Complexity Analysis Of AGC Signals In Thermal Power Units

Because of renewable energy in- grid and the generation load become more and more complex, the frequency fluctuation of power network is frequent. The power grid side hopes the high velocity, large scope and high frequency of variable load operation in the thermal power units which participate in the frequency. However, variable operating condition of the unit coal consumption far outweigh the stability condition and the executing agency action is too frequent to unit safety adverse. So the thermal power units hopes to be able to operate with a rated load. From the point of view of the power generation task, based on the completion condition, the "two rules" assessment was proposed. By using this rule the compensation and punishment in thermal power units were proceeded. But only considering the task completion without considering the difficulty of the task itself for thermal power units is unfair. The contribution of thermal power units in the scheduling process to maintain the stability of power grid frequency can not be entirely fair evaluated. The thermal power units hopes the grid could consider the task completion, and also consider load change complexity to appropriate compensation and evaluation. In the view of the questions, the complexity of the load change was analyzed.The AGC instruction signal has random fluctuation characteristics. Through the comparison analysis of different complexity, the sample entropy was introduced to analyze the complexity in signal. Using the common signal, the validity and accuracy were affirmed. The typical signal of AGC instruction for the 660 MW Super Critical Unit was analyzed. The results show that sample entropy can describe the complexity of load change quantitatively. It is an effective method for analyzing AGC command signal complexity.The object of the coordinated control system was analyzed. A load-pressure control model was established and its input and output characteristics was analyzed. The load of different types and frequencies of different types were simulated and analyzed by using load pressure model in the 600 MW subcritical direct cooling air cooling unit. The response ability of the unit to the load was observed from the output curve. It was discovered that the amplitude of the load change is within the range of 60~80MW, which is in the resonant frequency range of the units. At this time, the pressure of the turbine and fuel are very violent. The safety and stability of operation in the unit is extremely unfavorable.The characteristics of various types of AGC command signal under "O, R" two kinds of scheduling modes were analyzed. Using the sample entropy the complexity was analyzed. By observing the changes of the throttle pressure and fuel volume in curves, the actual operation of the unit was analyzed. The comparative analysis shows that the higher the sample entropy is, the worse the actual running situation is. In the two scheduling modes, there are a medium range of positive and negative change instructions. The medium range in the "R scheduling mode" appears more frequently. This AGC instruction is the most important influence on the safety operation of the thermal power unit.