Danish Khan

Dielectric properties of transformer oil based silica nanofluids

Nanofluids are prepared for use in high voltage engineering as insulating and heat transfer fluids, containing a small amount of nanoparticles. The term “nanofluid” was presented by Choi et al. at Argonne National Laboratory. Recently, nanofluids are being considered as next generation insulating and heat transfer liquids in due to their improved characteristics. Transformer oil-based nanofluids are being studied as an alternate for conventional mineral oil. In this paper, transformer oil-based silica nanofluids with different concentration (10% and 20%) were prepared. The AC breakdown strength of nanofluids was measured at high moisture level 20ppm. Nanofluids showed improved breakdown strength at high concentration and there was only a negligible effect on breakdown strength at low concentration.

Effects of open and closed loop system of a six-pulse three phase controlled rectifier on variation in load, firing angle and source inductances

This Paper discusses the Simulink Models of open and closed loop systems of a three phase controlled rectifier and its study in terms of variation of load. The relationship between the source inductance, firing angle and commutation angle is important as these entities directly affect the Total Harmonic Distortion (THD) of the power system and this paper uses a graphical method to develop a relationship between source inductance, firing angle and commutation angle. This paper also discusses some trade-offs of using a Proportional - Integral (PI) controller in the design of closed loop system of the rectifier circuit and the effects of using active filters to reduce the Harmonic Components of the source current that may lead to commutation failure in the three phase controlled rectifier circuit.

Hybrid Power Forecasting Model for Photovoltaic Plants Based on Neural Network with Air Quality Index

High concentration of greenhouse gases in the atmosphere has increased dependency on photovoltaic (PV) power, but its random nature poses a challenge for system operators to precisely predict and forecast PV power. The conventional forecasting methods were accurate for clean weather. But when the PV plants worked under heavy haze, the radiation is negatively impacted and thus reducing PV power; therefore, to deal with haze weather, Air Quality Index (AQI) is introduced as a parameter to predict PV power. AQI, which is an indication of how polluted the air is, has been known to have a strong correlation with power generated by the PV panels. In this paper, a hybrid method based on the model of conventional back propagation (BP) neural network for clear weather and BP AQI model for haze weather is used to forecast PV power with conventional parameters like temperature, wind speed, humidity, solar radiation, and an extra parameter of AQI as input. The results show that the proposed method has less error under haze condition as compared to conventional model of neural network.

Humid free efficient solar panel

The paper examines the impact of the humidity on the Solar panels which makes a space for the drastic variation in the power generated and makes the device less efficient. Humidity readily affects the efficiency of the solar cells and creates a minimal layer of water on its surface. It also decreases the efficiency by 10-20% of the total power output produced. Moreover, to handle this issue, all around characterized measures are required to be taken to guarantee the smooth working of the solar panels utilized in humid areas. In connection with this issue, Karachi, the biggest city of Pakistan which is located near the costal line touching Arabian Sea, was taken as a reference city to measure the humidity range. In Karachi, the average humidity lies between 25-70% (as per Pakistan Meteorological Department PMD), that indirectly leads in decreasing power acquired from a Solar Panel and develops various complexities for the solar system. The system on average experiences stability issues, such as those of power fluctuations etc., due to which, the whole solar system installed observes abnormal variations in acquired power. Silica Gel was used as a desiccant material in order to assure dryness over the solar panel. More than four experiments were conducted with the usage of water absorbent to improve the efficiency and to make system more power efficient.The paper examines the impact of the humidity on the Solar panels which makes a space for the drastic variation in the power generated and makes the device less efficient. Humidity readily affects the efficiency of the solar cells and creates a minimal layer of water on its surface. It also decreases the efficiency by 10-20% of the total power output produced. Moreover, to handle this issue, all around characterized measures are required to be taken to guarantee the smooth working of the solar panels utilized in humid areas. In connection with this issue, Karachi, the biggest city of Pakistan which is located near the costal line touching Arabian Sea, was taken as a reference city to measure the humidity range. In Karachi, the average humidity lies between 25-70% (as per Pakistan Meteorological Department PMD), that indirectly leads in decreasing power acquired from a Solar Panel and develops various complexities for the solar system. The system on average experiences stability issues, such as those of po...

Solar Powered Water Pump Lifting Agriculture

Because of the energy crisis in Pakistan farmers are getting serious difficulties in irrigating their crops under such increasing diesel costs. There is a need to facilitate the farmers in alternative ways of powering their water pumps. There are lots of alternative ways, powering water pump, but most economical way is the solar pumping which can bring great outcomes in Farmers of Pakistan whom are facing serious difficulties in irrigating their crops under such severe energy crisis and ever increasing diesel costs. According to one estimate, In Pakistan more than 1Million pumps are in use, out of which 750,000 are diesel driven pumps. If we replace 25% diesel pumps by solar pumps, we can save about 3570 MW of electricity. In this paper 220 W motor is used to operate two days without sunshine or power from the PV panels, 40Wh was required daily as back up, supply a minimum of 880 Wh. Since this is a 12 V system, 880Wh/12V = 73.3 Ah was employed A battery bank should be at least 73.3 Ah, here, since the controller selected had a deep discharge protection at less than 30% of battery capacity, a bank of at least 105 Ah was required. For this project a 105 Ah battery was used as backup and all the simulation is done in the matlab.

Insulating properties of transformer oil-based silica nanofluids

Two types of colloidal dielectric fluids with 20% concentration of nanoparticles are manufactured by dispersing SiO2 nanoparticle with transformer oil by different preparation methods in order to improve the dielectric properties of mineral oil. The AC breakdown voltage of pure oil and prepared nanofluids were measured according to IEC standard methods at 20ppm. The AC breakdown voltages of two nanofluids were 1.05 times and 1.11 that of base oil respectivelyThe possible modification mechanism of silica nanoparticles on insulating properties of transformer oil was discussed on the trap characteristics of host oil and nanofluids. The results confirmed that mineral oil modified with Silica nanoparticles hold a promise to improve its insulating properties.

Comparison of transmission losses and voltage drops of GIL(Gas Insulated transmission line) and overhead transmission lines

In a power system the loads are connected to the generation plants through transmission lines. The transmission lines are overhead and underground cables. From last forty years the new technology is included in the underground cable GIL. GIL has lot of advantages on underground cables and overhead transmission lines such as low transmission losses, less capacitive load, reliability, personal safety, same operation as overhead lines and with negligible electric aging. GIL can handle much more power than overhead lines due to his large conductor area. GIL is best for high voltages. GIL can be our future lines specially in big cities due to increasing population and size of big cities. In this paper the losses and voltage drops of same voltage rated overhead lines are compared to GIL lines. The simulation in PSCAD is done using the parameters of overhead and GIL lines of same rated voltages (230 KV, 345KV, 500KV, 765KV, 1100KV). The length of line is taken as 100km in both cases. The comparison graphs of percentage losses and voltage drops are plotted using MATLAB.