Ehab H.E. Bayoumi

Frequency Adaptive CDSC-PLL Using Axis Drift Control Under Adverse Grid Condition

This paper presents a new technique to adapt the cascaded delayed signal cancellation phase-locked loop (CDSC-PLL) using a proposed axis drift control (ADC). When grid frequency changes, the estimated grid angle by PLL drifts with a residual error proportional to the frequency change value thus, the accuracy and performance of the conventional CDSC-PLL is deteriorated which can lead to malfunction of the connected applications. Accordingly, CDSC-PLL type has to be adaptable to frequency changes with high immunity to grid disturbances. Designing frequency adapted CDSC-PLL is complex and needs a dedicated design due to the high nonlinearity introduced by adaptive loops. The ADC is proposed as an online adaptive technique that contains a self-tuned DSC operator to mitigate the grid disturbances and a PI controller to perform the adaptation task. The proposed technique is mathematically analyzed and systematic tuning methods are presented. A new analysis for CDSC under off-nominal sample parameter is presented and verified. The robustness of proposed adaptive controller is investigated under parameters uncertainty and various grid disturbances. The proposed technique is numerically and experimentally verified.

Minimal overshoot direct torque control for permanent magnet synchronous motors using Hybrid Bacteria Foraging-Particle Swarm Optimization

This paper presents a robust torque, flux and speed controllers design method for permanent magnet synchronous motor (PMSM) drive using Direct Torque Control (DTC). A simple algorithm is presented to adjust the parameters of torque, flux and speed controllers. This mini-max optimization problem is solved using Hybrid Bacteria Foraging-Particle Swarm Optimization Approach (BF-PSO). The solution thus obtained is global optimal and robust. The proposed technique eliminates common problems including; torque ripples, low speed and integration drift. As well as it characterized by fast tracking capability, minimal overshoot responses, and robust to load disturbances and low speed operation. Results prove the effectiveness and viability of the proposed technique.

Adaptive cascaded delayed signal cancelation PLL based fuzzy controller under grid disturbances

Phase Locked Loop plays a crucial role in synchronizing medium voltage converters. PLL has to precisely and continuously track the grid voltage vector angle and feed it to the converter control loop. Grid disturbances such as voltage dips, harmonics, DC-offset and frequency changes have undesired effects on the estimated angle and as a consequence, the rectifier behavior will be deteriorated. A robust PLL design is essential to provide high immunity to grid disturbances and enable for converter ridging-through during severe disturbances. Using pre-filters to mitigate the grid disturbances slow down the overall system dynamic performance. This paper presents a novel method to ride-through wide range of disturbances by combining an Adaptive Cascaded Delayed Signal Cancellation (CDSC) operator as a pre-filter with a Fuzzy Controller. The obtained results show that the proposed scheme has a great potential for synchronizing high power converters under highly distorted grids.

Power electronics in renewable energy smart grid: a review

Extensive manipulation of new power electronics technologies in renewable energy is predictable to grant efficiency improvements in smart grid evolution. This paper explores possible relationships between power electronics converters and renewable energy in smart grid. The generated power output from renewable energy is generally difficult to control, a power electronics converters capable of implementing high-speed and high-accuracy control is needed for the mass adoption of renewable energy in smart grid. Photovoltaic and wind energy are selected to be analysed as two main types of renewable energy used in smart grid. A smart grid will allow connectivity of the photovoltaic and wind turbines as intermittent sources of energy. Using photovoltaic and wind turbines with power electronics converters and enhanced control techniques can support a grid with reactive power and protect the equipment during severe grid disturbances are important issues to be addressed.

A Fast Recovery Technique for Grid-Connected Converters After Short Dips Using a Hybrid Structure PLL

Repeated faults in an industrial grid have affected a steel manufacturing plant and resulted in frequent tripping of all medium voltage converters. The reason for the trips was a synchronization fault due to a severe short duration voltage dip. Converters need a relatively long time to resume its normal operation after dip recovery due to the capacitors precharging process. If the capacitors discharging is prevented, the converter can resume its normal operation after being synchronized. The synchronization process is performed by a phase locked loop type SRF-PLL with a very low bandwidth and low-pass in-loop filter, which delays the recovery process. In this paper, a solution for the aforementioned trip is presented by proposing two different synchronization hybrid schemes. The first scheme is assuming the converter already lost the synchronization, and a ride-through sequence is implemented to prevent the capacitor from discharging. The second scheme is proposed to prevent the synchronization fault and to recover the converter quickly after dip ends. Both schemes are implemented using a single-input fuzzy logic controller to obtain a very fast response. The performance of the proposed schemes is validated through simulation and a prototype experimental setup.

Power electronics in smart grid consumption systems: a review

Electrical energy consumption is increasing year by year progressively. The smart grid, unlike the current grid system, built on demand response and consumer-based power dissipation. Meantime, the needs for electricity are growing rapidly and will continue to accomplish faster than other energy sources over the next decades. Power electronics is the technology coupled with the competent conversion, control, and conditioning of electric energy from the source to the load. The power electronics community is generally aware of the large energy savings potential, therefore they focus on several key application areas, where the energy savings potential is the largest, such as: building and lighting, power supplies, vehicle to grid and industrial drives. In this review paper, the power electronics roles are specified, illustrated and introduced in smart grid consumption energy systems.

Power electronics in smart grid distribution power systems: a review

Distributed generation (DG) in smart grid (SG) is being employed as a means of achieving increased reliability for electrical power systems as regarded by consumers. As the most of DG technologies utilise renewable sources, the power electronic interface plays a vital role to match the characteristics of a DG unit with the grid requirements. This paper presents the power electronics capabilities required for DG systems in SG to convert the generated power into useful power that can be directly interconnected with the utility grid and/or that can be used for consumer applications. Because of the enhancement and the different power ranges of power electronics devices, the development of advanced power electronic interface that is scalable to meet different power requirements, with modular design, lower cost, and improved reliability, will improve the overall performance and durability of smart grid distributed power systems.

New current references calculation for dual vector controlled three level active rectifiers under asymmetrical voltage operation

This paper introduces an effective nonlinear current references calculation to enhance the performance of the dual vector control under asymmetrical grid for three level neutral point active (NPC) rectifiers. Maintaining the DC-link voltage at the desired level without oscillation is the main target for such kind of application. The asymmetrical grid voltage or voltage dip introduces negative sequence components with badly penetrates through the rectifier control loop casing DC-link to oscillate with twice grid frequency. Conventional vector control (VC) technique failed to meet the control targets under unbalance operation of grid voltage as twice grid frequency ripple pollutes the DC-link voltage. Dual vector control (DVC) concept is implemented to control the positive and negative sequence currents separately. The conventional DVC control scheme can be enhanced by incorporating line power losses for calculating the reference currents. Maintaining the DC-link voltage at the desired level without any symptom of twice grid frequency ripples is one of the control targets which can be achieved by selecting the proper constrains for calculating the current references. The proposed enhanced DVC scheme performance is verified under asymmetrical voltage dip test. The entire system is modeled and simulated with real system parameters of a 7 MW multilevel NPC-type active rectifier.