Grid-tied Solar Inverter Research Articles

Grid-connected Systems Powered by Solar Energy Implemented with Fuzzy based Voltage Source Converters

Solar energy systems connected to the electrical grid are known as grid-tied solar power systems or solar power-connected grid systems. Grid-tied solar inverters are only capable of producing active electricity since they are made to produce power at a unity power factor. The grid alone can meet the load’s requirement for reactive power. Reactive power drawn from the grid relative to active power has increased significantly with the sharp rise in the deployment of distributed energy resources based on renewable energy. This has an impact on the grid’s power quality. The amount of reactive power that the grid must supply will decrease if the grid-tied solar inverter is designed to be intelligent enough to provide reactive power in addition to active power. This work’s primary goal is to generate the necessary pulses for a three-phase inverter, which will aid in producing reactive power and ultimately help achieve the work’s primary objective. Fuzzy logic is a complex approach that takes advantage of the flexibility and adaptability of fuzzy systems to manage Voltage Source Converters (VSCs) for three-phase inverter operation. The primary circuit is simulated in the MATLAB/Simulink environment, giving the desired results.

Modeling and Simulation of Grid-Tied Three-Phase PV System in Lahore, Pakistan

This research examines the implementation of grid-tied solar inverters in Lahore’s energy infrastructure, considering the city’s growing energy demands. Utilizing MATLAB/Simulink for modeling solar photovoltaic systems in Lahore’s arid climate, our study focuses on a house in Askari X housing society, Lahore, Pakistan, with a 5.1 kW load. The results demonstrate the expected system variation of a Grid-Tied PV System during grid disruptions, and the model’s consistent performance across varying irradiance conditions suggests potential economic advantages through net metering. These findings offer practical insights into the economic feasibility and dependability of grid-tied solar inverters in Lahore, highlighting their potential to contribute to the city’s energy needs.

Low voltage ride through control strategy for grid-tied solar photovoltaic inverter

Abstract This paper presents a low voltage ride through (LVRT) control strategy using an active power oscillations based reference current generation approach for grid tied solar photo voltaic (SPV) system under line-to-ground (LG) and double line-to-ground (LLG) faults. Proposed control strategy minimizes the harmonics injected into the grid, as well as oscillations in injected reactive power and DC-link voltage. Further this control strategy provides a dynamic control of active and reactive powers, the flow of sinusoidal currents into the grid, and avoids the disconnection between the utility grid and SPV system during faults. A proportional resonant (PR) current controller is developed in a stationary reference frame to achieve the power quality by fulfilling the grid codes. Simulation and experimental results are presented to highlight the merits of the proposed control scheme.

Comparison between a Cascaded H-Bridge and a Conventional H-Bridge for a 5-kW Grid-Tied Solar Inverter

This paper compares the cost and efficiency of two inverter topologies for a 5-kW grid-connected solar inverter application: the Conventional H-Bridge Inverter (CHB) and the Cascaded H-Bridge Multilevel Inverter (CHBMLI). Emphasis is put on power switches and passive elements with a detailed study of the losses. Both designs respect the same constraints (cost, efficiency, and junction temperature of the transistors) to ensure a fair comparison between both topologies. The work highlights the important parameters when choosing the components (MOSFETs, capacitors, and magnetic cores for the inductors). The DC-link voltage ripple and the output AC current ripple are the key parameters for the design of the passive elements (capacitors and inductors). On top of that, the transistors MOSFETs are chosen, in both topologies, to limit the conduction losses (by selecting the Rdson) and the switching losses (by selecting the Qrr and dv/dt). Real components are picked in order to make the comparison as complete as possible. Numerical simulations are performed using the MATLAB platform. All equations and parameters are provided. A CHBMLI prototype was built with eight independent H-Bridges to validate the proposed design with thermal and efficiency measurements.

A novel low-cost solution for mitigating the loss of power supply probability in grid-tied Solar PV systems during daytime grid-outage scenario

In this paper, a novel method has been proposed and implemented to mitigate the loss of power from grid-connected solar PV systems during the grid outage condition. This loss during daytime grid outages usually occurs because of the built-in islanding feature of the commercially available grid-tied inverters. Unlike other existing grid outage mitigation methods such as; using the expensive hybrid inverters and other battery backup inverters, the proposed method introduces a battery-less topology which can avoid the significant cost of battery pack itself and associated auxiliary control circuits, its operation and maintenance. An optimized low capacity (around 5% of grid-tied inverter rating) DC-AC interface system in the form of a stand-alone inverter has been introduced to provide the reference AC bus for keeping the grid-tied solar inverter operational even during the daytime grid outage. The interface system is energized from a solar PV-powered DC bus instead of the commonly used high-capacity battery backup. The method also ensures the maximum available energy extraction from a grid-connected solar PV Plant without renovating the existing grid-tied solar inverters. The experimental validation has been done by a practical 2kW p grid-tied inverter and a 200VA stand-alone inverter interfaced solar PV system operation and control under sunny and cloudy day scenario. The proposed low-cost grid outage mitigation method is a generalized one and hence can be very useful for scalable grid-connected solar PV power plants also.

PreMSat: Preventing Magnetic Saturation Attack on Hall Sensors

Spoofing a passive Hall sensor with fake magnetic fields can inject false data into the downstream of connected systems. Several works have tried to provide a defense against the intentional spoofing to different sensors over the last six years. However, they either only work on active sensors or against externally injected unwanted weak signals (e.g., EMIs, acoustics, ultrasound, etc.), which can only spoof sensor output in its linear region. However, they do not work against a strong magnetic spoofing attack that can drive the passive Hall sensor output in its saturation region. We name this as the saturation attack. In the saturation region, the output gets flattened, and no information can be retrieved, resulting in a denial-of-service attack on the sensor.Our work begins to fill this gap by providing a defense named PreMSat against the saturation attack on passive Hall sensors. The core idea behind PreMSat is that it cangenerate an internal magnetic field having the same strength but in opposite polarity to external magnetic fields injected by an attacker. Therefore, the generated internal magnetic field by PreMSat can nullify the injected external field while preventing: (i) intentional spoofing in the sensor’s linear region, and (ii) saturation attack in the saturation region. PreMSat integrates a low-resistance magnetic path to collect the injected external magnetic fields and utilizes a finely tuned PID controller to nullify the external fields in real-time. PreMSat can prevent the magnetic saturation attack having a strength up to ∼4200 A-t within a frequency range of 0 Hz–30 kHz with low cost (∼$14), whereas the existing works cannot prevent saturation attacks with any strength. Moreover, it works against saturation attacks originating from any type, such as constant, sinusoidal, and pulsating magnetic fields. We did over 300 experiments on ten different industry-used Hall sensors from four different manufacturers to prove the efficacy of PreMSat and found that the correlation coefficient between the signals before the attack and after the attack is greater than 0.94 in every test case. Moreover, we create a prototype of PreMSat and evaluate its performance in a practical system — a grid-tied solar inverter. We find that PreMSat can satisfactorily prevent the saturation attack on passive Hall sensors in real-time.

Interval type-2 fuzzy logic controller based grid-tied solar PV inverter with active and reactive power control

Solar photovoltaic industry is continuously thriving to improve the performance of power management systems with technology advancement. In the power system, balancing active and reactive power injection and absorption plays a pivotal role in maintaining Grid regulation and power factor and thus improving the efficiency and power handling capability. The Grid-tied solar PV inverters can be the cost-effective solution for reactive power compensation. Solar photovoltaic (SPV) system with the Grid-tied inverter is to produce active and reactive power in various ecological conditions. The Grid-tied PV inverter injects active and reactive power into the grid according to the desired value by the Grid requirements. The Proposed system uses decoupled P-Q theory with Interval type-2 Fuzzy Logic Controller (IT2-FLC). Also, the proposed controller minimizes the Total Harmonic Distortion (THD) and produces regulated output power compared to the other control techniques. The proposed IT2-FLC is compared with a Type-1 Fuzzy Logic Controller (T1-FLC) and conventional mathematical PI controller for performance analysis using simulation. A 75 kW Grid-tied inverter is designed in simulation to prove the effectiveness of the system through Matlab/Simulink. A smaller rating prototype model is developed to verify the simulation results.

A Novel Per Unit (P.U.) Integer Format Applied to the Control of a Grid-Tied Solar PV Inverter

In advanced power electronic applications such as a grid-tied solar photovoltaic (PV) inverter, control algorithms demand high-level computational support, typically provided by an expensive 32-bit digital-signal-processor (DSP) or microcontroller. In cost-sensitive markets, this may prove to be a significant component of the overall cost of the system. Using a low-cost 16-bit microcontroller is, therefore, highly desirable. However, it poses certain challenges such as fewer bits for the mathematical and logical operations, computations in the fixed-point environment, and lower speeds. In this article, a novel per-unit integer system is proposed towards using a low-cost microcontroller for complex computations, which overcomes the above limitations while maintaining the core functionality in a fixed-point environment. An improved hybrid phase locked loop implementation scheme, that uses the p.u. integer system has also been presented, which significantly reduces the execution time for grid-synchronization. To demonstrate the performance of the proposed concepts, control of a grid-tied PV inverter has been implemented on a low-cost fixed-point microcontroller (dsPIC33FJ16GS402) as well as on an advanced DSP microcontroller (TMS320F28069). Timing analysis and experimental results for a 1 kW grid-tied PV system confirm that the performance of the system using a low-cost microcontroller is comparable to that of the advanced microcontroller.

Internet of things based smart energy management in a vanadium redox flow battery storage integrated bio-solar microgrid

In this paper, an optimized energy management scheme for Solar PV, Biogas, Vanadium Redox Flow Battery (VRFB) storage integrated grid-interactive hybrid microgrid system has been implemented using a low-cost Internet of Things (IoT) based smart communication platform. The energy monitoring and control architecture of the proposed system consists of four main parts; 1) Low-cost energy meter for real-time data acquisition for multiple renewable energy sources (Solar PV, Biomass), VRFB storage, grid and loads. 2) Monitoring, control & fault detection using Raspberry-Pi (Single Board Computer) platform and MODBUS over TCP/IP platform. 3) Cloud-based remote monitoring unit (RMU) using Message Queuing Telemetry Transport (MQTT) server and ThingSpeak Middleware. 4) Capacity measurement of biogas production along with automatic start/stop control of biogas engine-generator. 5) VRFB storage scheduling for peak demand shaving. A PSCAD simulation study has been done to realize the hybrid microgrid interconnection. The developed smart communication system performance is validated by a practical 10kWP solar PV, 15kVA biogas plant, 6 kWh VRFB storage integrated hybrid microgrid which satisfies peak demand management and ensures zero loss of power supply probability for dynamic load profile. Four real-life case studies have been done for the practical realization of the proposed energy management algorithm performance. Another significant contribution of this paper is the utilization of the solar PV power even during grid outage scenario at day time. It is made possible by intelligent interfacing of biogas power generator which acts as a reference AC bus for the grid-tied solar inverter and thus the available solar PV power can be used to serve the critical loads during grid outage condition. The proposed smart hybrid microgrid solution claims to be a generalized one, low cost compared to existing alternatives and applicable to satisfy scalable community energy security as well.

The Implementation of Effective Modulation Schemes to Improve the Power and Harmonic Losses in Grid-Tied Solar NPC Inverter

The growing energy demand, rising fossil fuel prices, and exceeding greenhouse gas emissions require large-scale integration of clean and renewable energy resources. Solar Photovoltaic (PV) system is the potential prospective energy resource to overcome the challenges of conventional grid. Effective power conversion topologies are the prominent need of the PV system to optimize the power and harmonic contents. Three level neutral point clamped (NPC) inverter comparatively produces less harmonics and increases the power delivery compared to the conventional and two-level inverters. Therefore, this research presents the deployment of three level NPC inverter to optimize the switching and power losses in grid connected 250 kW solar PV array. Moreover, power generation, current and voltage characteristics, and fast Fourier transform analysis is performed in MATLAB / Simulink directory with the help of Simpowersystem and Simelectronics toolboxes. To optimize the switching and power losses, sinusoidal PWM and space vector PWM are used to control the duty cycle of IGBT power switches in the proposed NPC inverter. The grid side 3 phase AC output voltage of the proposed inverter is connected to 15 kV grid with the help of 3 phase step up transformer. For 3 phase grid-tied system, the performance evaluation section of the proposed research shows the effectiveness of space vector PWM over sinusoidal PWM.

Vehicle-Solar-Grid Integration: Concept and Construction

Vehicle-solar-grid (VSG) integration is a novel vehicle-to-grid concept that utilizes otherwise underemployed residential grid-tied solar inverters and electric vehicle batteries to provide ancillary services to the grid. The bidirectional flow of power in turn can provide revenue that can offset the cost of the vehicle and the photovoltaic system. This paper describes the VSG concept and the design and construction of an installation, which has demonstrated it in practice.

Output Voltage Variations of Grid-Tied Solar Inverter due to Changes in Connected Domestic Load and Their Mitigation

Output Voltage Variations of Grid-Tied Solar Inverter due to Changes in Connected Domestic Load and Their Mitigation

Development of High-Voltage 4H-SiC GTOs for Grid-Tied Solar Inverters

A growing demand for smart and flexible photovoltaic power conversion and pulsed-power systems is leading to rapid development and commercialization of medium voltage 6.5 - 24 kV, wide-bang gap rectifiers and switches. Conventional silicon bipolar switches are limited to roughly 8 kV breakdown voltages and scaling up the voltage rating requires very thick wafers presenting significant manufacturing challenges. Very thick drift layers of silicon devices also translate into a very high minority carrier charge injected during forward conduction for an efficient conductivity modulation, hence leading to an extremely slow switching speed and poor efficiency. In this paper USCi presents the development of 6.5 kV 4H-SiC gate-turn-off thyristors (GTOs) with multiple floating guard-ring edge termination, and describes their application in an AC-link grid-tied solar inverter system.