Slides for the PSERC Webinar on October 4, 2016

TITLE: Hybrid EMTP and Transient Stability Simulation:Application to Power System Problems

This talk deals with the development of a new electromagnetic transient (EMT)-transient stability (TS) hybrid simulation platform and its application to a variety of problems in power systems. A new EMT-TS hybrid simulation platform, which integrates PSCAD/EMTDC and the open source power system simulation software InterPSS has been developed. A combined interaction protocol with an automatic protocol switching control scheme is proposed. A multi-port three-phase Thé venin equivalent is developed for representing an external network in an EMT simulator. Correspondingly, the external network is represented in three-sequence, and a three-sequence TS simulation algorithm is developed. These techniques allow simulation of unsymmetrical faults within the internal network without the constraint of phase balance at the boundary. The proposed hybrid simulation approach is applied to a detailed FIDVR study on a large WECC system. The study shows that a normally cleared single-line-to-ground (SLG) fault in the transmission system could lead to a FIDVR event, with compressor motors of the air conditioning units on the faulted phases stalling first, followed by a propagation of motor stalling to the unfaulted phase. Moreover, similar events are observed in simulations with a wide range of load compositions. The effect of the point-on-wave (POW) at which a fault is applied on the occurrence of a FIVDR event is also analyzed. Test cases involving LCC HVDC and VSC based HVDC will also be discussed.

Slides for the PSERC Webinar on November 15, 2016

TITLE: Architectures and Algorithms for DistributedGeneration Control of Inertial-Less AC Microgrids

This talk discusses the problem of frequency regulation in islanded ac microgrids with no inertia, i.e., those consisting entirely of generators interfaced through power electronics. The control architecture we propose to achieve this is designed to drive the average frequency error to zero while ensuring that the frequency at every bus is equal and that the operating point that results is stable. We also introduce a distributed implementation of the proposed control architecture that relies on a combination of several distributed algorithms. Two of the algorithms, which are well-established consensus-type algorithms, allow the generators and loads to acquire global information needed for making control decisions; the third algorithm, which we propose herein, enables the generators to obtain output values that balance the total demand for load without violating line flow constraints. Collectively, these algorithms eliminate the need for a centralized entity with complete knowledge of the network, its topology, or the capabilities or properties of the generators and loads therein. Moreover, the distributed implementation we propose relies on minimal measurements, requiring only that the power injection at each bus be measured. To verify our proposed control architecture and the algorithms on which its distributed implementation relies, we analytically show that the resulting closed-loop system is stable and establish convergence of our proposed algorithm. We also illustrate the features of the architecture using numerical simulations involving a six-bus networks.