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Real-time Cosimulations for Hydropower Research and

Development

Power and Energy DepartmentIdaho National Laboratory

Manish Mohanpurkar, Ph.D.Yusheng Luo, Ph.D.

Rob Hovsapian, Ph.D.

Introduction• Hydropower is the largest producer of renewable energy in the U.S.

with over 60% penetration• Multiple configurations exist for hydropower generation:

– Conventional hydro - fixed speed– Advanced hydro - adjustable speed

• Conventional hydropower is based on synchronous generators operating at fixed speed

– Participate in primary energy market• Advanced hydro is typically based on induction machines with speed

control through power electronics– Additional potential to participate in the ancillary service markets

• Challenges – lack of framework to determine and compensate for stability due to rotating inertia and participation in wider avenues

Status of Hydropower & Renewables

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Other Renewables

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Percentage of hydro power generation to the total electricity generation for leading hydro producers of the world

Electricity generation by hydro and renewable energy sources in the U.S. (Y-axis: electricity generated in million MWh)

Motivation - I• Rapid increase in non-deterministic and variable generation resources

at transmission and distribution network– Results in reduced inertia in grids

• Hydropower is versatile, emission free, and deterministic source of energy

• Till recent years was utilized as load following and peaking units• Pumped Storage Hydro (PSH) is the only proven grid level storage

technique that is economically feasible• Advances in power electronics allow the adjustable speed operation • Ideal storage characteristics of PSH and AS-PSH

– Quick response (~15 MW/s)– Large capacity (several 100 MWs)– No emissions during operation– Transmission infrastructure available for interconnections

Motivation - II• Developing physics based vendor neutral, dynamic models capable of

capturing events at a sub-second level for hydro systems• Mechanical and hydro systems have response times ranging from few

seconds to few minutes– A typical ramping rate of an advanced hydropower plant is 5 to 15

MW/seconds– Change of state of gate from sensing to controls to execution is few

minutes• Electrical system dynamic events and faults occur in sub-second to a

few seconds– A typical 1L-G fault exists for a few cycles and protection systems

are activated• Technical Gap: A multi domain, true co-simulation environment with

models to analyze and provide a stability quantification framework

Objectives of AS-PSH modeling

• Creating physics based, vendor neutral model that can provide a dynamic and transient response in real time

• Capability of simulating several different modes of operation of AS-PSH with reasonable practicality

• Capability to co-simulate the hydro-dynamics with other domains i.e., electrical, mechanical, and thermal as needed

• Demonstrate participation in both real time energy and ancillary service market

• Capability of providing an environment for Controller-Hardware-In-the-Loop (CHIL), Hardware-In-the-Loop (HIL), and Power-Hardware-In-the-Loop (PHIL) to serve as a verification and validation platform

• Similarity in control architecture of a Type-3 wind turbines

Pumped Storage Hydropower (PSH) Transient Simulation Modeling

≈≈≈≈≈≈

DFIG

• Develop transient EMT models in small time steps (5 - 50 s) to better understand the dynamic interactions between electromagnetics and hydrodynamics

• Study the hydrodynamic behaviors such as water hammering and flywheel effects due to sudden load and fault conditions

• Conduct System level testing and analysis on the Real Time Digital Simulator

• Provide a greater understanding of variable renewable interactions and the value of energy storage

Co-simulation of the electromagnetic & hydrodynamic transients

Adjustable Speed Pumped Storage Hydro• Two primary subsystems within a typical AS-PSH

– Hydraulic subsystem– Electric subsystem

• Several modes of operation– normal generation, normal pumping, idle, down fringe generation,

up fringe generation, down fringe generation, etc.

Physics Based Modeling• Models developed capable of capturing sub-cycle events in both

domains• Coupled partial differential equations used for the development of

models• Basic water flow dynamics and solution by ‘Integral Transform’:

– H(x,t) is pressure head, U(x,t) is the fluid velocity, a is the pressure wavevelocity, g is gravitational acceleration, D is internal diameter of the pipe,and f is a friction factor

DUfU

xHg

tU

xU

ga

tH

2

2

Unit Step Load Change• Large step load is simulated along with the controller signal and output

Real Time AS-PSH model• Physics based model of the AS-PSH hydro circuit, power electronic

converter, converter controls, and a test power system• Multiple test scenarios in real time are simulated

– Balanced faults– Unbalanced faults– Unit step load changes

Real-time Co-simulation of Hydro and Electrical Events• Response of the AS-PSH to electrical faults

Unbalanced fault: 1 Line to ground fault Balanced fault: 3 Line to ground fault

Motivation - III• Large hydropower plants may not be possible due to numerous

constraints such as regulatory, environmental, and limited resources• Immense potential of small sized (< 100 MW) Run-Of-the-River (ROR)

hydropower plants is identified – 65,500 MW untapped hydro-resources in the U.S.

• Innovation – Emulate the response of a large hydropower plant by coordinating a group of smaller ROR plants

• ROR hydropower plant operation is typically determined by irrigation schedules and hence ‘non-dispatchable’

• Constant speed operation is the most suited mode for such applications

• Communications and controls in industry accepted and vendor neutral approach adopted to demonstrate effectiveness

Proposed Solution• A cohesive operation of multiple ROR hydropower plants and an

optimal Energy Storage System (ESS)• ESS comprises of supercapacitors, flywheels, and batteries• ESS is capable of short to long term support based on ROR power

output and response requests• Coordination and controls between the components is based on

‘Siemens Smart Energy Box (SEB)’• SEB is an open platform developed by Siemens and is readily available • ROR does not have the inherent storage flexibility therefore it can only

participate in the primary energy market• ROR plus ESS coordinated operation via SEB will be connected to test

and actual power systems to register response to dynamic conditions

ROR Hydropower plus ESS Operation

Market description

Proposed Primary Secondary Tertiary

Reserve type Power electronically interfaced

Spinning Spinning Non-spinning

Timescale of response

Smaller (µs – ms)

Medium(ms – s)

Longer (s – minutes)

Longer (minutes –hours)

Timescale of discharge

µs – minutes several minutes 30 minutes – 2 hours

several hours

Application Transient stability, power quality corrections

Operating reserve for regulation, fault recovery, power quality

Operating reserve for slow dynamics, voltage support, contingency

Load leveling, energy arbitrage, firming, contingency

Example technologies

Supercapacitors, flywheels

Synchronous generators, batteries

Synchronous generators, batteries

Pumped hydro, gas turbines

Front End Controller Development• Develop physics based ESS models and vendor neutral topologies in

real time environment• Develop Front-End-Controller (FEC) to receive grid management

signals and respond as needed • FECs will be developed for each ESS component

• Verification and validation via Controller-Hardware-In-the-Loop (CHIL) of FEC in real time environment

• Assess the economic and financial value streams of ROR HPPs• HIL testing based on RTDS links between INL and NREL with the

controllable grid interface • Dynamic grid and market conditions to be simulated

• RTDS link between the two labs is an outcome of an existing LDRD effort at INL

• Control Architecture for integrating ROR HPP with ESS and power grid

Accomplishments and Progress

Real Time Environment

Storage Devices

INL

Super capacitor

Hardware in the Loop Devices

I/O

ROR models developed collaboratively

Battery (80kW)

Flywheel model

Simulated Devices

Battery modelHydro model

Electric Grid model

Inverter controller

Siemens Smart Energy

Box

Power electronics interface

I/O

Permanent Magnet based Hydro Power Plant

Induction Machine based Hydro Power Plant

Induction Machine based Hydro Power Plant

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Con

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NREL

Power Market Interface

Primary Energy Market

Spot Market

Ancillary Service Market

Data for economic analysis generated

to be used with PLEXOS and

FESTIV type tools

Front End Controller Interface

ANL

Proposed Framework

HIL based testing with NREL• A controllable grid interface at NREL will be used remotely via RTDS

links to perform hardware performance validation of the developed framework

• Data generated from dynamic grid and market conditions will be analyzed by Argonne National Laboratory and Energy Exemplar

• Economic feasibility and revenue data will be generated for business case

Concluding Remarks• Real Time Power and Energy Group, INL is actively involved in multiple

hydropower related projects • Brief review of two current projects at INL by Wind and Water Program

Technologies Office is discussed– Dynamic modeling of Adjustable-Speed Pumped Storage Hydropower

Plant• Co-simulation of hydro and electrical events in real time at sub-second regime

– Integrated Hydropower and Storage Systems Operation for Enhanced Grid Services

• Cohesive response of multiple ROR hydropower plants and storage to provide ancillary services

• A physics based, vendor neutral modeling approach is adopted in real time environment with sub-second resolution

• True real time co-simulations performed to analyze systems• Multiple DOE labs, industry, and utilities with complimentary skills to

form teams

Thank you&

Questions