Renewables from a TSO Perspective

M.BENA, SmartGrids Director, RTE, French TSO Vienna, 18 May 2015

8500 employees

Owner and Operator of the Assets

100 000 km UHV and HV lines (400 kV -> 63 kV)

Consumption ~ 480TWh

State-owned company

Largest TSO in Europe

46 interconnections

RTE in Europe

3

Context (1/2)

A major evolution of the electric system is in progress•Today :The electric System used to rely on large synchronous power plants, able to ensure the generation/demandbalance and provide ancillary services (voltage control, frequency control)• Tomorrow :Generation mix will include many decentralized and little generation means, interfaced with inverter-basedcomponents. They will be less predictable, more variable and less controllable.

=> As a consequence : changes are needed to ensure the reliabily of the System and solutions have to befound at the European Level.

ENTSO-E identified several ways to make progress :Develop a more robust Transmission Grid and a more efficient Market Design, able to get advantage

of all efficient flexibilities Increase the Flexibility of Consumers and Generators Develop Smarter Control Centers to optimize the use of infrastructures

GridCodes are a key element

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Context (2/2)

« Connected» Codes•Connection Codes define the requirementsof the installations• Operation Codes define the use of thesecapacities for the System needs

• Market Codes define Designs to takeadvantage of the use of the availablecapacities

Connection

Requirements for generators (RfG)Demand Connection Code (DCC)NC HVDC

• OperationOperational Security Principles (OS) Operational Planning and Scheduling (OPS)Load Frequency Control and Reserves (LFC)

MarketCapacity Alloction and Congestion Management (CACM)Forward Capacity Allocation (FCA)Electricity Balancing (EB)

The question is…

What is the « critical » levels of integration of Renewablesin the European Mix ?

Integration of significant proportion of RES into the grid is technically and economically possible with …

• Adapted rules for connection, more flexibility and services from RES• Dedicated tools and accurate forecasts,• Coordination between Distribution and Transmission System Operators (DSO and

TSO)• Research Projects

… and coordination between European TSO to integrate these productions at a large scale.

Noone knows…but…

Grid Stability- ability to go through a voltage dip- reactive injection in case of contingency

Requirement for Generators (RfG) Code

Main fields where PV units will contribute are :Frequency

- ability to stay connected between 47,5 Hz and 51,5 Hz- ability to control the generated power, in case of under or over frequency- for large units, technical ability to contribute to frequency control- for large units, if the TSO needs it, ability to generate inertia

Voltage Control, for large units- ability to stay connected in a predefined range, for units connectes to high voltage grid- ability to control reactive power- ability to contribute to voltage control

It sets the expected performances for the contribution to the Electric System securityAll generators have a role to play, depending on their characteristicsOne main objective is to avoid a massive lost of small generating unitsfollowing a disturbance on the system

Significant grid users defined by each TSO

D

C

A

B

RPT

RPD

Requirements for frequency control (frequency ranges, limited frequencysensitive mode,

ROCOF…)

Requirements for automatic control (FRT

capability,…)

Active contribution for frequency and voltage controls

800W

PB<1MW

PC<50MW

PD<75 MWOu U>110 kV

The GridCode gives a definition for these four categories mais let each country give moreprecise national ranges (ongoing discussions in France)

PV in future : Grid Code Requirements

PV will participate in :

- voltage control

- frequency control

- synthetic inertia

- fast reactive current injection

Requirements forGenerators (RfG):

Wind farm, PV, synchronous machine…. depends on capacity (MW) 

and voltage in connectionpoint

A balance at any time…• Between demand and production• On behalf of users of the electricity

transmission system • Imbalances due to outages of

power plants, error forecasts of demand… or RES

• Considering also exchanges on interconnections

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Balancing by RTE

Schedules of Production

Demand

Impact on balancing

Balancing Mechanism• With conventional

productions and consumers directly connected to the transmission grid

• RES are excluded of the BM

Influence of RES on interconnections

Reserves have to be available• To ensure this balance and the

security of the system

RES generation and size of tertiary reserves• Forecast error for wind and PV

production taken into account in dimensioning total hazard RTE should cope with.

Time frame

Operational reserves (MW)

Ancillary services

(Automatic)PR

SR

Tertiary reserve

sec 10’ 15’ 2h 8h

500 to 800 MW

>608 MW

PR: Primary Reserve (for Frequency Control)

SR: Secondary Reserve (Load-Frequency Control)

Reserves and RES forecasts

Without previsions norobservations

Impa

ct o

n re

serv

es

TimeFrame

With previsions only

With previsions and observations

The need for RES Supervision

IPES: a system dedicated to RESA tool to collect data relative to wind farms and to provide information to end-users in charge of managing the grid.

Monitoring wind generation with IPESA complete interface to provide different types of data, from measures to forecasts and location of the wind (+ PV) production.

Geographical information about wind & PV farms (location, installed capacity, load factor…)

Technical information (capacity, measures, forecasts…)

Graph of production on a 6 days period (installed capacity, production estimation, forecasts…)

IMPLEMENTATION PLAN 2016 - 2018

RESEARCH & DEVELOPMENT ROADMAP 2013–2022

Inertia, control and protection of large power systems with large share of inverter-based components

The integration of large amounts of renewable generation with power electronic interfaces and introduction of HVDC links into the power system will necessitate a review of how to operate and control transmission networks.

The goal of this topic is to investigate how power systems will behave when the transmission network is fed by large amounts of inverter-based generation, and identify what must be done to allow this equipment to be integrated into the system safely.

More and more components in the European power system are based on power electronics. This equipment feeds harmonic current into the system that, in some cases, can lead to unstable behaviour and impair the reliability of the power system. Entire areas might potentially be fed only by inverter-based generation, such as from HVDC offshore energy.

Therefore, fault detection, power system stability and control, de-rating of transformers due to higher harmonics and harmonic distortion must all be studied. Appropriate tools and methods for building models must be identified for this purpose.

Current control and protection schemes must be reviewed and may need to be redefined to allow stable, reliable and economic operation of the network.

Expected Impact

・ Maximising the volume of renewable generation input whilst keeping the system stable

・ Anticipation of future potential problems

・ Clarification of how this may lead to new control / projection schemes and definition of grid connection rules

Thanks !

Michel.bena@rte-france.com