Collaborative Research: Improving electric power dispatch to ensure reliable, secure and economic transmission.

选择满足需求的运行成本最低的发电组合是电力系统运行中公用事业和独立系统运营商(ISO)职能的核心。此外，公用事业公司和ISO必须确保输电线路在正常情况下和在线路停电或故障情况下都在限制范围内运行。这些输电限制可能会限制可用于调度发电机的选择。在这些限制范围内运行的发电和输电系统被称为安全的。维护安全，同时寻求最大限度地减少发电的运营成本，是公用事业和ISO业务的核心职能，涉及主动考虑可能发生的许多可能的停电。如果确实发生了停机，则随后必须更改派单，以便系统能够承受下一次停机。然而，一般而言，恢复安全所需的这些行动并没有在公用事业和ISO的程序中明确建模。这意味着，当前系统的运行方式可能是未充分利用那里的传输容量，从而导致比必要的调度成本更高，或者在发生单一故障时可能威胁可靠性的运行方式。这项工作寻求系统的方法，以更好地表示输电的局限性，更好地表示事故后的安全恢复，从而改善发电机调度。这些研究生将接受电力工程、优化理论和控制系统方面的培训。学生将有机会与德克萨斯州立法和公用事业委员会互动，STEM外联活动将延伸到为代表不足的少数民族服务的南哈莱姆初中和高中。该提案旨在提高应急后州在地区输电组织(RTO)和独立系统运营商(ISO)调度优化中的代表性，以更好地确保输电能力既不会未得到充分利用，也不会运行在危及可靠性的水平上。输电能力利用率的提高将有助于通过调度更多较低成本的资源来降低电力供应的总体成本，并通过减少与输电有关的风能削减来促进可再生资源的整合。相反，在输电可以以乐观的方式运行的情况下，改进的事故后状态表示将提高可靠性。这些改进将通过更全面的调度方法来实现，这些方法明确地模拟紧急情况后的纠正行动，而不是通过昂贵的传输升级。由于线路的阻性发热和线路额定温度的相互作用，输电系统支持电力流动的能力通常受到连续和短期热限制的限制。每条线路的限制都不同，在某种程度上也取决于周围的条件。这些限制包含在RTO/ISO派单模型中。RTO/ISO调度的标准公式使用安全约束的最优潮流(SCOPF)，SCOPF通过近似线路和其他元件上的事故后潮流来表示事故。通常，事故后流量的限值反映的是短期输电限值，高于连续额定值，隐含的假设是，在线路上的温度升高超过可接受的限值之前，可以通过(未建模的)事故后纠正措施将流量降低到连续额定值范围内。其方法是利用细粒度分布式最优潮流的最新进展，将事故后潮流的轨迹显式表示为最优潮流公式，从而使事故前潮流的隐含限制既不保守也不乐观。这将使现有传输能力得到更好的利用。还将研究减少必须在优化中明确表示的偶发约束的数量的系统方法。

Choosing the least-operating cost combination of electric power generation to meet demand is at the heart of utility and Independent System Operator (ISO) functions in the running of an electric power system. Additionally, utilities and ISOs must ensure that transmission lines will be operated within limits both under normal conditions and in the event of an outage, or failure, of a line. These transmission limitations can limit the choices available for dispatch of generators. A generation and transmission system operated within these limits is said to be secure. Maintaining security while seeking to minimize the operating costs of generation is a central function of utility and ISO operations and involves pro-active consideration of the many possible outages that might occur. If an outage does actually occur, then the dispatch must subsequently be changed so that the system can withstand the next outage. Generally, however, these actions needed to restore security are not explicitly modeled in the procedures of utilities and ISOs. The implication is that current systems might be operated in a manner that under-utilizes transmission capacity there resulting in more expensive dispatch than necessary or operated in a manner that could threaten reliability in the event of a single failure. This work seeks systematic methods to better represent the limitations on transmission and better represent the post-contingency restoration to security so as to improve electric generator dispatch. The graduate students will be trained in electric power engineering, optimization theory, and control systems. Students will be provided opportunities to interact with the Texas Legislative and Public utility commission, and the STEM outreach activities will extend to the South Harlem middle and high schools that serve underrepresented minorities.This proposal aims at improving representation of post-contingency states in Regional Transmission Organization (RTO) and Independent System Operator (ISO) dispatch optimization to better ensure that transmission capability is neither under-utilized nor operated at levels that jeopardize reliability. Improved utilization of transmission capacity will contribute to lowering the overall cost of electricity supply by enabling more of the lower cost resources to be dispatched, and contribute to enhancing the integration of renewable resources by reducing transmission-related wind curtailment. Conversely, in cases where transmission may be operated in an optimistic manner, improved representation of post-contingency states will improve reliability. These improvements will be achieved by more comprehensive dispatch methodologies, that explicitly model post-contingency corrective actions, rather than through costly transmission upgrades. The capability of the transmission system to support flows of power is typically limited by both continuous and short-term thermal limits due to the interaction of resistive heating of lines and line temperature ratings. The limits vary from line to line and also depend to some extent on ambient conditions. These limits are incorporated into RTO/ISO dispatch models. Standard formulations of RTO/ISO dispatch use security-constrained optimal power flow (SCOPF) that represent contingencies by approximating the post-contingency flows on lines and other elements given a pre-contingency dispatch. Typically, the limits allowed for post-contingency flows reflect short-term transmission limits and are higher than the continuous ratings, with the implicit assumption that the flows can be reduced to being within continuous ratings through (unmodeled) post-contingency corrective actions before the temperature rise on the lines exceeds acceptable limits. The approach is to utilize recent advances in fine-grain distributed optimal power flow to explicitly represent the trajectory of post-contingency flows into the optimal power flow formulation, so that the implied limit on pre-contingency flows will neither be conservative or optimistic. This will enable better utilization of existing transmission capacity. Systematic methods to reduce the number of contingency constraints that must be explicitly represented in the optimization will also be investigated.