Process modeling from step test
Цель: Изучить тему «Process modeling from step test» и закрепить её практическими заданиями и самопроверкой.
2 акад. часа чтение и разбор теории, решение задач, работа со схемой или виртуальным стендом и проверка понимания.
Основной материал
Simple model can be identified by small controlled step in manipulated variable and recording PV. From response estimate gain, dead time and time constant. Это называется process reaction curve approach.
Conditions
Test must be safe, disturbance-free enough, and not drive process outside limits. In production formal approval needed. Step amplitude should be big enough above noise but small enough not to disrupt operation.
Estimation
K from final change; theta from delay onset; tau from 63 % point after delay or tangent methods. Model need not be perfect to guide tuning.
Практическая работа
Given trend: output step +10 %, PV begins change after 2 min, final +5 °C, reaches +3.16 °C at 7 min. Estimate K=0.5 °C/%, theta=2 min, tau≈5 min.
Самопроверка
• Что дает step test?
• Как estimate K?
• Как estimate theta?
• Как estimate tau?
• Почему test requires safety approval?
Что нужно запомнить
- Simple model can be identified by small controlled step in manipulated variable and recording PV.
- From response estimate gain, dead time and time constant.
- Test must be safe, disturbance-free enough, and not drive process outside limits.
- Step amplitude should be big enough above noise but small enough not to disrupt operation.
- K from final change; theta from delay onset; tau from 63 % point after delay or tangent methods.