Page 286 - Modern Control of DC-Based Power Systems

Simulation 245

6.3 SUMMARY

Throughout this chapter the application of the generation control
strategies presented in Chapter 1, Overview—Voltage Stabilization of
Constant Power Loads (CPLs), were shown on two test systems. The
first consisted of the cascaded converter configuration presented in
Section 6.1. In this system, the influence of different constant power load
representations (ideal, PI, PID) was presented. The simulation results are
in line with the conclusion of the theoretical analysis presented in
throughout Chapter 2 and assuming that the ideal CPL representation
would represent the worst case condition is not correct especially for con-
trol strategies that are model based, like the Synergetic Control. Under
the simulation case of load increase from 10.3 MW - 17.8 MW all con-
trol methods were able to stabilize the bus voltage with a minor voltage
drop during load increase, although none could be identified as “The
best” since depending on system requirements each column in Table 6.2
could be weighted differently; expressly, certain aspects like straightfor-
wardness of control design and synthesis are not to be underestimated.
The second test system was a parallel source multiconverter system
representing the circumstances in ISPSs. Throughout the course of this
book a great number of simulations have been performed (even/uneven
power sharing, averaged/switched LRCs, filtered/non filtered measure-
ments, PI Droop/no-PI Droop, ideal CPL/switched CPL, load
increase/decrease, LRC disconnection); from these combinations a few
scenarios were presented, to be exact:
• Even power sharing;
• Averaged LRC—with ideal CPL—no-PI Droop—Load increase;
• Averaged LRC—with ideal CPL—with-PI Droop—Load decrease;
• Averaged LRC—with ideal CPL—LRC disconnection;
• Switched LRC—with ideal CPL under filtered measurements—no-
PI Droop;
• Switched LRC with switched CPL under filtered measurements—no-
PI Droop.
All presented controllers achieve the goal of voltage stabilization under
even and uneven power sharing conditions. Hence, generation side con-
trol asserts success in addressing the key technical issue of bus voltage reg-
ulation [1] and can enable the deployment of MVDC on ISPSs. The
Synergetic control exhibited oscillations in the transient response for the