j. a. p. lopes, "the merge control concept - microgrids and evs - development of management...

J. A. Peças LopesINESC Porto/FEUP([email protected])

The MERGE control concept ‐Microgrids and EVs ‐

Development of management solutions for integrating EV in microgrids for normal and islanding operating conditions

Electric Vehicle Integration Into Modern Power Networks

24 September 2010DTU, Copenhagen

Introduction

Large Scale integration of EV in Electric Power Systems requires the adoption of an advanced management and control concept capable to deal with:• Market participation of EV consumers;• Technical grid restrictions;• Maximization of the integration of renewable power sources.

Microgrids can exploit the presence of EV to increase their robustness of operation, regarding:• Increased integration of local microgeneration from renewable power

sources;• Improve islanding operating conditions in terms of:

• Dynamic behavior;• Extension of the islanding mode operating time.

A multi‐level hierarchical control and management concept needs to be developed

Conceptual Framework for EV Integration Into Electric Power Systems

Type of charging points

Charging points can present different characteristics according to the location


Overview of the different information flows

An ICT model was developed, identifying the involved parties and the associated information flows.

The supplier / aggregator


a) The grid structure (a possible representation)

Microgrids

Multi‐microgrids


b) The EV supplier/aggregator

Single EV do not have enough “size” to participate in electricity markets

If grouped through an aggregator agent, EV might sell several system services in the markets

The EV suppliers/aggregators:

are completely independent from the DSO

act as an interface between EV and electricity markets

group EV, according to their owners’ willingness, to exploit business opportunities in the electricity markets

develop their activities along a large geographical area (e.g. a country)



EV supplier/aggregator structure:

Regional Aggregation Unit

Microgrid Aggregation Unit


CVC

CVC

CVC


MV Level

LV Level

Smart MeterVC

Smart MeterVC

Smart MeterVC

Smart MeterVC

Smart MeterVC

Smart MeterVC

EV Owner

EV Owner

EV Owner

EV Owner

EV Owner

EV Owner

SUPP

LIER

/AG

GR

EGA

TOR

Regional Aggregation Unit



CVC

CVC

CVC


MV Level

LV Level

Smart MeterVC

Smart MeterVC

Smart MeterVC

Smart MeterVC

Smart MeterVC

Smart MeterVC

EV Owner

EV Owner

EV Owner

EV Owner

EV Owner

EV Owner

• Regional Aggregation Unit (RAU) – located at the HV/MV substation level and covering a region (e.g. a large city) with ~20000 clients

• Microgrid Aggregation Unit (MGAU) – located at the MV/LV substation level and covering a LV grid with ~400 clients

2. Conceptual Framework for EV Integration Into Electric Power Systems


To enable bidirectional communication between EV and suppliers/aggregators:

Single EV:

• Must have a specific interface unit the Vehicle Controller (VC)

• Will be connected to LV networks through VC

• The VC enables bidirectional communication between the EV and the MGAU

• The VC may be located in the smart meter to which EV will connect to charge

Fleet of EV:

• Might be used only one controller for the entire fleet the Cluster of Vehicles Controller (CVC)

• Will be connected to MV networks through CVC

• The CVC enables bidirectional communication between the EV and the RAU



Single EV bidirectional communication

EV

AMM

µG

µG

Storage

Period during which a single EV will be connected to the

grid and the required battery SOC at the end of that time

EV Charger

EV is plugged-in and its owner defines the disconnection hour and the required battery SOC

Broadcast of set-points to adjust EV control parameters in accordance

with the market negotiations

DSOAggregator

Information about interruptions and disconnection orders in

case of grid problems

Power consumed

MarketResponsible for the

grid technical operation


c) Interconnected systems

Normal operation – Market environment

PLAYERS

TSO

GENCO

DSO

Elec

trici

ty M

arke

t O

pera

tors

Market Operation

Electric Energy

Technical Validation of the Market Negotiation (for the transmission system)

Reserves

Electricity Retailer

Electricity Consumer

Electric Energy

Communicates withSell offer

Buy offerTechnical validation of the market results

Reserves

PLAYERS

TSO

GENCO

DSO

EV Supplier/Aggregator

Elec

trici

ty M

arke

t O

pera

tors

Market Operation

Electric Energy


Reserves

EVOwner/Electricity

Consumer



Electric Energy



Reserves

PLAYERS

TSO

GENCO

DSO


Elec

trici

ty M

arke

t O

pera

tors

Market Operation

Electric Energy

Electric Energy


Electric Energy

Reserves

Reserves

EVOwner/Electricity

Consumer



Electric Energy



Reserves

PLAYERS

RAU

MGAU

TSO

GENCO

DSO


Elec

trici

ty M

arke

t O

pera

tors

Market Operation

Electric Energy

Electric Energy


Electric Energy

Reserves

Reserves

EVOwner/Electricity

Consumer



Electric Energy



Reserves

PLAYERS

RAU

MGAU

TSO

GENCO

DSO


Elec

trici

ty M

arke

t O

pera

tors

Market Operation

Electric Energy

Electric Energy


Electric Energy

Reserves

Reserves

Parking Parking BatteryReplacement

BatteryReplacement

EVOwner/Electricity

Consumer

Parking Facilities

Battery Suppliers



Electric Energy



Reserves

• GENCO – Generation Company

• TSO – Transmission System Operator

• DSO – Distribution System Operator

• RAU – Regional Aggregation Unit

• MGAU – MicroGrid Aggregation Unit



Normal operation – Market environment

EV suppliers/aggregators forecast the EV market behaviour for the next day and prepare their buy/sell bids

Prior to market negotiations, to avoid lines overloading and voltage problems, the DSO evaluates the aggregators’ buy/sell bids changes may be required

Aggregators will buy energy during low demand periods (cheaper) and sell in peak hours will “flatten” the load diagram

Aggregators will buy/sell electricity and provide reserves competing directly with GENCO

After market closure, TSO proceeds to the evaluation of the load/generation schedules changes may be required

Every day the aggregator manages EV according to the market negotiations through set‐points sent to VC and CVC

Every fixed period (~15 min), the EV SOC must be communicated to the aggregator, to assure that EV owners requests are met

PLAYERS

RAU

MGAU

TSO

GENCO

DSO


Market Operation

Electric Energy

Electric Energy


Electric Energy

Reserves

Reserves


BatteryReplacement

EVOwner/Electricity

Consumer

Parking Facilities

Battery Suppliers

Electricity Consummer


Electric Energy

Controls (in normal system operation) At the level ofCommunicates with

Sell offerBuy offer

Technical validation of the market resultsControls (in abnormal system operation/emergency mode)

Reserves



Abnormal system operation or emergency mode – EV managed by the DSO

PLAYERSCONTROL HIERARCHY

DMS

CAMC

CVC

MGCC

Control Level 3

VC

RAU

MGAU

TSO

GENCO

DSO

Control Level 1

Control Level 2


Transmission System

Generation System

Technical Operation Market Operation

Electric Energy

Electric Energy


Electric Energy

Reserves

Reserves


BatteryReplacement

EVOwner/Electricity

Consumer

Parking Facilities

Battery Suppliers

Electricity Consummer


Electric Energy

Controls (in normal system operation) At the level ofCommunicates with

Sell offerBuy offer

Technical validation of the market resultsControls (in abnormal system operation/emergency mode)

Reserves

DMS – Distribution Management System CAMC – Central Autonomous Management System MGCC – MicroGrid Central Controller CVC – Cluster of Vehicles Controller VC – Vehicle Controller



Abnormal system operation or emergency mode – EV managed by the DSO

When grid normal technical operation is compromised, market management is overridden by the DSO

Within a LV microgrid, a single MGCC controls all EV batteries through VC the MGCC is installed in the MV/LV substation

Within a multi‐microgrid environment, all CVC and MGCC in a given MV grid are managed by a single CAMC the CAMC is installed in the HV/MV substation

If needed, CAMC may also control EV, sending set‐points directly to VC

All the CAMC are under the supervision of a single DMS directly controlled by the DSO



Low voltage microgrids environment:

Storage Device

MV

LV

MGCC

Wind Generator

Microturbine

Fuel Cell

PV Panel

Load Controller (LC)

Vehicle Controller (VC)

MicroGrid Central Controller (MGCC)

Microgeneration Controller (MC)

Load

EV EV

EV

EV



Medium voltage multi‐microgrid management architecture:

DMS

CAMC

LC

MGCC

Control Level 1

Control Level 2

Control Level 3

MCLoadSVC OLTCDG CVC VC

LV / Microgrid level

MV level


d) Isolated systems

System operator is responsible for the management of an isolated system regarding local generation, transmission and distribution levels

In the absence of an electricity market, aggregators are useless

Normal system operation:

VC and CVC are controlled by the system operator through MGCC and CAMC

Day‐ahead, the system operator optimizes EV charging using forecasted data on load and generation profiles

During the day, it updates this solution providing real time pricing consumers shift EV charging for cheaper electricity periods harmonizing the load/generation diagram

In some cases, EV response to the system operator’s request may be mandatory to provide safety of operation and to allow increasing the intermittent RES penetration


d) Isolated systems

Abnormal system operation or emergency mode:

The system is controlled in the same way as described for interconnected systems

ONTROL IERARCHY

DMS

CAMC

CVC

MGCC

Control Level 3

VC

Control Level 1

Control Level 2

Transmission System

Generation System

3. Microgrid Islanded Operation

PEV are controllable charges and mobile storage devices that need to be controlled and managed.

Grid connection through inverters (VSI or PQ control mode)

Microgrid Central Controller

3. Microgrid Islanded OperationGrid Interface for PEV

Defining inverter control is a key issue for Smart Charging during normal operation and to ensure MG stable operation during islanding mode.

In interconnected normal mode PEV inverters can be operated in a PQ control mode

During islanding emergency operation a modified PQ control solution should be adopted, provided that a VSI is controlling the MG frequency

actireacti

QP,

1sT1

Q

)ii(kvv ref* i ,v i,v

P battery settings are definedfrom a droop control mode responding to:a) Frequency or voltage changesb) or responding to a hierarchicalsignal.

3. Microgrid Islanded OperationGrid Interface for PEV

• The control law during islanding operation

actireacti

QP,

1sT1

Q

)ii(kvv ref* i,v i,v

MG frequency

Setting point for the battery active power

Additionally an active power voltage droop model can be also adopted.

Defining the set point: Local generation scarcity is taken into account with priority regarding local voltage

3. Microgrid Islanded OperationGrid Interface for PEV – controlling frequency and voltage

Different control laws and droops

otherwise

if

_

___

Vset

Vsetfsetfsetset P

PPPP

Set poit of the inverter


Example

An Example in a three‐phase unbalanced system with single phase EV grid connection (V2G devices)

StorageBalancing unit

• Control of EV batteries

3. Microgrid Islanded OperationResults

Different control laws and droops

Disturbance: One single-phase and one three-phase load were disconnected and reconnected


The control of the EV charging discharging can also take into account the need to balance the system, regarding voltage unbalance

Voltage balancing canbe obtained by changingthe charging rate of EV batteriesin the different phases.

4. Conclusions

New management and control architectures are required to deal with large scale integration of EV in electrical distribution grids.

Smart metering can be adopted to support the development of this control / management concept and serve to provide metering solutions uder this framework.

Combined management of EV charging / discharging together with the control of microgeneration sources brings resilience to microgrid operation, namely in islanding mode.

j. a. p. lopes, "the merge control concept - microgrids and evs - development of management...

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