Ahmed Aboushady

Glasgow Caledonian University | GCU · Department of Mechanical, Electrical and Environmental Engineering

This paper aims to propose inductive wireless power transfer (IWPT) technology for pinpointing fault locations in LV distribution underground cables following the use of other pre-location methods. The proposed device is portable, hence battery-powered, and operates by scanning for faults above ground via inductive coupling with the de-energized ca...

Modern solutions for precise fault localisation in Low Voltage (LV) Distribution Networks (DNs) often rely on costly tools such as the micro-Phasor Measurement Unit (μPMU), which is potentially impractical for the large number of nodes in LVDNs. This paper introduces a novel fault detection technique using a distribution network digital twin withou...

Operators in the North Sea are looking for solutions to reduce their carbon emissions to meet the North Sea Transition Authority's target of carbon-neutral assets by 2050. Wind energy as an offshore mature technology has been adopted in all electrification concepts proposed for neutralizing assets emissions, despite its challenges in terms of inter...

Patients diagnosed with cancer receive different types of treatments based on the type and the level of the tumour. An emerging treatment that differs from well-developed systematic therapies (i.e., Chemotherapy, Radiotherapy, and Immunotherapy) is Tumour Treating Field (TTF) treatment. Tumour behaviour under TTF treatment varies based on the elect...

This chapter presents a simple method to efficiently predict the rotor speed for a sensorless vector control technique applied to induction motors (IMs). The motor is supplied by a Simplified Split-Source Inverter (S3I), which provides dc-boosting and ac-inversion processes during input voltage sag. It also has a wider modulation range and a lower...

There is a growing concern about the high degree of non-technical losses (NTL) in developing countries especially sub-saharan Africa. Whereas several studies have employed artificial intelligence (AI) to analyze NTL, a major drawback in these studies is the focus on customer data only without considering the possible contribution of electricity dis...

Three-phase converters based on insulated-gate bipolar transistors (IGBTs) are widely used in various industrial applications. Faults in IGBTs can significantly affect the operation and safety of the power electronic equipment and loads. It is critical to accurately detect power inverter faults as soon as they occur to ensure system availability an...

Inverters with Quasi-Z-Source Networks (QZSN) provide DC-DC boosting and DC-AC conversion in a single stage. It offers reduced cost, complexity, and volume compared with the classical two-stage conversion system, which is composed of a boost converter followed by a Voltage-Source-Inverter (VSI). Further, QZSI provides superior conversion characteri...

Power converters generate switching common mode voltage (CMV) through the pulse width modulation (PWM). Several problems occur in the drive systems due to the generated CMV. These problems can be dangerous to the insulation and bearings of the electric machine windings. In recent years, many modulation methods have been developed to reduce the CMV...

Due to their many advantages over their counterparts, such as Z-source inverters (ZSIs), split-source inverters (SSIs) have recently received much attention as single-stage boost inverters. This paper discusses a multiphase version of the SSI topology for the first time. Among multiphase systems undergoing a revolution in the research area, five-ph...

This paper proposes a buffered microgrid with a modular grid interface consisting of a modular back-to-back converter. The proposed method provides a flexible strategy that enables both the load and generation expansion of the microgrid, with no sizing constraints on the initial stage. The method maintains the physical separation of the buffered mi...

Power Electronic Transformers (PETs) are considered as an emerging solution for power conversion due to their benefits over the low frequency power transformers (LFPTs) such as lower size, multi-port structure and different control functionalities. However, unbalanced load conditions may limit the reduction of size due to using bulky capacitors to...

This paper aims to critically analyze the IEEE Std 1234-19 and other power cable fault-finding technical guides produced by leading industries to assess their applicability in practice to the underground low voltage distribution network (LVDN). The analysis reveals that there is no clear distinction between the fault-finding techniques and procedur...

This paper proposes a multiport DC-DC converter for EV fast-charging stations. The proposed converter is comprised of Ring-Connected Dual Active Bridge (RCDAB) DC-DC converters, where the connection point between every two adjacent DABs provides a DC port. Bypass switches are added to each DAB to eliminate unnecessary power processing stages in the...

This paper proposes a new active power flow controller for DC-DC multi active bridge (MAB) converters with minimum current point tracking (MCPT) to minimize conductive losses. Unlike recent efforts in this area, the proposed controller does not require look-up table for implementation nor complex non-linear converter modelling and is not circuit pa...

DC transmission grids are the promising electrical networks in the near future especially with the high penetration of large scale renewables. This paper proposes a modified version of the dual active bridge (DAB) DC/DC converter with AC link capacitors generating reactive power to compensate for non-active power consumption; hence mitigating curre...

The common two challenges in high voltage dc (HVDC) multi-terminal transmission are the dc fault isolation and the dc voltage stepping up/down. Additionally, interconnecting voltage source converter (VSC) and line commutated converters (LCC) based HVDC network topologies has been challenging. This paper, introduces a new dc-dc converter topology co...

This paper proposes a new controller for power regulation in dual active bridge (DAB) DC−DC converter based on a new scheme that tracks minimum RMS current to ensure minimum losses. The proposed controller is based on an implementation of perturb and observe (P&O) tracking method that enables minimum current point tracking (MCPT) at any desired lev...

Millions of people worldwide suffer from lack of reliable electric energy supply. Energy justice scholarship has noted that small scale decentralized renewable energy offers a unique opportunity to democratize local energy provision, increasing the access to and affordability of electricity for those who are currently on the margins of centralized...

Although a modular multilevel converter (MMC) is universally accepted as a suitable converter topology for the highvoltage dc transmission systems, its dc fault ride performance requires substantial improvement in order to be used in critical infrastructures such as transnational multi-terminal dc (MTDC) networks. Therefore, this study proposes a m...

This paper presents a comprehensive and generalized analysis of the bidirectional dual active bridge (DAB) DC/DC converter using triple phase shift (TPS) control to enable closed loop power regulation while minimizing current stress. The key new achievements are: a generic analysis in terms of possible conversion ratios/converter voltage gains (i.e...

This study presents a high-performance controller based on the Lyapunov stability criterion that enhances the dynamic performance and disturbance rejection capability of resonant DC/DC converters when compared with classical PI control. The series-parallel resonant converter (SPRC) is used as the candidate converter to which this controller design...

This paper presents the design, development and testing of a 30kW, 200V/900V modular multilevel converter (MMC) based DC/DC converter prototype. An internal LCL circuit is used to provide voltage stepping and fault tolerance property. The converter comprises two five level MMC based on insulated gate bipolar transistors (IGBTs) and metal oxide semi...

Fast isolation and detection of DC faults is currently a limiting factor in high power DC transmission grid development. Recent research has shown that the role of DC/DC converters is becoming increasingly important in solving various DC grid challenges such as voltage stepping, galvanic isolation and power regulation. This paper focuses on an addi...

One of the main challenges of voltage source converter based HVDC systems is DC faults. In this paper, two different modified half-bridge modular multilevel converter topologies are proposed. The proposed converters offer a fault tolerant against the most severe pole-to-pole DC faults. The converter comprises three switches or two switches and 4 di...

This paper proposes a multi-loop controller for phase-controlled series-parallel resonant converter. Output voltage is solely measured for control and inner loop is used to enhance closed loop stability and dynamic performance compared to single-loop control. No additional sensors are used for inner loop variables. These are estimated using a Kalma...

Reactive power flow increases dual active bridge (DAB) converter RMS current leading to an increase in conduction losses especially in high power applications. This paper proposes a new optimized triple phase shift (TPS) switching algorithm that minimizes the total reactive power of the converter. The algorithm iteratively searches for TPS control...

This paper focuses on the behaviour of the cell capacitor discharge currents during DC faults in half-bridge modular multilevel converters. Active switches, not designed for fault conditions, are tripped to minimize discharge currents effect on the semiconductor switches. Two levels of device protection are commonly in place; driver level protectio...

Several papers have been published recently on TPS control of dual active bridge (DAB) converter, however, no complete study of the converter operation behaviour exists, that takes into account all switching modes in both charging and discharging (bidirectional) power transfer. In this paper, six switching modes and their complements with opposite...

Besides research on reliability, efficiency and grid impact challenges imposed by the wind energy industry, research on compact design of multi-modular interfacing DC/DC converters is growing rapidly. This paper addresses the application of multi-modular resonant-type DC/DC converters for offshore wind high power HVDC transmission systems. The attr...

This paper proposes a linearized large signal state-space model for the fixed-frequency phase-controlled series-parallel resonant converter. The proposed model utilizes state feedback of the output filter inductor current to perform linearization. The model combines multiple-frequency and average state-space modeling techniques to generate an aggre...

This paper proposes a predictive output voltage controller for the phase-controlled series-parallel resonant converter. The objective of this controller is to enhance closed loop system robustness and dynamic performance compared to conventional PI control. First, the converter non-linear large signal behavior is linearized using a state feedback b...

This paper presents a new analysis providing further insight into the steady state characteristics of the phase-controlled LCC-type series-parallel resonant converter operating above resonance. An analytical expression is obtained for the converter voltage transfer function in terms of phase angle. The effect of varying the phase angle on ZVS and Z...

This paper proposes a linearized large-signal state space model for phase-controlled series-parallel resonant converter. The model combines multiple-frequency and average state-space modeling techniques to generate a universal model with DC state variables that are easier to control compared to the fast resonant tank dynamics. In order to perform l...

A linearized model of the phase-shifted series resonant converter is necessary for closed loop design. With fixed PI con- trol design, the converter does not have good disturbance rejec- tion capability and cannot always cope with a wide range of un- certainties. In this paper, a PI self-tuning mechanism based on a fuzzy logic scheme is proposed. I...

This paper provides an analytical discrete small-signal state-space model of the phase-shift modulated series resonant converter used to obtain an explicit linearized phase-shift to output voltage transfer function. This transfer function is useful for linear closed loop control design. Initially, the effective duty-ratio to output voltage transfer...

This paper proposes a new modular configuration for ac/dc conversion based on the concept of “building block” converter units. The modular system architecture comprises low-power units which can be connected in parallel to achieve higher power levels. Using such a design, medium voltage dc levels can be reached without the need of bulky step-up tra...

This paper presents steady-state ac analysis of the series resonant converter with phase-shift and frequency control. Analysis for the converter operation above resonance is performed. A simple analytical expression for the converter input/output voltage gain as a function of phase-shift and frequency is derived. Different converter operation modes...