Xingpeng Li

Real-Time Contingency Analysis With Transmission Switching on Real Power System Data

Transmission switching (TS) has shown to be an effective power flow control tool. TS can reduce the system cost, improve system reliability, and enhance the management of intermittent renewable resources. This letter addresses the state-of-the-art problem of TS by developing an AC-based real-time contingency analysis (RTCA) package with TS. The package is tested on real power system data, taken from energy management systems of PJM, TVA, and ERCOT. The results show that post-contingency corrective switching is a ready to be implemented transformational technology that provides substantial reliability gains. The computational time and the performance of the developed RTCA package, reported in this letter, are promising.

Harnessing Flexible Transmission: Corrective Transmission Switching for ISO-NE

Despite the significant attention transmission switching (TS) has gained over the last decade, important challenges remain. This paper addresses the state-of-the-art challenges of TS by studying the benefits of corrective switching using authentic Independent System Operator of New England (ISO-NE) data and software. Thus, the results and analyses presented in this paper are more convincing than any other study conducted to date. TS is successfully implemented for reliability applications as a corrective mechanism. ISO-NE maintains N -1 reliability based on the preventive dispatch and enforcing proxy reserve requirements along with N - 1 - 1 reliability based on reserves and interface limits. This paper incorporates TS as a corrective mechanism in response to both the N - 1 and N - 1 - 1 events. Not only does this paper investigate the capability of corrective switching to alleviate thermal overloads but also the economic benefits of corrective switching with actual market data and in-house market software at ISO-NE. The results show that corrective TS can improve the reliability of the system and save millions of dollars each year by providing a cheaper corrective action alternative for ISO-NE. The results also suggest that TS would provide more significant benefits for systems with more transmission congestion such as Pennsylvania New Jersey Maryland, Midcontinent Independent System Operator, and Electric Reliability Council of Texas.

Real-Time Contingency Analysis With Corrective Transmission Switching

Transmission switching (TS) has gained significant attention recently. However, barriers still remain and must be overcome before the technology can be adopted by the industry. The state-of-the-art challenges include AC feasibility, computational complexity, the ability to handle large-scale real power systems, and dynamic stability. This paper investigates these challenges by developing an AC corrective TS (CTS) based real-time contingency analysis (RTCA) tool that can handle large-scale systems within a reasonable time. The tool quickly proposes multiple high-quality corrective switching actions for contingencies with potential violations. To reduce the computational complexity, three heuristic algorithms are proposed to generate a small set of candidate switching actions. Parallel computing is implemented to further speed up the solution time. Moreover, time-domain simulations are performed to check for dynamic stability of the proposed CTS solutions. The promising results, tested on the Tennessee Valley Authority (TVA) system and actual energy management system snapshots from the PJM Interconnection (PJM) and the Electric Reliability Council of Texas (ERCOT), show that the tool effectively reduces post-contingency violations. It is concluded that CTS is ripe for industry adoption for RTCA application.

Fast heuristics for transmission outage coordination

Preventive maintenance is key to extending the lifetime of transmission lines and to avoiding unnecessary replacement costs. Maintenance forces transmission assets to be taken out of service temporarily, which changes the network topology and may influence the system security margin as well as the energy markets. Therefore, transmission outage coordination is very critical. While industry practices typically examine the reliability impacts of outage coordination, this paper evaluates the impacts on both reliability and market economics. The procedure of practical outage coordination is first introduced in this paper. The extensive formulation to co-optimize the outage scheduling problem and the day-ahead unit commitment problem is then presented. The complete formulation with an exact algorithm can guarantee the optimal solution but that comes at the cost of a long solution time. Four fast heuristics are examined in order to solve this complex mathematical program. Case studies demonstrate the effectiveness of the four proposed heuristics. The solution time is significantly reduced while quality solutions are still obtained. The numerical results show that transmission outage coordination could have a great impact on the energy markets such as changes in LMP.

A hierarchical energy management strategy for grid-connected microgrid

A novel hierarchical energy management strategy for grid-connected microgird is proposed in this paper. The proposed concept follows the idea of multiple time-scale coordination and consists of day-ahead layer, adjustment layer, and real-time layer. The day-ahead layer is based on look-ahead multi-step optimization techniques and the predicted availability of renewable energy sources. Future operational states of the controllable units in the microgrid could be determined ahead of time. The adjustment layer adjusts power output of online units by using the data at the dispatch time. Then, real-time layer is utilized to maintain the exchange power between the external macrogrid and the microgrid constant. In addition, energy storage plays a critical role in three dispatch and control layers. A typical microgrid system is simulated to demonstrate the performance and effectiveness of the proposed hierarchical energy management strategy.

A data-driven heuristic for corrective transmission switching

Utilizing flexibility of the transmission network has gained significant attention recently. Prior efforts have shown that various benefits could be achieved by appropriately changing the network topology. This paper focuses on the reliability gains that can be achieved through corrective transmission switching (CTS). A full AC contingency analysis is conducted to identify critical contingencies that would result in violations. CTS is employed on these critical contingencies to test for violation reductions. A data-driven heuristic is proposed in this paper to identify the candidate switching list. This heuristic, also referred to as enhanced data mining (EDM) approach, provides a static lookup table consisting of corrective switching solutions, which is fast and effective. The lookup table can be created through a straightforward data mining technique. Simulations on the TVA system demonstrate the effectiveness and efficiency of the proposed heuristic.