Hybrid RE Power Plants: A Global Perspective on Technology ... · • Renewables cannot be involved...

Hybrid RE Power Plants:

A Global Perspective on

Technology Trends (SAARC Energy Centre – 16th April 2019)

www.siemens.com/power-technologies Unrestricted © Siemens AG 2019

Unrestricted © Siemens Industry, Inc. 2019

16th April 2019 SI DG SW&C-PTI

Hybrid RE Plants

Table of content

• Economics of hybrid RE power plants 5

• Operational and design challenges 9

• Solutions for combined operation of multiple RE assets 14

• System level benefits of solar-wind hybrid power plants 18

• Regulatory / fiscal / policy tools for hybrid RE concept 21

• Case studies 23



Hybrid Renewable Energy Systems

• Erratic energy sources like wind and solar are not dispatchable, that is, available on command of utility

dispatchers

• Sometimes or often, the wind blows when it is cloudy, or the sun shines when the wind is calm

• A system that combines various energy sources is called a “hybrid” system

• Diesel generators are often used for “reliable” power, and wind or solar are used to decrease the fuel

costs

• Studies of a site can indicate the optimal combination of wind, solar, and diesel (or gasoline) to provide

power at the lowest overall annual cost

Typical Case Study - Communities w/o access to power grid

These communities will need to plan for

• Various forms of electricity production

• Storage of energy

• Recovery and disposal of excess heat

• Power management and control hardware and software

• Simulation and forecasting models for setting and maintaining reasonable cost of energy



Hybrid Renewable Energy Systems

• In a full hybrid system, the engine runs continuously and the wind/solar sources subsidize (add to) the

available energy, saving fuel by shutting down the engine whenever possible

• The inverter is synchronously matched to the power frequency and voltage, providing more or less power as

is available

• As long as the engine works and the diesel fuel lasts, system availability is high

• If the renewable sources are low, the fuel will be used faster (and require replenishment more often)

• If the engine fails and there is no storage (battery), the system will only have the varying renewable energy

and might not function at all due to voltage variations

• Solar energy might carry the load until mid-afternoon, but the wind system would be too variable in many

locations



Hybrid RE Plants

Economics of hybrid RE power plants



Energy Source Cost Choices

Assess cost of various mixes of energy, enter total costs, sketch contours to seek lowest cost region

Wind

Solar

Fuel

0%

0%

0%

100%

100%

100%

50%

50%

50%

$

$

$

$

$

$ Hypothetical

Cost Line

http://dna-view.com/triangle.htm

0%S, 100% F

100%W, 0% F

33.3%S, 33.3%W, 33.3% F



Economics - Hybrid Renewable Energy Systems

1 GEV MP-C Wind

Turbine =

131 T of diesel fuel

saved / year

100 kWp =

44 T of diesel fuel

saved/year



Optimizing the design for the best ROI of hybrid RE concept



Hybrid RE Plants

Operational and design challenges



Operation/Design Challenges for ANY Renewable Site

Typical Issues / Challenges

• Generation far from load -> needs transmission investment (who pays?, local resistance, etc.)

• (AC or DC transmission?) / PV-QV curves / Transfer Limit Analysis / Onshore-Offshore installation?

• Needs Wind and Solar Irradiation forecasting tool

• Needs extra dynamic compensation (CAPEX) – narrow nominal PF-range (if any ~ old Type 1 / 2 WTGs)

• Harmonics

Operator Challenges:

• Stability issues (increased Regulation needs) – sudden weather change / sandstorm

• Reverse Power Flow (protections)

• Acceptable range of voltage increase after plant connection (2-3%)

• Negative Energy Prices (!) – Market issue

• Renewables cannot be involved in Unit-dispatch / AGC

• Set DNE (do-not-exceed) limit (max output, short term forecast)

• Future: real-time telemetry (IEC 61850-based), auto-forecast, auto dispatch



Operation/Design Challenges for HYBRID Renewable Site

• Site dependence of renewable sources (Site survey with long term data acquisition & forecasting)

• Hybrid renewable energy system design (Configuration and sizing of the hybrid system components with the

objectives)

• Supplying the power reliably under varying atmospheric conditions

• Minimizing the total cost of the system

• Maximizing the system efficiency by efficient energy flow management strategies

• Optimization through simulation studies under real operating conditions for a reasonable tradeoff among

conflicting design objectives

• Economic viability (cost-benefit analysis of hybrid system for reasonable payback period)

• Real world application

• Design of power conditioning devices with maximum power point operation of energy sources

• Optimal energy management strategies and their testing with laboratory prototype hybrid controller

• Development of hardware and associated software for field-implementation



Other Operation / Design Challenges

• The location is the prime driver of the cost-analysis • When the remoteness and lack of roads makes fuel-hauling or helicopter transport too costly, the

wind or solar components must be increased to ensure reliable power • Matching of the load times to the energy times determines the need for storage capacity • Load matching for time of day limits output as well • Diesel engines must be sized for highest load to carry the loads in normal operation • The savings is never greater than the fuel savings Battery Storage? • Batteries provide a form of storage • They are required for wind and solar energy, but diesel (gasoline) generators could run to carry the

load • Large battery systems require some maintenance checks but usually last for many years (7-20 • Adding storage means that the energy available is “leveled” and unnecessary engine starts are

avoided



Risk profile of renewable energy projects

• Energy resource assessment, site

location, design, technology

• Grid connection, offtake agreement

• Permitting, land acquisition

Project Development Project Construction Project operation

Actual site conditions, Suitability of the Equipment

to local conditions (Logistics)

EPC track record, Project

management

Regulatory change,

interconnection

Reliability of Equipment, suitability to local conditions (corrosion, cyclones…),

Local O&M competencies

Interest rates, labour costs

Regulatory change

Technical

Commercial

Regulatory

Risk Level



Hybrid RE Plants

Contemporary solutions for combined operation of multiple RE assets



Multiple Asset Operation

Wind/Diesel

• Wind/diesel systems work well where sunlight is limited, as above the Arctic Circle or below the Antarctic Circle

• Wind turbines have worked well at the South Pole Station, but diesel generators are also hard at work there

• Gasoline engines also can be used, but may lack the life of a heavy diesel engine

Solar/Diesel

• Solar power has a much more stable short term output than wind power; the solar energy is less “volatile” than

wind to use an economics term.

• As the insolation rises in the morning, the diesel engine might be shut down until late afternoon or when clouds

reduce solar power for a certain number of minutes

• The controller could run the diesel engine only when the battery voltage drops below a very low set point, such

as 10.5 volts and stop the diesel when the battery voltage rose to approximately 13.9 volts

Tripartite Systems

• More complex than the wind/solar type

• The system balance between wind and solar is determined as in a conventional system, adjusting the costs of

each to match the available energy

• Each of these sources offsets the need for diesel consumption, yet including some diesel capacity improves the

availability and reliability of power



Multiple Asset Operation

Power Controller

System monitoring by computer allows programming of automated supervisory monitoring and determines

actions to take in response.

The system functions in software might include

• Start an engine

• Control battery charging

• Control energy load dumping for wind turbine

• Change loads to match available power

• Engage engine clutch

• Report alarms to a distant operator



Managing Intermittent energy and Variable load

Network analyzer

Power instructions

Power instructions

Samoa 550 kW wind farm

(running)

Kiribati 500 kWp PV plant

(building)

Mauritania 4.4 MW wind farm

(running)

1.3 MWp PV plant

(building)

PV + inverter Voltage

Frequency

Current

Flickers coef.

Harmonics (%)

Grid resilience



Hybrid RE Plants

System level benefits of solar-wind hybrid power plants



System Based Benefits

• Decrease environmental pollution (Reduction of air emission)

• Energy saving (Reduction of air emission)

• Abatement of global warming (CO2 and other green house gases are not produced)

• Socioeconomic development (Develops employment opportunities in rural areas)

• Fuel supply diversity (Diversity of energy carriers and suppliers)

• Distributed power generation (Reduces requirement for transmission lines within the electricity grid)

Managing Intermittent

Energy and Variable Load



Market potential

• Extendable to a generalized solution for any kind of stand-alone site.

• Independent of continuous availability of the renewable source as well as grid power availability.

• Power converters are modular in nature

• For any kind of critical load in stand-alone site

• Telecom towers

• Cold storage plants

• Hospitals

• Military establishments

• Fuel stations

•



Hybrid RE Plants

Best regulatory, fiscal and policy tools for promotion of hybrid RE

concept



Typical Regulatory / Policy Drivers

• CO2 targets

• Sustainability Initiatives

• Renewable Share Increment targets

• Energy Efficiency Related Initiatives

• Energy Market Related Drivers (privatization, trading, etc.)

• Targets on decreasing petroleum-dependency

• Targets on decreasing primary fuel import

• Increase IPP generation model

• Keep generation away from consumers

• Environment Initiatives

• Smart Grid Penetration Initiatives

• Energy Tariff Related Regulations

• Job Creation Targets

• Poverty Alleviation

• Waste Reduction Targets

• Enhance competitiveness of agro-industries

• Better Financing Opportunities



Hybrid RE Plants

Case studies



Case Study 1: Wind/diesel on mining site

AVERAGE WIND SHARE: 30%

FUEL CONSUMPTION: - 30%

DIESEL SAVINGS: 4 800 T /year

= 1 TURBINE PAID FOR

EVERY 3 MONTHS!

Location Kiribati

Hybrid

Technology

Hybrid Wizard controller

Installed

Capacity

PV: 1.3 MWp (400 + 500 + 400 kWp)

Diesel: 5.45 MW

Peak load 3500 kW (Week)



Case study 2: Ensuring Grid Stability - Hybrid PV system for

remote island

POSSIBLE

OVERCAPACITY OF PV PRODUCTION

DURING WEEK-END

Hybrid Wizard:

Real time management of PV

and Diesel power plants

Fuel savings: 596 T / year



Case study 3: High penetration Wind-Diesel system for island

070226

Wind

Genset

PV Wind

Genset

PV

WIND POWER

BATTERY

AVERAGE RE SHARE

PEAK RE SHARE

RE USAGE

DIESEL SAVINGS

1.37MW

NO

40%

70%

100%

1 039 m3/year

1.92 MW

YES

70%

90%

100%

1 418 m3/year

Option 1: Hybrid Wizard

without Battery storage Option 2: Hybrid Wizard

+ Battery storage for spinning reserve

Capex: - 35% vs Option 2 Capex > Budget

Location Caribbean Island

Hybrid

Technology

Hybrid Wizard

controler

Installed

Capacity

Wind: 1.925MW

PV: 114kW

Diesel: 1.9 MW

Battery for spinning

reserve

Peak load 1.3 MW



Conclusion

• Combinations of energy sources will provide more reliable power than any one source alone --- energy

diversity

• Diesel, propane, or gasoline engine-generators produce power on demand, and can self-start when the

power line voltage is dropping

• Natural gas can be piped to some areas

• When wind or solar energy is available, the fueled generator will shut down, saving its fuel cost

• Although overall costs could be higher, the power is more reliable



THANK YOU FOR YOUR ATTENTION!

Gergo Varhegyi

Head of Siemens PTI Middle East

SI DG SW&C-PTI

Siemens Building, Masdar City, 47015

Abu Dhabi, UAE

Phone: +971 2 588 0245

Fax: +971 2 616 5369

Mobile: +971 56 511 8362

E-mail: [email protected]

siemens.com/power-technologies

mailto:[email protected]

Hybrid RE Power Plants: A Global Perspective on Technology ... · • Renewables cannot be involved...

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