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This paper presents design and implementation of a 20 kVA division-summation (D-Σ) digital controlled three-phase four-wire multi-function inverter system. The inverter can be operated in grid-connected or stand-alone mode to act as a renewable-energy ac power-supply system. In the stand-alone mode, since the D-Σ digital control law includes load impedance estimation, the inverter can track sinusoidal...
This paper proposes dc current offset compensation technique of grid connected inverters which may applicable to medium-scale solar farms, or any group of grid connected inverters confined within a relatively small area. DC current injection into ac grid severely affects distribution system components such as isolation transformers, measurement units and protective relays. The proposed dc current...
Arc faults in photo-voltaic (Pv) systems are dangerous events and can create huge damage. In order to decrease the number of these events, arc fault detectors are used. The advantages of the here presented detection algorithm are the relatively low computational demand and the ability to work with most standard analog-digital converter (Adc) contained in micro controllers.
Impedance is an important parameter to analysis the stability of microgrid. Stability criteria have been developed in terms of source and load impedances for both dc and ac systems, and it is often helpful to have techniques for impedance measurement. First, the theoretical impedance of microgrid is calculated in this paper. Second, a new method of impedance measurement for microgrid is introduced...
This paper focuses on conducted electromagnetic interference (EMI) emissions and propagation in the DC network of grid connected building integrated photovoltaic (PV) system. The investigated PV system, consists of ten solar panels, cabling and the grid-connected one phase inverter. The EMI simulation model of the real PV system has been developed with the aid of impedance analyzer measurements of...
In this paper, the implementation of the ripple correlation control technique maximum power point tracking (RCC-MPPT) and the current control based-on the rotating reference frame application for a single-phase voltage source inverter (VSI) grid-connected photovoltaic system (GCPVS) is proposed. The algorithm has been developed using the mean function to generate the sign of direction to track the...
The high penetration of photovoltaic systems in low voltage distribution networks can cause power quality problems due to the increased level of harmonics. In this paper an overview of the relevant power quality standards is provided along with an investigation of the harmonics generation in LV networks. Hardware experiments of harmonics measurements of PV inverters are conducted where the influence...
The combination of “electric mobility” and “renewable energy production” heavily demands for energy storage systems. Investigations of technical possibilities to use the stored energy of electric vehicles (EV) and so called plug-in hybrid electric vehicles (PHEVs) for smoothing the grid load and reduce power peaks are inalienable. Within the limits given by the car's battery management system consumption-driven...
In the last decade, the use of voltage-source multilevel inverters in industrial and utility power applications has been increased significantly mainly due to the many advantages of multilevel inverters, compared to conventional two level inverters. These advantages include: 1) higher output voltage at low switching frequency, 2) low voltage stress (dv/dt), 3) lower total harmonic distortion (THD),...
Grid-tied photovoltaic inverter manufacturers rarely reveal the type of power electronic circuit topology and the type of technique used to track maximum power, control of power injected into the grid, and method used to avoid islanding operation. In this paper, an attempt is made to gain such information on a commercial 2.5 kW inverter by measuring the voltage and current waveforms under normal operation...
This paper describes an observer for the diagnosis of the DC link voltage sensor for an electrical drive composed of a Permanent Magnet Synchronous Machine (PMSM) and a 3H bridge level grid connected inverter. The dynamics of the DC Voltage is function of duty cycles and the phase currents. Then, the observer can be used in a Fault Tolerant Control scheme to detect a DC link voltage sensor fault....
With increased renewable power penetration level the system operators of power grids require low-voltage ride-through (LVRT) capability of renewable power plants. The LVRT-capability has to be verified during the process of certification with precisely defined short circuit tests on a reactance based test bench. For the development of the fault ride through (FRT) capability the cost intensive reactance...
Researchers often want to compare two or more photovoltaic panel technologies under real-world conditions to obtain a comprehensive understanding of module performance. A well-controlled study typically necessitates installing a string of modules for each technology. However, real-world effects of prevailing wind direction, site obstructions, and array edge effects can introduce uncontrolled variation...
With increasingly high penetrations of PV on distribution systems, there can be many benefits and impacts to the standard operation of the grid. This paper focuses on voltages below the allowable range caused by the installation of PV on distribution systems with line-drop compensation enabled voltage regulation controls. This paper demonstrates how this type of under-voltage issue has the potential...
Induction motor can be run as variable speed a. c. drive under the umbrella of recent technology advancements. Pulse width modulated (PWM) inverters are used to feed drive efficiently. Problems observed due to conventional inverter like: common mode voltage (CMV), total harmonic distortion (THD) in line voltage waveform, electromagnetic interference, inverter induced bearing current and shaft voltage...
The control performances of the hybrid PWM inverter according to the phase current measuring method is presented in this paper. The hybrid PWM strategy consists of space vector pulse width modulation (SVPWM) and 6-step modulation. SVPWM is performed to reduce the harmonic components in the low speed region, and 6-step modulation is applied to increase the maximum speed of the IPMSM in the high speed...
In a modern hybrid vehicle where several switched converters are connected to a common high voltage DC-bus, current and voltage harmonics will arise due to the switching events in the inverter. In order to determine the behavior of the complete system, models that include switching characteristics, control parameters of each device and high frequency behavior of the cabling and the battery must be...
The effects of the three level inverter on the core losses of a SynRM are investigated particularly at the stator yoke and tooth. A comparative study on the effects of space vector pulse width modulated (SV-PWM) two and three level inverter on the iron/core loss are analyzed. A SynRM stator made of silicon steel, M36, 0.35 mm thickness is used. The machine was driven from a two and three level inverters...
Commercially available electrical machines are generally not optimized for a broad operating range, as required in e.g. vehicle traction applications. The required mechanical angular velocity of the wheels for electrical vehicle propulsion is relatively low (around 1,000 rpm), while the torque demand is high (around 500 Nm). This combination requires an adequate solution in the mechanical, electromechanical...
This paper presents a novel on-line condition monitoring method that is based on the input voltage and measured line current of a Brushless DC motor drive system. The time-frequency signal processing method of Hilbert Huang Transform is applied to extract the characteristic component of line current and then obtain the required equivalent electrical impedance, which is utilized for health monitoring...
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