Load shedding control method and system

Abstract

The invention belongs to the technical field of gas turbine design, and relates to a load shedding control method and system. The method comprises the steps that firstly, after an electric generator trip signal is detected, electric generator stator current and gas generator conversion rotating speed are obtained; according to limit value of the two parameters, whether load shedding transient process control is started or not is judged, and load shedding transient process control comprises the steps that the fuel amount corresponding to the idling rotation speed serves as the target oil adjusting amount of the rotor turn-down process in the load shedding transient process, and according to the pre-determined minimum gas-oil ratio, the fuel oil changes in the curve control adjusting processcan be limited; and when the power turbine descending rotating speed is smaller than the set value, jumping out of the load shedding transient process control is carried out. The trip signal and a current signal are introduced, the power turbine guide device circulation area is adjusted, and therefore the load shedding of a gas turbine can be accurately judged in time, the gas turbine performancedegradation slows down, and the power turbine guide device circulation area adjusting technology is adopted.

Description

Technical field [0001] This application belongs to the technical field of gas turbine design, and particularly relates to a load rejection control method and system. Background technique [0002] When gas turbines are used in isolated grid power generation in the field of emergency backup power supply and marine power propulsion, they will inevitably face circuit breaker tripping problems caused by generator and load failures, overloads, etc., that is, load rejection occurs, and the power turbine output shaft will instantly lose all Load, and its output power is basically unchanged. The huge power imbalance on both sides of the shaft system will cause it to withstand a large acceleration. If the control is not timely, over-rotation protection parking or rotor flying will occur. [0003] Generally, industry standards require gas turbines to have the ability to dump load without stopping under 100% of the rated operating conditions. At the same time, the power turbine rotor speed ove...

AI Technical Summary

Problems solved by technology

[0008] 1) The conventional gas generator and power turbine speed cascade closed-loop adjustment scheme can maintain the steady-state power generation frequency at 50 Hz, and its stability adjustment quality for linear or approximately linear load changes is good, but for strong nonlinear, changing speed The suppression effect of fast isolated grid power generation load disturbance is average, and the adjustment followability is poor

[0009] 2) The speed acceleration of the power turbine can reflect the change of the load, but it is difficult to distinguish whether it is a normal sudden drop, a load shedding under low working conditions, or a load shedding under high working conditions, and there is a certain time delay, which leads to control The response time of the system is long

[0011] ① It is necessary to extend the transition section of the turbine casing, increase the design of the bleed valve and bleed pipeline, etc., resulting in an extension of the axial size and weight of the gas turbine

[0012] ②The selection of deflation according to the increase in the speed of the power turbine cannot quickly suppress the increase in the initial acceleration

[0013] ③Due to the high temperature at the inlet of the power turbine, venting here not only has special requirements for the vent valve and pipeline materials, but also has potential safety hazards of high-temperature gas leakage

[0014] 4) The technical scheme of increasing the moment of inertia of the power turbine, reducer and generator shafting needs to redesign the shafting structure of the power system, which will not only increase the cost, but also increase the mass and size of the unit

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