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The transformer-less Photovoltaic (PV) power inverters are mostly well-liked and exceedingly recommended for grid-connected PV power systems because of low cost, small size and high efficiency. Nevertheless, the injection of Direct Current (DC) is effectively involved in grid-connected PV inverters without isolating transformers. An improved and efficient control method is presented in the paper,...
The modular multilevel converter (MMC) has become one of the most promising converter technologies for medium/high-power applications, specifically for high-voltage direct current (HVDC) transmission systems. One of the technical challenges associated with the operation and control of the MMC-based system is to precharge the submodule (SM) capacitors to their nominal voltages during the startup process...
The grid-tied low voltage photovoltaics are expanded day by day. Aiming for a high penetration level, the Fault Ride Through Capability (FRTC) standard should be extended to these units as well. In this paper, the behavior of Single Phase Grid Connected PV Systems under faulty conditions is investigated. For this purpose, a SPWM controlled full bridge voltage source inverter is used. The proposed...
This paper presents the improved dynamic performance of the National Grid of Pakistan by the application of a 50(ind)/450(cap) MVAR SVC system at the 220/132kV New Kotlakhpat (NKLPT) Substation in Lahore — the first project of its nature in Pakistan. This paper demonstrates results from voltage stability studies carried out in PSSE using dynamic load models showing the voltage recovery without and...
Nowadays, even small and medium sized power generators are required to ride through low-voltage faults without disconnecting themselves from the grid. To the modular multilevel converter (MMC) in a battery energy storage system based on split batteries (sBESS), this presents a unique requirement: In case of a low-voltage grid-fault, the arm voltages leave their steady-state trajectory which can lead...
In Queensland, Australia, the statutory regulation for an electricity distribution network is to deliver a voltage within ± 6% to customers from the nominal value of 240 V. Typically, voltage control is determined using the system load as the main driver. This approach gives preference to customers that use more energy. This paper presents a customer-weighted method to control the voltage regulation...
The paper presents a new digital-controlled single-phase transformer-based inverter for non-linear load applications. A capacitive full-bridge circuit with high bandwidth is added to provide instant current under non-linear load condition and thereby reducing the voltage harmonics significantly to meet the harmonic standard, IEEE 519–1992. The redundant capacity, cost, size and weight of line frequency...
This paper presents a new robust control strategy to improve the steady-state and transient stabilities of a grid connected large scale photovoltaic (PV) system. The grid codes for PV system to provide dynamic grid support are getting stricter due to the substantial increase in the power generation from grid connected PV systems, in recent years. The proposed control scheme helps quick voltage recovery...
The Micro Grid concept has the potential to solve major problems arising from large penetration of distributed generation in distribution systems. A Micro Grid is not a robust system when compared to a power system. Therefore, proper control strategies should be implemented for a successful operation of a Micro Grid. This paper proposes the use of a central controller for the improvement of the dynamic...
This paper discusses a controller based on a proportional-repetitive control for a dynamic voltage restorer (DVR). Repetitive control can achieve zero steady-state error of tracking sinusoidal signal, but it doesn't make a quick response to the disturbance and needs at least one fundamental cycle to function properly. The control system based on proportional-repetitive controller, in stationary frame...
This paper proposes a high performance control in a d-q reference frame for a single-phase grid connected converter. The proposed control allows to obtain easily an infinite control loop gain at fundamental frequency and a superior disturbance rejection: this assures only active current injection thus maximum conversion efficiency and decreases current distortion. The control has been implemented...
Half-bridge DC-DC converter with a current doubler rectifier is suited for low-voltage high-current on-board DC-DC converters. Due to the fact that peak-current-mode cannot be directly applied to the conventional half-bridge DC-DC converter, the voltage-mode control is most likely utilized. However, in this case, the DC current sharing between two inductors of the current-doubler rectifier cannot...
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