State Prediction in the Presence of Input, State and Output Delays: Application to Compressor Surge Control Using Active Magnetic Bearings

该研究项目的目标是开发新的设计方法，用于在存在输入、输出和状态时滞的情况下控制工程系统。这些方法将帮助工程师减轻延迟对稳定性和性能的不利影响。多级离心式压缩机是应用最广泛的工业设备之一，耗能大。它们用于驱动天然气管道，是建筑供暖、通风和空调系统的基本组件。将项目成果应用于喘振不稳定问题，将使这些压缩机能够更高效地运行，从而降低运行成本和减少整体能源消耗。通过弗吉尼亚大学的旋转机械与控制(ROMAC)联盟，研究团队将与主要压缩机制造商的工程师互动，以制定和传播针对该行业面临的主要技术挑战的解决方案。当输入延迟大于状态延迟时，时滞系统中的传统预测器反馈会导致非因果控制律。初步调查表明，即使对于这种情况，也有可能构建一个因果状态预测器。其基本思想是将预测时间划分为每个都比最大状态延迟短的部分，并在预测时间内递归地执行预测。由此产生的状态预测器是因果的，但是无限维的。这个项目的主旨是设计方法来安全地实现无限维预报器。预计这一结果将带来强大的新工具，用于控制同时存在输入、状态和输出延迟的系统。该项目的一个完整部分是将理论结果应用于利用主动磁轴承控制多级离心式压缩机的喘振不稳定性。

The objective of this research project is to develop new design methods for controlling engineering systems in the presence of time delays arising in the inputs, outputs, and states. These methods will help engineers alleviate the adverse effects of delays on stability and performance. Multistage centrifugal compressors are one of the most widespread types of industrial equipment, and consume significant amounts of energy. They are used to drive natural gas pipelines and are essential components for building heating, ventilation, and air conditioning systems. Application of the project results to surge instability will enable higher efficiency operation of these compressors, thereby lowering operating costs and reducing overall energy use. Through the Rotating Machinery and Controls (ROMAC) consortium at the University of Virginia, the research team will interact with engineers from major compressor manufacturers, to formulate and disseminate solutions to major technical challenges faced by the industry.Conventional predictor feedback in time-delay systems leads to noncausal control laws when the input delays are larger than the state delays. Initial investigations indicate that it is possible to construct a causal state predictor even for this case. The fundamental idea is to partition the prediction time into sections that are each shorter than the maximum state delay, and carry out the prediction recursively over the prediction time. The resulting state predictor is causal, but infinite dimensional. The thrust of this project is to devise methods to safely implement the infinite-dimensional predictor. The results are expected to lead to powerful new tools for control of systems subject to simultaneous input, state and output delays. An integrated part of the project is to apply the theoretical results to the control of surge instability in multistage centrifugal compressors by use of active magnetic bearings.