Towards Joint Electricity and Data Trading: A Scalable Cooperative Game Theoretic Approach

This paper, for the first time, proposes a joint electricity and data trading mechanism based on cooperative game theory. All prosumers first submit the parameters associated with both electricity and data to the market operator. The operator utilizes the public and prosumers' private data to forecast the distributed renewable generators (DRGs) and quantify the improvement driven by prosumers' private data in terms of reduced uncertainty set. Then, the operator maximizes the grand coalition's total payoff considering the uncertain generation of DRGs and imputes the payoff to each prosumer based on their contribution to electricity and data sharing. The mathematical formulation of the grand coalition is developed and converted into a second order cone programming problem by using an affinepolicy based robust approach. The stability of such a grand coalition is mathematically proved, i.e., all prosumers are willing to cooperate. Furthermore, to address the scalability challenge of existing payoff imputation methods in the cooperative game, a two stage optimization based approach is proposed, which is converted into a mixed integer second order cone programming and solved by the Benders decomposition. Case studies illustrate all prosumers are motivated to trade electricity and data under the joint trading framework and the proposed imputation method significantly enhances the scalability

Consensus-Based Distributed Control for Photovoltaic-Battery Units in a DC Microgrid

In this paper, a distributed cooperative control scheme, considering the state-of-charge balance and power limits of battery-storage units (BSUs) in the consensus protocol, is proposed to achieve the average bus voltage consensus in a dc microgrid with photovoltaics. The state variable defined in the consensus protocol enables all BSUs to charge or discharge together without introducing circulating currents among BSUs. Furthermore, by incorporating power limits of BSUs in the defined state variable, power violation of the BSUs can be prevented. The consensus-based distributed control only utilizes neighbor-to-neighbor communication to realize the global consensus, and, thus, avoids the single point of the failure compared to the conventional centralized control. Simulation and experimental results demonstrate the efficacy of the proposed method in an islanded dc microgrid under different testing scenarios

Advanced control of multi-microgrids for grid integration

Thanks to tremendous growing interest, the significant number of microgrids form a system called Multi-Microgrid, where multiple microgrids are interconnected to support local loads and exchange power to or from grid. Industry demands for advanced control and optimal coordination among microgrids with consideration of high penetration of renewable energy and complex system architectures. This thesis focuses on different key aspects of power systems and microgrids to develop novel approaches targeting the problem. Firstly, different topologies of microgrids are studied from the literature review and most popular system architectures are considered in the study for proposing advanced control techniques. Distributed control systems with nested formation in the microgrids are proposed for improved power sharing strategy. The distributed control is designed to achieve self-healing capability of multi-microgrids during any contingency event. Local controllers of the inverters in each microgrid are interconnected through the nested formation. A nested optimization algorithm is designed to achieve power exchange between different microgrids. Multi-terminal HVDC network based multi-microgrids have been proposed for advanced control strategy due to its widespread application in power system. Adaptive droop control has been proposed based on consensus algorithm and matrix-based solutions to provide frequency support and power sharing between AC microgrids through the HVDC network. The proposed adaptive droop algorithm is featured to maintain frequency and voltage during contingency events and ensure efficient power sharing. Distributed hierarchical control system is proposed as well for multi-microgrids with nested formation-based optimization techniques to ensure proper power sharing in four-level based multi-microgrid topologies. The algorithm features energy management within the multi-microgrid through virtual controllers of primary and secondary frequency control. In addition, to the energy management issue, low system strength of grid has been considered to offer a wide range of areas under the advanced control of multi-microgrid. In that regard, single machine infinity bus model has been considered to implement control of grid forming inverters for integration with weak grid. Novel grid resynchronization and virtual synchronous generator control has been proposed to achieve multi-microgrids integration with weak grids. Then, various simulation studies are performed to test the effectiveness of the proposed controls. The time domain simulations are performed on EMT power system tool PSCAD under different operating conditions, such as loading variations, N-1 contingency events, grid frequency change disturbance, islanding conditions etc. In addition to the time domain simulation studies, stability analysis of the proposed control has been carried out. In the stability analysis, pole-zero map, Nyquist plots and Bode plots have been demonstrated to analyse the stable conditions of the proposed control. The optimization algorithms results are also included in the simulation studies to reflect the performance of the control. Finally, the advanced control solutions outcomes through time domain and stability results are compared with conventional control. It has been demonstrated that all proposed solutions perform better than conventional approaches and reflect significant improvement on the multi-microgrids. Furthermore, industry standards have been considered in the weak grid integration study and case studies are carried out based on power industry practices, including industry regulatory grid codes according to the power industry in Australia. The results indicate that the proposed controls are able to satisfy industry grid codes