• Journal of Electrical Engineering and Technology
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• v.10 no.1
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• pp.109-117
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• 2015

This paper proposes the comparison results of various optimal power flow algorithms (OPF) to calculate the locational marginal prices (LMP) of the unreduced full scale Korean transmission system. Five different types of optimal power flow models are employed: Full AC OPF, Cubic AC OPF, Quadratic AC OPF, Linear AC OPF and DC OPF. As the results, full AC OPF and cubic AC OPF model provides LMP calculation results very similar to each other while the calculation time of cubic AC OPF model is faster than that of the Full AC OPF. Other simplified OPF models, quadratic AC OPF, linear AC OPF and DC OPF offer erroneous results even though the calculation times are much faster than the Full AC OPF and the Cubic AC OPF. Given the condition that the OPF models sometimes fail to find the optimal solution due to the severe complexity of the Korean transmission power system, the Full AC OPF should be used as the primary OPF model while the Cubic AC OPF can be a promising backup OPF model for the LMP calculations and/or real-time operation.

• Asian-Australasian Journal of Animal Sciences
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• v.13 no.10
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• pp.1407-1413
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• 2000

Oil palm frond (OPF) is a new non-conventional fibrous feed for ruminants. Evaluation on the nutritive values and digestibility of OPF was carried out using goats. In a completely randomised design, 20 local male goats were assigned to evaluate fresh and different types of processed OPF. A 60 day feeding trial was done to determine the digestible nutrient intake of fresh, ensiled and pelleted OPF and its response on live weight gain of goat. The pelleting of OPF increased (p<0.05) intake compared to fresh or ensiled OPF. The OPF based mixed pellet (50% OPF with 15% palm kernel cake, 6% rice bran, 6% soybean hull, 15% molasses, 2% fishmeal, 4% urea, 1.5% mineral mixture and 0.5% common salt) increased (p<0.05) nutrient intake, digestibility and reduced feed refusals. The mixed pellet also increased digestible dry matter intake (DDMI) and digestible organic matter intake (DOMI) at 80% and 63% level respectively than the fresh OPF. The increased digestible nutrient intake on the OPF based mixed pellet, resulted in increased live weight gain of goats. Furthermore, OPF has a good potential as a roughage source when it is used with concentrate supplement. OPF based formulated feed in a pelleted form could be used as a complete feed for intensive production of goat and other ruminants.

• Asian-Australasian Journal of Animal Sciences
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• v.16 no.4
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• pp.625-634
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• 2003

Oil palm fronds (OPF) are one of the main by-products of the oil palm industry in Malaysia. It contains about 38.5 % crude fibre with ME values of about 5.65 MJ/kg dry matter. OPF has great potential to be utilized as a roughage source or as a component in a complete feed for ruminant animals. This paper briefly reviews the availability of OPF in Malaysia and its importance in the local beef and dairy industry. About 26 million metric tonnes of OPF are produced on dry matter basis annually during pruning and replanting operations in the plantations. The nutritive value of OPF and studies to improve its feeding value is highlighted. The optimum level of inclusion for ruminant feeding is 30 % and improvement to intake and digestibility can be further enhanced with addition of other oil-palm by-products. Performances of beef and dairy cattle fed fresh OPF or as silage, pellets and cubes are shown. Good quality OPF silage can be produced without using any additive and the significant improvement on the rate of growth and milk yield were shown. With good formulations, OPF based diets can allow live weight gains of between 600-850 g/day and for local crossbred dairy animals, milk yield of about 11.1 to 20.3 liter/day can be obtained. Pellet based on ground OPF seemed to be less well utilized for ruminant feeding due to its smaller particle size. OPF based cubes which have longer particle size is more suitable for beef and dairy cattle. Long-term feeding of OPF based feeds have been shown to produce good quality carcasses, and the meat is safe for consumption.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.412-413
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• 2006

This paper proposed the transmission planning mechanism in competitive power markets. This mechanism used Optimal Power Flow(OPF) to calculate operation cost and Contingency Constrained OPF(CC-OPF) to consider N-1 contingency outage. In addition, this algorithm deduced a yearly transmission planning using Dynamic Programming(DP).

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.301-303
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• 2005

This paper presents long-term shunt capacitor planning using optimal power flow. OPF allows the planning engineer to find feasible solution with minimal amount of engineering time. We used OPF for Shunt capacitor planning to get an optimal solution. The result of OPF is compared to the analysis by the conventional loadflow method and it is proved that OPF gives more cheaper and better planning solution. With the result, we analyzed the operational perspective for the reactive power supply and demand.

• Asian-Australasian Journal of Animal Sciences
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• v.19 no.9
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• pp.1305-1313
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• 2006

Five male dairy goats (Saanen), 4.6 month old with a body weight of 21.4 ($SD{\pm}1.6$) kg, were used to examine 5 dietary urea treatments in a $5{\times}5$ Latin Square experimental design. The five levels of urea were 10, 20, 30, 40 and 50 g urea/kg DM of steam-treated oil palm fronds (OPF) and dry matter intake tended (p>0.05) to increase with increasing urea supplementation up to 30 g/kg OPF (77.7 g/kg $BW^{0.75}$), but decreased (p<0.05) with 40 and 50 g urea/kg OPF (67.4 and 63.7 g/kg BW0.75, respectively) supplementation. Similarly, dry matter, organic matter, crude protein, neutral detergent fiber and hemicellulose digestibilities increased (p<0.05) with the addition of urea to 30 g/kg OPF but thereafter decreased (p<0.05) with 40 and 50 g/kg OPF. Ruminal pH, ruminal $NH_3$-N concentration and plasma urea concentration increased linearly (p<0.01) and quadratically (p<0.01) as a consequence of addition of urea to the diet. Excretion of total purine derivatives (PD) by goats fed 30 g of urea/kg OPF was highest (p<0.05) followed by goats fed 20, 40, 10 and 50 g of urea/kg OPF. Microbial N (g N/day) and efficiency of microbial N supply expressed as g N/kg organic matter apparently digested in the rumen were higher (p<0.05) in goats fed 30 g of urea/kg OPF (5.5 g N/day and 22.0 g N/kg DOMR, respectively) than in goats on 10 and 50 g of urea/kg OPF treatments. However, the former did not differ from goats fed 20 g of urea/kg OPF (3.9 g N/day and 16.6 g N/kg DMOR, respectively). Ruminal VFA concentration, protein/energy ratio, N absorption and N retention increased (p<0.05) with the addition of urea to the diet up to 30 g/kg OPF but decreased (p<0.05) with 40 and 50 g/kg OPF. This implies that the optimal level of urea supplementation in an OPF based diet was about 30 g urea/kg OPF.

• Asian-Australasian Journal of Animal Sciences
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• v.13 no.8
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• pp.1113-1120
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• 2000

Productivity, nutrient contents, in vitro gas production and in sacco degradability of different fractions and whole OPF were determined to assess the feeding value of OPF as a ruminant feed. An in vivo digestibility trial was also carried out using goat. Freshly harvested OPF was randomly collected, partitioned and weighed. An OPF from 21 years older palm weighed 13.4 kg and the annual fresh matter yield of petiole, leaflet and midrib was 46.5, 11.8 and 3.4 ton/ha, respectively. Leaflet contained 439, 926, 698, 501, 168, 196, 748 and 52 (g/kg) of dry matter (DM), organic matter (OM), neutral detergent fiber (NDF), acid detergent fiber (ADF), cellulose (CE), hemicellulose (HC), total carbohydrate (TC) and non fiber carbohydrate (NFC), respectively. Petiole contained lower (p<0.01) DM, CP and EE contents than leaflet. Organic matter, CE and TC contents were higher (p<0.01) in petiole compared to leaflet. Silica and lignin contents were highest (p<0.01) in midrib followed by leaflet, whole OPF and least in petiole. The Ca, P, Na, K and Mg contents (g/100 g DM) of leaflet were 0.529, 0.182, 0.039, 0.876, and 0.168, respectively. In vitro DM digestibility (g/100 g) at 48 h of leaflet, petiole and midrib was 32.7, 38.7 and 30.2, respectively. The in sacco DM degradation (g/100 g) at 48 h of leaflet was higher than that of whole OPF, petiole and midrib. The in vivo digestibility of DM, OM, CP and ADF of whole OPF was 52, 56, 43 and 26%, respectively. It can be concluded that leaflet is the most nutritious fraction of OPF and midrib is the least. The nutrient content and digestibility of the whole OPF showed that OPF could be an alternative roughage source for ruminant diets.

• Asian-Australasian Journal of Animal Sciences
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• v.13 no.7
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• pp.941-947
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• 2000

Three fistulated Malaysian local bulls were used in a $3{\times}3$ Latin square design to determine the effects of different levels of concentrate with oil palm (Elaeis guineensis Jacq.) frond (OPF) on rumen pH and $NH_3$-N concentration, and DM degradability of different fractions of OPF. Three diets namely, 60% OPF pellet and 40% concentrate (Diet 1), 50% OPF pellet and 50% concentrate (Diet 2) and 40% OPF pellets and 60% concentrate (Diet 3) were used. The levels of concentrate in the diets affected rumen pH and $NH_3$-N concentration. The pH and $NH_3$-N concentration almost in all hourly samples did not show any difference (p>0.05) among the diets except the 6 h and 9 h samples. The highest (p<0.01) $NH_3$-N concentration was obtained on Diet 3 followed by Diet 2 and Diet 1, but there was a slightly higher (p>0.05) pH on Diet 1. The $NH_3$-N concentrations of rumen liquor at 9 h sampling on Diet 1 and Diet 2 were below the critical level (50 mg/liter) required for efficient fermentation of fibrous feeds. The in sacco DM degradation of different fractions of OPF was affected by diets. The DM degradation of fractions of OPF was higher on Diet 3, which showed differences (p<0.01) with the other diets. It was found that a higher level of concentrate (60%) with OPF gave a higher rumen $NH_3$-N concentration that increased the DM degradation of OPF fractions. The results showed that OPF could support an efficient rumen function in terms of $NH_3$-N concentration and pH when ${\leq}50%$ in the diet. A higher level of OPF (>50%) does not support an efficient rumen fermentation in terms of $NH_3$-N concentration, and resulted in lower DM degradation values of the fractions. The results suggested that there is a need to supplement additional nitrogen to OPF based diets.

• Proceedings of the KIEE Conference
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• 2001.05a
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• pp.20-23
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• 2001

Stability aspects have often been incorporated in the dispatch/pricing procedure using trial and error methods, or approximated in the dispatch optimization directly as a set of linear constraints on generation/transmission. This paper presents introduction of PSS/OPF and voltage instability analysis using the program. Additional advantages offered by FSS/OPF are easier procedures, less computation and avoidance of engineering judgement in identifying the amount of shunt requrement at the candidate buses.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.390-391
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• 2006

The economic dispatch problem is important in both power system planning and operation, although there have been major advances in defining and solving more complete Optimal Power Flow(OPF) problems, there exists a need for constrained economic dispatch techniques which, though not as rigorous or as exact an OPF, are fast enough to be used on desktop computers. This paper presents a DC-OPF algorithm that is based upon Relative-Contribution Index in Generators. The transmission constraints are modeled as linear constraint based on a DC-Power-Flow model. An detailed illustrative example is presented.