural zero crossing of the voltage, thereby providing commutation for the thyristors. The results in the intermediate rating study targeted on a 100-kW design using power transistors in a full-bridge circuit connected to a 60-Hz three-phase transformer. Three bridge circuits are provided to interface with the polyphase utility. The switching strategy for the power transistors is based on a sine wave shape of current with a controlled deadband.
71 citations
"Microcomputer Control of a Resident..." refers background in this paper
...All the symbols in (1)-(3) can be defined as I cell output current,...
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TL;DR: A hybrid electric vehicle drive control system under microcomputer control where the propulsion power is shared between a gasoline engine and a dc motor is described.
Abstract: This paper describes a hybrid electric vehicle drive control system under microcomputer control where the propulsion power is shared between a gasoline engine and a dc motor. The control functions have been developed, analyzed, and implemented with highlevel language in a dual Intel 8086 microcomputer system. The drive system has been integrated and tested, and shows excellent results.
14 citations
TL;DR: A microprocessor-based control system is described for an electric vehicle where the microprocessor has the responsibility of propulsion feedback control, drive system sequencing control, battery ``fuel gauging,'' battery charging/equalization control, and some amount of diagnostics.
Abstract: A microprocessor-based control system is described for an electric vehicle where the microprocessor has the responsibility of propulsion feedback control, drive system sequencing control, battery ``fuel gauging,'' battery charging/equalization control, and some amount of diagnostics. The system functions were analyzed and implemented in Intel-8080-based hardware and software. The control system was tested systematically in the laboratory and in the field and shows excellent performance.
12 citations
"Microcomputer Control of a Resident..." refers background in this paper
...All the symbols in (1)-(3) can be defined as I cell output current,...
[...]