1. Introduction
Gotikhel Hydropower Plant (GHP) is one of the nearest Isolated Micro Hydropower Plant (MHP) from the main city out of 650 isolated MHPs available in Nepal which still supplies electrical power to 173 Households, one hull machine and one school. The extension of national grid has made life of MHPs insecure as consumers want the energy from more reliable source i.e. from national grid. In the context of Nepal, especially in rural areas, construction of MHPs are very costly and because of unplanned extension of national grid, some of MHPs are in closing conditions and same cases will continue more in future. So, there is a huge risk in big investments and valuable efforts of villagers.
Synchronization of MHPs to the national grid will be the ultimate solution for the existence of MHPs in Nepal. So, this Master Thesis will also focus on grid connection of GHP and consequent impacts on technical as well as financial sectors before and after the grid connection of GHP.
2. Objectives
Taking GHP as a private/ community pilot project for grid connection in Nepal, the following objectives of grid-connected MHPs has been generalized:
• To ensure optimum use of national resource and fulfill the possible new demand of energy in rural areas since grid connection and Power Exchange Agreement (PEA) allow the Rural Electrification Entity (REE) to sell their excess energy to Nepal Electricity Authority (NEA) grid and the REE can purchase the required energy from the grid when the demand of its members surpass the generation by MHP(s) under it.
• To facilitate development of new MHPs by local communities, Individual Power Producers as they can profiteer by selling the excess energy to the grid.
• To ensure market for spill energy of MHPs.
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3. Contents of the thesis
This thesis includes following:
• Introduction of GHP
• Problem Analysis of GHP
• Technical aspects of GHP
- Turbine and turbine selection
- Turbine Control System
- Generator
- Distribution Transformer
- Switchgear Equipment
- Protection system
- Transmission and distribution systems
- Instrumentation
- Single line diagram of GHP
- Synchronization
• Short circuit and load flow analysis
• Financial aspects of GHP
• Impacts of grid connection
• Conclusion
Table of Contents
1. INTRODUCTION
1.1 GENERAL
1.2 GOTIKHEL MICRO HYDROPOWER PLANT
1.3 OBJECTIVES OF GRID CONNECTION OF GHP
2. GHP IN GENERAL
2.1 GENERAL LAYOUT
2.2 SALIENT FEATURES OF GHP
3. PROBLEM ANALYSIS OF GHP
3.1 PROBLEM ANALYSIS OF EXISTING GHP
3.1.1 Forebay
3.1.2 Penstock
3.1.3 Pelton Turbine
3.1.4 Induction/ Asynchronous Generator
3.1.5 Electrical Cabinet
3.2 PROBLEM ANALYSIS FOR GRID CONNECTION
4. TECHNICAL ASPECTS OF GRID CONNECTION
4.1 TURBINE AND TURBINE SELECTION
4.1.1 Pelton Turbine
4.1.2 Cross Flow Turbine
4.1.3 Turbine Selection
4.2 TURBINE CONTROL SYSTEM
4.3 GENERATOR
4.3.1 Synchronous Generator
4.3.2 Sizing of Synchronous Generator for MHP in Nepal
4.4 DISTRIBUTION TRANSFORMER
4.5 SINGLE LINE DIAGRAM OF GHP
4.6 SHORT CIRCUIT ANALYSIS OF GHP
4.7 SWITCHGEAR EQUIPMENT
4.7.1 Low Voltage Circuit Breaker
4.7.2 Surge Arrester
4.7.3 Fuses
4.8 PROTECTION SYSTEM
4.9 CONNECTION BETWEEN GHP AND NEA
4.10 INSTRUMENTATION
4.10.1 Current Transformer
4.10.2 Meter
4.11 SYNCHRONIZATION
5. LOAD FLOW ANALYSIS OF GHP
6. FINANCIAL ASPECTS OF GRID CONNECTION
6.1 METHODS USED FOR FINANCIAL ANALYSIS OF GHP
6.1.1 Internal Rate of Return
6.1.2 Net Present Value
6.1.3 Benefit/ Cost Ratio
6.1.4 Payback Period
6.2 FINANCIAL ANALYSIS OF GHP
7. POSSIBLE IMPACTS OF GRID CONNECTION
7.1 TECHNICAL IMPACTS OF GRID CONNECTION
7.2 FINANCIAL IMPACTS OF GRID CONNECTION
8. CONCLUSION
9. ANNEXES
9.1 SUBSIDY POLICY OF MHPS IN NEPAL
9.2 PEA
9.3 GROUND CLEARANCE
9.4 DOMESTIC CONSUMERS OF NEPAL
9.5 ROYALTY ARRANGEMENTS FOR HYDROPOWER OF NEPAL
9.6 CALCULATION
Research Objectives and Themes
This master thesis investigates the technical and financial feasibility of connecting the Gotikhel Micro Hydropower Plant (GHP) in Nepal to the national grid without interrupting the existing isolated load. The primary objective is to ensure the sustainability of rural micro-hydropower plants facing pressure from national grid extensions by enabling grid synchronization, thus allowing for energy exchange, surplus power sale, and reliable power supply during grid load shedding.
- Technical design requirements for grid synchronization, including turbine control and synchronous generator selection.
- Short-circuit and load-flow analysis of the GHP system to ensure operational safety and stability.
- Financial viability assessment using indicators such as Net Present Value (NPV), Internal Rate of Return (IRR), and Payback Period.
- Impact analysis of grid connection on plant efficiency and resource optimization.
Excerpt from the Book
1.1 General
Hydropower is the most matured, reliable and largest renewable source of power generation. At present, about 20% of the world’s total electricity supply is from hydropower. The world’s hydropower installed capacity increased from 695.8 GW in 2001 to 888.8 GW in 2009 [1]. Though fossil fuels dominate generating electricity, more than 60 countries use hydropower for meeting more than half of their electricity needs. Due to the adverse impacts of large hydropower plants in environmental sectors (deforestation, rehabilitation and others) as well as in economy (huge investment, high risk); Small Hydropower Plants (SHPs) has turned into an excellent and abundant source for power generation especially in developing countries. SHPs are easier to construct and commission due to uncomplicated designs. SHPs facilitate community participation and capitalize on local skills for plant construction.
Mini/ Micro Hydropower Plants (MMHPs) and Pico Hydropower Plants (PHPs) are used in developing countries to provide electricity to isolated communities where the electricity grid is not available. China, Nepal, Vietnam and many South American countries have developed a large number of MMHPs and PHPs that are providing electricity to many households in the last 30 years [2]. According to European Small Hydropower Association (ESHA), the classification of SHPs with respect to capacity is as shown in table 1.1.
Summary of Chapters
1. INTRODUCTION: Provides an overview of the importance of hydropower for rural electrification and introduces the specific case study of the Gotikhel Micro Hydropower Plant.
2. GHP IN GENERAL: Describes the current physical layout, salient features, and the operational status of the existing Gotikhel Micro Hydropower plant.
3. PROBLEM ANALYSIS OF GHP: Details the identified technical deficiencies in the current plant configuration and discusses the challenges posed by potential grid connection.
4. TECHNICAL ASPECTS OF GRID CONNECTION: Outlines the necessary technical upgrades, including turbine selection, generator replacement, switchgear, protection systems, and short-circuit analysis.
5. LOAD FLOW ANALYSIS OF GHP: Presents load-flow studies to test the system’s capability to transfer energy and maintain voltage levels under various operating conditions.
6. FINANCIAL ASPECTS OF GRID CONNECTION: Evaluates the economic viability of the grid connection through investment costs, operation and maintenance expenditures, and profitability analysis.
7. POSSIBLE IMPACTS OF GRID CONNECTION: Discusses the anticipated technical and financial consequences of integrating the plant into the national grid.
8. CONCLUSION: Synthesizes the findings and provides a final assessment on the feasibility and benefits of connecting the GHP to the national grid.
Keywords
Hydropower, Gotikhel Micro Hydropower Plant, Grid Connection, Nepal, Rural Electrification, Synchronous Generator, Digital Turbine Controller, Load Flow Analysis, Short Circuit Analysis, Financial Analysis, Net Present Value, Internal Rate of Return, Renewable Energy, Power Exchange Agreement, Sustainability.
Frequently Asked Questions
What is the core focus of this research?
The research explores the technical and economic feasibility of connecting existing, isolated micro-hydropower plants in Nepal to the national grid to ensure their long-term sustainability.
What are the primary themes investigated in the thesis?
The study focuses on grid synchronization technical requirements, system protection, short-circuit and load-flow analysis, and a comprehensive financial evaluation of the proposed project.
What is the main goal of connecting GHP to the national grid?
The primary goal is to prevent the abandonment of local micro-hydropower plants when the national grid reaches rural areas, allowing them to sell surplus power and maintain electricity supply during load shedding.
Which scientific methodology is utilized for the plant analysis?
The author performs technical calculations according to VDE/IEC standards for short-circuit analysis and uses manual load-flow calculations verified by simulation software, alongside standard financial modeling metrics.
What topics are discussed in the main body of the work?
The main body covers the selection of synchronous generators, installation of Digital Turbine Controllers, design of protection systems, and specific financial cash-flow scenarios over a 25-year period.
How would you describe the main keywords characterizing this work?
Key terms include Micro Hydropower, grid synchronization, load flow, short circuit analysis, financial viability, and rural electrification in the context of Nepal.
Why is the replacement of the existing induction generator necessary for grid connection?
The existing induction generator is inadequate for grid synchronization because voltage regulation in island mode is difficult and it requires reactive power, making it unsuitable compared to a synchronous generator.
What role does the Power Exchange Agreement (PEA) play in this project?
The PEA is essential for managing the commercial, legal, and financial relationship between the local rural electrification entity and the national grid provider, facilitating the sale of excess power.
How does the author propose to handle power demand fluctuations?
The author suggests using a Digital Turbine Controller to manage water flow and frequency, alongside a two-way metering system to account for energy injected to the grid and energy drawn from the grid.
- Quote paper
- Suman Budhathoki (Author), 2011, Grid Connection of Gotikhel Micro Hydropower Plant without Interrupting Isolated Load, Munich, GRIN Verlag, https://www.hausarbeiten.de/document/181739
