Hybrid Controller for Renewable Energy Power Plant in Stand-alone

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Hybrid Controller for Hybrid Controller for Renewable Energy Power Plant Renewable Energy Power Plant

in Stand-alone sitesin Stand-alone sites

Dr. Prabodh Bajpai Assistant Professor Electrical Engineering Department, IIT Kharagpur

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Outline

Introduction

Technology aspects

Benefit to the Industry

Commercialization prospective

Hybrid Controller for Renewable Energy Power Plant in Stand-alone sites

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Introduction Uncontrolled Renewable energy sources essentially

have random behaviors. eg: Solar, Wind, etc. Power production from Uncontrolled sources is

independent of human intervention Hybrid power systems may contain controlled and

uncontrolled energy sources and energy storage elements with appropriate control systems

Stand-alone hybrid power systems take advantage of the complementary nature in profile of the renewable energy sources

Hybrid power systems ensure continuous and reliable power production


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Possible Renewable Hybrid Energy Systems1) Wind/PV/FC/electrolyzer/battery system 2) Micro-turbine/FC system3) Microturbine/wind system4) Gas-turbine/FC system5) Diesel/FC system6) PV/battery7) PV/FC/electrolyzer8) PV/FC/electrolyzer/battery

system

9) FC/battery, or super-capacitor system

10) Wind/FC system11) Wind/diesel system12) Wind/PV/battery

system13) PV/diesel system14) Diesel/wind/PV system15) PV/FC/ SMES system

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Wind and solar power generation are two of the most promising renewable power generation technologies.

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DG/Battery Hybrid Solution: Merits Easy to install and low cost on site construction Highly integrated intelligent hybrid power system

for control and protection Inclusion of battery back up reduces the DG size

Saving in diesel and reduction in maintenance of diesel generator

Reduced operating time and enhanced DG life Specially designed deep cycle battery available in

market Rechargeable in a short time, Long cycle life under STC, High DoD (Depth of Discharge)

555


DG based Hybrid Solution : DemeritsDG as energy source has problems of : Pollution

air, noise, heat Dependence of fuel

world-wide increase of oil prices; limited resources in future Transport to the sites

long distances and cost intensive transports Storage of the fuel at site

safety problems - explosions, vandalism No unattended operation is possible

high personnel cost High maintenance cost and limited life-time of DG

Hybrid Controller for Renewable Energy Power Plant in Stand-alone sites 6

Hybrid Renewable Energy SystemsOn the other hand, the proposed renewable energy

based system helps in: Decrease environmental pollution

Reduction of air emission Energy saving

Reduces production and purchase of fossil fuels 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


Challenges Site dependence of renewable sources

Site survey with long term data acquisition & forecasting

Hybrid renewable energy system designConfiguration and sizing of the hybrid system components

with the objectives:Supplying the power reliably under varying atmospheric

conditions Minimizing the total cost of the systemMaximizing the system efficiency by efficient energy flow

management strategiesOptimization through simulation studies under real

operating conditions for a reasonable tradeoff among conflicting design objectives

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ChallengesEconomic viability

Cost-benefit analysis of hybrid system for reasonable payback period

Real world applicationDesign of power conditioning devices with maximum

power point operation of energy sources Optimal energy management strategies and their

testing with laboratory prototype hybrid controllerDevelopment of hardware and associated software for

field-implementation


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Technology aspects Technology aspects


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IntroductionSolar PV based renewable power plant with FC,

Battery and DG as backup sourcesHybrid controller to implement the energy

sources changeover logic based on optimal energy management strategy.

Automatic mode of operation in the hybrid controller for FC and DG changeover operations.

Laboratory prototype of hybrid Solar PV-Fuel Cell-Battery-DG system for upto 5 kW load


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A typical stand-alone PV-Fuel cell-Battery hybrid energy system:

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System DevelopmentRobustness of the controller to fluctuating weather

conditions and load demand is being rigorously tested, monitored and documented.

Hybrid controller comprises of:◦ Solar DSCAM (master controller) and two slave controllers,

the Fuel Cell DSCAM and DG DSCAM ◦ Individual power conditioning units for SPV, Fuel Cell and

DG system to provide regulated DC output on the DC bus.• The master and slave controllers interact to

provide switching and control signals for the converter units.

Hybrid Controller for Renewable Energy Power Plant in Stand-alone sites13

SPV-FC-BATTERY-DG HYBRID ENERGY POWER PLANT

Discharging

ChargingSupply to

Load

PV Power

FC Power

DG Power

SOLAR PV ARRAY (Primary Source)BATTERY BANK ( Back Up Source)

FUEL CELL SYSTEM (Back Up Source)

CONTROLLER

DIESEL GENERATOR (Back Up Source)

LOAD

H2 storage

H2 Supply

Experimental Test Results


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Load 0.75 kW

Load 1 kW

Experimental Test Results


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Load 0.75 kW Load 1 kW

Excess Current Battery ChargingBattery Charging

Merits of TopologyMerits of solar PV charge controller and

Fuel Cell charge controller ◦ Optimal charging of the batteries and maximum power

extraction from solar PV and FC ◦ Supervisory functions to prevent damage to the battery◦ Effective interface to inter connect Solar PV modules, Fuel

Cell, Battery Bank and the load◦ Battery reaches a high state of charge under all operating

conditions◦ Work in tandem with the SMPS based power plant to

optimize the charging capability of the FC/SPV and protect the batteries from overcharge


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Important Features of Topology◦ Use of solid-state devices to control the charging current to

the battery and supply power to the load simultaneously

◦ Blocking devices to prevent reverse current flow from the battery to the FC/SPV during cloudy days or other charging modes

◦ Lightning / transient protection to protect the control circuitry from damage due to excessive voltage

◦ Programmable charging capacity, change over settings and peak power point

◦ Programmable maximum power point tracking (MPPT) logic with the built in embedded logic controller


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Solar resource assessment (SRA) system


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•Measures weather parameters like• solar insolation (W/m2),• ambient temperature (0C) and• relative humidity(%)

•Weather data at defined intervals is measured using sensors

•Data is sent continuously to a central server through GPRS and is monitored online

Necessity of weather monitoring•Inspecting the feasibility of a site for a solar energy project

•Site comparison and selection based on weather data

•Long term energy assessment helps in effective system sizing and cost minimization

•Helps to predict the performance of SPV

Remote Monitoring SystemRemote Monitoring System


Sensors

Hybrid Controller

cRIO-9073, Data acquiring, Generating and logging

Monitoring StationRemote PC

Benefit to IndustryBenefit to Industry


Market potentialExtendable 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◦ ATMs


Commercialization prospectiveCommercialization prospective


Cost-benefit analysisNet present value = Total lifetime savings –

Total lifetime investmentSavings include revenue generated from the

hybrid PV system by replacing the DG-battery system, the carbon tax benefit and savings in the operational cost of the system.

Investment includes the extra first cost which is the difference between the Capex of the hybrid PV system and the Capex of the DG-Battery system


Cost-benefit analysis CAPEX for hybrid PV system to meet 4kW

peak load will around 50Lakh INR The lifetime of both the systems considered

to be 30 years. Economic analysis for different scenarios

gives payback period between 5-10 years


Real world applicationProof of concept verified with a laboratory

prototype

Field site testing with stand-alone load application needs to be done

The Technology Transfer may take place as per One Time License Payment or Revenue Sharing Model or any other criteria mutually agreed



Component size and priceComponent size and priceComponent Pricing

PV (per Wp) 70

Battery (per kwh) 7,000

H2 tanks(per m3) 400

Fuel cell(per kW) 2,00,000

Diesel Generator (per kW) 33,000

Diesel (per litre) 40

Component Size

PV (Wp) 16500

Battery in hybrid PV system(kwh) 57.6

DG in hybrid PV system (kW) 5

H2 tanks (m3) 120

Fuel cell (kW) 4.56

DG in DG-Battery system (kW) 25

Battery in DG-Battery system( kWh) 105

Financial Assumptions Hybrid PV system:• CAPEX is the total initial cost of the system. OPEX in case1 =1% of CAPEX+ 100% of Battery cost in every 5

years+100% of FC cost every 10,000 hours of operation+ operating cost of FC @Rs 417/hr +operating cost of DG @Rs 50/hr.

OPEX in case2 =1% of CAPEX+ 100% of Battery cost in every 5 years+100% of DG cost in every 15 years + operating cost of FC @Rs 417/hr+ operating cost of DG @Rs 50/hr.

DG/Battery system:• CAPEX is the total initial cost of the system. OPEX =2% of CAPEX+100% of Battery cost in every 5

years+100% of DG cost in every 8 years + operating cost of DG @Rs 50/hr.

The lifetime of both the systems was considered to be 30 years. The present diesel cost was assumed to be Rs 40/litre. The annual escalation in diesel cost was assumed to be @ 10 %

Capex and Opex comparisonsHybrid PV/FC/DG/Battery

system

DG/Battery system

Comparison of savings & investments for hybrid PV/FC/DG/Battery system

NPV and Payback PeriodLonger FC operation Longer DG

operation

With carbon tax benefit 23,344,047 35,527,795

Net present value

Without carbon tax benefit

16,463,765 29,068,754

With carbon tax benefit

5 4

Payback period

Without carbon tax benefit

7 6

Documents

Hybrid Controller for Renewable Energy Power Plant in Stand-alone