Md. Alamgir Hossain

Intellectual capital reporting in a South Asian country: evidence from Bangladesh

Purpose – The purpose of this paper is to examine the intellectual capital reporting (ICR) practices of listed non‐financial companies in Bangladesh as an example of a South Asian developing country, and to empirically investigate some company characteristics as determinants of such practices.Design/methodology/approach – This is an empirical study of ICR by 90 listed companies in Bangladesh in 2008‐2009 using content analysis of annual reports. The study uses a weighted disclosure index and ordinary least squares regression analyses to test the association between company characteristics and the extent of ICR.Findings – The study finds that despite the stock market growing significantly during the recession period, there is a tendency of companies not to disclose IC. The study also confirms that size and industry are important attributes to explain the IC disclosure (ICD) issues in Bangladesh. Unlike prior studies, the study finds that the IT sector does not tend to disclose more extensively, and that co...

Droop Control for islanded microgrids with compensating approach

This paper proposes a droop control algorithm to distribute load changes automatically between two inverter-sourced generators in an islanded microgrid. A compensating approach is added to the conventional droop control scheme in order to add a power offset to the active power so that the output powers of the inverters remain balanced if the output of renewable energy varies. The droop control parameters are chosen based on eigenvalue analysis obtained from linear modal analysis. In this paper, it is shown that the proposed control method ensures effective power sharing and provides good performance under diverse operating conditions without the need for communication.

Primary voltage control of a single-phase inverter using linear quadratic regulator with integrator

This paper proposes a linear quadratic regulator with integral action, ensuring fast dynamic response and resisting capability of voltage deviation from instantaneous reference grid voltage, to control the inverter voltage that can also be used in a microgrid. The proposed control strategy is based on a linear quadratic regulator, minimizing the cost function of the system, with integral action used to impede voltage degradation from a reference voltage for outside disturbances of the system, such as abrupt load change. The combined integral term assists to recover the voltage difference between grid and reference grid voltage. The validity of the proposed controller has been tested with linear and non-linear loads under various conditions. In both cases, the effectiveness of the controller has been proved. The result of the proposed controller is good to track the instantaneous reference grid voltage.

Analysis of Indirect Lightning Phenomena on Solar Power System

A threat of solar power systems is lightning induced voltage, which can damage the photovoltaic generators and its ancillary equipment, has been examined in this paper. The induced voltage due to lightning strike can be reduced using a lightning protection system; however there is a possibility of getting damage of system equipment from electromagnetic interference. The induced voltage on the Power Condition System (PCS) of solar power system is analyzed using electromagnetic analysis approach. The effects of strike height and soil resistivity have been considered for analyzing the induced voltage on a system. We examine, with the increasing strike height and rising soil resistivity how the induced voltages of a system are affected. We found that with the increasing strike height the induced voltage also increases except the line to ground voltage, and with the rising soil resistivity induced voltages are approximately constant excluding frame voltage. Virtual Surge Test Lab (VSTL), which utilized the finite-difference time-domain (FDTD) method for solving Maxwells electromagnetic equations, was used to compute the induced voltages. The solar power system was modeled with thin wire structures having good representational capacity of a steel frame and power line to induced voltage.

Exploitation of Biogas Resources for Electric Vehicle Charging Station in Bangladesh

The abrupt increase of the electric vehicles in Bangladesh needs huge amount of power. As a result, alternative energy sources are emphasized due to limited fossil fuels in order to develop a sustainable energy sector with environment friendly resources. Bangladesh has an enormous potential in the field of renewable resources like biogas and biomass. This paper presents 20 kW electric vehicle charging station (EVCS) utilizing biogas resources where maximum energy requirement is 100 kWh. In this paper, the biogas based EVCS is designed using MATLAB Simulink and HOMER software. Daily 15-20 electric vehicles can be recharged their batteries using the proposed charging station. The proposed system offers lower cost of energy compared to the grid electricity. Moreover, the proposed charging station shows 68.75% reduction in CO2 emission than grid based charging station. In addition, the proposed EVCS will save monthly

Proportional reactive power sharing for islanded microgrids

16.25 and

Study and protection of lightning overvoltage on DC cables of solar power generation

27.50 respectively for easy bike and auto rickshaw type electric vehicles in Bangladesh.

Present Energy Scenario and Potentiality of Wind Energy in Bangladesh

In this paper, droop-based automatic control schemes are presented to control parallel inverter-interfaced distributed generators (DG) in a way that proportional reactive power sharing is possible in islanded microgrids under different structures. This paper modifies the conventional reactive power-voltage (Q-V) droop control strategy used in inductive (L-type) islanded microgrids by implementing voltage control law in overall control operation such that reactive power becomes inversely proportional to the reactive droop gain if the initial values of inverter-interfaced voltage-sources are the same. Reactive power sharing approach for resistive (R-type) islanded microgrids is also included in this paper; in which it is shared depending on rate-of-angle of voltage-sources, i.e., reactive power-frequency (Q-f) droop. The proposed control methods utilize linear modal analysis to design both types of droop-based controllers. A 5-bus microgrid with 4-parallel inverter-connected DG units is considered for simulations under load changing phenomenon where results show the excellency of the designed control schemes.

Voltage Tracking of a Single-phase Inverter in an Islanded Microgrid

In this paper, lightning induced overvoltage on DC cables of solar power panel, which was laid on the ground and an underground level with proper insulation thickness, was investigated when a lightning strike at a nearby place and its proper protection scheme was verified. The result shows that on ground cable voltage is approximately 28.83% more than that of the underground cable having soil resistivity 100Ω-m. Moreover, when soil resistivity increases to 1000Ω-m then the underground cable voltage is less about 48.50% than that of the on ground cable. The induced voltage caused by lightning electromagnetic interference on DC cables of solar power system at power conditioning subsystem (PCS) is analysed using electromagnetic field analysis approach. The FDTD method was applied to calculate induced voltage. Virtual Surge Test Lab (VSTL) is used for FDTD calculations, which solve Maxwells electromagnetic equations with least approximations. The model of solar power system was represented with thin wires.