Automatic control system of GTE (GTU) rotor rotation frequency.

5.1 General information

Generally, the ACS of GTE is called the set of GTE (GTU) as a control object with a number of automatic devices (regulators, limiters, automatics), which specifically act on the engine in order to obtain the specified engine performance.

Rotor rotation frequency of GTE for the most modern and advanced engines is selected as controlled parameter, so ACS rotor rotation speed is the main control system for any type of GTE (GTU).

This ACS contains of engine as a controlling object and the rotor speed controller.

In the theory of automatic control the regulator is a device that measures the current value of the controlledparameter, compares it with avalue, which is given, determines thereby deviation of the controlledparameter from given value and produces the desired control effect on an object which is under control. The control action value depends on the measured deviation.

At rotor rotation frequency controlling the regulator must firmlymaintain the given value of this parameter for a given leveland quickly, without large variation renew it at deviationfrom the operating mode or atexternal conditions changes.

The main requirements to the rotor rotation frequency ACS:

· high static accuracy preset of given value of a controlled parameter at external conditions changing in the operational range;

· high regulation quality, which is characterized by minimal transition process variations, a small time of transition process and small regulation size of controlled parameter in the transition process;

· high operational reliability at high and low environment temperature and under vibration.

In particular, rotors rotation frequency regulators of GTU compressor stations must provide high static accuracy of rotor rotation frequency, characterized by relatively staticerror of regulation at 0.25 ... 0.5% from the maximum value.

The relatively static error of precision hydromechanical controllers of the modern compressor stations GTU is not more than 0.2 ...0.25%, and electronic controllers - not more than 0.1 ...0.15%. The value of overshoot, i.e. acute jump in transient process in modern regulators does not exceed 2 ... 3% of maximum speed, and the total duration of the transition process for transport GTE at a sharpoverregulation from an idling mode to a maximum mode (full accelerationtime) is within 5 to 9 s and depends on the polarmoment of inertia of the rotor and excess moment on turbine shaft.

For the GTP compressor stations acceleration time depends also on the polar moment of inertia of the rotor natural gas supercharger.

Rotation speed regulators more fully satisfied such requirements. These regulators are based on the principle of controlled values deviation. Accordingly, the modern ACS of GTU applies rotation frequency controllers, enabled by a closed circuit with respect to the control object (see Fig. 2.1).

Date: 2015-02-16; view: 955