Corrective control: stability analysis of Unified Controller combining frequency control and congestion management

This paper analyses stability of the Unified Controller (UC) that combines frequency control and congestion management and therefore makes it possible to move from preventive to corrective power system control. Earlier work by the authors of UC proved asymptotic stability of the methodology but the proof was based on a simplified first-order model of the turbine and turbine governor. We show that a higher order model of the turbine governor leads to eigenvalues with small but positive real parts. Consequently, we develop a modification of the methodology that decouples the physical and control systems and therefore results in all the eigenvalues having negative real parts. We illustrate the effectiveness of the modification on a realistic model of 39-bus model of New England power system implemented in Power System Toolbox (PST)

Hybrid open points: an efficient tool for increasing network capacity in distribution systems

This letter introduces the Hybrid Open Point (HOP), a device consisting of an electromechanical switch connected in parallel with a power converter, for the purpose of providing additional network capacity in interconnected distribution systems. The HOP switch is used for bulk power transfer at low-cost, whilst the HOP converter provides targeted power transfer when the HOP switch is open. The device can replace either a Normally Open Point (Type 1 HOP) or a Normally Closed Point (Type 2 HOP). Simple interconnection and teed interconnection configurations are studied considering fault level and radiality constraints, with realistic use-cases identified for both HOP types. The HOP is shown to provide secure network capacity more cost-effectively than the classical Soft Open Point

Minimum cost curtailment for distributed generation voltage management

Paper presented at PSCC 2008, 16th Power Systems Computation Conference, July 14-18, 2008, Glasgow, ScotlandThe penetration of DG is increasing on distribution networks across the world. As a result, networks are being pushed closer to their operating limits. In particular, voltage rise has been identified as a key barrier to further DG capacity. Active management of the voltage constraint may be possible, leading to a form of constraint management at distribution level for the first time. Here a novel method is proposed, which minimises the cost of curtailment. It takes advantage of the dispatchable capability of certain forms of DG, such as biomass, hydro or landfill gas. There are a number of well established methods for congestion management on the transmission network. A number of these are applied to voltage management on the distribution network and used for comparison with the new minimum cost method. The variability of voltage sensitivities andmarket prices is also investigated, with their impact on the cost of curtailment quantified.Science Foundation IrelandConference detailshttp://www.pscc2008.org/Charles Parsons Energy Research AwardsConference website: http://www.pscc2008.org/. Not published in International Journal of Electric Power and Energy Systems. AV 22/9/201