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The insertion of grid connected photovoltaic (PV) in the power systems have occurred mainly at low and medium voltage. Besides, due to solar irradiance variation, these converters have excess capacity that can be used to provide ancillary services to the main grid. Therefore, this work is focused on the analysis of how PV inverters can perform ancillary services, supporting the grid. Control strategies...
The main objective of a photovoltaic (PV) inverter is to inject the PV power into the ac-grid. Generally, due to variations in solar irradiance, inverters operate bellow their rated current. Therefore, this current margin can be used to ancillary services, such as harmonic current compensation. However, it is necessary to study the photovoltaic inverters voltage and current capability effects during...
The multifunctional operation of photovoltaic (PV) inverters consists in using the PV inverter for ancillary services as reactive power injection and harmonic current compensation. The multifunctional operation can improve the ac-grid power quality. Thus, this paper presents a dynamic method based on the Second Order Generalized Integrator coupled with a Phase Locked Loop (SOGI-PLL) structure to detect...
Nowadays, non-linear loads are one of the major issues regarding the system power quality. Additionally, the growing presence of distributed generation (DG) systems, which employs converters to connect power sources to the grid may also affect power quality due to its switching. To better utilize such converters, multifunctional operation is usually employed. In order to reduce the harmonics generated...
In the future, medium-frequency transformers (with a frequency range of 5–100 kHz) will be major components in dc–dc converter applications, for both medium-voltage direct current and high-voltage direct current networks. Importantly, the corresponding power losses should be accurately calculated in order to reach performance targets (very high efficiency). This paper reviews the most known analytical...
The inverter multifunctional operation is based on the harmonic current compensation, generated by nonlinear loads. The traditional harmonic detection methods tracks all harmonic contents of the load current and the control tuning tends to be complex with low flexibility. In many works, the proportional resonant (PR) controllers are used to control the inverter current reference. However, one PR controller...
Single and three-phase photovoltaic inverters are essential components of the photovoltaic (PV) systems to extracting the PV power and injecting it into the grid. Thus, in order to extract the maximum power of the solar array for various solar irradiation tracks, it is used a maximum power point tracker (MPPT) algorithm. Due to variations in solar irradiance, inverters have a current margin, which...
This paper presents an inverter control scheme, based on proportional-resonant controllers, where the inverter works in multifunctional operation. In this case, the reactive power and harmonic compensation of the load are ancillary services. A resonant control is implemented in stationary reference frame (αβ), where is not necessary the use of a phase-locked loop (PLL). The instantaneous power theory...
The main objective of a photovoltaic (PV) inverter is inject the PV power into the grid. However, due to variations in solar irradiance, inverters have a current margin, which can be used in reactive power and harmonics compensation. This possibility, known as multifunctional operation, can be interesting in terms of power factor improvement and reduction of nonlinear loads impact at point of common...
Unbalanced voltage dips are common disturbances in power systems. Therefore, grid-connected photovoltaic systems need to be able to work during these disturbances. Conventional control strategies do not consider the negative sequence current control, which is an important limitation. In this context, this paper compares through simulations four strategies of negative sequence current control: Notch...
Power inverters are essential components of photovoltaic systems and are designed to process the rated power generated by solar plant. Due to variations in solar irradiance, inverters have a current margin, which can be used in reactive power and harmonics compensation. This possibility, known as multifunctional operation, can be interesting in terms of power factor improvement and voltage control...
The steady state operating curves of three design variants of a five-phase induction machine are assessed and compared to a standard three-phase induction machine of the same size which is taken as the basis for the comparison. The performance in terms of torque, power factor, stator current and efficiency are analyzed for different load conditions. The operating curves are determined by means of...
This work deals with the influence of magnetic saturation on machine's parameters of a surface mounted permanent magnet synchronous machine driven by an ideal six-step three-phase inverter. In order to investigate and describe each machine's parameter, a review on Frozen Permeability Method is developed. Further, a general machine design characteristics are presented. At last, some simulation by means...
The insertion of distributed generation systems has growth in the last years. The use of switching converters can produce voltage and current harmonics in the point of common coupling (PCC). In this context, this work presents the use of the passivity-based control in a single-phase inverter connected to the grid. The performance of this technique is compared with the conventional proportional integral...
The photovoltaic systems are extremely dependents on the climatic conditions in which they are submitted. For to represent this influence, there are in the literature three models of the solar photovoltaic panel: the equivalent circuit, the mathematical model and the multi-physical model. This paper compares these models using a grid connected photovoltaic system. Simulations of grid disturbances,...
This work presents an analysis of four topologies of Phase Locked Loop ?? PLL, applied in wind power inverters. The SRF-PLL, DDSRF-PLL, DSOGI-PLL and a MATLAB/Simulink PLL model are compared when there are harmonics in the point of common coupling (PCC). The simulations represent a wind farm with one synchronous generator of 1.5 MW using full converters. The results show that the harmonic produced...
This paper presents a robust control strategy for tracking sinusoidal reference signals with zero steady state error and harmonic compensation in Uninterruptible Power Supplies - UPS. Multiple resonant controllers are derived for DC-AC inverters when supplying energy to (uncertain) nonlinear loads to obtain a nice tradeoff between transient response and disturbance rejection regardless possible load...
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