1. Problems that solved by adaptive controllers

1.1 The need for adaptive controllers

Industrial digital controllers are used to control complex dynamic plants (processes) in different real-life applications such as power engineering systems, natural gas and petroleum industry, nuclear technology etc. Each controller operates in accordance with some control algorithm, which is depended on control objectives, properties and parameters of the plant, system uncertainties and external disturbances. The control algorithm is realized in some programming language (C, ST, etc) supported by concrete electronic device (embedded system). The only special software allows the embedded system became the status of control device (controller). That is why the term controller is closely related to the software that implements some control algorithm into the embedded system.

The main performance index of the control system is declination (control error) of the plant output from the reference signal, for instance, reference temperature of heating system or reference generator voltage. So, in real-life systems control errors imply heat and electric losses.

The control system parameters and dynamic properties of the plant vary with time due to changing of the operating modes. This implies large control errors. Therefore self-tuning control algorithms adaptive to changes of control system parameters need to be developed.

1.2 Advantages of frequency adaptive controllers

The conventional adaptation processes are not realizable if the plant operates under unknown large external disturbances. So, the existed adaptive controllers are inoperative in this case. These new frequency adaptive controllers work effectively even in the case of large external disturbances.

1.3 Innovation core

The adaptation process is based on plant identification and control synthesis. Identification of the plant parameters is complicated by variations of external loads (for example, fluctuations of ambient temperature of heating system or changing of power consumers), which are called by exogenous disturbances. These operation conditions require special control and identification algorithms. The proposed adaptive controllers are based on the new plant parameters identification method (finite-frequency identification) developed by project supervisor. The method uses harmonic test signal to reduce the influence of external disturbances on the identification result. The amplitude and the frequency of the test signal are self-tuned in such way that guarantees small variations of the plant output.

2. The present project state and possible applications

At the present time the frequency adaptive controllers PID-I and CHAR-25 are developed, patented and realized on the industrial platform WinCon-88341. The controllers were tested on the test-bed «OWEN- WinCon», where the industrial controller OWEN imitates the plant to be controlled.

The test results show the high effectiveness of the controllers.

We work on the implementation of adaptive controllers for real-life control systems. In particular, we use our controllers to control the processes of heating of bar for synthesis of superhard material (Technological Institute for Superhard and New Carbon Materials), for vacuum electric arc furnace (Metallurgical Plant “Electrostal”), for processes of heating of bar in induction furnace (JSCo “Machine building plant”).

3. Researches related to theory of frequency adaptive control

We conduct research in the field of adaptive control more than 30 years. The subjects of our research studies are: controller synthesis, identification, adaptive control. The results are published in the papers of professors A.G. Alexandrov, V.N. Chestnov, Yu. F. Orlov and their colleagues and ex-students.