Технические науки/12.Автоматизированные системы управления на производстве.

Татаринова С.С., к.т.н. Маршалов Е.Д., Староверова Е.Б.

Ивановский государственный энергетический университит

Development of automatic control of once-through boiler load

An urgent task nowadays is to increase power reliability, efficiency and agility of equipment. Benchmark tests are rather complicated and dangerous because they disrupt equipment operating mode. That can lead to serious accidents. So the use of specialized training complexes is relevant and appropriate.

The phase of fuel feeding control is an important phase boiler plant regulation as here further reliability and efficiency of thermal power plants is defined at large.

This work deals with management automatic system (MAS) of fuel feeding of the boiler. It includes a combustion controller.

The main fuel is natural gas.

Automatic gas control system is designed for automatic control of gas flow to the boiler and controls the following regulatory units:

-gas regulator (side A);

-gas regulator (side B);

MAS gas feeding operates pressure control valve on the gas supply to the boiler and it includes two controllers: [1]

-gas regulator;

-gas pressure regulator.

Each of the two adjusting valves (AV) on the both sides of a boiler can operate in flow control mode or pressure control mode. Controller mode is selected on each side by its own switcher and specification for the controller on each side is set by setpoint devices: for the pressure and flow rate separately.

The following diagram (Fig. 1) is used to regulate the boiler operation of the 5^th generator unit of Thermal power plant-25 of open joint stock company "Mosenergo".

Fig.1. Design scheme of gas regulator of boiler TGMP-314P.

A gas flow regulator receives a gas flow rate signal. A gas pressure regulator receives a gas pressure signal. The transition from the pressure regulator to the gas flow regulator and back is performed by means of a gas regulating circuit switch "Pressure /Flowrate". Pressure control mode is spare and can be used when the flow control is ineffective (when readings of gas flow sensors are unstable due to low flow for example when kindling). In power control mode gas consumption is adjusted according to the electric load. Gas control mode of unit load is carried out by switching preselection to boiler power regulator mode. In this mode the gas MAS gets a ready task from the unit load controller.

Boiler power regulator (BPR) clarifies the task on fuel consumption. BPR data is added to the direct channel of the given power. [2]

When testing using the simulator transients were obtained on all channels of interest. Later they were transformed to the transient response.

Next to the channel frequency response and transfer functions characterizing the object on the appropriating channel were obtained.

Automatic control system (ACS) of load of once-through boiler TGMP 314-P was also designed using the training complex unit of 250 MW thermal power station-25 of open joint stock company "Mosenergo" [1]. Parametric optimization of the channels was performed. They are "% stroke regulating the gas valve (RGV) -A- gas consumption in the thread A", "% stroke RGV -A- gas pressure in the thread A", "% stroke RGV -A- Power Generator; deregulation of the system amounted to 2%, which appropriates to the standards.

       Controller mode on each side is selected by its own switch and controller task on each side is set by setters - for the pressure and the flow rate separately. For switch realization in software «Vissim» the block <merge> is provided. The result of switch circuit work is shown in Figure 2.

Fig.2. Regulator transition from pressure control mode to flow rate regulation mode under perturbation task.

Requirements specification was developed ACS of once-through boiler load, algorithmic and parametric synthesis with the ideal and the real regulators was held, the optimal parameters of regulators settings were evaluated.

Designed ACS allows for the possibility of switching from flow rate control mode to standby gas pressures regulation mode. Also the fuel consumption imbalance on either side of the boiler is taken into account .

In the future it is planned to use the feature of the simulator-foot complex to develop a full-fledged SCADA load of once-through boiler.

References

1. Инструкция по эксплуатации автоматических регуляторов энергоблока №5. Москва, 2011. - 171 с.

2. Теория и технология систем управления. Многофункциональные АСУТП тепловых электростанций. В3-х кн. Кн. 3. Моделирование/ Под общей ред. д-ра техн. наук, проф. Ю.С. Тверского; ФГБОУВПО «Ивановский государственный энергетический университет имени В.И. Ленина». – Иваново, 2013. – 208 с.