Models of Battery Storage Systems for Power System Analysis VI - Models of... · Models of Battery Storage Systems for Power System Analysis International Seminar on “Energy Storage

Models of Battery Storage Systems for Power System Analysis

International Seminar on “Energy Storage Options for Renewable Energy Integration” “Energy Storage Options for Renewable Energy Integration”

at India Habitat Centre on 29th January 2018

Flavio FernandezDIgSILENT GmbH, Germany

Models of Battery Storage Systems for Power System Analysis

International Seminar on “Energy Storage Options for Renewable Energy Integration” “Energy Storage Options for Renewable Energy Integration”

at India Habitat Centre on 29th January 2018

Flavio FernandezGmbH, Germany

Outline

• Introduction

• Overview battery storage simulation models

• Application cases

- Transient stability analysis- Transient stability analysis

- Quasi-dynamic simulation

• Model validation

• Summary and Outlook

1st International Integration Conference, India

Overview battery storage simulation models

2

Introduction

• Battery storage is an effective tool to ensure system

grid levels, in particular with increasing penetration of variable renewable

generation (VRG) such as wind and photovoltaic

• It is anticipated an increasing deployment of battery storage systems at all grid

levels and therefore increasing needs for their simulation at system planning levels and therefore increasing needs for their simulation at system planning

and operation stage

• Simulation models

- The wider the range of applications, the

- Degree of detail of the simulation model has to be in line with the

discharge) and the response time of the battery storage system

application


Battery storage is an effective tool to ensure system flexibility and balancing at all

grid levels, in particular with increasing penetration of variable renewable

generation (VRG) such as wind and photovoltaic

It is anticipated an increasing deployment of battery storage systems at all grid

increasing needs for their simulation at system planning increasing needs for their simulation at system planning

the various the models required for simulation

Degree of detail of the simulation model has to be in line with the duration (of the

time of the battery storage system of the desired

3

Introduction

ApplicationGeneration Level

Description

Governor response

Automatic dynamic response of the generator to frequency changesStorage can compensate lack of governor response of VRG


Frequency regulation

Second by second adjustment of power to match load and regulate system frequencyStorage can free up generation capacity for energy production

Balancing/real-time dispatch

Adjustment of production market-based on minute by minute basis to match demandStorage can mitigates price spikes due to volability of VRG

Max. Power Requirement

Duration Requirement

Response

response of the Up to 10% of generator rating

Seconds to few minutes

Fast (miliseconds)

4

~ 5% of peak demand (large systems), can be higher in small islanded systems

~15-30 minutes

Fast (miliseconds)

based on minute by minute basis to

Storage can mitigates price spikes

1 hour or more Slow, max. up/down rampsacc. to grid code

Introduction

ApplicationT&D Level

Description

Congestion relief Storage VRG during grid congestion and deliver when capacity is available (hence increase capacity factor of VRG and reduce curtailment)

Voltage support Storage can attend local demand or reduced curtailment of distributed


reduced curtailment of distributed generation due to voltage regulation problems

Grid reinforcement deferral

Storage can defer transmission reinforcements or distribution substations upgrades (transformers) due to peak load growth

Reliability enhancement

Reduce non-supplied energy and supply interruptions due to outages

Max. Power Requirement

Duration Requirement

Response

grid congestion and deliver when capacity is available

Varies with application

~hours slow

Storage can attend local demand or Varies with application

~minutes to hours, varies

slow

5

to voltage regulation application hours, varies

with application

substations upgrades (transformers)

Varies with application

~hours slow

supply interruptions due to outages ~ 1 to 10 MW (varies with feeder size)

~hours fast (alternative to switching)

Battery Storage Simulation Model

Detailed EMT-type models

: faste

r re

sponse –

short

er

dura

tion

Various simulation models available, which result appropiated for different simulation types and application cases:


Manufacture specific / generic RMS

transient stability models)

Steady-state models for quasi: faste

r re

sponse

short

er

dura

tion

type models

Various simulation models available, which result appropiated for different simulation types and

6

Manufacture specific / generic RMS-type Models (or

transient stability models)

state models for quasi-dynamic simulation


Current source (fund. Freq.)

1st International Integration Conference, India 7

Detailed EMT-models

Quasi-dynamic models


• Battery model represents the physical

characteristics of the battery and depicts the

terminal voltage and the internal resistance as a

function of several inter-related variables

− Internal resistance depends on the State of

Charge (SOF)


Charge (SOF)

− Battery (cell) capacity strongly depends on

the discharge current (e.g. Peukert‘s equation

for lead acid batteries)

• Models needs to account for the different

discharge profiles (high/low duty cycles)

• Parametrization from manufactures‘ data (a.o. use of lookup tables)

of the battery and depicts the

terminal voltage and the internal resistance as a

State of

8

strongly depends on

the discharge current (e.g. Peukert‘s equation

Models needs to account for the different

Parametrization from manufactures‘ data (a.o. use


0

1

Frquency MeasurementElmPhi*

AC-VoltageStaVmea

Frame_BatteryCntrl:

PQ-MeasurementStaPqmea

Frequency ControlElmDsl*


Control blocks will vary with functional specifications

0

Frquency MeasurementElmPhi*

AC-VoltageStaVmea

cosref;sinref

1

2

3

0

1

0

1

2

0

0

1

2

1

3

4

PQ-MeasurementStaPqmea

Frequency ControlElmDsl*

PQ-ControlElmDsl*

ConverterElmGenstat*

Battery ModelElmComp,ElmDSL

Charge ControlElmDSL*

id_ref..

id_r..

delt..

dpref

Icell

SOC

Ucell

9

Battery Storage: Control Functional

• Active Power Response

• Ramp limitation


Source: ENTSO-E Network Code for Requirements for Grid Connection Applicable to all Generators

Functional Specifications

10

for Grid Connection Applicable to all Generators

Battery Storage: Control Functional Specifications

• Implementation in PowerFactory DSL Simulation language for frequency control

1

0

PV_Control:

pin

dpref

Frequency control


3

4

2

vref

vin

dpref


Implementation in PowerFactory DSL Simulation language for frequency control

0

PV_Control:

012

30123- {K+1/sT)}

Kp,Tip

id_max

(1/(1+sT))Tr

dp

deltai

yi2yi1id_ref

dpref

11

10123

-Deadband_Offset_Lim

AC_deadband,Kq

iq_max

iq_min

{1/sT}Tiq

iq_max

iq_min

0123

id_min

(1/(1+sT))Trq

dv

vref

vin iq_refo11deltaU(1)

dpref


• Dynamic voltage support, i.e. provision of

(reactive) transient short-circuit current to

limit the propagation of the voltage dip to

the rest of the network



12


• Fault ride through profile (protection block): during external faults,

system shall remain connected to the network for voltage dips within the FRT profile



Fault ride through profile (protection block): during external faults, the battery storage

remain connected to the network for voltage dips within the FRT profile

13

Outline

• Introduccion

• Battery storage simulation models

• Application cases• Application cases


• Summary


Battery storage simulation models

14

Example 1: BESS for Frequency Regulation in Islanded System

• Hydro/diesel/photovoltaic system, with high penetration of PV: up to 70% of peak demand (instantaneous penetration)

• Under certain circumstances of high pv penetation, lost of the major diesel unit results in of load shedding (or even total system backout) due to lack of governor response (so far provided by diesel units only)

• Battery energy storage system (BESS) shall improve frequency regulation

15

• Battery energy storage system (BESS) shall improve frequency regulation

• Dimensioning of the BESS system:

− Rated power (MW)?

− Duration: 5 minutes (to bridge start up time of diesel units)


Hydro/diesel/photovoltaic system, with high penetration of PV: up to 70% of peak

Under certain circumstances of high pv penetation, lost of the major diesel unit results in of load shedding (or even total system backout) due to lack of governor response (so far

Battery energy storage system (BESS) shall improve frequency regulation

4MW

9MW

6MW

6MW

Load

3MW

3 years later

Hydro

6MW

25MW

DIESEL3

MW

6MW

?? MW BESS

Battery energy storage system (BESS) shall improve frequency regulation

(to bridge start up time of diesel units)

Active power setpoint basedon frequency measurement. Adjustable droop anddeadband

Active and reactive power


16

Active and reactive power control. Priority in the activepower control (adjustable)

Charge controller in the innerloop. Takes into account SOC of the battery to define thefinal id and iq setpoints


[Hz]

Loss of thelargest power plant in theisland


17

LIMIT:

Disconnection of generationoccurs at 47,5 Hz

Frequency range allowedafter disturbance


Example 2: Voltage control / MW Curtailment

• 2MW wind turbine generator connected at the remote end of a MV distribution feeder

• Frequent curtailment due to violaton of voltage constraints

− Voltage at PCC not allowed to exceed 1.04

− DNO curtails ative power injection to control voltage

18

− DNO curtails ative power injection to control voltage

• To enhance plant factor, a battery storage system shall storage curtailed generation and deliver it after voltage violation clearance

• Dimensioning of the BESS system:

− Rated power – fixed % of WTG rating, 0.4MW in this case

− Energy? – trade-off between BESS cost and total curtailed energy


2MW wind turbine generator connected at the remote end of a

Frequent curtailment due to violaton of voltage constraints

exceed 1.04 p.u.

DNO curtails ative power injection to control voltageDNO curtails ative power injection to control voltage

To enhance plant factor, a battery storage system shall storage curtailed generation and deliver it after voltage violation

fixed % of WTG rating, 0.4MW in this case

off between BESS cost and total curtailed


• Control modelling approach

- SOC kept at minimum during normal operation conditions

- Voltage above 1.04pu

• Charge battery as far as SOC<100%

• Curtail wind generation (P=f(U) characteristic) if battery is fully charged or battery is already charging at nominal power

- Voltage below 1.04pu (and battery above minimum SOC)- Voltage below 1.04pu (and battery above minimum SOC)

• Deliver stored energy to the grid

• Implementation in a quasi-dynamic simulation model

- Simulation time step: 15 minutes

- Simulation run: 1 year

- Retain integrator for energy calculation/SOC



SOC kept at minimum during normal operation conditions

Curtail wind generation (P=f(U) characteristic) if battery is fully charged or battery is already charging at

Voltage below 1.04pu (and battery above minimum SOC)Voltage below 1.04pu (and battery above minimum SOC)

dynamic simulation model

Retain integrator for energy calculation/SOC

19

Quasi-dynamic model




20


Assumptions:• Feed-In Tariff 0,10$/kWh• Storage costs 1.700$/kWh (life span 20 a)• Max charging power 0.4MW• Storage energy size from 0.4MWh – 2MWh

Battery size in MWh

CurtailedEnergy inMWh/year

Costs energycurtailed in Mill.$/20a

Batteryin Mill.$/20a(1.700$/kWh)

0 342 0,68 0

0,4 283 0,57 0,68

1 237 0,47 1,7

1,5 214 0,43 2,5

2 194 0,01 3,4

21


Battery costsin Mill.$/20a

$/kWh)

0

0,68

1,7

2,5

3,4

0.68 0.57 0.47 0.430.010

0.68

1.7

2.5

3.4

0 0.4 1 1.5 2

Mil

lio

n $

MWh of installed battery capacity

Cost of curtailed energy Cost of Batteries

Outline

• Introduccion

• Battery storage simulation models

• Application cases


• Summary


Battery storage simulation models

22

Model Validation

• Certification of the Electrical Characteristics of Power Generating Units and

- In Germany, FGW developed guidelines for the certification of wind,

storage systems in the medium-, high and extra high

- Part 4: Demands on Modelling and Validating Simulation Models of the Electrical Characteristics

of Power Generating Units and Systems

• Required tests/measurements

• Comparison procedure: definition of stationary ranges, transient ranges, etc.

• Tolerance and error limits

• Database for manufacture specific models:

- http://www.wind-fgw.de/publikationen/datenbanken/

• Parametrization of generic models can be verified against manufacture specific models


of the Electrical Characteristics of Power Generating Units and Systems

In Germany, FGW developed guidelines for the certification of wind, pv, combusting engines,

, high and extra high-voltage grids

Part 4: Demands on Modelling and Validating Simulation Models of the Electrical Characteristics

Comparison procedure: definition of stationary ranges, transient ranges, etc.

Database for manufacture specific models:

fgw.de/publikationen/datenbanken/

Parametrization of generic models can be verified against manufacture specific models

23

Model Validation


• Illustrative example of a

successfully validated

model

• Transients at 12.9s and

17.2s due to series reactor

switching

• Deviation in voltage

recovery to due saturation

of stepup trafo (not

considered in RMS

simulations)

24

Summary

• It is anticipated an increasing deployment of battery storage systems at all grid levels and

therefore increasing needs for simulation of battery storage systems

planning and operation stage

- Two examples shown particular application in combination with variable renewable generation

(VRG)

• Simulation model has to be fit for purpose• Simulation model has to be fit for purpose

- Details of the representation and simulation

discharge) and the response time of the battery storage system

(minutes to miliseconds)

- Model validation might be required for specific applications


It is anticipated an increasing deployment of battery storage systems at all grid levels and

increasing needs for simulation of battery storage systems at system

Two examples shown particular application in combination with variable renewable generation

fit for purposefit for purpose

Details of the representation and simulation step sizes have to in line with the duration (of the

time of the battery storage system of the desired application

might be required for specific applications

25

Summary

• Selection criteria:

- Model adequacy for the intended application

- Numerically stability

• Maximum integration step size

- Simulation performance

• Of particular importance for bulk power system


• Of particular importance for bulk power system

simulations, due to the large number of units in

the model (ENTSO-E grid model: ~ 23.000

buses, with around 1.100 synchronous

generators connected at 100kV or higher and

no static generation)

• Embedded storage at distribution level may

result in additional challenges

application

Of particular importance for bulk power system

26

Of particular importance for bulk power system

simulations, due to the large number of units in

E grid model: ~ 23.000

generators connected at 100kV or higher and

Embedded storage at distribution level may

Outlook

• Data exchange / Portability of dynamic models

- Promote the use of standard generic model

available

- Standard interface (e.g. IEC61400-27) for the exchange of compiled models

• Model aggregation

- Suitable aggregation of wind/pv generating units, retaining main park characteristics- Suitable aggregation of wind/pv generating units, retaining main park characteristics


Portability of dynamic models

Promote the use of standard generic model – parametrization by manufactures not always

27) for the exchange of compiled models

Suitable aggregation of wind/pv generating units, retaining main park characteristicsSuitable aggregation of wind/pv generating units, retaining main park characteristics

27

Thanks for your attention!

Flavio FernandezDIgSILENT GmbH, Germany

Thanks for your attention!

Flavio FernandezGmbH, Germany

Documents

Models of Battery Storage Systems for Power System Analysis VI - Models of... · Models of Battery Storage Systems for Power System Analysis International Seminar on “Energy Storage