Provision of ancillary services by renewable hybrid generation in low frequency AC systems to the grid

Abstract

Wind energy high penetration levels in power systems lead to continuous power imbalance due to the intermittent nature of wind power. This paper proposes and investigates different methods to enable a hybrid generation system to provide frequency support to the grid. The hybrid generation is 100% renewable and composed of a wind farm and hydropower plant (HPP) of comparable generation capacities, and they are interconnected through a Low Frequency AC system (LFAC). The grid-tie is composed of a Voltage-Source Converter based High-Voltage, Direct Current (VSC-HVDC) junction that acts as frequency changer to maintain the grid nominal frequency. The HPP provides two types of ancillary services: wind power smoothing and frequency drops mitigation to avoid the use of thermal generation and battery energy storage. The paper offers different control methods to provide the two AS with improved coordination between the different controls in the hybrid generation system and complying with the common requirements of Grid Codes. The results obtained show that the frequency at the LFAC can tolerate mild drops to provide frequency support to the grid. The controllers' parameters have a clear impact on the frequency response at both systems. Simulation environment is MATLAB and Simulink.

A Simulation of Market-based Non-frequency Ancillary Service Procurement Based on Demand Flexibility

“…The PV inverters in [28] are used for reactive power and harmonic current compensation based on different control strategies applied to single-phase and threephase PV inverters. Similarly, wind generation is used as a base for AS provision in [19], [29]. References [21], [28] and [30] also consider the acquisition of AS at a domestic level using a specific appliance, e.g., a fridge-freezer.…”

“…Table I presents a list of works related to AS acquisition at local level classifying the asset used to provide AS, the AS product, the AS type, the AS variable, and the AS negotion. References [14], [19], [24] - [29] consider DERs as an asset for AS provision. Besides, [15], [32] and [37] provide AS from the ideal operation of the system as a whole.…”

Onsite Tests of Controlling a Large Constant Speed Centrifugal Chiller for Grid Frequency Regulation

“…Renewable energy is projected to reach 40% of the global grid power generation in the 2040s [1]. However, the high penetration of such intermittent renewables would put high stress on the stability and safety operation of the grid [2].…”