Question

An interconnected 60 Hz power system consists of one area with three turbine-generator units rated 1000, 750, and 500 MVA respectively. The regulation constant of each unit is (R = 0.05) per unit based on its own rating. Each unit is initially operating at one-half of its own rating when the system load suddenly increases by 200 MW. Determine

(a) the per-unit area frequency response characteristic
(b) on 1000 MVA system base.
(c) the steady-state drop in area frequency, and
(d) the increase in turbine mechanical power output of each unit. Assume (AP_ref) of each turbine generator remains constant. Neglect losses and the dependence of load on frequency.

Answer 1

To determine the per-unit area frequency response characteristic, scale the per-unit values to a 1000 MVA base and calculate the increase in per-unit frequency and power output. The steady-state drop in area frequency can be found by multiplying the increase in per-unit frequency by the system base frequency. The increase in turbine mechanical power output can be calculated by multiplying the increase in per-unit power by the base power rating of each unit.

Step-by-step explanation:

The per-unit area frequency response characteristic can be determined by calculating the change in per-unit frequency for a given change in per-unit power output. In this case, the system load increases by 200 MW, which can be converted to per-unit power using the base MVA of 1000 MVA. The increase in per-unit frequency can be calculated using the regulation constant of each unit.

To convert the per-unit values to a 1000 MVA base, the per-unit frequency and power outputs need to be scaled accordingly. The steady-state drop in area frequency can be calculated by multiplying the increase in per-unit frequency by the system base frequency of 60 Hz. The increase in turbine mechanical power output can be calculated by multiplying the increase in per-unit power by the base power rating of each unit.