Coordinated Voltage Control in Real Time Simulations of Distribution Network with Distributed Energy Resources
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Koordinoitu jännitteensäätö hajautettuja energiaresursseja sisältävien jakeluverkkojen reaaliaikasimuloinnissa
Voltage rise effect in distribution networks poses challenges in future when increasing amount of Distributed Energy Resources(DERs) are connected to the network, and currently is the limiting factor of the network's DER hosting capacity. Passive approaches reinforce the network to increase the hosting capacity but alternatively coordinated voltage control schemes are capable of utilizing the DERs widely across the network. Using reactive power capability of distributed generators, production curtailment or substation voltage control in coordination, desired network voltages can be achieved and e.g. losses minimized. However, this requires accurate information on the state of the whole network. Distributing the automation and control decision making across network voltage levels reliefs data transfer burden to control centers where the decision making is typically centralized. This allows better utilization of large scale of resources in optimizing the network operation. With Substation Automation Units(SAUs) the above can be realized in distribution networks. This thesis presents the SAU based architecture, and required algorithms to demonstrate a decentralized automation system and coordinated voltage control in a distribution network. Case study was performed for real LV distribution network in Real-Time Digital Simulator. Main focus was to verify correct operation, and to analyze performance of coordinated voltage control compared to other control schemes under real and artificial network conditions. Under demanding network conditions, coordinated voltage control proved to be superior by avoiding over-voltages and conductor thermal limits. The results validate viability of the automation architecture and effectiveness of the coordinated voltage control scheme. Real network demonstrations are follow-up for this thesis' work.