Application Of Dual Control Strategy In Automatic Control System Of Power Plant

Large-scale new energy power is developing rapidly. The stochastic volatility of output power and the sensitivity to grid disturbances of power electronic equipment make the safe and stable operation of power system face big challenge. And higher requirements of peak regulation and frequency modulation ability are put forward for thermal power units which is in important position in power plant. The rational use of thermal power unit energy storage can improve regulation capability of peak and frequency. From measurement, control, operation, management and other aspects storage efficient use can be reaslized. This paper studies the problem of dual control object.Taking the coal pulverizing system, condensate throttling and load-pressure object as examples, analyzing the common feartures of those process and summing up the general characteristics of the dual object. It consists of two input channels and one output channel. One of the input channels presents the actual differential characteristics, another input channel displays the large inertia and delay feature.Two control methods of dual object are presented in this paper: the compensation object method and the equivalent analysis method.The compensation object method is using compensating effect to turn the dual object into a single input single output object. Then according to single loop negative feedback control strategy to design system. The compensation transfer function expressions of several typical dual objects are given by calculation. And examples are taken for system designing and simulation test. The results show that the compensation object method displays good effect when the object dynamic characteristic is relatively simple, while compensation link forms becomes more complex when the dynamic characteristics is complex. Equivalent analysis method constructs an output which is related to two inputs. It makes dual object into a double input double output object. Then learn from the thought of decoupling control system to design the control system. Taking the thermal power units “boiler and turbine” mode coordinate control system as an example, combining the operation data to analysis two loop coupling characteristics, then two loop coupling control object can be equivalent to external disturbance plus constant disturbance dual control object. This process explains the feasibility of equivalent analysis method in the reverse angle.Based on the equivalent method, parameters setting method whose adjustment may be quantitative is proposed. And the convergence of the tuning process is proved by mathematical reasoning. Finally this method is applied to a 600 MW unit. The load instruction disturbance experiments show that the performance of control system is improved greatly.In a word, this paper analyzes the properties of the dual object and puts forward two ways to design control system. It provides an important idea to solve the thermal power unit energy storage depth usage problem.