The changing resource mix is creating significant concerns with the owners, operators, and regulators of the bulk power system (BPS), as the new resources do not behave in the same way as the legacy resources, and reliability may be impacted. Large rotating machines have historically provided energy, as well as essential reliability services such as inertia, to help the power system to recover from a frequency event, ramping capability to follow changing loads and voltage support. Many of the new resources either cannot provide these essential reliability services, or were not initially designed to provide them. They were designed to provide renewable energy to serve the load.
