A Multipurpose Reference System Based on the Hybrid Power Grid of Cape Verde

Abstract

Reference systems are key enabling platforms facilitating the evaluation and comparison of different methods and technologies prior to prototyping and field deployment. In the context of the energy transition, where the number and diversity of the grid-related research is ever expanding, we propose a reference system based on two islands of Cape Verde. These isolated power systems capture the behaviour of modern, mid & large size grids ranging from 20 to 100 % renewable energy penetration, accommodating a very diverse technological mix. The topology is based on the real transmission system as of 2021, considers sector coupling and the role of power electronicsinterfaced units. The Open-Access data was provided by the local system operator and the largest renewable utility of the country. The main objective is to enable off-the-shelf usage by minimizing the amount customization required for any possible study. In that way, it is suitable for a range of traditional and modern studies such as: power flow, energy management, control, stability, reliability, resiliency etc. We showcase the usefulness of this reference system with four short studies regarding grid strength, frequency stability, optimal sizing & placement of battery systems and synthetic inertia provision.

Decarbonizing energy islands with flexibility-enabling planning: The case of Santiago, Cape Verde

“…The binary-integer product 𝜈 𝑜 𝑡,𝑗 𝜎 𝑛 𝜙 𝑡 ,𝑗 is linearized with the auxiliary variable 𝜈 𝑥 𝑡,𝑢 defined in (21) which requires constraints ( 22)- (25). While, the product 𝜎 𝑛 𝑦,𝑗 𝜎 𝑚 𝑦,𝑗 is linearized with the auxiliary variable 𝜈 𝑧 𝑦,𝑢 defined in (26) which requires constraints ( 27)- (31). This integer-integer product is linearized by expressing one of them as a binary number using multiple binary variables.…”

“…This way, the FGEP can be used, not only to plan the most suitable generation and storage mix, but also to shed light on how different policies aiming for the electrification of other energy sectors will affect the overall IES. We have selected the island of Santiago in Cape Verde as the study case given the available Open Access dataset [31,32], and the current goals of the local government of reaching 100% RES-based system by 2050, the ongoing direct and indirect electrification of road and maritime transport via EVs and hydrogen vessels, respectively [33,34].…”

“…Also, it is worth mentioning how the large distances among the islands and the water depth prevents their interconnection. This work employs part of the data available in the recently published Cape Verde Reference System (CVRS), which describes the topology, components, renewable resource and demand profiles of Santiago and São Vicente islands [31]. We focus on the first since it holds 56% of the population, represents 58% of the overall demand, and it has the highest potential to implement DR strategies due to its industrialization level.…”

“…The FGEP configuration is summarized in Table 3, where the base load, RU and RD requirements are expressed as a fraction of the baseline from [31]. A yearly discount rate 𝑟 of 5% is considered ) are taken from the recommendations from IEA [56];…”

A Computationally Efficient Formulation for a Flexibility Enabling Generation Expansion Planning

“…The Cape Verde Reference System [39] is used to evaluate the computational dimension of the proposed formulation in Case A, and the differences in optimal configuration, cost distribution and emissions when flexibility is integrated in a GEP via sector coupling in Case B. We use the isolated network of São Vicente, and plan it for a 20 years horizon with 12 equivalent weeks per year and hourly resolution considering the operational characteristics and costs presented in Table I.…”