The Puerto Rico Grid Redesign Study considers a 10-year planning horizon from year 2020 to 2030. It was supported by advanced techno-economic simulation analysis performed by the ProsumerGrid Integrated Grid+DER Planning Studio®. The study determines the optimal portfolios from a set of broad distributed energy resource (DER) technologies and policy options for transmission, subtransmission, distribution and customers, and meets a set of specific grid requirements and strategic objectives. The specific objectives of this study were to:
- Confirm the long-term vision for Puerto Rico’s electricity system and identify strategic objectives, grid requirements and their success metrics.
- Develop a portfolio of technologies that enable new grid functionality necessary to meet the stated grid requirements and strategic objectives.
- Develop advanced techno-economic assessments of various redesign options at the levels of transmission (T), subtransmission (ST), distribution (D) and consumer critical facilities.
- Develop a multi-layer system architecture and integrated Grid Redesign for a highly resilient, sustainable, economic and customer-centric electricity system.
This study follows a formal Integrated Grid Redesign™ methodology. This process is based on systems architecture principles that support integrated multi-layer (from devices to markets) and multi-scale (T/ST/D) design and validation of complex electricity systems. The methodology also enforces design consistency and integrity and provides clear success metrics and clear mapping of technology options to from grid functionality to strategic objectives.
The Integrated Grid Redesign process is enabled by a novel optimization-based techno-economic analysis, which includes transmission, subtransmission, distribution, critical facilities and key types of distributed energy resource (DERs) options. While optimization-based tools have been broadly available for bulk electricity resource planning, the problem of optimally integrating DERs at the distribution level is new for the industry. Therefore, an analytical tool that supports techno-economic analysis of DERs at the distribution level was needed.
The distribution level simulations use the T/ST boundary conditions (Locational Marginal Price and locational expected restoration times) in order to identify optimal DER portfolios for various distribution circuits. In this study, data was prepared for all the PREPA feeders, but only twenty-two (22) feeders were studied in detail. These feeders corresponded to the islands of Vieques and Culebra, Old San Juan and the area of the Mall de las Américas.
Each one of the distribution feeder simulations determined the optimal portfolio of DERs with respect to: a) all possible locations, which included hundreds or thousands of nodes, b) various types of DERs including solar PV, energy storage, distributed generation and demand response and c) the optimal sizes of the DERs. A comprehensive list of assumptions regarding circuits, DER parameters, DER costs, and financial considerations were utilized. The optimal DER simulations for each distribution system (feeder) also included the baseline simulation and six additional sensitivity simulations: a) higher PV and storage costs, b) decreasing long-term demand forecast, c) lower VOLL, d) larger DG units and e) higher CO2 costs. The solution of the distribution level optimal DER determinations includes probabilistic modeling of the cases with and without connection to the main grid and consideration of the boundary T/ST LMPs and expected locational restoration times.
The simulation of critical facilities and microgrids was conducted in detail for two use cases: Centro de Convenciones and Hospital de la Concepción. The simulations included the baseline and four sensitivity scenarios. In addition, data was prepared for 250 large commercial and industrial customers and detailed optimal DER simulations were conducted for 40 critical facilities.
This study proposes a strong, DER based, bottom-up Integrated Grid Redesign that incorporates 30% of distributed renewable energy by 2030 coupled with the implementation of advanced sensing, control and automation.
The DER-based grid must be developed together with reinforcements to the entire grid and it must be coupled with sensing and controls to provide the ability for islanding and autonomous operation of individual customers, critical facilities and strategically designed groups of customers to form larger microgrids. Strategic improvements in the data models, in particular the T/D interfaces and distribution circuit secondaries can further realize higher fidelity grid models that can support all related DER operational, planning and financial decisions. A market layer must be developed that supports the population demand for higher energy resilience, energy economy and reduced emissions. PREPA could extend its current business model to support new model propositions that enable DER-based grids.
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