Various approaches for power balancing in grid-connected and islanded microgrids

One of the promising solutions to reduce power imbalance, an undesired impact of intermittent renewable energy sources, is to supply the loads by means of local distributed energy resources in the form of a microgrid. Microgrids offer several benefits such as reduction of line losses, increased system reliability, and maximum utilisation of local energy resources. A microgrid, during its islanded operation, is more susceptible to the frequency and voltage fluctuation caused by a sudden dispatch either from the generation or load. Therefore, additional control is required to manage either the output power from the generation side or the demand from the end-user side. Thus, appropriate and efficient control and monitoring systems need to be installed. However, the cost of such a system will reduce the rate of investment return on microgrid projects. This research has focused on developing various techniques to maintain the voltage and frequency within acceptable limits in microgrids, taking into account various influencing factors. This study proposes an additional active power management technique through the use of inverters, that can maintain the microgrid’s frequency when the generated power in the microgrid is much higher than its demand. Also, to facilitate the microgrid’s transition from grid-connected to islanded mode, the inverters can be controlled with a soft starting ramp. Moreover, a control function employing a droop control method is proposed in order to reduce the output power of the renewable sources when the microgrid frequency is much higher than the nominal frequency. On the other hand, when the demand is higher than the generated power, managing the demand under a demand response program is proposed as a means of maintaining the microgrid stability. This is an inexpensive solution which will not reduce the rate of investment return on the microgrid project. However, this requires the installation of appropriate enabling technologies at the utility and end-user sides. Moreover, the participation from demand response participants is influenced by the profit earned from engaging in the program. Therefore, in this research, the technical and economic benefits of demand response deployment are analysed in detail. The execution of the demand response program through load-shifting, reducing the appliances’ consumed power, and load-shedding causes customer discomfort. To minimise this discomfort, in this thesis, suitable strategies are suggested for various groups of loads. Furthermore, each load profile contains information on its capacity, flexibility, and operating time. The proposed approach ensures that the loads with a larger capacity and flexibility are the most preferred ones to be controlled during demand response events so that customer discomfort and the number of affected loads can be minimised. Also, this study examines the load’s economic value, power losses, emission factor, and cost of energy production to maximise the microgrid operator’s profit as a result of deploying the demand response program. Meanwhile, to encourage end-users’ engagement in demand response programs, the microgrid operator should offer incentives to the customer as compensation for any incurred costs and discomfort felt. The given incentives should be such that both the microgrid operator and the end-user gain the maximum profit. Therefore, this study proposes an approach for calculating the level of incentives that should be given to the participants by comparing the differences between ongoing revenue and the cost of energy with and without demand response

PEMAMPATAN DATA CITRA BERWARNA DENGAN ALIHRAGAM WAVELET HAAR

Selama ini belum pernah dilakukan penelitian mengenai pemampatan data citra berwarna menggunakan alihragam wavelet Haar dengan penyandian Hufman. Oleh karena itu, pada tugas akhir ini dibuat perangkat lunak sistem pemampat data citra berwarna dengan alihragam wavelet Haar dan penyandian Huffman. Langkah-langkah pada penelitian ini antara lain : penerapan dekomposisi citra menggunakan metode dekomposisi baku alihragam wavelet Haar 2 dimensi, pengenolan, kuantisasi, dan penyandian koefisien citra dengan metode penyandian Huffman, merekonstruksi citra dari koefisien citra termampat, mengukur kinerja sistem pemampatan citra menggunakan parameter PSNR, indeks kualitas, dan rasio pemampatan. Dari hasil penelitian dapat disimpulkan bahwa dekomposisi baku alihragam wavelet Haar hanya bisa bekerja dengan baik pada citra dengan ukuran 2N x 2M . Nilai rasio pemampatan yang dihasilkan alihragam wavelet Haar dengan penyandian Huffman jauh besar jika dibandingkan rasio pemampatan yang hanya menggunakan penyandian Huffman. Jika citra uji mempunyai detil yang lebih seragam akan diperoleh rasio pemampatan yang semakin besar, begitu juga indeks kualitas yang diperoleh akan semakin besar. Pengenolan koefisien yang bernilai kecil menghasilkan rasio pemampatan yang semakin besar sedangkan indeks kualitas yang diperoleh semakin kecil. Kata-kunci - alihragam wavelet Haar, dekomposisi, rekonstruksi, pengenolan, penyandian Huffman, indeks kualitas

Task-Based Language Teaching Criteria in Textbook for Senior High School in Indonesia

The current study focused on activities and tasks that concluded in an English textbook used in a senior high school in Indonesia based on the TBLT's criteria. This study analyzed the content of an English textbook for senior high school grade X. The subject of this study was an English textbook titled "Pathway to English." The researchers used the qualitative descriptive method, especially in the analysis content, to analyze the tasks in the textbook. The researchers conducted this study in August 2022 at the library of IAIN Palangka Raya. The researchers utilized an observation instrument and an observation assessment form suggested by Akmal. Findings indicated that the textbook matched the standards for a good task based on Akmals' instruments. It showed that eight activities were classified as "strong" tasks, and seven obtained "weak" tasks. Moreover, this book also contains the four language skills with 12 activities of the book has more than one of the language skills in each activity and fulfills the criteria. In conclusion, this study indicates that the book is compatible with the Task-based Language Teaching (TBLT) criteria. However, the textbook mostly lacks the aspect of real-life activity and students' negotiation

Development of Mathematics Comic Learning Media for Students of Class VII SMP/MTs Based On Culture

This study aims to develop a culture-based mathematics comic learning media using research and development or R & D methods with the ASSURE model. This development research was conducted in three Junior High Schools (JHS) in one sub-district, Pasar Minggu sub-district, South Jakarta. This research has been tested to various experts, namely: two material experts with very good categories and a percentage of 86%, 72% from one linguist with a good category, 96% from one development expert with a very good category, and get a percentage 3,4 with a good category from one graphic design expert. While the results of one to one test evaluations get an average of 84% which falls into the good category, small group test with a percentage of 85% with a very good category, and a large group test using the t-test results obtained tcount > ttable. Based on the evaluation results from several experts, using learning media in the form of mathematical comics is considered feasible and can increase students' interest and learning outcomes