Integrating high levels of variable renewable energy into electric power systems

As more variable renewable energy(VRE)such as wind and solar are integrated into electric power systems,technical challenges arise from the need to maintain the balance between load and generation at all timescales.This paper examines the challenges with integrating ultrahigh levels of VRE into electric power system,reviews a range of solutions to these challenges,and provides a description of several examples of ultra-high VRE systems that are in operation today.

Guest Editorial:Special Section on Integrating Ultra-High Levels of Variable Renewable Energy

Wind and solar energy have seen significant decreases in the cost of these technologies over that last decade which has lead to increasing levels integrated into the grid.They also offer unique benefits such as no fuel costs,quick installation,and no pollution.But as more variable renewable energy(VRE)such as wind and solar is integrated into electrical power systems.

Economic Dispatch Considering Hourly Capacity Allocation with a Variable Renewable and Hydro-Based Generation Portfolio

The objective of this paper is to assess an economic dispatch considering a power system portfolio, which includes predominant amount of hydro power and increasing quantities of intermittent renewables in relation to the total electric capacity. With growing importance of intermittent wind and solar generation taking part into power systems worldwide, there is need for greater chronological resolution to estimate the flexibility of the power system to offer firm capacity. In this way, a linear optimization model operating hourly is developed to calculate the minimum power system cost, while stablishing the capacity allocation to meet the projected load throughout one-year simulation, as an estimation of how the hourly economic dispatch impacts the scheduling of generators belonging to a power system with this portfolio composition. A central focus is how to operate the available hydro capacity to back up intermittent renewables, evaluating the physical hydro operating constraints, monthly energy balance and maximum power availability. A case study was simulated based on the Brazil’s power system configuration, showing that existing hydro capacity provide hourly flexibility to back-up intermittent renewables, potentially saving 1.2 Billion R$, about 3.6% of total system cost referred to 2019. It is worthwhile to realize that the developed methodology can be employed to other power systems with similar capacity portfolio structure for the purpose of calculating its optimum allocation for a specified region and target year.

Characterization and Trading of Energy Level and Energy Shift Considering Virtual Power Plant

The capability of shifting the electricity generation or consumption to proper time of the day,also defined as energy shift(ES),is the key factor to ensure the power balance,especially under high penetration of variable renewable energy(VRE).However,the ES is not characterized and traded as an independent product in current market mechanisms.In this letter,the marginal utility of an ES is assessed and leveraged to characterize the effective ES,while a novel market scheme is proposed considering the trading of both ES and energy level(EL).The proposed scheme can well integrate ES producers such as virtual power plants that cannot be rewarded sufficiently to actively participate in the current market because they are principally labeled as EL consumers.Finally,the novel concept and mechanism are illustrated by a numerical study and verified to outperform the existing price schemes on integrating the ES resources and VRE.