Power System Management with intermittent generation Renewable energy, power systems and forecasts

MEDELEC

16th April 2014

SUMMARY

1. Renewable generation: principles and current status 2. Power system management with renewable

generation 3. The grid and the renewable generation 4. Monitoring renewable generation

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3

01

Renewable generation: principles and current status

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Wind power: principles

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From the windmill … • Average power: 3MW • Large dimensions (diameter and

nacelle height = 80m) • Partly connected to the grid

through power electronics • With a known operating range

MEDELEC – 16th April 2014

0.5 Pn

Production (MW)

Pn

Vitesse démarrage

Vitesse décrochage

Vent

Courbe caractéristique du domaine de fonctionnement d’une éolienne

Characteristic curve of a farm? … to generation farms • With variable configurations • Whose operating mode depends on the

many factors (environment, localization…) • Generally connected at the distribution

level, so usually not directly observable by the System Operator.

Overview of a windmill Windmill operating domain

charasteristic curve Generation (MW)

Starting wind speed Dropping wind speed

Wind

P = f(w)?

Power

Wind

Photovoltaic: principles

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A power generation without moving parts • Various installation configuration • From individual household roofs to large scale fields • Mainly depending on sunshine but also on other factors (temperature, snow…) • Fully connected to the grid through power electronics

Direct radiation

Temperature

Clouds

Wind

Indirect (diffuse and reflected) radiation

Geographic location Altitude

Technology Peak power

Tilt

Inverter characteristics

Maximum subscribed power

Characteristics (not known) Meteo

Subscribing data

Orientation

Renewable energy in France and continental Europe

Wind and PV in continental France (mid 2013)

• 12 GW installed (wind: 8 GW, PV: 4GW)

• Wind: more than 800 farms (>1MW)

• PV : around 250 large installations (>1MW) … and more than 280 000 small ones!

• Largely connected at the distribution level (<63kV).

• Between 50 and 70 GW are expected in 2030

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In continental Europe • Around 180GW installed in

December 2012…

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Installed wind power by department on 2013-03-31 (MW)

Installed PV power by department on 2013-03-31 (MW)

Source: SOeS with data from ErDF, RTE, SEI and distribution companies

PV Wind

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Intermittent generation Thanks to meteo geographical diversity, the total generation variations are overall smoothened compared to the local ones.

For wind power…

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Load

rat

io (

%)

Continental France Brittany One farm in Brittany

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Intermittent generation … and for PV.

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PV generation variations From the installation to the national level with 10 mn timesteps

Installation Substation Department Region France

Load

rat

io (

%)

Compararison with conventional generation

Incertain and variable generation… • Yes for wind and PV • No for reservoir hydroelectricity, geothermal power, tidal stream generation, biomass generation Importance of forecasts at various horizons.

…with various connections to the grid…

• Yes for wind of PV. • No for other renewables • Windmills: DFIG (Double Fed Injection Generator) • No more synchronous machines • No more inertia Both advantages and drawbacks for the stability of the grid.

…mainly at the distribution level

• Partly non observable and non controlable (for the System Operator and sometimes even for the Distribution System Operator) • Distribution grids are generating power Importance of information exchanges with the DSO.

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02

Power system management with renewable generation

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System Balancing Real-time balancing…

• Between load and generation • In the name of the Balancing

Responsible Parties (BRPs) • Handling all differences linked to the

tripping of power units, to load forecasts errors

Adjustment made by RTE

Σ Generation schedules of BRPs + Renewable gen forecasts

Load

… also including • Generation variation from renewable

energy sources • Thus the use of renewable

generation forecasts for short-term balancing.

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Renewable generation (wind+PV) and French load From 2013-01-15 to 2013-01-31 (half-hour averages)

Fren

ch lo

ad (

MW

)

Rene

wab

le g

ener

atio

n (M

W)

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Frequency control: The importance of reserves… Balancing and various controls

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seconds

Primary Reserve (FCR)

Secondary Reserve (FRR)

Tertiary Reserve (FRR)

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Reserves should be available… • To ensure the balancing of the system

Renewable generation and reserve sizing • Variable generation forecast errors (wind and PV)

taken into account to estimate the aleas that have to be handled by RTE

Horizon

Operationnal reserves (MW)

Ancilliary services

(Automatic)

PR

SR

Tertiary reserve

few s 10’ 15’ 2h 8h

500 to 800 MW

>608 MW

PR : Primary reserve

SR : Secondary reserve

Sizing of reserves for balancing

Ren. Gen. variability rapid reserve ≤15mn

Ren. Gen. forecast errors slow

reserve ≥ 30mn

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At a given time for one horizon: Generation

Consumption

Wind

PV

total alea accepted risk level

Minimal margin required versus horizon

Mar

gin

(MW

)

Horizon (hour) Disconnection of a thermal generation unit

Load forecast error PV or wind generation forecast error

Total alea at a given time for a given horizon Xth quantile determined according to the

accepted risk of requiring to exceptionnal means

Generation

Consumption

Wind

risk

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Impact of renewable generation on margins

On the reserves … • Intermittent generation add « noise » to the balancing • For wind, given their dynamic characteristics at the French level:

On primary reserve (FCR): no impact (slow dynamic) On secondary reserve (FRR): no or limited impact for now if real time metering

available. Significant impact forecasted above 8-10GW connected On tertiary reserve (RR): significant impact. Actions are to be taken (forecast, tele-

metering, margins) • For PV, studies are ongoing.

Without forecasts and real-time observation

Only with forecasts

With forecasts and real-time observation

Req

uire

d m

argi

n vo

lum

es

Horizon (in hour)

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03

The grid and the renewable generation

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Network safety implies real-time management of congestions on the transmission system

Being compliant with operational rules and so, mastering the flows on the grid, requests reactivity regarding renewable generation dispatching.

« The delays for building renewable installation and network elements may leads to congested situations on the grid »

• 1 year ½ to 3 years ½ to build a plant

• 6 to 10 years to build a connecting line

Grid operation with variable generation

Grid operation with variable generation One example* of grid management:

1. Part of grid with low load and high wind generation.

2. If a constraint appears in one substation (N-1), injections may result in overloadings.

3. Wind forecasts are monitored and alarms configured in order to anticipate overloadings. Monitoring of

wind forecast

* Automates may also be integrated to automatically limit the generation of installations in case of overloading

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Grid maintenance with renewable generation

Forecasts may be used to optimize the scheduling of the preventive maintenance

1. Part of grid with hydro and wind generation

2. One-day maintenance operation to be scheduled

3. Monitoring of the wind generation to optimize the scheduling when the generation level is low.

Monitoring of wind forecasts

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Grid development

Long-terme forecast study (10 to 20 years) taking into account the evolution of the energy mix

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Source : RTE – schéma décennal 2012

Larger and more volatile North-South flows linked to the development of wind and PV in France and neighbour countries.

Wind

PV Sea

Biomass

Development of renewable energy according to the European Commission

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04

Monitoring renewable generation

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IPES V1 – A renewable generation monitoring system

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Cartographic representation

Element detail

Alarm zone

Generation curves

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Screen shots (1/2)

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Screen shots (2/2) Installed capacity per DSO (ErDF, ELD)

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