A Micro-hydro Electronic
Load Controller (ELC) for
the Developing World
Shoan Mbabazi and Jon Leary
Overview
• Aims and Objectives
• Introduction to Micro-hydro
• Micro-hydro System Components
• Control Systems
• Electronic Load Controllers (ELCs)
• Existing ELC Designs
• Continuing the Project
Aims and Objectives
• To design and construct an alternative Electronic Load Controller (ELC) for use in developing countries, with particular emphasis on:
– Simplicity of Design
– Ease of Manufacture
– Robustness
– Ease of Maintenance
– Affordability
Project Outline
0 4 8 12 16
Building and Testing a Prototype
Circuit Design
System Modelling
Analysis of Existing ELC Designs
Micro-hydro System Analysis
Micro-hydro Background Research
Week
Mini-project 1
Jon and Shoan
Mini-project 2
Shoan
Introduction
Introduction to Micro-hydro
• <100kW
• Micro-hydro vs. full-scale hydro
• Usually ‘run-of-river’
• Tried and testedP = η ρ g Q H
P = Mechanical power produced at the turbine shaft (W)η = Hydraulic efficiency of the turbineρ = Density of the water (kg/m3)g= Acceleration due to gravity (9.81m/s2)Q= Volume flow-rate (m3/s)H= Effective pressure head (m)
(Harvey, 2006)
Why Use Micro-hydro in the Developing World?
Grid Micro-hydro
Cheaper in urban, peri-urban and most rural settings
Often cheaper in remote locations
Requires expensive and inefficient transmission lines
Can operate a local mini-grid or charge batteries
Generally relies on non-renewable resources
100% renewable
Can be unreliable in many developing nations
Standalone systems have inherent reliability issues
City-based energy tariffs Locally managed
Micro-hydro System Components
Components of a Typical Micro-hydro System
Turbine Drive Mechanism
Generator
Mechanical Power
Electrical Power
Pressurised Water
Hydraulic Power
Electricity
(Harvey, 2006)
Synchronous vs. Asynchronous Generators
Synchronous (Alternator) Asynchronous (Induction)
rpm = shaft speed (rpm)f = electrical frequency (Hz)p = number of magnetic poles on the generator windings
s = slip (varies between 0-10% depending on loading and size of the machine
Expensive, for schemes under 30kW. Can use cheap and widely available induction motors in reverse.
Voltage regulator usually built in. Voltage and frequency must be regulated.
Usually do not require external excitation.
Requires external excitation.
Control Systems
Why is a Control System Needed?
• To maintain the desired:
– Frequency and voltage
• To electrical equipment
– Shaft speed
• Of power generating equipment
Turbine Drive Mechanism
Generator
Mechanical Power
Electrical Power
Pressurised Water
Hydraulic Power
Mechanical vs. Electrical Control
(Harvey, 2006)
Speed sensor
Hydraulic valve
ElectricitySystem Monitoring
& Circuit Protection
Control System
System Monitoring
& Circuit Protection
Dump Loads
Useful Power
System Monitoring
& Circuit Protection
User Loads
Excess Power (Potentially
Useful)
Electronic Load Controllers (ELCs)
What is an ELC?
(Ludens, 2010)
What is an ELC?
Power in = Power out
{(VinIincosθin)ηin} ={(VoutIoutcosθout)ηout}
V – Voltage, I – Current, Cosθ – Power Factor, η - Efficiency
(Ludens, 2010)
How an ELC works
(Portegijs, 2000)
Modes of Control
(Sp
irax
Sarc
o, 2
01
0)
Load Regulation Strategies
• Binary Load
– Advantages
• Minimal harmonics
– Disadvantages
• Fixed dump load sizes
• Requires large number of dump loads
• Effectiveness limited by number of dump loads (P
ort
egijs
, 20
00
)(H
end
erso
n, 1
99
8)
Load Regulation Strategies
• Phase Angle Regulation– Advantages
• Can use any number/size combination of dump loads
– Disadvantages• Harmonics
• Effectiveness limited by timing accuracy of trigger pulse
(Po
rteg
ijs, 2
00
0)
(Po
rteg
ijs, 2
00
0)
Existing ELC Designs
Existing ELC Designs
• Open-source designs available online
– Hummingbird• Analogue
– Homo Ludens (HL)• Digital
• Both use PI control and phase angle regulation
The Hummingbird ELC– ≤10kW (30kW with mods.)
– Synchronous and asynchronous generators
– Advantages• Cheap and readily available
components used
• No additional equipment is required once its built
• Analogue – widely understood
– Disadvantages• Too many circuit
components
• Scheme specific (Portegijs, 2000)
Homo Luden’s (HL) ELC– ≤25kW
– Synchronous generators only (could be adapted)
– Advantages• Easy to design, install and
maintain
• Minimal circuit components
• Can be tailored to each systemeasily by changing software parameters
– Disadvantages• PIC programming
• Digital – too hi-tech?
(Ludens, 2010)
Improving Existing ELC Technology
• Advantages of existing technology over mechanicalgovernors
– Cheaper
– Quicker
– More robust
• Disadvantages of existing technology
– Complex
– Expensive
– Maintenance?
Proposed Design Specification
• It must:– Maintain constant
frequency/voltage
– Be robust and affordable
• It should:– Be modular
– Minimal components (no moving parts)
– Easy to install
– Synchronous/asynchronous, 50/60 Hz, single/3-phase
– Load priotisation
– Self-diagnostic
Continuing the Project
Future Work
0 4 8 12 16
Building and Testing a Prototype
Circuit Design
System Modelling
Analysis of Existing ELC Designs
Micro-hydro System Analysis
Micro-hydro Background Research
Week
Mini-project 1
Jon and Shoan
Mini-project 2
Shoan
Questions....?
References
[1] A. Harvey, Micro-hydro Design Manual. Rugby: Intermediate TechnologyPublications, 2006.
[2] H. Ludens. (2010, Electronic Load Controller for microhydro system. Available: http://ludens.cl/
[3] J. Portegijs. (2000, 6 December ). The `Humming Bird' Electronic Load Controller / Induction Generator Controller.
[4] Renerconsys, "Digital Load Controller for Synchronous Generator: Manual Instruction," 2010.
[5] D. Henderson, "An Advanced Electronic Load Governor for Control of Micro Hydroelectric Generation”, 1998
[6] Spirax Sarco, “Basic Control Theory”, 2010. Available: www.spiraxsarco.com