This project aimed to develop an innovative method of operating networked microgrids to achieve optimal economic benefits, high operating robustness and efficient security support for power systems.
With large-scale installation of distributed generation, energy networks are evolving from conventional passive systems to active decentralised systems such as microgrids. To reduce greenhouse gas emissions and alleviate dependence on fossil fuels, renewable energy sources such as wind and solar dominate today’s microgrids. Unlike conventional fossil-fuel generators, however, wind turbines and solar photovoltaics only generate intermittent, volatile and non-dispatchable power. The uncertainties and intermittency can significantly impair microgrid operation, in terms of reducing economic benefits and triggering operating constraint violations. Thus, it is sensible to develop a robust coordinated operation approach for microgrids to account for uncertainties.
On the other hand, power systems must stay within security and economic constraints. Security constrained optimal power flow (SCOPF) is a powerful tool to balance conflicts between security and economic requirements. As microgrids proliferate, they provide an opportunity to support post-contingency control by managing multiple networked microgrids simultaneously. Therefore, a novel robust SCOPF that accounts for the development of networked microgrids is necessary for future power system security.
This project aimed to develop a robust framework for microgrids to coordinate various distributed energy resources, including distributed generation, energy storage and demand response, as well as a robust SCOPF method using networked microgrids to implement post-contingency control.
This project proposed two microgrid coordination methods aimed at maximising profits for the microgrid operator while satisfying operating constraints. One method focused on energy storage and direct load control, the other on day-ahead price-based response and regular adjustment of distributed generation units. Simulation results indicated high robustness and efficiency. It is concluded that both proposed methods can provide significant economic and technical benefits.
The project also proposed a new SCOPF tool that is able to maintain security in an uncertain operating environment. Multiple microgrids are coordinated to support post-contingency control, i.e. corrective control actions. Rigorous modelling that quantifies the cost for control actions and accounts for uncertainties and contingency cases means robust and secure performance of the SCOPF using multiple microgrids can be achieved. Numerical simulations demonstrate the high effectiveness of the robust SCOPF method. For industrial applications, it can help the system operator enhance system security while optimising economic performance under large-scale intermittent renewable power integration and microgrid deployments.
In future works, the proposed robust coordinated operation framework is expected to be applied in practical microgrid operation problems such voltage/VAR control, demand-side management and multi-energy (power, thermal and gas) dispatch. The proposed robust SCOPF method is expected to be extended considering frequency and voltage stability and resilient operation under disasters.
Zhang, C., Xu, Y., Dong, Z. Y., & Ma, J. (2017). Robust operation of microgrids via two-stage coordinated energy storage and direct load control. IEEE Transactions on Power Systems, 32(4), 2858-2868.
Zhang, W., Xu, Y., Dong, Z., & Wong, K. P. (2017). Robust security constrained-optimal power flow using multiple microgrids for corrective control of power systems under uncertainty. IEEE Transactions on Industrial Informatics, 13(4) 1704-1713.
Zhang, C. , Xu, Y., Dong, Z. Y., & Wong, K. P. (2018). Robust coordination of distributed generation and price-based demand response in microgrids. IEEE Transactions on Smart Grid, 9(5), 4236-4247.