The Role of Low-Load Diesel in Improved Renewable Hosting Capacity within Isolated Power Systems

Abstract

Isolated communities are progressively integrating renewable generation to reduce the societal, economic and ecological cost of diesel generation. Unfortunately, as renewable penetration and load variability increase, systems require greater diesel generation reserves, constraining renewable utilisation. Improved diesel generator flexibility can reduce the requirement for diesel reserves, allowing increased renewable hosting. Regrettably, it is uncommon for utilities to modify diesel generator control during the integration of renewable source generation. Identifying diesel generator flexibility and co-ordination as an essential component to optimising system hosting capacity, this paper investigates improved diesel generator flexibility and coordination via low-load diesel application. Case study comparisons for both high- and low-penetration hybrid diesel power systems are presented in King Island, Australia, and Moloka`i, Hawai`i, respectively. For King Island, the approach details a 50% reduction in storage requirement, while for Moloka`i the application supports a 27% increase in renewable hosting capacity.

An Energy Management Approach for Isolated Power System using Low Load Diesel

“…During periods of excess RE absorption, a diesel engine operates at low load in Hybrid Isolated Power System (HIPS). At certain situations, the operator has two options: keep a constant diesel output while spilling extra RE, or reduce diesel output while absorbing more RE [24]. LLD technology is the capability to run diesel generator below conventional load limits in order to accept greater RE input.…”

“…LLD technology can be simulated by modifying engine specific delay (τ1). Utilizing the Watson method to forecast τ1, the value must be 0.3-0.5ms greater for LLD as compared to conventional generators [24].…”

Review of Efficiency Improvement Technologies of Wind Diesel Hybrid Systems for Decreasing Fuel Consumption

“…Using low load DG allows the decrease in fuel consumption of WDHS with high wind penetration rate by 6.3%, compared to running fixed speed generators, as well as the decrease in the ESS installed capacity. However, frequent purging is required for the engine normal operation and its service life maintenance in this operating mode [84]. Diesel engines operating at low loads must be brought up to high loads (at least 40-50% of full power) regularly to avoid operational problems.…”