Mansoor Asif

National University of Sciences and Technology | NUST · Department of Electrical Engineering (EE)

Renewable energy sources tied to a utility grid require non-linear control algorithms to provide an efficient and stable output under different operating conditions. The maximum power point tracking (MPPT) approach is necessary for power generation due to non-linear behavior of photovoltaic (PV) power plants. In changing environmental and partial s...

Renewable Portfolio Standards (RPS), enforced as part of environmental regulations, are taking precedence worldwide to promote investments in renewable energy sources (RES). From the grid perspective, one of the bottle-neck factors that limits large-scale RES integration is the transmission network congestion. Dynamic Thermal Rating (DTR) is a smar...

Owing to the economic, social, and political problems in the expansion of transmission infrastructure, novel transmission topologies are in demand to efficiently utilize the existing infrastructure. On the other hand, there is a tremendous increase in wind power generation around the globe. One of the main challenges hindering the penetration of la...

Increasing the rating of the HVDC cable causes an inevitable increase in the heat generated inside cable. Thus, it is necessary to improve the thermal conductivity of the Cross-linked polyethylene (XLPE) insulation material used in the extruded cable for effective thermal management. Also, several methods have been proposed so far to increase the t...

Many geographical constraints and aesthetic concerns necessitate the partial use of cable sections in the High Voltage DC (HVDC) transmission line, resulting in a mixed transmission line. The overhead sections of mixed lines are exposed to lightning strikes. The lightning strikes can not only result in flashover of overhead line (OHL) insulators bu...

The current and voltage in High Voltage DC (HVDC) line is not pure DC but contain superimposed ripple components. The current ripple in core of HVDC cable magnetically induces a voltage in the sheath, whereas the voltage ripple causes the flow of charging current from core to sheath. The knowledge of sheath voltage is necessary to ensure compliance...

The half bridge (HB) modular multilevel converter (MMC) technology is considered a breakthrough to mitigate the shortcomings of the conventional voltage source converter (VSC) in high-voltage direct-current (HVDC) grid application. However, interruption of the DC fault is still a challenge due to fast di/dt and extremely high levels of DC fault cur...

The influx of a switching impulse during DC steady-state operations causes severe electrical stress on the insulation of HVDC cables. Thus, the insulation should be designed to withstand a superimposed switching impulse. All major manufacturers of DC cables perform superimposed switching impulse breakdown tests for prequalification. However, an exp...

The modular multilevel converter (MMC) is the most promising converter topology for implementations of voltage source converter (VSC) high-voltage direct-current (HVDC) grid. Existing research has focused on operational characteristics and improvement of efficiency by optimizing the control. Among various MMC topologies, a full bridge (FB) sub-modu...

The key obstacle in implementing high-voltage direct current (HVDC) grid, which is considered as the future of power grid, is the absence of effective DC circuit breaker (DCCB). At present, HVDC grid could be based on half-bridge (HB) or full-bridge (FB) voltage source converter (VSC). Among these two converter topologies, FB topology has an advant...

The black-box arc model is known to be a useful technique to simulate dynamic arc-circuit interaction by reflecting arc characteristics. Existing researches have shown that the black-box model has been widely used to analyse the ac arc characteristics of SF(6) and air circuit breakers. Due to the enormous energy and steep rise rate (di/dt) during d...

Growing urbanization coupled with increased power demands have led to an increasing use of mixed power transmission lines with sections of overhead lines (OHL) and the underground cables. Due to differences in surge impedance of cables and OHL, voltage surges experience reflections and refractions at their boundaries which make the transient behavi...

The eventual goal of high-voltage direct-voltage (HVDC) systems is to implement HVDC grids. The modular multilevel converter (MMC) has been identified as the best candidate for the realization of an HVDC grid by eliminating the shortcomings of conventional voltage source converter (VSC) technology. The related research has focused on efficient cont...

Renewable energy sources are integrated into a grid via inverters. Due to the absence of an inherent droop in an inverter, an artificial droop and inertia control is designed to let the grid-connected inverters mimic the operation of synchronous generators and such inverters are called virtual synchronous generators (VSG). Sudden addition, removal...

To meet the growing power demand of the future, utilities and researchers have considered the addition of dc circuits in existing transmission corridors. The previous research has focused on analyzing the field environment, steady state induction and the negative effects of induction in the hybrid transmission lines. The overhead ground wires (OHGW...

Interface between Liquid Nitrogen (LN2) and PPLP of the SJB is very vulnerable to the surface flashover. Therefore, it is necessary to investigate the surface flashover characteristics of dielectric materials including LN2 and PPLP for the insulation design of the SJB. PPLP has two orientations according to the direction of fiber in Kraft paper tha...

The eventual goal of HVDC systems is to implement HVDC grids. One of the key obstacle in realization of HVDC grid is the absence of DC Circuit Breaker (DCCB). Several prototypes of DCCBs for HVDC grid have been proposed, but no commercial solution has been developed yet due to insufficient dc fault current breaking capabilities and unreliable prote...

Simulated Self-Generated - Particle Swarm optimization (SSG-PSO) toolbox that automatically generates PI control parameters veryquickly in PSCAD is designed. This toolbox operates by utilizing transient simulation to evaluate objective function and convergesthe fitness values of objective function through PSO algorithm during run time simulation of...

Background/Objectives: The stability of High-Voltage Direct Current (HVDC) system is improved by optimization of system's control parameters. The simulation model of HVDC network is designed in Power Systems Computer Aided Design (PSCAD) and the Proportional Integral (PI) parameters optimization are achieved by using simplex algorithm. Simulation b...