Maximum Frequency Deviation Calculation In Power Systems

The system power is not a constant value, but always changing. in a stablesystem, generation power and electricity power basically balanced all the time. Thepower is the main factors affecting the frequency, when generating power andelectricity power balance, the frequency basically get stability, when generatingpower more than use electric power, the frequency of system increased, if not, thesystem frequency decreased. When the system frequency is lower than48Hz, thepower system will collapse. In our daily lives, almost all of the electrical equipmentfrequencies are50Hz, that is, the electrical equipment can work in this frequency. toensure the user and power plant operation and security. We need to adjust and controlthe frequency, the changes of the system frequency makes no more than±0.2Hz.This paper introduced some basic concepts of frequency in power system, thestatic and dynamic characteristics of the frequency. And give some definitions andconcepts of the frequency adjustment, and some problems of the frequency adjustment.Because of isolated effect caused great harm to the power system, to stabilize theoperation of the system, there must be some anti-islanding capability.Large frequencydeviations due to a number of disturbances are frequent in small isolated powersystems. The maximum frequency deviation in the system is limited to prevent othergenerator tripping. It is important to have an accurate model to calculate it, for systemoperation.A new simplified model to calculate the maximum frequency deviation wheneither a generator or load-related disturbance occurs in these systems is presented.This model takes into account the response of governor-prime mover even whendifferent technologies are present in the power system. Model parameters can beeasily obtained from either more complex models or from test records. Simulationresults for an actual power system aimed at checking the model accuracy arepresented. High accuracy is obtained while computation time is reduced due to thesimplicity of the model. By comparing the governor-prime mover model to the othermodel, the proposed model has better adaptability to different power generationtechnologies, so we can consider apply the model to other systems.