University of Twente Student Theses
Power flow optimization of a renewable energy production hub
Linde, Frederic Paul (2024) Power flow optimization of a renewable energy production hub.
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| Abstract: | A rapidly changing energy landscape gives rise to new means of energy generation. Wind turbines are gaining traction as a cost-efficient renewable energy source (RES). They present opportunities and challenges alike. Naturally, a RES like wind power is uncontrollable. For large-scale utilization, energy delivery from such a source must be reliable. Large variations in production must be reshaped to fit an uncertain, dynamic demand. The replacement of traditional means of energy generation by inverter-based technology is accompanied by dwindling grid inertia. Its deployment has the potential to increase grid stability. Key is the utilization of grid-forming inverters (GFMIs) that can actively stabilize the voltage and frequency on the grid. It can be combined with a control strategy like droop control, relating the grid stabilizing variables to the power flow. This thesis combines a GFMI with droop control and an advanced control strategy to manage the power flow inside an energy hub. The goal is a stable power supply from an uncontrolled source. Proposed is a novel concept, combining the design of an energy production hub with a 3-stage hierarchical model predictive control (MPC) scheme. The hub’s novelty is an integrated energy storage system (ESS), comprising an H2 cycle, a battery unit, and a supercapacitor (SC). The control scheme complements the hub by lever aging forecasts to anticipate production-demand mismatch. It minimizes the mismatch by devising power and state of charge (SOC) setpoints, regulating the storage elements. Detailed exploration focuses on the middle layer, the steady-state target optimization (SSTO) layer. It forms the link between the other two layers, aiming to diminish the mis match between the plant and its model. Functionally, it manages the power flow between the turbine, ESS, and the grid via the inverter and a coupling reactance. Contributed is a mathematical model of the SSTO layer with a quadratic objective func tion. Herein, equations describing the coupling reactance and droop control are reformu lated into constraints. It is investigated whether their addition improves the setpoint syn thetization in the SSTO layer. Conducting a simulation study, an optimization and a plant model are set up. After formulating the optimization model, it is implemented on the plant model to determine how the plant’s dynamics are affected. The simulation shows that the RES power setpoint can be altered by considering the coupling reactance dynamics in the SSTO layer. Power flow changes due to frequency deviations can be adjusted with the droop control gain. With it, the MPC can fulfill grid forming functions. The results are significant because the power flow on the RES side provides power to the inverter. The flow changes in response to varying demands in active and reactive power and to fluctuations in voltage and frequency. |
| Item Type: | Essay (Master) |
| Faculty: | EEMCS: Electrical Engineering, Mathematics and Computer Science |
| Programme: | Systems and Control MSc (60359) |
| Link to this item: | https://purl.utwente.nl/essays/102929 |
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