Search

The risk of unstable subsynchronous oscillations (SSO) in DFIG-based wind parks radially connected to transmission lines with series capacitive compensation is typically assessed with numerous electromagnetic transient (EMT) simulations, which is a time-consuming process. However, not all operating scenarios present risk of SSO and require such a detailed investigation. This paper proposes two charts based on impedance equivalents of wind generators obtained through frequency scans to quickly map which combinations of parameters can create unstable SSOs and which combinations are risk-free. With the information, engineers can immediately filter out scenarios with no risk of instability and conduct detailed studies on fewer scenarios that are truly critical. These charts can be obtained with simple equations that use only information readily available in practice to engineers, without the need to run any computer simulation. The charts also reveal the key operating conditions that can increase the risk of an unstable SSO and provide real-time quantitative insights into how close a wind park is to an instability. Application examples are provided to illustrate how this approach can help engineers speed up studies to identify the risk of SSO. [ABSTRACT FROM AUTHOR]

The challenges power systems engineers are facing today require the development of new system planning tools for analyzing generation and environmental policy options in the transmission-constrained electricity market. The requirements of a power-system equivalent to be used with such tools are very different from those assumed in the traditional network reduction process. To solve this issue, a novel structure-preserving network equivalent is proposed in this paper for modeling large power systems in the context of analyzing policy options and emissions. In the proposed method, a power system is first clustered into zones based on the similarity of the power transfer distribution factors (PTDFs); network reduction is achieved by aggregating buses (generators/loads) on a zonal basis and modeling inter-zonal transactions (power flows) using equivalent transmission lines. The proposed equivalent is superior to existing bus-aggregation-based equivalents in its accuracy under both the base case and change-case operating conditions. In addition, the method is more computationally efficient than other bus aggregation methods proposed heretofore. This paper also examined several classic clustering techniques and identified their performance and computational efficiencies when applied to very large power systems. The proposed network equivalencing approach is tested on an illustrative six-bus system as well as the 62,000-bus and 80,000-branch Eastern Interconnection (EI). [ABSTRACT FROM PUBLISHER]

Presents a closure to the Discussion on the paper, "Interval Power Flow Analysis Using Linear Relaxation and Optimality-Based Bounds Tightening (OBBT) Methods." [ABSTRACT FROM PUBLISHER]