Stability Studies

The stability study is of a particular value in industrial plants with their own generators and or those with very large motors.

The study provides an analysis of the transient response of these rotating machines following system disturbances and the behavior of the system in relation to the power company tie.

The study is used to determine the effect on generators and or motor performance, system voltage and frequency, all as a function of time.

The study results are due to the following disturbances:
The abrupt changes occur in the system existing loading. This includes the starting effect of large motors on the utility tie and /or local generators.
SC event takes place and its effect on local generators, from which the maximum critical operating time of the protective relays can be determined. (This is the maximum permissible time after the fault inception which the machine can withstand before any
damage occurring.)

The partial loss of local generation or the loss of the power company ties which can occur, and the corrective action needed through load shedding schemes.

The study results will show the machine variables including; turbine input power, generator output power, accelerating power, frequency deviation, rotor angle, field voltage and current, terminal voltage magnitude and angle, and generator current and angle. This data will be shown over the nominal transient time interval of 1 or 2 seconds. The study will plot the swing curve of power angle over the transient power period.
The study will give the magnitude and angle of voltage and frequency deviation, a summary of power flows, and line currents for any bus in the system. The load flow study is a pre –requisite to the system stability study.