Feasibility Study of Pumped Hydro Energy Storage

for Ramea Wind-Diesel Hybrid Power System

Sheikh Mominul Islam, EIT, M.Eng.

Email: mominul511@gmail.com

Newfoundland Electrical and Computer Engineering Conference

November 4th, 2010 St. John’s, Newfoundland

Outline

Introduction

Motivation

Sizing

Dynamic simulation

Conclusion

Introduction:

Isolated southern island of Newfoundland which was first incorporated to the province in

1951.

It has population of 674.

Nearest community is Burgeo which is about 20kM away by ferry service.

Average fuel consumption is 18,000L/week in summer and 22,000L/week in winter.

Electricity selling price is 0.1495/unit.

Over view of Ramea

Introduction:

Over view of Ramea Electrical system

2775kW diesel plant, Six 65kW wind

turbines and three 100kW newly

installed wind turbines

The average load is 550kW

312.5kW fuel cell system under

construction

200kW load for dumping excess

energy produced by the system

30kVAR fixed capacitor bank for

each 65kW wind turbine for

supplying reactive power demand.

Motivations:

Analysis of existing Ramea wind-diesel-hydrogen system:

HOMER is used for analyzing the existing wind-diesel-hydrogen system.

Average wind speed is 6.08m/s at 10m

height

Maximum wind speed during winter is

21.6m/s

Daily load profile varies from

350kW to 610kW

Maximum load goes to

1100kW during winter

Motivations

Analysis of existing Ramea wind-diesel-hydrogen system:

Excess electricity from the wind turbines is converted to hydrogen

using an electrolyser.

Hydrogen is compressed and stored in three large tanks.

Stored hydrogen is used to generate electricity when needed

Expected renewable

fraction is 37% with the

contribution of 1% from

Hydrogen system

Cost of Energy is

0.248$/kWhr

Hydrogen generator will

run 702hrs/yr

Sizing

Analysis of proposed Ramea wind-diesel-pumped hydro system:

Overall efficiency of the battery was reduced to 70% to represent a pumped hydro

energy storage system.

A 250kW converter is considered between AC and DC bus

Renewable energy fraction is considered 37%

Sizing

HOMER simulation result of Ramea wind-diesel-pumped hydro system:

Battery bank (consisting of Trojan T-105 batteries) should have 500 batteries.

Cost of Energy is 0.218$/kWhr

Diesel required 783, 529L/yr

Sizing

Electrical performance of Ramea wind-diesel-pumped hydro system:

Total energy required 4,281,096 kWh/year and 37% of that will be met by the wind energy

Almost only one diesel generator is running at a time

Diesel required 783, 529L/yr

Expected energy in and out of battery system:

Sizing

Battery will be most used in July and August while it will be least used in May. Maximum power output from battery storage is 147kW during the month of

April.

Calculations:

The hybrid system required 500 Torjan T-105 batteries (each 1350Whr).

So the potential energy stored in the upper reservoir should be.

Potential Energy = mgh,

→ 1350 × 3600 × 500 = mgh = (volume * desnsity)*g*h

Volume, V = 100081.9

50036001350

h

For a head h = 63m, required reservoir size will be V = 3932m3

For area of 2000m2, required reservoir height will be 2m

Calculations:

Possible maximum daily average power , 147kW ~ 150kW

gHQP

For, H = Gross head in m (63m), g = 9.81 m/s2 and

η = Hydro turbine efficiency = 70%.

The flow rate, Q = 0.347 m3/s

For the Ramea site the expected flow rate is 0.347 m3/s and head is 63m therefore the best

selection is a Pelton or Turgo type turbine.

Dynamic simulation of grid connected PHS:

The pump is considered as a 150kW centrifugal pump with induction

machine

The hydro turbine is considered as 150kW unit with a synchronous

machine coupled to the system bus.

Community load is considered as a constant load

The system was simulated for 24s

During off peak hour the pump will be operating for pumping water to

upper reservoir

During peak demand the hydro turbine will be operating.

Dynamic simulation of grid connected PHS:

SIMULINK representation of Diesel-wind-hydro hybrid power system in Ramea

o

vwt

v

tatw

V

zTtmV

Tdt

dVVVV

5.10),(

1,

Wind field equation:

Vw = the wind speed

Va= Average wind speed

Vt= Turbulent component of wind speed

mw(t)= Random white noise

Z = Turbine height

V0= Maiden wind speed

Dynamic simulation of grid connected PHS:

Dynamic simulation of grid connected PHS

Expected power changes in a transient condition in the Ramea Hybrid power system

Hydro pump is

operating

Hydro turbine is

operating

Dynamic simulation of grid connected PHS:

Expected transients in the Ramea hybrid power system

Hydro turbine is

operating Hydro pump is

operating

Conclusions:

Diesel fuel saved by 94,782L per year

Cost of energy reduced by 0.03$/kWh

All excess electricity will be stored in hydro storage

Available sea water can be used

63m height is available for water head.

No extension of power line is required as Man of War hill

is near to the existing system

Voltage and frequency variation are within limit

Future recommendation:

Battery system can be replaced by actual pumped hydro system.

Soft starter can be used for reducing system transients.

Variable speed hydro pumped storage can be considered.

Variable load can be considered.

Acknowledgement:

M. Tariq Iqbal

Nalcor energy (Newfoundland Hydro)

The Leslie Harris Centre of Regional Policy and Development,

MUN

Thank you

For your attention and presence

Question / Comments