Arcing High Impedance Fault Detection Using Real Coded Genetic Algorithm

Safety and reliability are two of the most important aspects of electric power supply systems. Sensitivity and robustness to detect and isolate faults can influence the safety and reliability of such systems. Overcurrent relays are generally used to protect the high voltage feeders in distribution systems. Downed conductors, tree branches touching conductors, and failing insulators often cause high-impedance faults in overhead distribution systems. The levels of currents of these faults are often much smaller than detection thresholds of traditional ground fault detection devices, thus reliable detection of these high impedance faults is a real challenge. With modern signal processing techniques, special hardware and software can be used to significantly improve the reliability of detection of certain types of faults. This paper presents a new method for detecting High Impedance Faults (HIF) in distribution systems using real coded genetic algorithm (RCGA) to analyse the harmonics and phase angles of the fault current signals. The method is used to discriminate HIFs by identifying specific events that happen when a HIF occurs

Effect of Nitrogen, shading and intercropping on alfalfa-ziziphus agroforestry system under arid land conditions

To assess the arid lands agroforestry potential, a field experiment was performed at the Agricultural Research Station of King Abdulaziz University, located at Hada Al-Sham during the 2013 and 2014 seasons. Alfalfa was evaluated in a Ziziphus agroforestry system at a distance of 1 m, 2 m and 4 m from the ziziphus tree and were supplied with three different levels of nitrogen fertilizer 0 kg/ha, 200 kg/ha and 400 kg/ha in the form of commercial Urea. The fertilizer were subdivided into split doses and applied as manual broadcasting after each cutting. A split-split plot design was used with three replications. Forage growth rate and biomass accumulation were measured at ten different intervals approximately at a period of 30-40 days. Forage was harvested in 10 different cuts and all this data consisting of plant height, fresh biomass accumulation and dry biomass accumulation and leaf nitrogen content were also measured. Statistical analysis described significant impact for intercropping, planting distance and nitrogen fertilizer on all studied traits. The maximum effect of urea fertilizer was documented for the highest dose of 400 kg/ha but it was statistically non-significant to 200 kg/ha. Distance of planting from the Ziziphus tree produced variable trend for all forages at different cut numbers but 2 m produced maximum plant height and biomass accumulation for most of the cut numbers. The interaction of 200 kg N/ha, intercropping and 2 m distance produced optimum forage growth and biomass accumulation as compared to the sole plantation under no fertilization. Â

Modelling arcing high impedances faults in relation to the physical processes in the electric arc

There is an increasing demand for more detailed and accurate modelling techniques for predicting transient response of power systems caused in particular by high impedance arcing faults (HIF). This is particularly so in relation to the design and development of improved equipment and new protection techniques. Accurate prediction of fault transients requires detailed and comprehensive representation of all components in a system, while the transient studies need to be conducted into the frequency range well above the normal power frequency. The HIF is a very complex phenomenon and exhibits very high nonlinear behaviour. The most distinctive characteristics are nonlinearity and asymmetry. The nonlinearity arises from the fact that the voltage-current characteristic curve of the HIF is itself nonlinear. It is observed that the fault current has different waveforms for positive and negative half cycles which is called asymmetry. The nonlinearity and asymmetry exist in every cycle after HIF. In order to obtain a model for a HIF, it is necessary to develop a model that gives the above mentioned characteristics, as well as the harmonic content of the HIF

The evolution of high impedance fault modeling

There is an increasing demand for more detailed and accurate modelling techniques for predicting transient response of power systems caused in particular by high impedance arcing faults (HIF). This is particularly so in relation to the design and development of improved equipment and new protection techniques. Accurate prediction of fault transients requires detailed and comprehensive representation of all components in a system, while the transient studies need to be conducted into the frequency range well above the normal power frequency. The HIF is a very complex phenomenon and exhibits highly nonlinear behaviour. The most distinctive characteristics are nonlinearity and asymmetry. The nonlinearity arises from the fact that the voltage-current characteristic curve of the HIF is itself nonlinear. It is also observed that the fault current has different waveforms for positive and negative half cycles, which is called asymmetry. The nonlinearity and asymmetry exist in every cycle after the HIF. In order to obtain a good representation of a HIF, it is necessary to develop a model that gives the above mentioned characteristics, as well as the harmonic content of the HIF. This paper introduces a new HIF model, it also reviews and summarizes some of the methods for modelling high impedance faults and the developments which led to them

A Digital Technique for Online Identification and Tracking of Power System Harmonics Based on Real Coded Genetic Algorithm

Current and voltage waveforms of a distribution or a transmission system are not pure sinusoids. There are distortions in these waveforms that consist of a combination of the fundamental frequency, harmonics and high frequency transients. This paper presents an enhanced measurement scheme for identification and tracking of harmonics in power system. The proposed technique is not limited to stationary waveforms, but can also estimate harmonics in waveforms with time-varying amplitudes. This paper presents a new method based on Real Coded Genetic Algorithm, which is a technique for optimization inspired by genetics and natural evolution. The algorithm was tested using simulated data, and effects of sampling rate studied. Results are reported and discussed

Analisis Terhadap Implementasi Program Desa Vokasi Untuk Mengembangkan Potensi Sumberdaya Manusia Pedesaan (Studi Pada Desa Reksosari, Kecamatan Suruh, Kabupaten Semarang, Jawa Tengah).

Latar belakang desa vokasi adalah adanya permasalahan pengangguran dan rendahnya kualitas pendidikan (kecakapan hidup) yang terjadi di pedesaan. Di sisi lain, pedesaan memiliki potensi sumberdaya alam yang besar yang dapat memberikan penghasilan bagi masyarakat disekitarnya. Namun karena kemampuan masyarakat terbatas, mereka belum mengelola sumberdaya alam dengan baik. Inti dari program desa vokasi adalah: pemberdayaan masyarakat, proses pembelajaran, dan keunggulan komparatif local. Penelitian tentang program desa vokasi dilakukan untuk mendeskripsikan implementasi program, dampak program terhadap peningkatan kemampuan masyarakat dalam mengelola sumberdaya alam, dan mendeskripsikan faktor-faktor yang menjadi penghalang maupun sebagai pendukung program desa vokasi. Untuk menjelaskan hasil temuan dalam penelitian, maka teori yang digunakan adalah teori kebijakan publik khususnya implementasi kebijakan, teori pemberdayaan dan teori pendidikan. Penelitian ini menggunakan metode deskriptif dengan pendekatan kualitatif. Penelitian ini dilakukan di Desa Reksosari dengan fokus adalah mengukur tingkat keberhasilan program desa vokasi di tahun pertama, melihat dampak yang dihasilkan dari program tersebut terhadap peningkatan kemampuan masyarakat dan melihat faktor-faktor yang mendukung atau melemahkan program. Hasil penelitian menunjukkan bahwa strategi implementasi program tergantung pada penafsiran pelaksana program terhadap konsep desa vokasi itu sendiri. Terdapat dua model pemahaman terhadap program ini, yaitu: pertama, peningkatan sumberdaya alam sebagai langkah awal dan kedua, peningkatan sumberdaya manusia sebagai langkah awal. Implementasi program desa vokasi pada tahun pertama berhasil di implementasikan. Keberhasilan dalam implementasi ini diukur dengan cara membandingkan kenyataan dengan indikator keberhasilan yang ada dalam program. Dampak program desa vokasi pada masyarakat belum terlihat karena program ini membutuhkan proses dan waktu yang lama. Proses pembelajaran tidak bisa langsung menunjukkan perubahan yang signifikan terhadap kemampuan masyarakat dalam mengelola sumberdaya alam. Pengelolaan sumberdaya alam masih menggunakan caracara yang tradisional. Peningkatan penghasilan yang diharapkan terjadi, ternyata belum terlihat, karena pada tahun pertama program digunakan untuk memperkuat organisasi unit usaha dan merintis kegiatan yang telah disepakati. Program desa vokasi dapat berjalan karena ada komitmen dari pemerintah desa dan kemauan masyarakat untuk menerima dan berusaha untuk memberbaiki kehidupan ekonomi. Di sisi lain, program ini menghadapi tantangan untuk merubah kebiasaan (budaya) yang buruk yang ada di masyarakat dan membuat jaringan pemasaran yang kuat. Dapat saya simpulkan bahwa program desa vokasi merupakan program pemberdayaan masyarakat melalui proses pembelajaran yang berupaya menggali potensi sumberdaya yang ada di desa untuk dimanfaatkan sehingga desa memiliki keunggulan komparatif lokal dan harapannya, permasalahan pendidikan dan keterampilan yang rendah serta masalah pengangguran dapat teratasi di kemudian hari. Implementasi program dan pelaksanaan kegiatan yang ada dalam program desa vokasi membutuhkan evaluasi. Dari hasil tersebut, rekomendasi yang saya berikan terbagi menjadi dua yaitu rekomendasi yang berhubungan dengan keilmuan dan rekomendasi yang berhubungan dengan program desa vokasi. Rekomendasi yang berhubungan dengan program antara lain: membuat mekanisme evaluasi yang baku, memperbaiki mekanismepembelajaran, pengelolaan keuangan dan pemasaran

A novel methodology for on-line identification of arcing high impedance faults on overhead power distribution feeders

A novel methodology for online identification of arcing high impedance fault on overhead power distribution feeders Abstract Electrical utilities use overhead energized conductors to transport electrical energy to consumers. There are millions of kilometres of overhead distribution lines in the world supplying energy for industrial, commercial and residential customers. In low and medium voltage overhead distribution systems, overhead conductors are exposed to the surrounding elements and to abnormal conditions. High impedance faults (HIFs) on distribution feeders are abnormal electrical conditions that cannot be detected by conventional protection schemes and their detection is considered to be generally a difficult problem. Such faults usually occur when a distribution line conductor is contacted by a high resistance grounded object, such as a tree, or when&quot; a conductor breaks and falls on a poorly conducting earth surface. The main problem is that HIFs do not draw sufficient fault current to be easily identified, and the presently available protection systems and relays are incapable of accurately distinguishing high impedance faults, such as a downed power line conductor, from other normal system events and activities. These faults pose a threat to human lives and properties when neighbouring objects come into contact with the lines and energized conductors.</p