4.4_micro grid design_bello_epri/snl microgrid

© 2016 Electric Power Research Institute, Inc. All rights reserved.

Mobolaji BelloPower System Studies

August 29, 2016

Micro grid design: Considerations & interconnection studies

2© 2016 Electric Power Research Institute, Inc. All rights reserved.

Outline

Process

work

aroundKey areas

of interest

Use cases

& analytics

tools

Summary

Microgrid

overview


Microgrid overview

• Are DERs able to regulate the voltage and frequency within the island?

• Any issues with parallel grid operation?• How is re-synchronization checked

against criteria such as out-of-phase, large change in voltage?

Are existing telemetry / tele-control/ metering adequate?

• Are the fault contributions from DERs sufficient to allow satisfactory operation of protection systems?

• Are existing protection schemes adequate?

Plan, design, operate, control, monitor and optimize seamlessly

Microgrids And obviously many more…..

• Black starting

• Reliability

• Etc.


Microgrid Detailed Technical Design

Microgrid Project Objectives

Design Basis and Rationale

Performance Criteria

Site Descriptions

• Electrical & Thermal Needs• Generation Assets• Critical Load Needs• Power Distribution Equip.

DER & Microgrid Controller

Codes & Standards

Control NeedsCommunication Needs


DER Characterization

Renewables ▪ Solar Photovoltaics

▪ Solar Thermal

▪ Wind

Fossil Fuels Tech ▪ Boiler

▪ Fuel Cell

▪ Microturbine

▪ NG Genset

▪ Diesel (backup)Energy Storage

▪ Electrical (Power, Energy)

▪ Thermal (Chiller, Refrig.)

Thermal Tech ▪ Heat Pump

▪ CHP

▪ HVACR

▪ Solar Thermal

Other

▪ Electric Vehicles

Electric Storage• Aggregate capacity of all units (kwh)

• Maximum charge rate

(fraction of total capacity charge in one hour)

• Maximum discharge rate

(fraction of total capacity discharge per hour)

• Minimum state of charge

• Charge efficiency

• Discharge efficiency

• Decay/self-discharge (fraction of total capacity per hour)

----------------------------------

• Fixed cost ($)

• Variable Cost ($/kw or $/kwh)

• Lifetime (years)

• O&M fixed costs ($/year)

Solar Photovoltaics• # of modules

• Module rating (kW DC)

• Module Size (m2)

• Efficiency (%)

• Inverter size (kW AC)

• Total land area (m2)

----------------------------------

• Capital cost ($)



• O&M variable costs ($/year/kW)

Microturbine• Max Power (kW)

• Sprint capacity (% of power)

• # of sprint hours (hours)

• Fuel type

• Efficiency (ratio)

• CHP capable? (yes/no)

• Alpha (power to heat ratio)

• NOx emissions rate (kg/hr)

• Maximum annual operating hours (hours)

• Minimum loading (% of power)

----------------------------------

• Capital cost ($)



• O&M variable costs ($/year/unit)

• NOx treatment costs ($/kg)

Electric Vehicles• Multiple locations

• Min connect/disconnect SOC

• Max charge hours

• Battery size

• Efficiency

• Decay

• etc.

t

Connect

Disconnect

SOC


Data Collection Modeling Impact studiesCommissioning

& operation

Process

o Compliance with protocols

o Model validationo Submission of

modelso Real time ops &

monitoring

o Network models

•Load types

•DER types

•Operation topology

o Protection info

o Scenarioso Clear SOWo Model validationo Grid impact studies

o Steady stateo Fault analysiso Protection

coordinationo Stability studies


Design Analysis

volta

ge

time

limits

unacceptableovervoltage

Curr

ent

Impedance

Relay desensitization

Watt

s

Impedance

Load Only

Load and PV

Ener

gy

Time

unserved energy

Energy exceedingnormal

Design Analysis Approach

Load Analysis

Protection & Reliability

DER Sizing & Design

Distribution System Modeling, Simulation & Optimization

Microgrid Controller Architecture & Design

case by case look needed

Location √no impact

Location XPotential risk

• Steady State load flow

• System Dynamic

• Harmonics

• Flicker

• Controls

• Operation seq.

• Fault Current

• Black Start


Key interests

• Is the micro grid gen(s) is enough to support the islanded load? • Verify compliance to planning & voltage stability requirements

Load flow

• Is existing protection adequate?• If not, try various options

Protection analysis

• Events (loss of large load, load step & fault clearing capabilities)• Fault Ride Through capabilities of various inverter-based DERs

Dynamic studies


Dynamic studies

Grid connected - all DERs in parallel

Separation of the µ- grid due to main

grid blackout

Black-starting supplying crucial

loads

Islanded - with ALL gens

Island - with selected gens

Resynchronization

Plant(s) Operation

mode

Use generic models for controllers and protection equipment


Use cases: Current projects

ConEd• Highly meshed• Huge fault levels• Balanced• 216V• Various DER scenarios

SCE• Radial• Unbalanced• 12kV• 80 buses/nodes• 39 lines, 12 loads• 1 shunt capacitor

• Directional over current• Analyze more options

• Early stages

• DER-CAM

• Deep dive


Analytic tools

Steady state, fault

Steady state, fault, dynamic, protection, ALL

Protection


Detailed Design Analysis – Tools

Source: LBNL Paper LBNL-6708E

Need to apply a consistent modeling framework

Allow existing models to feed new analysis

PSCAD/EMTP-RV/MATLAB DesignBase

DIGSILENT

PSS/SINCAL

CYMDIST

SynerGEE

Transient DynamicTime-Series

Analysis/Slow Dynamics

Time-Series Analysis/SS

StepsSteady State

All

OpenDSS/Grid Lab D/DEW

Microseconds Milliseconds Seconds Minutes Hours Days

A variety of MC capabilities requires a variety of models to understand

• Performance

• Grid interaction

• System Protection Scheme Impact


Available ToolsSoftware Tool Affiliated Org. Tool Type

CYMDIST CYME International T&D Inc. Planning and simulation of distribution networks, including load flow, short-circuit, and network optimization analysis.

DER-CAM Lawrence Berkeley National Laboratory (LBNL)

Techno-economic tool for microgrid design and operation.

DesignBase Power Analytics Broad platform for electrical system design, simulation, and optimization.

EMTP-RV POWERSYS Solutions Power system transients simulation, load flow, harmonics.

EUROSTAG Tractebel Engineering GDF Suez

Power system dynamics simulation; full range of transient, mid- and long-term stability; steady-state load flow computation.

GridLAB-D Pacific Northwest National Laboratory (PNNL)

Distribution system simulation and analysis.

HOMER Homer Energy LLC, National Renewable Energy Laboratory (NREL)

Techno-economic tool for microgrid design and operation.

OpenDSS Electric Power Research Institute (EPRI)

Distribution system simulation and analysis.

PowerFactory DIgSILENT GmbH Power system analysis tool for load flow and harmonics in transmission, distribution, and industrial networks.

PSCAD Manitoba HVDC Research Center

Power system transient simulation, load flow simulation.

PSS/E Siemens Power Technologies International (Siemens PTI)

Load flow, dynamic analysis, and harmonic analysis of utility and industrial networks.


Simulation Tools - Comparison

Power Flow, balanced

Power Flow, unbalanced

Short Circuit

Relay Coordination

Arc Flash

Harmonic Analysis

Transient Analysis

Dynamic Analysis

Quasi Steady-State Analysis

EMTP-RV, Simulink, PSCAD

Aspen, Cape

DesignBase, PowerFactory

PSLF, PSS/E

OpenDSS

GridLAB-D

Best choice

Can be done, but not preferred choice

Cannot be done

ToolStudy


Summary“Microgrids” brings many technical needs: Good PSA tools available

No one-size fits all protection scheme works for all microgrids

Action planContinue testing various protection schemes

Level of dynamic studies details depends on so many factors i.e. gen types, operation philosophy etc.

Best protection scheme depends on microgrid objective

• Network

• Objective

• Scenarios

• Modeling

Grid requirements

Controllability

Monitoring

Reliability


Together…Shaping the Future of ElectricityJeff Smith

[email protected]

865.218.8069

Mobolaji Bello

[email protected]

865.218.8005

Arindam Maitra

[email protected]

704.595.2646

mailto:[email protected]



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