Pontificia Universidad Católica de Chile Departamento de Ingeniería Eléctrica. Experiencia europea

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1 Pontificia Universidad Católica de Chile Departamento de Ingeniería Eléctrica Experiencia europea Hugh Rudnick Van De Wyngard FORO Integración de energía renovable a gran escala: Desafíos del operador del sistema eléctrico 22 de Junio de 2011

2 Chile se compromete con las renovables Ley N (2008) obliga a que un 10% de la energía comercializada provenga de fuentes renovables ERNC al 2024 Analizando elevar la cuota a un 20% 10% 9% 8% 7% 6% 5% 4% % anual fijo 0,5% anual adicional 2

3 Desafíos operacionales energías renovables Comportamiento variable, con gradientes importantes. No acople de forma de generación con curva de la demanda. Baja confiabilidad para cubrir las puntas de demanda. Reducida producción en periodos de punta de verano e invierno. Dificultad de predicción: tasas de error fuertemente crecientes con el horizonte de previsión. Desconexión intempestiva ante caídas de tensión. Eólica y solar 3

4 Impacto de las renovables en el mercado 4

5 Unión Europea pionera en su desarrollo 5

6 Objetivos Unión Europea Directive 2009/28/EC-targets an overall quota of 20% share of renewables in final consumption of energy by In terms of electricity generation, share of renewables will reach between 30-35% by 2020 Based on intermittent and unpredictable sources-expected wind (42%) and photo voltaic (4%) Hydro (31%) and biomass (22%)-flexible and relatively controllable energy sources Wind and solar generation will be far more challenging to integrate in the system; will have the greatest influence in reshaping of the electricity markets and grids over the next decade. 6

7 Capacidad instalada en España 7

8 Capacidad instalada en Alemania 8

9 Impactos en requerimientos Increased renewables will lower the need for generation from fossil fuelled power plants. Base load plants, including low carbon technology such as nuclear and fossil fuelled plants with CCS, may have to be operated intermittently. Flexible conventional power plants will still be required, but will be operating fewer hours than similar plant in today s market There will be greater requirements for ancillary services to balance the system and redispatch services to deal with transmission congestion. Urgent requirement to expand and reinforce the transmission system and integrate markets. 9

10 Impactos en seguridad Security of supply may also be affected in a number of different ways. Short term volatility will increase due to the very different merit curves produced by weather dependent renewables, such as that on a windy and sunny day and those on a cloudy day without wind. Development and accommodation of renewable energy sources is only possible with the speedy introduction and effective implementation of market integration. 10

11 Volatilidad de precios aumentará For wind-energy, marginal generation costs are very low. Depending on the amount of expected wind energy, there will be a different structure of marginal costs in the market and, as a consequence, a shift of the supply curve Spot prices Market price Demand curve Spot prices Market price Demand curve Merit order Merit order Baseload Plant Medium load Plant Depending on the wind injection and the actual supply/demand curve, prices will change much more from hour to hour compared to a case without wind injection. Peak Plant Wind Farm 11

12 Se originarán precios negativos Increasing injection of RES will lead to more periods of time (mainly during weekends and especially during night hours) in which there is a combination of a very high injection of wind energy with low demand of electricity. Conventional plants will have to be regulated downwards. But technical minimum output requirements will imply they may need to be shut down. Other constraints, such as minimum down time; ramping rates for up and downwards regulation, etc., will imply preferring to keep plants running. Negative prices will arise, because it is still cheaper to pay somebody for taking the energy than stopping the plant and starting it again shortly thereafter. Some power exchanges have introduced negative price boundaries and force to disconnect or reduce wind output. 12

13 Precios negativos en ERCOT- EEUU 13

14 Mecanismos controlar precios negativos Development and introduction of smart grids, will allow household customers the negative spot prices and thereby get the direct signals to respond and adapt their consumption behaviour accordingly, depending on the type of supply contract. Negative prices will also stimulate investments in different electrical energy storage facilities which consume electrical energy when prices are low and deliver it back to the grid at times when prices are high (pump storage). Strengthening transmission: regions with abundant low price injection should be provided with sufficient grid capacity to export the low (and in particular negative) prices to other price areas. Negative prices would probably not occur if there were no grid constraints. 14

15 Necesidad repensar reservas Traditionally, the amount of balancing energy, or reserve, provided by controllable thermal or hydro generation had to be sized to balance variations in demand or forced outages of largest production unit. Therefore, the reserve was mainly required for upwards regulation. Large penetration of intermittent and in particular wind generation introduces additional requirements for balancing products and services. Wind generation has a limited predictability; in order to cope with the forecast error, larger amounts of flexible sources are necessary. Even with perfect forecasting, wind generation will remain intermittent, i.e. non-controllable, and very variable from one hour to another, and for this reason additional flexibility is required. 15

16 Predicción eólica Wind forecast error can be either negative or positive thus requiring not only upwards, but also downwards regulation. However, in general, there is a portfolio effect which partially reduces the wind forecast error by considering the cumulative output from all wind farms as compared to the forecast error from an individual wind farm. Electricity systems with a high penetration of wind generation have higher exposure to problems related to the grid stability. The availability of an appropriate amount of reserve power plants and their flexible dispatch becomes increasingly important to provide the necessary ancillary services. 16

17 Intermitencia/ impredictibilidad eólica Day-ahead forecast errors of between and MW occurred in November On the 24 th there was a high level of wind generation during off peak hours, whilst this reduced by about 7000 MW during peak hours. 17

18 Efecto protección turbinas eólicas Over-speed protection of wind turbines when wind blows at high speeds: difference of over 6000 MW in Spain on 23rd/24th January 2009 between wind generation forecast and actual production, as a result of over speed activation protection. 18

19 Se requerirá más reservas Need to procure higher amounts of reserve as compared to similar sized system without intermittent generation. About 0,25 to 0,3 GW of additional reserve per GW of additional wind capacity is required. Additional requirements imply an increasing amount of mandatory dispatching of thermal units. Reduces the capability of generators to manage their portfolio (trading with these units is limited), and reduces thus the offers on the commodity market. Costs to reserve the band of secondary regulation and the additional spinning reserve for tertiary purposes are socialized in most markets. Higher wind penetration might not only affect the costs for balancing the system, but depending on the location of the wind generation, a higher congestion management cost via redispatching will become necessary. 19

20 Generación eólica con similares exigencias Directive should not exempt wind generators from their scheduling and balancing obligations. Wind generation development should be promoted through the regular support schemes and not through specific grid and market arrangements (including congestion management arrangements) which could generate adverse effects and market distortions. Best practices show some measures to ensure a proper integration of wind generation in the markets as the adscription of wind farms to centralized Control Centers, which allows the system operator monitoring and control of renewable energies and to collate real time measurements of their production in order to perform real time security analysis to enable the co-ordination of associated balancing actions. 20

21 Predicción eólica ha mejorado, pero Errors in forecast of day-ahead wind generation have decreased in the last few years but they are still much higher than errors when the forecast is made few hours before real time. Figure shows level of error in wind generation prediction when forecast is made 48 hours in advance. 21

22 Se requerirá capacidad de respaldo Wind is primarily an energy resource and not a capacity resource, with a key value in terms of offsetting fuel consumptions and the resulting emissions. Load factor duration curve on an hourly basis for the Spanish and German electricity system during 2008: average load factor of LOAD FACTOR DURATION CURVE OF WIND GENERATION ,74%. (Germany and Spain) 0,9 0,8 0,7 Germany Spain Load factor 0,6 55,2% 0,5 0,4 0,3 0,2 Average 21,74% 0,1 3,9% % of time (438 hours) hours 95% of time (8.345 hours) 22

23 Se requerirá capacidad de respaldo On average, only 3,9% of the total wind installed capacity has a level of firmness of 95%. Only a small share of wind capacity can be considered firm, therefore a considerable amount of conventional capacity is needed as flexible back-up generation. Around 55% of wind installed capacity has a level of firmness lesser than 5%. In fact, the level of injection of wind generation never reaches a percentage higher than 77% (this limit is higher in Germany but lower in Spain), so 23% of installed wind capacity can be considered as fully unavailable. Reduction of load factor plants of existing conventional plants will weaken their ability to recover its fixed costs and may lead to earlier decommissioning decisions. Market design rules may need to be reviewed. 23

24 Necesidad mayor flexibilidad de generación More flexible plants (like hydro, pump storage, OCGT and CCGT) will be required. Technological developments and investments might be made to allow for a quicker response (faster ramping speed) from conventional plants to provide support to the system, or to reduce the plants minimum operating levels from the usual values. Investment on variable speed pump turbines. Demand side management (DSM) instruments. Need for storage capacity (pumping plants, gas storage, district heating systems or electric vehicles). 24

25 Se puede requerir pagos por capacidad Most European markets are nowadays energy only markets. Some of them are complemented with capacity reservations, some others have capacity incentives schemes in place. Regional scale capacity investment incentives may have to be implemented if the prices do not provide enough return over capital. 25

26 Se requerirá mayor integración/transmisión Market integration tools - market coupling, cross-border intraday and cross-border balancing - are indispensable in ensuring and facilitating the contribution (on a competitive basis) of all available flexible sources throughout Europe. Grid reinforcements are the key enabler to allow markets cope with large volumes of intermittent renewables. The introduction of high levels of renewables will not only heavily affect both distribution and national transmission networks, but also transmission networks in adjacent and further away countries. 26

27 Condiciones de Chile Volumen importante de generación hidroeléctrica de embalse, con capacidad de regulación (en el Sistema Interconectado Central). Incertidumbre hidrológica puede reducir notablemente la capacidad de regulación. Contribución de embalses con reducción relativa en el tiempo, en la medida que crece la demanda. Resistencia pública creciente al desarrollo de nuevos embalses. Importantes restricciones de reserva/regulación rápida en el SING. Restricciones de transmisión restringiendo transferencias ERNC. Mini/micro hidros, biomasa y geotermia sin impactos significativos en la operación. Desafíos importantes con la incorporación masiva de generación eólica, y en menor grado solar, en la operación del sistema. 27

28 Pontificia Universidad Católica de Chile Departamento de Ingeniería Eléctrica Hugh Rudnick Van De Wyngard Profesor Titular Departamento de Ingeniería Eléctrica Pontificia Universidad Catolica de Chile Vicuna Mackenna 4860, Casilla 306, Correo 22, Santiago, Chile Fono or Fax