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In a power system, when extreme events occur, such as ice storm, large scale blackouts may be unavoidable. Such small probability but high risk events have huge impact on power systems. Most resilience research in power systems only considers faults on the physical side, which would lead to overly idealistic results. This paper proposes a two-stage cyber-physical resilience enhancement method considering energy storage (ES) systems. The first stage calculates optimal planning of ES systems, and the second stage assesses resilience and enhancement of ES systems during the disaster. In the proposed model, cyber faults indirectly damage the system by disabling monitoring and control function of control center. As a result, when detection and response process of physical faults are blocked by cyber failures, serious load shedding occurs. Such a cyber-physical coupling mechanism of fault, response, restoration process is demonstrated in the modified IEEE Reliable Test System-79 (RTS-79). Simulation results show compared with the physical-only system, the cyber-physical system has a more accurate but degraded resilient performance. Besides, ES systems setting at proper place effectively enhance resilience of the cyber-physical transmission system with less load Shedding.

High-cost generator units are at a cost disadvantage in electricity spot markets. This study focuses on revenue mechanisms of gas-fired units affected by power market reform in Guangdong province, China. For the first time, we compare impacts on market indicators of five settlement mechanisms: feed-in tariff (FiT), location marginal price (LMP), contract for difference (CFD), direct subsidy (DS), and estimated revenue method (ERM). In particular, we design key parameters, including authorized CFD and ERM of two kinds of government authorized contracts based on traditional dispatching patterns to avoid significant profit fluctuations brought by market reforms. We also analyze impact of factors such as climbing performance, seasonal load, and subsidy amount on the overall market and its players. Results of a case study show to directly subsidize gasfired units will lead higher-cost units to generate more electricity, with a resulting loss of social welfare. Disruption of market prices and provision of unreasonable incentives are fatal disadvantages of this subsidy method. The government and policymakers should consider financial means to adjust benefits to reduce production costs and increase social welfare. Also, by case analysis, the ERM shows its stable performance in revenue of high-cost units, while we find that authorized CFD is not applicable for gas-fired units whose output is unstable as a marginal unit frequently. Therefore, we suggest government agencies adopt ERM to sign contracts with gas-fired units, to attain a balance between fairness and efficiency.

The accuracy of the simulation model has a profound impact on the optimal operation of the energy hubs (EHs). However, in many articles, the constant model of the efficiency of equipment is adopted to formulate the operation system, which would probably lead to a simplification of the simulation models. But, EHs are typically operated under off-design condition due to the fluctuations in cooling, heating, electricity requirement. Moreover, even though the off-design characteristics are considered, few studies have suggested comparing the differences between those two models by considering the operation cost. In order to assess the effect of the off-design characteristics of EH on the optimal operation accuracy in this paper, two test cases are performed on the fixed and variable load conditions, respectively. In addition, the individual effect of off-design characteristics of each equipment on the optimal operation cost of the EH is also investigated through four optimization runs. It is worth mentioning that the optimal operation problem of the EH considering the off-design characteristics and on-off status of the equipment is a mixed integer non-linear programming problem (MINLP). By testing the design and off-design models on the two cases, the results of simulation demonstrate that the optimal operation cost for the off-design model is larger than that for the design model. Nonetheless, in the aspect of the authenticity of the system operation strategy, the off-design model performs better than the design model. Furthermore, a larger relative error of the system operation cost between the two models can be observed when the EH is operated under a relatively lower load condition, revealing that the influence of off-design characteristic on the optimal operation of EHs is too significant to be neglected.