A Novel Phase locked Loop Scheme for Grid Voltage Synchronisation Using the Energy Operator

A well-known issue with existing power systems is rapid and accurate synchronisation to grid voltages when the system is unbalanced under grid fault conditions and corrupted with harmonics. This paper presents a novel phase locked loop technique for grid synchronisation technique using the energy operator. A comparative study is undertaken to investigate the accuracy and robustness of this technique compared to existing grid synchronisation techniques

Active Harmonic Current Elimination and Reactive Power Compensation using Modular Multilevel Cascaded Converter

This paper presents a new application of modular multilevel cascaded converters (MMCC) for combined active harmonic current elimination and reactive power compensation in a power distribution line. A technique for simultaneous extracting harmonic components and reactive element in the load current is presented. A novel voltage control scheme for balancing the module intra-cluster capacitor voltages under distorted load current is incorporated. Simulation studies show the desired performance of the MMCC-based active power conditioning operating under PCC current distortion and varying load conditions

Voltage Synchronisation Techniques for Grid-Connected Power Converters

Standard synchronisation scheme for grid-connected power converters has been known to fail to correctly estimate the instantaneous phase angle of the grid voltages which are unbalanced and corrupted with harmonics. There are other advanced schemes which have been proposed to address this issue but a thorough comparison among the schemes is lacking. This paper presents a detailed review on five advanced grid voltage synchronisation schemes. A coherent investigation is performed to compare their merits and limitations considering a wide range of voltage distortions. This is verified through simulation and practical results

Control of A Modular Multilevel Cascaded Converter based Unified Power Flow Controller

This paper presents a novel configuration of unified power flow controller (UPFC) using a three-phase modular multilevel cascaded converter (MMCC) shunt connected on one end of the transmission line. This offers control flexibility, lower cost and losses compared to the conventional UPFC. The control scheme combines the power flow regulation at the series converter side and voltage control at the shunt MMCC part. An overall DC capacitor voltage balancing scheme is implemented to ensure all floating capacitors of shunt MMCC and series converter voltages can be maintained at their nominal values. Simulation studies of this MMCC-UPFC for a simple two voltage sourced power network are presented and results verifies its good performance under varying real and reactive power flow conditions