Field assessment of generators reactive capability

Utilizing generators´ reactive capability to the full has become critically important over the last ten years. Voltage stability studies reflect actual power system conditions only as long as utilities assess their generators´ actual reactive capability. Just as important, the system dispatchers and plant operators should be aware of the power system´s actual reactive capability and have a good understanding of the impact that power plants´ VAr production has on power system voltage. This paper describes the Public Service Company of Colorado´s experience in maximizing its generating units´ overexcited reactive capability. As a result of PSC´s effort, an additional 500 MVAr of previously unused reactive power were “released” to the power system. Furthermore, this paper presents PSC´s experience in educating power system dispatchers, power plant operators and engineering personnel on the subjects of voltage collapse phenomenon and VAr scheduling in a power system