Design of an Automatic Control Algorithm for Energy-Efficient ...
Design of an Automatic Control Algorithm for Energy-Efficient ...
Design of an Automatic Control Algorithm for Energy-Efficient ...
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6 The optimiser: <strong>an</strong> evolutionary algorithm approach 52<br />
<strong>for</strong>mulations are nonlinear <strong>an</strong>d c<strong>an</strong> contain discontinuities. Finally, it is <strong>an</strong> aim that the<br />
algorithm c<strong>an</strong> be used in future developments <strong>of</strong> the MUTE car (presented in Chapter 9).<br />
This may imply ch<strong>an</strong>ges in the HVAC-system <strong>an</strong>d integration <strong>of</strong> new components. The<br />
extension <strong>of</strong> the controller <strong>an</strong>d its adaption should not be too complicated.<br />
In summary the optimiser algorithm should fulfil the following criteria:<br />
• Robust<br />
• Safe<br />
• Low computational ef<strong>for</strong>t<br />
• H<strong>an</strong>dles discontinuities<br />
• Easy to extend<br />
6.2.2 Gradient based algorithms<br />
For the majority <strong>of</strong> online optimisation problems a so-called gradient method are used.<br />
A prominent <strong>an</strong>d efficient gradient-based optimisation algorithm is sequential quadratic<br />
programming (SQP) [31]. SQP exploits the first <strong>an</strong>d second order derivative in<strong>for</strong>mation.<br />
Compared to other algorithms, this generally leads to a lower number <strong>of</strong> function<br />
evaluations. On the other h<strong>an</strong>d it imposes more requirements on the system <strong>an</strong>d objective<br />
functions. As such it c<strong>an</strong>not h<strong>an</strong>dle non-continuous differentiable objective functions.<br />
Discrete variables are not applicable in this algorithm as well.<br />
Due to these downsides no gradient based method is applied.<br />
6.2.3 Evolutionary algorithms<br />
Evolutionary algorithms (EA) are stochastic methods that were first developed in the<br />
seventies. They were used to solve stationary optimisation problems, <strong>for</strong> example in<br />
construction design.<br />
This class <strong>of</strong> stochastic methods is inspired by biological evolution. A number<br />
<strong>of</strong> sets <strong>of</strong> design variables (so-called individuals) <strong>for</strong>ms a population. Each <strong>of</strong> them gets<br />
assigned a fitness value with the help <strong>of</strong> the cost function �, which could also be a vector <strong>of</strong>