Browsing by Author "Bian, Desong"

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    An Expert-based Approach for Demand Curtailment Allocation Subject to Communications and Cyber Security Limitations
    Bian, Desong (Virginia Tech, 2017-02-03)
    A smart grid is different from a traditional power system in that it allows incorporation of intelligent features and functions, e.g., meter reading, adaptive demand response, integration of distributed energy sources, substation automation, etc. All these intelligent features and functions are achieved by choosing appropriate communication technologies and network structures for the smart grid appropriately. The objective of this dissertation is to develop an AHP (analytic hierarchy process) - based strategy for demand curtailment allocation that is subject to communications and cyber security limitations. Specifically, it: (1) proposes an electrical demand curtailment allocation strategy to keep the balance between supply and demand in case of the sudden supply shortage; (2) simulates the operation of the proposed demand curtailment allocation strategy considering the impact from communication network limitations and simultaneous operations of multiple smart grid applications sharing the same communication network; and (3) analyzes the performance of the proposed demand curtailment allocation strategy when selected cyber security technologies are implemented. These are explained in more details below. An AHP-based approach to electrical demand curtailment allocation management is proposed, which determines load reduction amounts at various segments of the network to maintain the balance between generation and demand. Appropriate communication technologies and the network topology are used to implement these load reduction amounts down to the end-user. In this proposed strategy, demand curtailment allocation is quantified taking into account the demand response potential and the load curtailment priority of each distribution substation. The proposed strategy helps allocate demand curtailment (MW) among distribution substations or feeders in an electric utility service area based on requirements of the central load dispatch center. To determine how rapidly the proposed demand curtailment strategy can be implemented, the capability of the communication network supporting the demand curtailment implementation needs to be evaluated. To evaluate the capability of different communication technologies, selected communication technologies are compared in terms of their latency, throughput, reliability, power consumption and implementation costs. Since a number of smart grid applications share the same communication network, the performance of this communication network is also evaluated considering simultaneous operation of popular smart grid applications. Lastly, limitations of using several cyber security technologies based on different encryption methods - 3EDS (Triple Data Encryption Standard), AES (Advanced Encryption Standard), Blowfish, etc. - in deploying the proposed demand curtailment allocation strategy are analyzed.
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    Mitigating the Impact of Renewable Variability With Demand-Side Resources Considering Communication and Cyber Security Limitations
    Bian, Desong; Shi, Di; Pipattanasomporn, Manisa; Kuzlu, Murat; Rahman, Saifur (IEEE, 2019)
    With the rapid development of smart grid, the penetration of renewable energy resources is higher than ever and keeps growing. However, the output of renewable energy units, such as solar photovoltaics and wind turbines, is characterized by sudden and unpredictable changes. This paper proposes a novel electrical peak demand curtailment allocation (DCA) method to manage demand-side resources in response to fluctuations in renewable energy outputs. The proposed DCA method can curtail end-use loads faster than traditional demand response (DR) programs and prevent under frequency load shedding (UFLS) operation when facing sudden and unpredictable outputs of renewable energy. This DCA method considers DR potential and load curtailment priority. Case studies are conducted to demonstrate how the developed DCA method can be implemented to mitigate fluctuation in renewable outputs by curtailing electrical demand, considering communication network latency. This paper also evaluates the impact of applying different cybersecurity encryption methods on DCA operation. The simulation results prove that the developed DCA method can mitigate the impact of renewable energy fluctuation and respond fast enough to avoid traditional UFLS operation.