Unknown network time delay compensation and control method for NPCCS

Abstract

The invention discloses an unknown network time delay compensation and control method for NPCCS (networked parallel cascade control systems), and belongs to the technical field of single-input and double-output networked control systems with limited bandwidth resources. For the problems that in the NPCCS, due to a network time delay generated when network data is transmitted between nodes, the control performance quality of the NPCCS is reduced and even the systems lose stability, it is proposed that all real network data transmission processes in the NPCCS replace an inter-node network time delay compensation model; controller end-based two-degree-of-freedom IMC and controller end-based SPC are implemented for a primary closed control loop and a secondary closed control loop respectively;and the measurement, estimation or identification of the inter-node network time delay is removed from the system structure, so that the influence of an unknown network time delay on the NPCCS stability is reduced, the control performance quality of the system is improved, and the compensation and control of the unknown network time delay are realized.

Description

technical field [0001] A compensation and control method for unknown network delay of NPCCS (Networked parallel cascade control systems, NPCCS), which involves the intersection of process control, network communication and computer control technologies, especially the single-input and double-output networked control with limited bandwidth resources systems technology field. Background technique [0002] Cascade control systems (CCS) is an advanced control system widely used in process control engineering. CCS can quickly suppress the disturbance entering the auxiliary loop, and improve the dynamic performance and anti-interference ability of the closed-loop control system. CCS usually includes two closed-loop control loops, namely a primary closed-loop control loop (Primary closed control loop, PCCL) and a secondary closed-loop control loop (Secondary closed control loop, SCCL). [0003] CCS has two types of control system structure: one is series cascade control systems (...

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Problems solved by technology

[0010] (1) Since network delay is related to factors such as network topology, communication protocol, network load, network bandwidth, and data packet size, for network delays greater than several or even dozens of sampling periods, it is necessary to establish each closed-loop control loop of NPCCS It is currently difficult to accurately predict, estimate or identify mathematical models of network delay in

[0011] (2) In NPCCS, the network delay in the process of transmitting network data from the previous network node to the next network node, no matter what kind of prediction or estimation method is used in the previous node, it is impossible to know the subsequent network delay in advance The exact value of the resulting network delay

Time delay leads to system performance degradation and even system instability, and also brings difficulties to the analysis and design of the control system

[0012] (3) It is unrealistic to completely synchronize the clock signals of all network nodes in different distribution locations in NPCCS

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