Integrated Nepal Power System Research Articles

Composite reliability evaluation of Integrated Nepal Power System

Abstract the worth of reliability has been increasing with the advancement of technology. Based on the involvement of the various functional zones, the assessment of the reliability of the power system is divided into 3 Hierarchy levels (HL). The composite reliability (HL II) involves the availability of generation systems and transmission systems in evaluating the reliability of power systems. In this paper, the composite reliability of the Integrated Nepal Power System (INPS) is assessed using sequential Monte Carlo Simulation (MCS). Based on the trip data of the various Hydro Electric Power Plant (HEPP) units of Nepal and of transmission line, the artificial UP and DOWN sequence of the composite system is simulated. The power output of the Hydro-Electric Power Plant (HEPP) is varied based on the variation of seasonal flow. The system state is compared with the hourly load data of various load centers of INPS to determine the reliability indices like LOLP, LOLE, and EENS. As the eastern part of INPS doesn’t have a generating unit, it is found to have lower reliability. The reliability of INPS can be improved by improving the reliability of load centers that have a lower value of reliability indices.

Impact analysis of electricity pricing on the reliability of integrated Nepal power system

Abstract Time of Use of Electricity Pricing (TOU) strategy is adopted by many countries to reduce the peak load and minimize the cost of Electricity. In this research, the effect of the TOU tariff system on the reliability of the Integrated Nepal Power System (INPS) has been investigated. Implemented TOU is based on three time periods: Peak time, Flat time, and Valley time (PFV). The moving variable method is used to find the optimal PFV period in a day. Particle swarm optimization (PSO) is used to find optimal prices corresponding to the given periods, where two objective functions are converted to a single objective function. Prices are modeled with the demand response and a new load pattern of consumers after TOU has been obtained. Power plants of INPS are modeled into four states model and the Monte-Carlo simulation is used to find the generation adequacy indices like Loss of Load Probability (LOLP), Loss of Load Expected (LOLE), and Loss of Energy Expected (LOEE) before and after the implementation of the TOU. The risk level of INPS is reduced by 37% and peak load is reduced by 4.2% after the implementation of TOU. It is found that the reliability of INPS can be improved with the help of TOU

Impact Study of the Hetauda-Dhalkewar-Inaruwa Transmission Line on the Operation of Integrated Nepal Power System

Despite Nepal’s abundant hydroelectric resources, a substantial disparity exists between its electricity supply and demand. This discrepancy is exacerbated by the absence of high-voltage transmission lines, hindering efficient power evacuation from a handful of generating plants. This not only incurs financial losses for the utility but also compromises the reliability of the power supply. A prime example is the protracted delay in the construction of the 576 KM long Hetauda-Dhalkebar-Inaruwa 400kV double-circuit Transmission Line, primarily due to challenges posed by local residents unwilling to relinquish their land.The Integrated Nepal Power System (INPS) heavily relies on power generation concentrated in the central mid-hills region. The construction of the Hetauda-Dhalkebar-Inaruwa (HDITL) 400kV double-circuit Transmission Line is crucial for routing power to industrialize these areas, potentially bolstering the national GDP and generating employment opportunities. Furthermore, it is essential to connect the current hydropower output of around 2300 MW to the INPS system via a high-voltage transmission line to maximize its utilization. The HDITL project not only reduces line losses but also enhances grid stability. It facilitates energy export and direct transmission of high-generation power, such as the 456 MW from Upper Tamakoshi, thus saving approximately 400 MW of power and preventing losses for both the Government of Nepal (GoN) and the Nepal Electricity Authority. This research not only calculates the reduction in power and energy losses with the commissioning of HDITL but also assesses its monetary benefits. Utilizing INPS data and Digsilent Power Factory 15.1 for power flow analysis, the study estimates that HDITL can prevent a power loss of about 26.276 MW. Furthermore, it demonstrates that HDITL significantly improves the total generation power factor in INPS, from 0.88 to 0.99, and enhances the voltage profile, underscoring its critical role in Nepal’s energy infrastructure development.

Review of Various Transmission Loss Allocation Methods: A Case Study of Integrated Nepal Power System using Best Method

This paper presents a review of the most relevant and practical methods for allocating transmission loss in a deregulated market. They are the pro-rata (PR) method, the marginal allocation (ITL) method, the proportional sharing (PS) method, and the Z-Bus method. This study has also performed a qualitative comparison of four methods using the IEEE 14 bus system. Finally, the Z-Bus method is selected as the best option for implementation in the Integrated Nepalese Power System Network (INPS). As of 2022, the loss allocation is determined at all 132 and 220 kV substations of INPS. The study of transmission loss allocation for INPS is carried out for six different cases, considering the variation in patterns of energy generation and demand, i.e., system full generation, summer peak, winter peak, average peak, dry peak, and contingency condition. The result shows the load, like Kathmandu Valley, which is in the region of generation, and the generator, like in the eastern region, which is in the region of demand, are mostly compensated with negative losses. Loads in the western region and generators like the Upper Tamakhoshi, which are far from the generator or load, are assigned the highest positive loss. Loss allocation to load and generator can vary depending on the loading conditions that INPS is operating under. The generation is comparably distributed in the full generation, summer, and contingency instances; as a result, the loss allocation to both loads and generators is significant. However, the bulk of losses are only attributed to the generator side in the three other scenarios with less generation, when the majority of the generation is only aggregated in a specific location. This is a result of the remote generator's long-distance power flow, which raises system loss. As a result, the Z-Bus method assigned the generator side the majority of the losses. Additionally, the majority of INPS's generation is determined to be remotely located, which increases their risk of transmission loss. Because of this, INPS is best served by the Z-Bus approach, which takes into account the locations of buses within the network. In order to minimize system loss, this encourages big demand or generation to be positioned close to the center of generation or demand.

Techno-Economic Analysis of the placement of the Capacitor in the Integrated Nepal Power System

With the increasing load demand, Integrated Nepal Power System (INPS) is facing a stiff challenge to maintain voltage profile within the standards and reduce system loss. Among the loss reduction strategies, an immediate solution would be installation of reactive power compensators at the grid substations. The power flow study of existing system is performed and a genetic algorithm is used to find optimum placement of suitable size of the capacitor banks to be added in system. 6 substations with a total reactive power supply of 80 MVAR was determined as optimal size and location and the installation is also financially feasible. Moreover, the analysis of capacitors placed at the varying voltage levels implied that the most suitable voltage level for the capacitor installation is 11kV.

Impact Analysis of 220 Kv And 400 Kv Transmission Lines on The Integrated Nepal Power System

Power is an essential requirement for the economic development of any country. To maintain the generation of electric power at an adequate level the power has to be transmitted in a proper form to the consumer. For determination of line losses, voltage profiles and expansion of system, load flow analysis is most essential tools. This paper deals with the impact analysis of new 220 kV and 400 kV lines on Interconnected Nepal Power System (132 kV grid) in Electrical Transient Analyzer Program (ETAP). It represents the present scenario of the power system of Nepal and their impact analysis. Load flow result of existing 132 kV line shows that there is about 44.56 MW active power losses in the transmission line before any compensation techniques. After the Optimal Capacitor Placement, in the existing transmission line the active power loss decreases to about 34.224 MW as well as the voltage profile at each bus improves. The load flow result of the under construction 220 kV and 400 kV lines on the existing line shows that the total system loss would decrease to about 27.445 MW with the voltage profile improvement. The simulated model, result and analysis are presented in this paper.

Price allocation of transmission line usage in open access system using mega volt ampere kilometer and mega volt ampere cost method for integrated Nepal power system

The price allocation of transmission line usage for an open access system considering Integrated Nepal Power System (INPS) has been discussed in this paper using the MVA (mega volt ampere) - KM (kilometer) and MVA cost method. The price allocation has been compared for INPS (Integrated Nepal Power System) and IEEE 14 bus system. The transmission line costs in IEEE 14 bus system is based on average construction and operation cost whereas, the costs in the INPS is an actual cost of the present transmission system. The price has been first calculated for different bus with reference to slack bus and for different bilateral and multilateral transactions, using MW KM - MW cost and MVA KM - MVA cost methods. The active and apparent powers for the base case and transaction cases have been calculated using Newton Raphson Method. The prices from MVA KM - MVA cost method are higher than MW KM - MW cost method for both bilateral transaction and multi-lateral transaction indicating more reactive power support in addition to the real power loading due to transactions in the system. The result shows that MVA KM - MVA cost method requires incentives for reactive power support to the system such as INPS.

Determining the Hosting Capacity of Solar Photovoltaic in a Radial Distribution Network Using an Analytical Approach

Integrating high photovoltaic (PV) on distribution grid system has a positive impact by significantly reducing the losses and improving the voltage profile at the same time reducing the pollution of the environment However, integrating high proportions of PV in the distribution grid can bring the grid to its operational limits and result in power quality issues. The maximum PV capacity that can be integrated without incurring any grid impacts is referred to as the PV hosting capacity of the grid. This paper intends to evaluate the hosting capacity of solar PV in Dodhara-Chandani (DoC) distribution feeder as one of the feeder of Integrated Nepal Power System (INPS), considering grid parameters and operating condition in Nepal. Three main criteria were investigated for determining the hosting capacity of PV; reverse power flow, maximum voltage deviation of feeder and current carrying limit of conductor. The analysis has been performed by means of static load-flow simulation in Electrical Transient & Analysis Program (ETAP) and coding in MATLAB R2017a. The study shows that PV of rated capacity 687kWp can be installed at a point of interconnection (POI) whereas an optimal placement of solar PV is found to be at 18th node (in between starting and end of the feeder) considering minimum system losses. The minimum voltage profile at end of the feeder has improved by 8 % while the active power loss reduction of network has reduced by 83.6 % after the integration of solar PV. The results indicate voltage at different buses and the ampacity of most of the conductors have been improved after the integration of PV system into DoC feeder.

Use of Genetic Algorithm on Optimal Power Flow: An Illustration of Transmission Line Loss Minimization

This paper presents the usefulness and effectiveness of Genetic Algorithm on solving Optimal Power Flow (OPF) problem formulation of a real world power system. Optimization is a broad concept that is generally directly or indirectly related to cost factor. In this case, transmission lines loss minimization is presented as the objective of optimization problem formulation keeping all other technical factors and parameters under operating constraints. Results of this study, presented in the Integrated Nepal Power System (INPS) transmission line network show that the Genetic Algorithm is effective method to optimize the power flow via assigned objective of transmission loss minimization in much quicker and effective way when compared to conventional Newton-Rapshon method.

Adequacy Assessment of Integrated Nepal Power System

Modern electrical power systems have the responsibility of providing a reliable and economic supply of electrical energy to their customers. The economic and social effects of loss of electric service can have significant impacts on both the utility supplying electric energy and the end users of the service. Maintaining a reliable power supply is a very important issue in power system design and operation .The developing country including Nepal more often does not follow the modern planning criteria for system planning due to which we have to face problems like load shedding. This work is an exercise to detail reliability analysis of INPS using different reliability indices. The INPS has been divided into three regions and the reliability indices are found separately for each region. The two reliability indices LOLE and EENS are found to check the adequacy of generation. The load data and generation data used are all real from the only one utility of Nepal, NEA. The calculations are done according to the theory of reliability of power system on MATLAB programming. The results obtained in this work are quite satisfactory and represents the present condition of INPS.

Prospects of Storage and Pumped-Storage Hydropower for Enhancing Integrated Nepal Power Systems

An Integrated Power System (IPS) should have electrical energy generating plants for base load (e.g., nuclear and thermal plants) and peak load (e.g., hydropower plants) so that they can work in coordination in such a way that the demand is met in time. In Nepal, the Integrated Nepal Power System (INPS) is a hydro-dominated system where the base and intermediate power demands are covered primarily by run-of-river hydropower plants and the peak demand by seasonal storage and several diesel power plants of lower capacity. The INPS should have sufficient natural storage and forced storage power plants to improve the system’s reliability. On top of that, daily peak electrical demand could also be adequately covered by demand-side management, using a pumped-storage hydropower plant that can employ a system’s surplus energy during low demand period for pumping. To rectify this extreme imbalance of installed capacity in Nepal, this paper explores the prospect of storage and pumped-storage power plants for enhancing INPS. A case study of Rupa-Begnas pumped-storage hydropower is highlighted for these purposes.DOI: http://dx.doi.org/10.3126/hn.v15i0.11290HYDRO Nepal JournalJournal of Water, Energy and EnvironmentVolume: 15, 2014, JulyPage: 37-41

Benchmarking of Generation and Distribution Units in Nepal Using Modified DEA Models

This paper analyzes the performance of Nepalese Electricity Supply Industry (ESI) by investigating the relative operational efficiencies of the generating stations as well as the Distribution Centers (DCs) of the Integrated Nepal Power System (INPS). Nepal Electricity Authority (NEA), a state owned utility, owns and operates the INPS. Performance evaluation of both generation and distribution systems is carried out by formulating suitable weight restriction type Data Envelopment Analysis (DEA) models. The models include a wide range of inputs and outputs representing essence of the respective processes. Decision maker's preferences as well as available quantitative information associated with the operation of the Decision Making Units (DMUs) are judiciously incorporated in the DEA models. The proposed models are realized through execution of computer programs written in General Algebraic Modeling Systems (GAMS) and the results obtained are thus compared against those from the conventional DEA models. Sensitivity analysis is performed in order to check the robustness of the results as well as to identify the improvement directions for DMUs. Ranking of the DMUs has been presented based on their average overall efficiency scores.