Active power decoupling for differential boost inverter with linear and nonlinear loads using inverse model approach

Purpose This paper aims to investigate an improved control method and digital signal processor-based (DSP-based) digital implementation of three-phase standalone inverter. The proposed method is performance developed of the proportional-resonant controller (PRC) with harmonic injection technique, aiming to improve load voltages quality under different loads, especially nonlinear loads. The advanced proposed multi-loop controller is consisted of current harmonic loops for suppressing odd harmonic, which are analyzed in discrete-time domain. Besides, the voltage loop is also used to compensate the output capacitor voltage. Design/methodology/approach The proposed method can effectively enlarge output voltage stability with low total harmonics distortion and improve the dynamic transient response. The other advantage of the proposed PRC is the injection of the selective harmonic without any additional calculation compensator. Findings The method is given the opportunity to be controlled exactly all harmful outputs with high-quality voltage referenced of the standalone inverter. The proposed method is implemented using a DSP processor (TMS320F28335) and is verified on the 10 kVA three-phase standalone inverter prototype. Originality/value The proposed method is performance developed of the PRC with harmonic injection technique, aiming to improve load voltages quality under different loads, especially nonlinear loads.

This paper presents a control for a three-phase an eleven-level cascaded H-bridge inverter for photovoltaic (PV) system. The maximum power point tracking (MPPT) is capable of extracting maximum power from the PV array connected to each DC link voltage level. The MPPT algorithm is solved by fuzzy logic controller. Space vector pulse width modulation (SVPWM) algorithm uses a simple mapping to generate gate signals for the inverter. This is done to achieve high dynamic performance with low total harmonic distortion (THD). The validity of the system is verified through MATLAB/Simulink and results are compared with three-phase three-level, five-level, seven-level and nine-level cascaded H-bridge inverter for PV system in terms of THD. Finally, simulation results are presented to verify the effectiveness and accuracy of the proposed system.

Analysis and enhancement of PV efficiency with incremental conductance MPPT technique under non-linear loading conditions

A hybrid maximum power point tracking for partially shaded photovoltaic systems in the tropics

In photovoltaic (PV) systems, maximum power point tracking (MPPT) techniques are used in order to extract the maximum power from PV panels. So far, different MPPT methods have been presented. In all of these methods, two MPPT parameters, perturbation amplitude $(\Delta \mathbf{D})$ and perturbation period $(T_{p})$, have a great effect on the MPPT efficiency. In this paper, first, the dynamic behavior of PV systems are assessed in both steady and transient states with the use of the small signal model and the simulation. The PV operating point has different behavior in the steady and transient states; therefore, in the proposed method, first, a state of the system is identified. Afterwards based on characteristics of each state which are assessed in the dynamic behavior of the PV system, the MPPT parameters are optimized. $\Delta \mathbf{D}$ is variable and based on the slope of the P-V curve with two different scaling factors; furthermore, the linear and exponential functions are used to determine the variable $T_{p}$ based on an operating state. In order to prove the superiority of the proposed method over the existing methods, the simulations are done in MATLAB/Simulink and PSIM software, and also comparison is conducted between the proposed method and the previous works.

Photovoltaic (PV) modules subject to partial shading (PS) or inhomogeneous irradiation drastically decrease the PV string power output. An algorithm composed of maximum voltage point tracking (MVPT) and maximum power point (MPP) tracking (MPPT) is presented to restore part of the power loss caused by PS. The MVPT can simultaneously drive the operating point of series PV modules toward their respective MPPs and guarantee power peak uniqueness. The MVPT is performed by means of a controllable current transformer (CCT) disposed at the terminal of each PV module permitting a compatible current in the series path of a PV string. The CCT output current can be regulated using a dependent current source according to the MPPT algorithm. An appropriate CCT current determined by the MPPT algorithm can avert undue CCT activation and consequently reduces the switching and copper losses of the converter circuit. Experimental results validate that the proposed strategy can balance the PV modules' output current subject to PS and facilitate convergence to the theoretical global MPP.

Due to the Randomness and fluctuation of the photovoltaic (PV) system, Maximum Power Point Tracking (MPPT) algorithm is employed to ensure the maximum power extraction from PV arrays, when it is connected to the grid. The previous studies have indicated that the MPPT algorithm is one of the main causes of interharmonics emission in PV systems. The MPPT algorithm parameters such as perturbation step size inevitably have a strong impact on the interharmonics in the current injected to the grid. In general, a smaller MPPT perturbation step size will reduce the interharmonics emission level, but it will result in poor tracking performance of the MPPT algorithm. Thus, there is a trade-off between the MPPT efficiency and the interharmonics emission in PV system. In this paper, an interharmonics suppression scheme with variable step size MPPT algorithm was proposed. In the suppression scheme, two voltage values near by the MPPT voltage and two tracking step size are preset. When the dc-link voltage of PV is between the two preset voltage values, it means that the PV power near its MPP and the smaller perturbation step size implemented in the MPPT algorithm. Otherwise, the bigger perturbation step size is employed. It can greatly reduce interharmonics emission level and maintain the MPPT efficiency. Simulations have been carried out to verify the effectiveness of the suppression scheme.

This paper presents the study, development and application of new control techniques for photovoltaic power generation systems, connected to single-phase power grid in order to improve the efficiency of these systems in relation to control methods typically used. The work is divided into two main parts, which are related to tracking the maximum power point (Maximum Power Point Tracking - MPPT) and then the internal controller of boost quadratic converters - side of the photovoltaic panels - as well as the controllers the voltage inverter, the side of the single-phase mains. The first part of the work is the development of a heuristic goal algorithm for MPPT, which is based on the method of simulated annealing (Simulated Annealing - SA) and aims at determining the overall maximum point, seeking out solutions in a close vicinity, so as to prevent the docking local maxima in the curve of power output of the photovoltaic array, thereby improving the utilization of energy in partial shading situations. The second part presents the design of controllers based on internal model (Internal Model Control - IMC) with 1 degree of freedom (1 Degree of Freedom - 1 DOF) applied, first, the DC-DC Boost Quadratic converter, used for MPPT, and thereafter, a voltage inverter with LCL filter connected to the single phase power supply operating in current injection mode. A mathematical modeling of both converters and analyzed the compensation of internal feedback to the voltage inverter system corresponding to the disconnection of the mains voltage through the power strategy a head (feedforward). A basis of comparison for the performance analysis of IMC-1DOF converter is aiming at, is also applied to the current injection system, Proportional-Resonant Controller (P + Res). They are presented computer simulation and experimental results of both controllers, which allow you to check the system performance in low and non-linear local load network situation.

The single-phase inverters with higher-order filters are popular for grid interface of photovoltaic (PV) systems. Increasing penetration of these systems coupled with nonlinear loads impact grid voltage quality. The grid code restricts the injection of harmonic currents into the grid. To reduce the harmonic distortions in the current that is fed to the grid, this article presents a Proportional-Resonant (PR) controller for a HERIC inverter topology with an integrated input side dc-dc converter. The traditional controllers cannot restrict the injected current harmonic content when the grid voltage is polluted. To solve this problem a PR controller with Harmonic Compensators (HC) has been presented to limit the harmonic distortions. A 1.5kVA single-phase grid-tied inverter with an LCL filter on the output side has been simulated in MATLAB. Simulation studies on a grid-tied PV inverter have been carried out, and performance has been investigated and compared with other controllers for different levels of the injected grid current. The developed grid-tied inverter with a PR controller with HC is suitable for achieving low total harmonic distortion which guarantees that the system provides satisfactory performance according to the grid standards.

This paper presents genetic algorithm (GA) based maximum power point tracking (MPPT) for photovoltaic (PV) array integrated with battery storage unit (BSU) as power generation unit in standalone mode. PV generation depends on solar irradiance, site location and environmental factors like temperature, wind and. Thus output of PV output is fluctuating in nature and the addition of non linear load make the situation more critical. GA based MPPT for PV generation works for local optimal solution. DC/DC and boost converter has been used to obtain rated desired rated voltage. BSU acts as secondary source to ensure uninterrupted power supply. A suitable three phase voltage source inverter (VSI), at point of common coupling (PCC), provides regulated power supply. Boost converters incorporating proportional controller (PI) increases PV voltage up to 400V. Conventionally used perturb and observe (PO) algorithm has been used for comparative study. Controlled pulse width modulated (PWM) switching pulse for converter unit and single section LC filter at output terminal eliminates harmonic components. To exhibit the system compatibility resistive, reactive, asynchronous induction motor and nonlinear load has been switched at different instants for variable solar irradiance and temperature.

This paper proposes a straightforward control method for voltage control of a three-phase transformer-based inverter in uninterruptible power supplies or distributed generation systems. The approach offers a dual-loop design consisting inner current control loop and outer voltage loop. Sliding mode current controller provides desired bandwidth for voltage controller which consists of a state feedback term for stabilization and resonant term for harmonic damping. The proposed scheme provides fast dynamic response and low total harmonic distortion even for high power inverters with the limitations of switching frequency and LC filter components. Experimental studies for 2KVA linear and nonlinear loads using digital signal processors validate excellent performance of the proposed method.

Microgrids serve as primary links for diverse loads, while numerous locally situated power supply systems are concurrently established in various locations. Grid-integrated hybrid renewable energy power conversion systems have gained significant popularity in recent years. However, a novel and effective control methodology must be implemented to supply high-quality power at the local load bus. The 3rd Order Degree of Freedom – PID (3DOF-PID) controllers stand out among numerous controllers, demonstrating exceptional performance across a wide range of operating conditions. In this paper, a hybrid system comprising a solar power plant and a wind power plant is examined, with a focus on its benefits to the power grid. Furthermore, Sliding Mode Control (SMC) techniques are applied to all photovoltaic (PV) and wind power conversion systems to facilitate the operation of the boost converter as Maximum Power Point Tracking (MPPT) devices. A shared DC bus is created by combining all converters in the solar power facility and the wind energy conversion plant. An inverter is integrated between the DC bus and the utility grid's point of common coupling (PCC). The study presents a robust control strategy utilizing 3DOF-PID controllers to ensure high-quality power delivery at the PCC while accommodating a diverse range of load combinations, including both linear and nonlinear loads, as well as single-phase and three-phase reactive power loads. 3DOF-PID controllers have been created for each converter and incorporated using OPAL-RT technology and modules within a Real-Time Simulator (RTS). The results are presented through RTS to evaluate the suggested control methodologies for the power supply system that integrates grid-connected hybrid renewable energy sources (RESs).

Solar cell has the current-voltage (I-V) characteristic which is affected by the radiation and the temperature. To obtain the maximum electricity from the solar cells, the power converters for PV (photovoltaic) module have a function called MPPT (maximum power point tracking). The dc voltage and current are controlled to track the maximum power point (MPP) where the PV modules feed the maximum output power. AC module is composed of a PV module and a module integrated converter (MIC). The output port is connected with the ac wiring. Each module can operate with tracking the own MPP. In case of AC module, the basic characteristic of the PV module is well-known by the manufacturer. Therefore the domain of MPP is approximately predicted. In this paper, a novel MPPT method for the MIC is proposed. The proposed method takes full advantage of the known PV module characteristic. The I-V plane is divided into two domains by a linear function. One includes MPPs and the other one never includes MPPs under the normal temperature and radiation conditions. The operating point can be rapidly approached to the MPP using the linear function. Around the MPP, the algorithm is switched to the IncCond method. Circuit experiments have been carried out. The measured time taken for the approach to the MPP is reduced from 22 % to 48 % compared to the conventional algorithm. The proposed method is quite simple so that it can be easily applied to various MPPT algorithms

This paper presents a new maximum power point tracking (MPPT) method based on an incremental conductance (IC) algorithm, constant voltage, and look-up table approach. Convergence time, one of the indicators of MPPT quality, is considered for improving MPPT performance of photovoltaic (PV) modules. In this context, a novel hybrid MPPT approach has been proposed. This proposed method consists of three stages. In the first stage, the value of load resistance is calculated. Then the initial operation point of the PV module is determined by using the constant voltage method or look-up table approach. An IC algorithm is used in order to increase MPPT accuracy in the last stage. One of the novelties of this proposed approach is the determination criterion related to sample numbers of PV module current or solar irradiance. With the help of this approach, the initial operation point of the PV module is optimized before MPPT starts. Thus, convergence time is reduced. In this paper, a DC--DC boost converter has been designed to show the performance of the proposed approach. Then the proposed approach is compared with an IC algorithm. Experimental results show that the performance of the proposed approach is better than that of the IC algorithm in terms of convergence time. On the other hand, since the proposed approach is convenient for reducing convergence time, it can be used instead of variable step size algorithms. Furthermore, there are no topological constraints in the proposed approach. Therefore, this method can be easily applied to other converter topologies for low power or microconverter (module-based converter)-based applications.

This paper presents a control strategy applied for UPS with a low commutation frequency. An adaptive linear quadratic controller (LQR) for a DC/AC converter is presented. The controller gains are determined by minimizing a cost function. A recursive least square (RLS) estimator is used to identify the parameters model at different load conditions. The inductor current is estimated by a Kalman filter. The capacitor voltage and the inductor current are used as state variables. Simulation results show that the proposed strategy offers good performances for either linear and non-linear loads with low total harmonic distortions even at low frequencies making it very useful for high power applications