A test method for valve flow characteristics of steam turbine units in constant power mode

Abstract

A method for testing the valve flow characteristics of steam turbine units in constant power mode. The coordination mode is put into the CCS coordinated control system of the unit unit, and the AGC automatic generation control function and the primary frequency regulation function of CSS / DEH are withdrawn; The set bias of the main steam pressure is continuously increased at a rate, so that the valve opening continuously decreases with the continuous increase of the main steam pressure; synchronously record and collect the relevant thermal parameters under different load test conditions, and normalize and correct the original data And related calculations, the valve flow characteristics of the steam turbine unit are obtained, and then the setting or verification of the steam distribution function of the DEH system of the steam turbine unit is carried out. The present invention effectively reduces the systematic error and random error in the test process through the horizontal comparison between different loads or the repeated test of the same load, and significantly improves the test efficiency and test quality. The invention can be applied not only to the off-line setting or verification of the steam distribution function of the DEH system, but also to the online verification of the steam distribution function of the DEH system.

Description

technical field [0001] The invention relates to a method for testing the flow characteristic of a constant power mode steam turbine unit, which belongs to the technical field of steam turbine unit operation. Background technique [0002] Modern steam turbine units have widely adopted DEH (Digital Electro-Hydraulic Control System) digital electro-hydraulic control system to implement valve sequence management. The valve flow characteristic refers to the numerical correspondence between the inlet steam flow and the valve opening under the given steam distribution structure and valve sequence mode when the steam turbine unit operates with variable loads and constant parameters. In operation, the valve flow characteristic is the external manifestation of the steam distribution mode of the steam turbine unit; the steam distribution function of the DEH system must follow the inherent flow characteristic of the unit to realize the linear and precise adjustment of the inlet steam fl...

AI Technical Summary

Problems solved by technology

Practice shows that the conventional test has the following deficiencies: First, the setting of the test valve position is discretely distributed, and there are large human factors, so it is difficult to accurately grasp the nonlinear characteristic information of the flow characteristics of the control valve

Third, some units are limited by the functions of the DEH system, and the total valve position command needs to be manually assigned, which may cause a safety risk of non-stop of the unit due to misoperation; at the same time, in order to increase the number of test samples, the number of on-site manual assignments often reaches 300-400 times ( If the total valve position instruction interval is 0.1%)

Not only is the work intensity high, but also, due to the weak flow adjustment ability of the valve during the pre-opening stage and the idle stroke stage, the valve position changes rapidly; manual assignment often cannot keep up with the changes in the system state, and cannot guarantee the stable control and stability of soda parameters. Continuous sampling of door opening

Fourth, due to the large drop in unit load during the test (for example, a 600MW unit, the difference between the highest load and the lowest load is about 250MW), the test period is long and the test process is complicated, it is not suitable for multiple tests on site; the systematic error of the test and random errors often cannot be effectively eliminated by repeated testing

Therefore, it is difficult for conventional test methods to effectively capture and collect a sufficient number of representative test samples, which brings many uncertainties to the later adjustment of flow characteristics and overlap settings, resulting in low test efficiency and poor quality.

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