Generalised Predictive Control of a 12-bus Network Using Neutral-Point Clamped Voltage Source Converter UPFC

The paper presents the application of a UPFC to a case study of a 12-bus high power network. The UPFC shunt converter employs 8 3-level Neutral Point Clamped (NPC) voltage source converters (VSC) and 12 single-phase three-winding phase shifting transformers (PST), generating a 48-pulse output voltage. The 3-phase H-bridge series converter shares the same dc-link with the shunt one. The novel feature of this work lies in the use of a model-based generalised predictive current control law to the shunt converter for voltage and power flow control which has shown superior performance without additional filters compared to a P+I control scheme. In addition with the phase shift and switching angle control of each NPC-VSC output voltage, the topology offers improved harmonic performance and a zero-sequence blocking transformer is used for total triplen harmonics elimination

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

Variable Weighted Multi-Objective Multi-Dimensional Genetic Algorithm for Demand Response Scheduling in a Smart Grid

This research presents the optimized scheduling of demand response loads of a residential community of 30 houses using a multi-objective multi-dimensional genetic algorithm (MOMD-GA) with a variable weighted objective function. Incorporating day ahead hourly real time pricing (RTP), the MOMD-GA attempts to present possible optimized dispatch patterns with their associated penalties and constraints (environmental, consumers and suppliers) thus providing system operators (SOs) and distribution network operators (DNOs) sufficient data for real time decision making. The variable weights for each considered component of the cost function is chosen to force the MOMD-GA towards exploring optimum solutions with lower environmental cost. Further shown are the trade-offs in selecting particular dispatch bias (consumer, supplier, environmental and optimized) and the impact of the various dispatch scenarios on the cost of overall electricity bill of the community

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