Junjian Qi

Dr. Junjian Qi

orcid

Research Focus & Metrics

Academic Career Length

16Years (2011-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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23 January 2019 in IEEE Transactions on Power Systems
Verified
Journal Article
Closed access
JZJunbo Zhao
Junbo Zhao
Junjian QiJunjian Qi
Junjian Qi
ZHZhenyu Huang
Zhenyu Huang
AMA. P. Sakis Meliopoulos
A. P. Sakis Meliopoulos
AGAntonio Gomez-Exposito
Antonio Gomez-Exposito
ASAbhinav K Singh
Abhinav K Singh
This paper summarizes the technical activities of the Task Force on Power System Dynamic State and Parameter Estimation. This Task Force was established by the IEEE Working Group on State Estimation Algorithms to investigate the added benefits of dynamic state and parameter estimation for the enhancement of the reliability, security, and resilience of electric power systems. The motivations and engineering values of dynamic state estimation (DSE) are discussed in detail. Then, a set of potential applications that will rely on DSE is presented and discussed. Furthermore, a unified framework is proposed to clarify the important concepts related to DSE, forecasting-aided state estimation, tracking state estimation and static state estimation. An overview of the current progress in DSE and dynamic parameter estimation is provided. The paper also provides future research needs and directions for the power engineering community.

6 February 2019 in IEEE Transactions on Power Systems
Verified
Journal Article
Closed access
HSHongbin Sun
Hongbin Sun
QGQinglai Guo
Qinglai Guo
Junjian QiJunjian Qi
Junjian Qi
VAVenkataramana Ajjarapu
Venkataramana Ajjarapu
RBRichard Bravo
Richard Bravo
GYGuangya Yang
Guangya Yang

1 January 2018 in Applied Energy
Verified
Journal Article
Closed access
YLYang Li
Yang Li
BFBo Feng
Bo Feng
GLGuoqing Li
Guoqing Li
Junjian QiJunjian Qi
Junjian Qi
DZDongbo Zhao
Dongbo Zhao
YMYunfei Mu
Yunfei Mu

22 March 2017 in IEEE Transactions on Power Systems
Verified
Journal Article
Closed access
GHGang Huang
Gang Huang
JWJianhui Wang
Jianhui Wang
CCChen Chen
Chen Chen
Junjian QiJunjian Qi
Junjian Qi
CGChuangxin Guo
Chuangxin Guo
Boosting the resilience of power systems is one of the core requirements of smart grid. In this paper, an integrated resilience response framework is proposed, which not only links the situational awareness with resilience enhancement, but also provides effective and efficient responses in both preventive and emergency states. The core of the proposed framework is a two-stage robust mixed-integer optimization model, whose mathematical formulation is presented in this paper as well. To solve the above model, an algorithm based on the nested column-and-constraint generation decomposition is provided, and computational efficiency improvement techniques are proposed. Preventive response in this paper considers generator re-dispatch and topology switching, while emergency response includes generator re-dispatch, topology switching and load shedding. Several numerical simulations validate the effectiveness of the proposed framework and the efficiency of the solution methodology. Key findings include the following: 1) in terms of enhancing power grid resilience, the integrated resilience response is preferable to both independent preventive response and independent emergency response; 2) the power grid resilience could be further enhanced by utilizing topology switching in the integrated resilience response.

29 September 2014 in IEEE Transactions on Power Systems
Verified
Journal Article
Closed access
Junjian QiJunjian Qi
Junjian Qi
KSKai Sun
Kai Sun
WKWei Kang
Wei Kang
In this paper, the empirical observability Gramian calculated around the operating region of a power system is used to quantify the degree of observability of the system states under specific phasor measurement unit (PMU) placement. An optimal PMU placement method for power system dynamic state estimation is further formulated as an optimization problem which maximizes the determinant of the empirical observability Gramian and is efficiently solved by the NOMAD solver, which implements the Mesh Adaptive Direct Search algorithm. The implementation, validation, and the robustness to load fluctuations and contingencies of the proposed method are carefully discussed. The proposed method is tested on WSCC 3-machine 9-bus system and NPCC 48-machine 140-bus system by performing dynamic state estimation with square-root unscented Kalman filter. The simulation results show that the determined optimal PMU placements by the proposed method can guarantee good observability of the system states, which further leads to smaller estimation errors and larger number of convergent states for dynamic state estimation compared with random PMU placements. Under optimal PMU placements an obvious observability transition can be observed. The proposed method is also validated to be very robust to both load fluctuations and contingencies.

1 December 2016 in IET Cyber-Physical Systems: Theory & Applications
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Journal Article
Open access
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Junjian QiJunjian Qi
Junjian Qi
AHAdam Hahn
Adam Hahn
XLXiaonan Lu
Xiaonan Lu
JWJianhui Wang
Jianhui Wang
CLChen‐Ching Liu
Chen‐Ching Liu
The increased penetration of distributed energy resources (DER) will significantly increase the number of devices that are owned and controlled by consumers and third‐parties. These devices have a significant dependency on digital communication and control, which presents a growing risk from cyber‐attacks. This study proposes a holistic attack‐resilient framework to protect the integrated DER and the critical power grid infrastructure from malicious cyber‐attacks, helping ensure the secure integration of DER without harming the grid reliability and stability. Specifically, the authors discuss the architecture of the cyber‐physical power system with a high penetration of DER and analyse the unique cybersecurity challenges introduced by DER integration. Next, they summarise important attack scenarios against DER, propose a systematic DER resilience analysis methodology, and develop effective and quantifiable resilience metrics and design principles. Finally, they introduce attack prevention, detection, and response measures specifically designed for DER integration across cyber, physical device, and utility layers of the future smart grid.