Power System Engineering

Permanent URI for this collectionhttps://hdl.handle.net/20.500.14540/17985

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An Explicit Formula Based Estimation Method for Reliability of Urban Feeder in Kathmandu valley
(I.O.E, 2024-06) Pandey, Rajesh Kumar; Karki, Nava Raj
An innovative approach to reliability assessment in the planning phase of medium-voltage distribution systems is presented in this study. The method introduces a novel technique for estimating reliability indices, enabling their expression through explicit formulas while accommodating various network topologies. Initially, typical feeder structures are identified within the candidate area using a combination of tree edit distance and hierarchical clustering algorithms. Subsequently, for each typical network structure, a reliability evaluation model is established, incorporating factors such as fault isolation, load restoration, and the impact of reliability enhancement equipment, formulated through regression analysis. The feasibility and effectiveness of the proposed reliability assessment algorithm are validated through test cases, demonstrating its capability to achieve rapid and accurate reliability index calculations with minimal data requirements. This approach offers a systematic and efficient means of assessing distribution system reliability during the planning process, ensuring adaptability to diverse network configurations. Finally, this approach is implemented for Baneshwor 11 kV feeder distribution system.
OPTIMAL SITING AND SIZING OF SSSC IN INPS USING MODIFIED SALP SARM ALGORITHM CONSIDERING OPTIMAL REACTIVE POWER DISPATCH PROBLEM
(I.O.E, 2024-06) Karna, Priyanka; Chaudhary, Jeetendra
In a power system, effective coordination between generation and demand is crucial. With the growing demand for electrical energy, optimizing the operation of all components to maximize efficiency becomes imperative. FACTS devices are essentially tools designed to enhance the efficiency of the transmission system. In a power system network, these devices are employed to enhance the power transfer capacity of transmission lines. Their utilization results in improved voltage stability, transient stability, voltage regulation, reliability, and increased thermal limits within the transmission network. The Static Synchronous Series Compensator (SSSC) is a method of series compensation applied in the transmission system. Its purpose is to either raise or lower the voltage drop along the line, thereby managing the power flow through the transmission line. By introducing voltage in quadrature with the line current, the SSSC regulates the power flow by controlling the equivalent impedance of the transmission line. The SSSC's output voltage is entirely controllable and operates independently of the line current. The Optimal Reactive Power Dispatch (ORPD) problem is tough because of non linear and non-convex functions. Addition of SSSC makes the solution even harder by bringing in complex dynamics for controlling power flow. To deal with these challenges, we need smart techniques and computer methods to find good solutions with efficient and reliable optimization algorithm to solve the problem of ORPD and identify the optimal location and rating of SSSC. In this thesis, Modified Salp Swarm Algorithm is used to solve the ORPD with and without the SSSC controller to minimize power losses and voltage deviations as well as improve the voltage stability on the Intergrated Nepal Power System (INPS) system and hence the result is compared with the standards IEEE 30-bus system. After solving the ORPD problem and load flow analysis, initial line losses of 119.108 MW (5.8% of total load) reduced to 35.336
Modeling and Control of Automatic Generation Control of Upper Trishuli 3A Hydropower Plant.
(I.O.E, 2024-06) YADAV, NARENDRA; Adhikari, Sujan
With rising load demand resulting in mismatches between load and generation, simply producing electrical power is insufficient, particularly with today's sophisticated power systems. These mismatches generate changes in the frequency of the power system, rendering it unstable. Restoring the frequency to its normal value quickly is a critical and difficult operation. This task is managed by Automatic Generation Control (AGC), which is critical to preserving the power system's stability and reliability. This effort comprises modeling and control of AGC to reduce the frequency response settling time of the Upper Trishuli 3A (UT3A) hydropower plant, which is linked to the INPS in a double-area power system. Four scenarios are explored based on step load input to the system, using different controllers: PID, PSO-tuned SSSC, FLC, and ANFIS, with the goal of minimizing the Area Control Error (ACE) and stabilizing the frequency response of the UT3A hydropower plant under the AGC model. Among these controllers, ANFIS has been shown to be the most successful at reducing the frequency response settling time to its minimum value. This approach also addresses frequency instability, which can cause system breakdowns owing to synchronization failures in networked systems.
Reliability Assessment of Power Distribution System of Industrial Estate: A Case Study in Balaju Industrial Estate
(I.O.E, 2024-06) Rai, Mitra Kumar; Karki, Nava Raj
The main task of distribution system is to provide acceptable reliability, economic and quality service of electricity according to the demanded load value. To fulfill this task more accurately, the reliability assessment of the distribution system can be performed and measured using a wide variety of reliability indices. This study evaluates the reliability indices of industrial distribution network, Balaju Industrial District, and deals with the reliability of four different network configurations (Case 0-1-2-3) to increase reliability and achieve more realistic results. Using ETAP, distribution networks are designed, comparisons are made. Reliability changes achieved by network configuration have demonstrated the importance of optimal configuration planning to improve the uninterrupted and sustainable energy quality of the system. In addition, cost of electricity outage, i.e. unserved energy cost, is estimated in this paper based on industrial consumer survey for the financial analysis from the reliability point of view. Outage cost is estimated by production loss method, backup generation method and willingness to pay method. The overall and the best feasible value of cost of unserved energy of BID power distribution system is calculated by taking the weighted average of estimated values from production loss method and backup generation method, and it is found to be Rs. 28.26 per kWh.
Implementation of Demand Response Programs in Various Countries and Its Impact on the Bulk Power System Reliability
(I.O.E, 2024-07) Sapkota, Madhav; Karki, Nava Raj
Over recent decades, electricity systems have adopted demand-side participation features, including distributed generation, storage, and DR, recognized globally as vital for reliable power supply. Despite increasing electricity demand requiring robust infrastructure, DR effectively mitigates peak power scarcity by load redistribution, aligning with price fluctuations. This thesis explores diverse DR programs, originating from the late 1980s, with ongoing global research on efficacy and challenges in power market implementation. Utilizing MATLAB for coding and PSSE for power flow solutions, the thesis has two main objectives: investigating DR practices worldwide and integrating a DR model into a widely used RBTS 6-bus system for analysis. Peak demand assessment is pivotal, evaluating power system reliability indices within a reduced peak network context. The thesis introduces a comprehensive DR model, incorporating consumer behavior across scenarios and rationality levels, with Price Elasticity Matrices (PEMs) guiding DR calculation. Results indicate enhanced system reliability, supporting further demand management, especially through major DR programs. The thesis emphasizes tailored demand-side management approaches based on consumer categories, highlighting the importance of Incentive-based DR (IBDR)
Analysis of Arc Flash and Mitigation Techniques in Substation Protection of Attariya Substation Nepal
(I.O.E, 2024-06) Rai, In Bahadur; Mishra, Akhileshwar
An arc flash refers to an electrical explosion that might happen when there is a sudden and intense flow of current, occurring either between a conductor and the ground or between two conductors. Arc flashes produces intense heat and light, and can release large amounts of energy. Arc flash analysis is required to quantify the associated risk and minimize the possible consequences with optimal protective measures. The electrical power system in Nepal is in growing phase. There are number of substations being upgraded, new substation being constructed. However, the consideration of arc flash analysis in substation protection system are not found to the level it required. The primary goal of this study is to quantify possible risks linked with arc-flash incidents in the Attariya Substation, and devise effective mitigation techniques. There were unofficial record of number of incidents related to arc flash in Attariya substation such as fire in low voltage switchgear and arcing due to underground cable termination explosion. The transformers in Attariya substation has been upgraded with higher capacity, which might have resulted in higher fault level in the substation.
Participation of Nepal in Real Time Market in Indian Energy Exchange: Analysis of Optimal Bidding Strategies using Machine Learning
(I.O.E, 2024-06) Parajuli, Elina; Karki, Nawaraj
Precise load prediction is vital for electric utilities, as it provides crucial information for scheduling power generation, managing energy distribution, and optimizing resources. Nepal Electricity Authority, is currently participating in Indian Energy Exchange’s (IEX) Day Ahead Market (DAM) for the import/export of electricity which is itself a huge milestone for Nepal but is also required to forecast their loads in 15-minute intervals a day in advance with high accuracy to bid in the energy market. To discourage excessive power drawl or insufficient power injection, a frequency-based component called the deviation settlement charge (DSM) is incorporated into the bulk electricity pricing in the IEX market. Due to in accurate load forecasting, weather changes, holidays, Nepal has also been subjected to deviation charges to account for any deviations from the agreed-upon energy transactions. RTM provide a mechanism for balancing the fluctuations in supply and demand by allowing market participants to adjust their electricity purchases or sales in response to changing conditions. It also provides more flexibility and responsiveness compared to day-ahead markets, which can help grid operators manage their systems more effectively. Therefore, RTM bidding in addition to Day Ahead Market bidding is of paramount importance to handle this deviation.
Analysis of Effects of Loading Conditions on Condition Monitoring of Induction Machines
(I.O.E, 2024-06) Pokhrel, Chandan; Karki, Nawaraj
effectiveness, robustness, and high efficiency. However, as with all electrical machines, they are prone to degradation over time, necessitating expensive repairs and maintenance. Detecting faults early is critical to minimizing unplanned downtime and reducing operational costs. One significant fault that can significantly impact the performance of induction machines is broken rotor bars. Broken rotor bars can lead to various undesirable effects, including increased vibration, reduced efficiency, and potential catastrophic failure if left undetected. Motor current signature analysis (MCSA) is a widely adopted technique for monitoring the condition of induction machines during normal operation. By analyzing the frequency spectrum of the stator current, MCSA provides valuable insights into the health of the machine and can detect anomalies indicative of broken rotor bars. This study specifically focuses on analyzing the stator current signals of a squirrel cage induction machine to detect and diagnose broken rotor bar faults under different load conditions. The research employs a multi-layer perceptron (MLP) model, a type of artificial neural network known for its ability to learn complex patterns, to study the impact of varying operational loads on fault detection accuracy.
Reliability Enhancement of Electric Distribution Network Using Optimal Placement of Distributed Generation: A Case Study of 33/11 KV Udipur Substation Distribution feeders, Lamjung.
(I.O.E, 2024-06) Acharya, Bibas Raj; Karki, Nawaraj
Reliability can be considered as the capability of system to survive. Currently, consumers are demanding reliable and cheaper power supply with reduced interruption duration. It's widely acknowledged that nearly 90% of electricity interruptions generates from faults within the electric distribution system. Distributed generation (DG) emerges as a novel solution, strategically locating power generation closer to where it's needed most—load centers. By adopting DG, we can effectively mitigate reliability challenges within distribution systems while fostering a more resilient and efficient energy delivery framework. The primary cause of customer service disruptions stems from faults within the distribution system, particularly on radial distribution feeder lines. Additional contributing factors include adverse weather conditions such as windy rain, incidents involving animals, and intrusion from tree branches. These various elements collectively contribute to interruptions in customer service. This study focuses on integrating Distributed Generation (DG) into distribution systems to assess its impact on reliability. Optimal placement of DG is a critical design consideration significantly influencing distribution system reliability.
Signal Spectrum Based Condition Monitoring of Electrical Machines Based on Low Sampling Rate
(I.O.E, 2024-06) Paudel, Ashish; Gautam, Basanta K.
In the pursuit of enhancing condition monitoring techniques for electrical machines, this research addresses the intricate challenge of sampling rates in data acquisition. Conventional high-frequency sampling, while providing rich data, incurs substantial costs in memory, processing power, and computational time. Additionally, it introduces complexities related to data loss during acquisition setup. Aiming for a more balanced approach, this study explores the potential of low sampling rates, acknowledging the trade-offs in signal resolution. An innovative algorithm is proposed to harness the advantages of low sampling rates, circumventing the pitfalls of spectral leakages that often plague signal analysis. Notably, the proposed methodology eliminates the need for windowing functions, a traditional requirement in spectral analysis. The intricate process of window selection, crucial for narrowing the main lobe and reducing leakage energy, necessitates specialized knowledge. The proposed algorithm simplifies this aspect, presenting an effective solution without compromising analytical precision. This study investigates the feasibility and effectiveness of using a low sampling rate of 2 kHz for the condition monitoring of electrical machines, specifically targeting the detection of broken rotor bars (BRBs).
Application of meta-heuristic algorithms to reconfigure radial distribution system for optimal cost and reliability
(I.O.E. Pulchowk Campus, 2023-12) Karki, Sudeep
This research focuses on the application of Metaheuristic algorithms in the field of power system optimization. The specific problem used to demonstrate that is the reconfiguration of the radial distribution system in terms of reliability and system loss. The primary goal of this work is to analyze the performance of multiple metaheuristic algorithms in reconfiguring radial distribution systems. While all algorithms offer the solution to the problem, different algorithms favor different kinds of optimization problems and can find solutions faster and slower than others. GA, PSO, CSO, and GWO are considered for comparison. The problem formulated is to optimize the radial distribution system while maintaining strict radiality for maximum reliability and minimum system loss. For this, a new approach is suggested where reliability indices and network loss are converted to into monetary value. Minimization of this value is the primary optimization goal. Reliability indices are converted by considering losses arising to customers and utility due to faults.
Impact of V2G Integration on an Urban Distribution Feeder in Nepal. A Case Study of Baneshwor Feeder.
(I.O.E. Pulchowk Campus, 2023-12) Sah, Rupesh Kumar
The electrification of transportation through Electric Vehicles (EVs) gains momentum in the energy sector. The study emphasizes the increasing strain on distribution feeders, the backbone of local electricity. The addition of high-power electric vehicle charging station in distribution system can cause voltage drops, overloading of transformers and increase outage or disturbances. In Urban areas, clustering of CS can lead to distribution congestion. This thesis aims to placing charging station without physical restructuring of the network and distribution parameter should not violate operating region. Placement of charging station is based on novel Electrical Vehicle Placement Index (EVPI). Genetic algorithm is used for the optimal placement of charging station. This research also focuses on the integration of V2G technology as a dynamic tool for enhancing distribution reliability. A coordinated way of charging and discharging of vehicle. The analysis is carried out in IEEE 33 bus radial distribution system with five different test cases. The test case results strong and weak bus based on reliability index approach. Placement of CS at strong bus keeps the smooth operation while placing at weak bus, deteriorates system performance. Finally, this approach is implemented for real-time Baneshwor feeder distribution system.
The Optimal Placement of a Photovoltaic-integrated Dynamic Voltage Restorer for the enhancement of Power Quality within the Distribution System. A Case Study of 11kV Tanahusur Radial Distribution Feeder and 11kV Simara Industrial Feeder
(I.O.E. Pulchowk Campus, 2023-12) Dhakal, Prabin
In the context of power distribution, maintaining high Power Quality (PQ) is crucial. Voltage fluctuations like sags, swells, and harmonics can disrupt PQ. To address these issues, a sophisticated solution involving a Dynamic Voltage Restorer (DVR) has been devised. The DVR serves as a dynamic energy store, utilizing solar energy from Photovoltaic (PV) cells. To optimize this process, a smart algorithm called Maximum Power Point Tracking (MPPT) is integrated with Incremental Conductance method. This algorithm ensures that solar energy is harnessed efficiently and the system operates at its peak performance. To manage reactive power generation, a Voltage Source Inverter (VSI) is introduced. This component utilizes Pulse Width Modulation (PWM) techniques for precise control, enabling it to inject reactive power into the grid. For improved control precision, a Space Vector Pulse Width Modulation (SVPWM) strategy is implemented. This enhances the synchronization of voltage injection, mitigating phase angle mismatches and reducing harmonic distortions. Ensuring synchronization and power factor correction is achieved through a Proportional Resonant (PR) controller. This controller, when cascaded with a harmonic compensator, effectively minimizes undesirable harmonic components in the system's output current. This aids in maintaining a consistent power factor and a higher quality power output. The overall system's performance and effectiveness are evaluated through simulation using MATLAB 2023a software.
“Optimal Placement of Charging Station in Om Distribution Feeder of New Chabahil Substation Considering Dynamic Nature of Electric Vehicle Load”
(I.O.E. Pulchowk Campus, 2023-12) Sah, Nandkishor
Globally, the main goal of environmentalist is to reduce the problem of global warming and climate change whose one of the major sources is the existing fossil dependent transportation system, has forced many nations to implement pollution free battery-operated electric vehicle (EV) system which requires electrically operated charging station (CS). Due to this, the number of charging station integrated in the existing distribution system is increasing day by day and the increase in number is further motivated by the research being carried out for development of enhanced battery with cost optimization and subsidies provided by the Government body which is of big concern for the existing electrical distribution system
Study of Impact of NewButwal-Gorakhpur 400 kV Transmission Line on The Operation and Reliability of Integrated Nepal Power System
(I.O.E. Pulchowk Campus, 2023-12) Yadav, Gopal Kumar
In recent years, the significance and imperative of conducting impact studies on grid reliability evaluation have escalated. This thesis represents load flow analysis with a focus on improving resilience and efficiency after adding New Butwal-Gorakhpur 400KV cross border transmission line to existing power system of Nepal and simulation of 2028A.D. INPS network to find the reliability indices. The INPS is facing unprecedented challenges brought about by the increasing demand for electricity, the integration of hydropower and renewable sources, and the need for enhanced system reliability. This thesis reviews the current state of power systems and the challenges they face, including capacity constraints, energy losses. In this context, the integration of NB-G 400KV transmission line has emerged as a promising solution to address these challenges. The core of this research are used to assess the potential benefits, such as increased grid capacity, reduced transmission losses, improved power quality and reliability of the system after the integration of New Butwal-Gorakhpur (NB-G) line. Load flow analysis is carried out in DIgSILENT to find out system loss, voltage profile and reliability indices
Shunt Active Power Filter for Harmonics Compensation Based on Three Phase Voltage Source Inverters
(I.O.E. Pulchowk Campus, 2023-12) Maharjan, Arjun
Power quality of the power distribution systems have degraded because of the extensive use of power electronic devices. These nonlinear loads cause non-sinusoidal currents & voltages with harmonic components. Some of the major power quality issues due to non-sinusoidal currents and voltage with harmonic component are impact on power capacitor, Transformer, motors, telecommunication, energy and demand metering etc. Shunt active power filters (SAPF) are used to acquire balanced and sinusoidal supply currents via way of means of injecting compensation current. There are two major control loop namely outer control loop and inner outer loop with one extra loop. The outer control loop measures source current and voltage & generates the reference reactive & active power that to be compensated by the SAPF. The inner control loop effectively tracks the reference compensating currents in d-q coordinate using PI controllers. While extra loop is associated with capacitor of voltage source inverter (VSI). The constant voltage across the capacitor is maintained. So, there is active power loss which is achieved by comparing reference voltage with the standard voltage and send the error to the PI controller. Simulation results are obtained from MATLAB/Simulink under various non-linear load conditions. The cases considered here are as follows: i) 3 phase 3 wire full wave rectifier with varying load: The MATLAB/Simulink was developed and tested with load and result was compared with the traditional approach without harmonics compensation. The THD level is within limit as per IEEE 516 standard. ii) Different loading conditions: Same process as of case i) was performed and results are within limit as per IEEE 516 standard.
Dynamic Reconfiguration of Distribution Networks Considering the Dynamic Topology Variation
(I.O.E. Pulchowk Campus, 2023-12) Mainali, Sabin
Electrical distribution networks undergo dynamic transformations due to continuous alteration and variation of loads. These alterations necessitate engineering studies aimed at optimizing the distribution networks. Reconfiguring networks stands as a critical analysis process essential for enhancing and managing distribution systems (DSs). When starting with a stable initial DS, the distribution feeders can be reconfigured by adjusting switch statuses to enhance operational performance. Changes in the initial topology can occur due to equipment maintenance, system expansion, or fault incidents, with branch additions or removals. In this study, we introduce a dynamic reconfiguration approach that takes into account dynamic variations in the initial topology. This methodology integrates dynamic topology analysis and network reconfiguration to address current distribution network optimization issues. The original DS topology is characterized by a collection of independent topological parameters. Dynamic topology analysis helps to identify changes in the original topology and identify locations that are out of service in order to restore network connectivity. These topological parameters are then updated to determine the initial topology in present time.
Analysis of Distribution Transformer Overload Management Using Battery Energy Storage System
(I.O.E. Pulchowk Campus, 2023-07) Das, Umesh Kumar
Peak load power plants, certain types of renewable energy sources, are designed to provide electricity during periods of high demand when there is a significant increase in power consumption. These power plants typically have higher operational costs due to the need for quick start-up times and increased fuel consumption. To mitigate the reliance on expensive peak load power plants, suppliers often implement various techniques to reduce peak load and shift the demand to off-peak hours. Pumped storage hydro power plants work by using excess electricity during low demand period, such as at night or during weekends when power consumption is relatively low. The excess electricity is used to pump water from a lower reservoir to an upper reservoir. Then, during periods of high demand or peak load, the stored water is released to flow downhill through turbines, generating electricity and supplying it back to the grid. This process allows energy to be stored when the demand is low and released when the demand is high. It is found that using a battery bank, the energy can be stored and supplied to the Load to reduce the peak load of the respective Distributon Transformer. The installation of BESS at the point of existence of DT has been modelled and the simulation results obtained. The installation of BESS helps to reduce the peak loading of the DT including overloading and helps prevent the outage of the transformer. Based on the simulation results, a BESS of maximum 100kW, 2000Ah installed at the point of connection of DT of 200kVA results in number of overloading reduced from 264 kW to 180 kW. The simulation shows that the number of transformer outage is expected to decrease from 20.83% before the installation of BESS to 3% after the installation. Further, there will be a reduction in power and energy losses in the system as during the peak load condition, part of the load can be shared by the BESS which results in power loss reduction maximum of 84 kW and annual energy loss of 76.650 MWh at 50 percent annual peaking with daily hours. The voltage profile improvement is another front with voltage improving from 0.93 pu to 1.00 pu during peak load condition. Considering the fact that voltage plays crucial role in satisfactory operations of various household, commercial and industrial appliances, this has to be taken into account when deciding on techno-economical analysis of the proposed scheme. Under the assumptions for this research, the proposed scheme is potentially beneficial not only from technical aspects but also economical aspect as well. The investment cost of the BESS and inverter considered in the study at present value is NPR 530,000.00 whereas the monetaroy value of the energy saved annually has been found to be NPR 267062.00 for 90% overloading and peak time electricity cost of NPR 15.00 per kWh. Even for lower overloading percentage of 20 to 40 % of the rating of the DTs, the proposed scheme may be economically viable.
Financial Analysis of Utility Scale Photovoltaic System with Battery Energy Storage System in Nepal
(I.O.E. Pulchowk Campus, 2023-07) Shrestha, Narayan
Renewable energy technologies (RETs) are essential for mitigating greenhouse gas emissions and transitioning to clean energy sources. Among various RETs, solar photovoltaic (PV) systems have gained attention as efficient and effective solutions. However, PV generation is intermittent and variable due to the diurnal cycle of solar geometry and weather conditions. Battery energy storage systems (BESS) integrated into PV systems can address these challenges by storing energy for later use. Nepal’s energy sector mainly depends on hydropower, which can be affected by natural and seasonal variations. To improve energy security and diversify its energy sources, the government has set goals to increase the use of solar and other renewable energy technologies in power generation. Nepal's favourable geography and abundant solar radiation make it suitable for deploying solar PV systems. Nepal receives an average of 3.6 to 6.2 kWh/m2/day of solar radiation and around 300 days of sunshine annually.
Optimal Placement of Distributed Generation in Distribution Networks Using Grey Wolf Optimization
(I.O.E. Pulchowk Campus, 2023-06) Das, Mahendra Kumar
This thesis presents a comprehensive study on the integration of Distributed Generation (DG) into power systems, with a focus on the optimal placement and sizing of DG units. The research aims to investigate the impact of DG on system stability and power loss reduction, as well as to propose a novel optimization algorithm for the optimal placement and sizing of DG units. The integration of distributed generation (DG) is expected to play an important role in the electric power system planning and market operations. As DG are integrated into the distribution system, it results in operating situations that hampers the conventional system without generation directly connected at the distribution level.

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