Functional Design of the mCCHP-RES System - Design for Micro-Combined Cooling, Heating and Power Systems - page 280

Fig. 21 Multi-variable
control of a mCCHP system

m-CCHP system

V

Electrical
subsystem

u St

u p

P St

Th ermal
subsystem

T

u ph

Multivariable
controller

(Fig. 21 ) may give a smaller control to the Stirling engine than a monovariable
controller, so that the dissipated thermal energy should be as reduced as possible.
The electrical power delivered by the Stirling engine is not yet suf cient to

compensate the load, but it is completed by the energy accumulated in the battery.
Obviously, the completion is suf

cient only if the electrical overload does not last
very long. If this persists much longer, then, after the energy accumulated in the
battery is reduced to the minimum allowed level, the Stirling engine operates at
nominal power, even there is a risk of increasing the amount of the dissipated heat.
In the context of using a multivariable controller, the optimal control objective
may be formulated as follows: minimize the loss of thermal energy when the
voltage V and the temperature T are maintained in a given interval, around their
nominal values.

4 System Dynamics Analysis

Emil Ceanga, Marian Barbu and Sergiu Caraman

The analysis through numerical simulation has the following objectives:

to check the viability of different structural models for the mCCHP system, from
the point of view of the performances in steady state and dynamic regimes;

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to select the best functional model of mCCHP from the technical and eco-
nomical point of view that meet the requirements of ensuring the residence
microclimate in winter and summer regimes.

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