Partial Discharge Location Technique for Covered-Conductor Overhead Distribution Lines

In Finland, covered-conductor (CC) overhead lines are commonly used in medium voltage (MV) networks because the loads are widely distributed in the forested terrain. Such parts of the network are exposed to leaning trees which produce partial discharges (PDs) in CC lines. This thesis presents a technique to locate the PD source on CC overhead distribution line networks. The algorithm is developed and tested using a simulated study and experimental measurements. The Electromagnetic Transient Program-Alternative Transient Program (EMTP-ATP) is used to simulate and analyze a three-phase PD monitoring system, while MATLAB is used for post-processing of the high frequency signals which were measured. A Rogowski coil is used as the measuring sensor. A multi-end correlation-based technique for PD location is implemented using the theory of maximum correlation factor in order to find the time difference of arrival (TDOA) between signal arrivals at three synchronized measuring points. The three stages of signal analysis used are: 1) denoising  by applying discrete wavelet transform (DWT); 2) extracting the PD features using the absolute or windowed standard deviation (STD) and; 3) locating the PD point. The advantage of this technique is the ability to locate the PD source without the need to know the first arrival time and the propagation velocity of the signals. In addition, the faulty section of the CC line between three measuring points can also be identified based on the degrees of correlation. An experimental analysis is performed to evaluate the PD measurement system performance for PD location on CC overhead lines. The measuring set-up is arranged in a high voltage (HV) laboratory. A multi-end measuring method is chosen as a technique to locate the PD source point on the line. A power transformer 110/20 kV was used to energize the AC voltage up to 11.5 kV/phase (20 kV system). The tests were designed to cover different conditions such as offline and online measurements. The thesis evaluates the possibility of using a Rogowski coil for locating faults in MV distribution lines and a test bench of a 20 kV distribution network is developed. Different fault scenarios are simulated including earth and phase faults, arcing faults and faults caused by leaning trees. Results favourably show the possibility of using a Rogowski coil for locating faults in distribution networks.  

Investigation in fuel cells using 'hydro-genius teach'

The aim of this report is to deliver information's about the features of fuel cells. Along with it, this report gives details about activities of renewable energy. It covers analysis of theories and some experiments done using a set of tool called Hydro Genius Teach. The experiments are about advantages of fuel cells compared to other methods that have been used to produce electrical energy from the processes of renewable energy. Furthermore, methods on how fuel cells operate are also given. The main objective of this project was to analyse current usage of renewable energy in the world. The main focus is to do analysis on features of fuel cells as one of ways in renewable energy

Equipment Performance Due to Voltage Sags – Test Results for Contactor and Induction Motor

This paper presents experimental test results of contactor and induction motor performances when they were supplied by voltage sags. A Programmable source is used to generate various voltage sag characteristics. A small of contactor and induction motor were used for this purpose. Test results show that magnitude and duration are very important aspects that determine performance of the equipments. Influence of other characteristics such as point on wave and repetitive of voltage sag are discussed. Difference of point on wave of sag initiation will cause contactor performance is different for tripping. The occurrence of the second sag after the first one may affect the contactor performance. The contactor performance becomes sensitive when it is supplied by repetitive voltage sags. Voltage sag cause transient current drawn by the motor is too high and it occurs at recovery voltage instant and the value depending on magnitude of the sags. The current peak is not significant influenced by sag duration. The current peak in the second sag is similar to first sag. Therefore presence repetitive of voltage sags on induction motor is not influence on the current peaks

Economic Dispatch Analysis Using Equal Incremental Cost Method with Linear Regression Approach

The use of fuel is one thing that needs special attention, because most of the operating costs of a plant are fuel costs. One of the efforts to minimize the cost of generating fuel is called Economic dispatch. In this study, an Equal Incremental Cost method with a Linear Regression approach will be presented to obtain a minimum generation cost. The case taken is the Pangkalan Susu PLTU which operates two generating units. Based on the results of calculations using the Equal Incremental Cost method with the Linear Regression approach, the cost is -0.033% or an average of -13,111 $/hour

Mitigation of high voltage induction effect on ICCP system of gas pipelines: a field case study

An analysis of the high voltage induction effect on the impressed current cathodic protection (ICCP) system on pipelines parallel toward high voltage power lines was employed in this research. Mitigation of high voltage effect throught human and environment is necessary to implemented. Direct current induction was used to increase the electrical potential of the gas pipeline, from Klumpang to sicanang area, Indonesia. During the mitigation process, the highest induction value was obtained 0.00574 KV which is previously was 0.01732 KV, and occurred at the limit of the allowable secure touch tension value of 0.015 KV. The data that acquire from the measurement of test point of ICCP underneath the transmission line revealed a comparison data between field measurements occurred of mitigation process. The direct current induction method is found to be safe for ICCP system and environment

Online condition monitoring of MV cable feeders using Rogowski coil sensors for PD measurements

Condition monitoring is a highly effective prognostic tool for incipient insulation degradation to avoid sudden failures of electrical components and to keep the power network in operation. Improved operational performance of the sensors and effective measurement techniques could enable the development of a robust monitoring system. This paper addresses two main aspects of condition monitoring: an enhanced design of an induction sensor that has the capability of measuring partial discharge (PD) signals emerging simultaneously from medium voltage cables and transformers, and an integrated monitoring system that enables the monitoring of a wider part of the cable feeder. Having described the conventional practices along with the authors’ own experiences and research on non-intrusive solutions, this paper proposes an optimum design of a Rogowski coil that can measure the PD signals from medium voltage cables, its accessories, and the distribution transformers. The proposed PD monitoring scheme is implemented using the directional sensitivity capability of Rogowski coils and a suitable sensor installation scheme that leads to the development of an integrated monitoring model for the components of a MV cable feeder. Furthermore, the paper presents forethought regarding huge amount of PD data from various sensors using a simplified and practical approach. In the perspective of today’s changing grid, the presented idea of integrated monitoring practices provide a concept towards automated condition monitoring.fi=vertaisarvioitu|en=peerReviewed

The Effect of Distributed Generator Injection with Different Numbers of Units on Power Quality in the Electric Power System

Distributed Generation (DG) is a small capacity generator located in the electricity distribution system and is usually placed on buses that are connected directly to the load. Placement of distributed generation is one of the technical efforts to reduce voltage drop and power losses in the system. In addition, load flow analysis is a study to plan and determine the amount of power in an electric power system. The results of power losses after adding distributed generation were the best in the fifth experiment on bus 149, where the system experienced a total loss of active power (P) previously of 720,822 kW, to 682,939 kW and total loss of reactive power (Q) previously of 530.02 kVar, to 405.835 kVar. From the results of the calculation of the power flow using ETAP software (Electrical Transient Analyzer Program). So, it can be concluded that the electrical network system can be said to be good. The results obtained are the more DG (wind turbine generator) that is input into the bus it will reduce the voltage drop that occurs. After simulating the overall voltage drop, it still meets the standards according to the results of the Text Report on ETAP

Prototype of Automatic Watering and Fertilizing System for Oil Palm Seeds Based on Internet of Things

Watering and fertilizing are very important to maintain the quality of the oil palm seeds. If the oil palm seeds are not watered regularly the soil will dry out while the oil palm seeds generally need to maintain adequate soil moisture and require a loose textured soil medium. So far, farmers have not optimally fulfilled the needs for water and fertilizer for oil palm seeds because they still use manual and traditional methods. Technological developments have made it possible to create irrigation and fertilization techniques automatically. In this study, a prototype of an automatic watering and fertilizing system was designed and realized for oil palm seedlings using the NodeMCU ESP8266 as the main controller in addition to RTC, humidity sensors, relays, water pumps, LCDs, and smartphones. RTC is used for fertilization scheduling, humidity sensors to sense soil moisture levels, relays as automatic switches that turn on and off pumps, water pumps to pump water and liquid fertilizer, LCD to display information, and smartphones to monitor conditions and processes of watering and fertilizing coconut seedlings palm. The test results show that the prototype tool can work well. When the soil moisture is read by the humidity sensor less than 30% (dry soil condition) then pump one is activated and when the soil moisture is more than 60% (wet soil condition) then pump one turns off. Furthermore, fertilization can take place according to a predetermined schedule where the second pump will automatically activate with a duration of 20 seconds for each fertilization period