A Micro-hydro Electronic Load Controller (ELC) for the...

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