University of Groningen
Distributed control of power networks
Trip, Sebastian
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Publication date: 2017
Link to publication in University of Groningen/UMCG research database
Citation for published version (APA):
Trip, S. (2017). Distributed control of power networks: Passivity, optimality and energy functions. Rijksuniversiteit Groningen.
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Summary
S
ocial and technological developments resulted in an increase of electricity de-mand, generated by an ever increasing amount of renewable energy sources. Despite its potential benefits, a continuation of these developments poses signifi-cant challenges to the planning and operation of the existing power networks. An important operational aspect in power networks is the regulation of its frequency, which is the focus of this work.In the presence of more and smaller generation units, careful coordination among the individual parts in the power network is needed, ensuring proper overall functi-oning. We design and analyse distributed controllers, that ensure that actions taken by local controllers are consistent with global optimality objectives, such as the mi-nimization of generation costs. The total energy of the power network plays a major role in this process, enabling the derivation of useful system theoretic properties without detailed knowledge of all components. Particularly, this work shows that energy functions are suitable to derive passivity properties of various nonlinear po-wer system models, that form an excellent staring point for the controller design. Proposed controllers are shown to regulate the frequency and to obtain an econo-mic dispatch.
The presented results explicitly incorporate two aspects that received less atten-tion despite their practical importance. First, since generated control signals conti-nuously adjust set points at the generation side, it is important to take into account the behavior of the generation side in a satisfactory level of detail. To this end, this work incorporates the turbine-governor dynamics in a more realistic manner than generally done in stability studies on optimal frequency regulation.
Second, an important aspect of proposed distributed solutions is the exchange of information among controllers over an underlying communication infrastructure. The combination of the continuous physical system and the digital communication,
210 Summary leads to an overall (hybrid) cyber-physical system. As a result of the stability analy-sis, we derive explicit bounds on the required communication intervals.
We show that it is, although challenging, of importance to incorporate the gene-ration side and the communication network explicitly in the design phase of control-lers and that neglecting these aspects can result in an unjustified belief that stability of the network is guaranteed by suggested solutions.
