International Journal of Power and Energy Conversion (4 papers in press)

Regular Issues

• Design and verification of FPGA based prototype of VSG controller  
  by Praveen Kumar, Vinendra Sairamkrishna, Sachidananda Sen 
  Abstract: As distributed generation leads to loss of inertia that causes higher fluctuations in system dynamics and reduced frequency stability. This effect is very high in the case of microgrids (MGs). A virtual synchronous generator (VSG), which is the imitation of the synchronous generator, ascertained to be a reliable way to bring back the lost inertia. However, as phase-locked loop (PLL) is nonlinear, so its use in measurement of frequency and rate of change of frequency can degrade the response time, and it can become worst with lower voltages. In this work, a VSG controller without using PLL is proposed and the controller does not depend on the magnitude of voltage. The Verilog hardware description language is used to develop the hardware prototype of the VSG controller. The hardware is developed on the FPGA board viz. SPARTAN-3E FPGA. The prototype is verified and validated by the hardware-in-loop (HIL) in a real-time environment using a real-time digital simulator. Its performance is tested under various disturbances in the MG and results are compared with MG without VSG and with simulated VSG. Results suggests that the hardware prototype of VSG is stabilising disturbances in the MG to a great extent by providing virtual inertia.
  Keywords: field programmable gate array; FPGA; microgrid; phase locked loop; PLL; virtual inertia; virtual synchronous generator; VSG.
  
  
• Mass energy transfer effects of PEM fuel cell flow channels with correlation between geometric parameters and operating conditions  
  by Hoe-Gil Lee, Dakota Messer 
  Abstract: Proton exchange membrane fuel cells (PEMFC) are integrated to explore the effects of the design and analysis of the flow channel plate in a proton exchange membrane fuel cell. It investigates three primary channel designs under different operating conditions and examines the pressure and velocity distribution across the plate. The numerical and experimental results indicate that the grid-designed channel pattern is the most efficient for achieving an even pressure and velocity distribution across the flow channel plate. Testing three flow patterns with three materials and five inlet velocities revealed the grid design’s efficiency, ensuring smooth fluid distribution, especially with graphite material at 0.004 kg/s. The roughness analyses emphasised the efficiency of a level 0, correlating with decreased pressure and velocity, aligning with expected turbulent flow. The experimental set focused on grid design thickness variations, with a 0.4-inch thickness proving efficient, particularly at 0.004 kg/s.
  Keywords: bipolar plate; PEMFC; performance analysis; CFD simulation; flow channels.
  
  
• Machine learning model for wind direction and speed prediction  
  by J. Gowrishankar, K. Tamilselvan, N. Sakthi Saravanan, B. Murali 
  Abstract: The capacity to estimate wind direction and speed is essential for both the generation of renewable energy and the forecasting of weather. Near the ground, the performance of the mechanistic models that are the foundation of conventional forecasting is quite low. We will explore a different data-driven strategy that is based on supervised learning. We train supervised learning algorithms utilising the previous history of wind data. We use data from individual locations and horizons to conduct a systematic comparison of a number of algorithms, during which we change the input/output variables, the amount of memory, and whether or not the model is linear or non-linear. According to our findings, the ideal design as well as the performance of the system varies depending on the region. Our technique achieves an improvement in performance of 0.3 m/s on average when it is applied to datasets that are accessible to the public.
  Keywords: machine learning model; input/output variables; linear vs. non-linear model.
  
  
• Synthesis, characterisation and stability testing of graphene enhanced paraffin wax phase change material for energy storage  
  by Jvalant Trivedi, Mitesh Shah, Sachin Gupta, Aditya Bais 
  Abstract: Non-conventional sources of thermal energy must be widely recognised for effective environmental protection. Solar thermal is an effective replacement for regular sources but due to its intermittent nature depends largely on environmental conditions. Passive heat storage mediums such as phase change material (PCM) stabilise the energy output of non-conventional sources. Paraffin wax is the most common PCM used in heat storage applications such as solar thermal energy storage. Paraffin wax suffers from low thermal conductivity which makes it sluggish in charging-discharging time. The current study has experimentally investigated the effect of graphene nanoplatelet in weight concentrations of 1wt%, 3wt% and 5wt% in paraffin wax as base PCM. The results indicated that after each successive addition of nanoplatelets, an increment in thermal conductivity of 20.17% (1wt%), 37.34% (3wt%), and 58.80% (5wt%) were measured respectively when compared to base PCM. At the same time, the latent heat decreased with the maximum dip observed in the 5wt% sample. A stability analysis was conducted for the effect of adding SDBS surfactant as a stabiliser on the NEPCMs’ thermal conductivity after various cycles. A good hold on thermal conductivity with the SDBS Sample was illustrated.
  Keywords: phase change; energy storage; nanoplatelets; graphene; phase change material; PCM.