Page 258 - Modern Control of DC-Based Power Systems

222 Modern Control of DC-Based Power Systems

Figure 6.3 LQG estimate and current—Step 10.3 - 17.8 MW.

Figure 6.4 Adaptive backstepping estimates and current—Step 10.3 - 17.8 MW.

converter models and an ideal CPL, the measurement and the estimate of
the inductor current are identical, denoted by the blue and red curve. In
Fig. 6.3 it can be observed how the initial disturbance estimation error,
after the step increase in CPL current, converges after 0.02 s to the true
value of the CPL current. It can also be observed that the offset between
the red and green curve is exactly the linear current part. The shape of
estimates for the Backstepping virtual disturbance controller does not dif-
fer from the LQG estimates as both rely on an identical Kalman filter.
Fig. 6.4 depicts the estimates of the Adaptive Backstepping and the
CPL current, where there exists a slight difference between the estimates
P1 and P2 and here the exponential convergence rate of the estimated
values can be observed. An interesting observation is that both estimates