Deep-dives on resilience, cross-border sharing of resources and active participation of VRES in the ancillary service market
As part of the research series, conducted by Enel Foundation in cooperation with the leading consulting company CESI, looking at different scenarios for Variable Renewable Energy Sources (VRES) and interconnections deployment in South America at 2030, three topics have been investigated in further detail with reference to the first cluster covering Chile and Argentina: resilience, sharing of resources and participation in the ancillary service market.
The study on resilience aimed at assessing the impact of international interconnection lines on the ability of the power system to withstand extreme events (heavy storms, earthquakes, floods, etc.) and recover as fast as possible. In particular, probabilistic simulations have been carried out to evaluate system adequacy when the unavailability rate of equipment in a specific area – two regions in Chile north of Santiago – is highly increased due to the effect of extreme environmental conditions. Extreme natural events affecting electric power system cause a worsening on the security of supply, which quickly decreases with an increasing intensity of the critical event. The study simulated the expected ability of the system to supply the load in these conditions, finding that the new interconnection between Chile (Polpaico) and Argentina (Gran Mendoza) can significantly reduce energy not supplied up to more than 40% in the most critical week. Also the maximum unserved load can be almost halved thanks to the new interconnection line.
The higher security of supply due to the new interconnection ensures growing benefits with increasing system components unavailability (assuming that the interconnection remains available during and after the extreme event): the benefits from saved load during one week were estimated in the range of USD 12-69 millions.
The study on sharing of resources aimed at assessing the benefits and costs for the power system of Argentina and Chile deriving from cross-border sharing of reserve and balancing resources allowed by dedicating part of the transmission capacity to these services. By means of probabilistic simulations, the variation of benefits/costs linked to the corresponding reduction of the Net Transfer Capacity (NTC) was estimated.
A coordinated management of balancing resources with a part of NTC dedicated to the operating reserve sharing brings advantages to the interconnected Argentina-Chile system. The mutual support between countries allows to use less generation resources during operation, reducing system costs (the energy produced by “reserve generators” at high cost is reduced by 40%), and achieving the same levels of system security. Savings can exceed USD 24 million per year. This points to the opportunity to establish proper regulatory frameworks, agreements and operating procedures between the countries to allow to mutually rely on available resources.
The study on the participation of VRES plants in the operation and control of the power system aimed at analysing how their deeper involvement can lead to a better exploitation of resources reducing curtailments. VRES plants can bring a great benefit in the system operation when participating to the Ancillary Services Market (ASM) with downward reserve, thanks to the lower need of reserve from traditional plants and savings from reduced thermal generation re-dispatching. Proper control systems dedicated to real time control and mid- and short-term production forecasts allow a better integration of VRES in the power system. Improved load and generation forecasts and improved control of generation fleet by means of remote signals for limiting power from control rooms can reduce unnecessary reserve. In addition, distributed storage systems might help in keeping possible variations low and reducing the unbalances. This allows a very precise and optimized operation of the whole system, minimizing the risk of VRES generation curtailments.
A proper regulatory framework must be in place, allowing the presence of VRES in the ASM. Also, the rules for the definition of the price for the downward balancing reserve might need to be reviewed, as VRES do not have any cost saving due to avoided fuel consumption. For an optimal exploitation of the available resources especially in ASM, real time data exchange is essential, to allow TSO/DSO to examine them and plan the short term operation of the system. International protocols for communication are also defined for different types of power plants. The creation of a control room connected to many plants can be beneficial for their control and interface towards TSO/DSO.
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