Turbo Set Control for Load Shedding and Short-Circuit Distinction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Turbo sets in steam power plants face challenges in distinguishing between load shedding and short-circuit interruptions, leading to potential overspeeds and prolonged shutdowns due to the inability to differentiate between these events based on power drops at the generator terminals, especially during double faults.
Innovation Solution
A method for controlling a turbo set that generates distinct signals for load shedding and short-circuit interruptions, using a logical AND operation and time-measuring elements to differentiate between the two conditions, allowing for timely braking and acceleration of the turbine and preventing unnecessary shutdowns by avoiding filter circuits that cause time delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If filter circuits are used to distinguish between load shedding and short-circuit interruptions, then measurement precision is improved, but time delays occur that cause the turbo set to shut down during short-circuit interruptions
Solution Approach 1:
The detection system is segmented into multiple independent evaluation paths: one path uses filter circuits for accurate distinction between load shedding and short-circuit interruptions, while another path provides immediate response through direct signal evaluation. This segmentation allows the system to achieve both measurement precision and fast response time by processing signals through different channels simultaneously.
2Reliability
If the turbine is braked quickly to prevent overspeed during load shedding, then reliability is improved, but unnecessary braking occurs during short-circuit interruptions causing productivity loss
Solution Approach 1:
The control system uses feedback from multiple signal evaluation paths to determine the appropriate turbine response. By continuously monitoring both filtered and unfiltered power signals, the system receives feedback that distinguishes between load shedding conditions requiring turbine braking and short-circuit interruptions where the turbine should continue running, thus achieving reliable protection without unnecessary productivity loss.
3Speed
If the system responds immediately to power drops, then speed control is improved, but false detection of load shedding occurs during short-circuit interruptions
Solution Approach 1:
The system dynamically adjusts its response based on the evolving signal characteristics. Initially, the system responds quickly to power drops by evaluating unfiltered signals for immediate turbine control. As the system evolves, it dynamically switches to filtered signal evaluation to accurately distinguish between load shedding and short-circuit interruptions, achieving both fast initial response and accurate event distinction throughout the transient process.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The invention relates to a method for controlling a turboset having a turbine (3) and a generator (2), comprising the steps: providing a first signal (S1) indicating a reduction in the actual power output (PEL, 4) of the generator (2); generating a second signal (KU, 10) indicating a short circuit interruption as a function of the first signal (S1); resetting the second signal (KU, 10) according to a predetermined first time span (TKU) and blocking the second signal (KU, 10) during a predetermined second time span (TSPKU); braking and subsequently accelerating the turbine (3) as a function of the second signal (KU, 10); generating a third signal (LAW, 8) indicating a load shedding of the turboset after a predetermined third time span (TLAW) as a function of the first signal (S1) when the first signal (S1) is provided by a drop in the actual power output (PEL, 4) of the generator (2) to a predetermined negative value (GPNEG), and the actual power output (PEL, 4) of the generator (2) has become less than double the station supply (GP2EB) and the difference between a target power output (PSW, 5) and the actual power output (PEL, 4) of the generator (2) has become greater than double the station supply (GP2EB) of the turboset; and load shedding to the station supply of the turboset as a function of the third signal (LAW, 8).