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I'm working in a gas turbine power plant, GT6541, control System Speedtronic MARK IV.
We supplied load through national grid. Our grid frequency varies from 51.25 Hz to 48.75 Hz. During peak hour frequency varies drastically. We run the turbine in preselected mode. In preselected mode, MARK IV controls the TNR maintaining a constant difference between TNR and TNH, increases TNR when frequency increases and decreases when frequency decreases.
The problem is that, when frequency decreases drastically Mark IV cannot decrease TNR drastically, as a result load increases above the preselected load. Our turbine is little bit older and we cannot produce more than 33 MW in rated rpm, 50 Hz frequency. And we cannot produce more than 29 MW when frequency is less than 48.9 Hz. Suppose, we preselected the load in 32 MW. When frequency decreases from 51.2 Hz to 50.5 Hz load increases to above 34 MW and then machine goes to temperature control mode. The further drastic frequency drop may cause the turbine trip due to exhaust over temperature. When our frequency decreases drastically and turbine reaches to temperature control mode then we decrease TNR manually by pressing the manual frequency decrease button.
Now I want to know, Can we change the decrement rate of TNR for only Turbine operating at Temperature Control mode? Is the decrement rate available in control constant?
We supplied load through national grid. Our grid frequency varies from 51.25 Hz to 48.75 Hz. During peak hour frequency varies drastically. We run the turbine in preselected mode. In preselected mode, MARK IV controls the TNR maintaining a constant difference between TNR and TNH, increases TNR when frequency increases and decreases when frequency decreases.
The problem is that, when frequency decreases drastically Mark IV cannot decrease TNR drastically, as a result load increases above the preselected load. Our turbine is little bit older and we cannot produce more than 33 MW in rated rpm, 50 Hz frequency. And we cannot produce more than 29 MW when frequency is less than 48.9 Hz. Suppose, we preselected the load in 32 MW. When frequency decreases from 51.2 Hz to 50.5 Hz load increases to above 34 MW and then machine goes to temperature control mode. The further drastic frequency drop may cause the turbine trip due to exhaust over temperature. When our frequency decreases drastically and turbine reaches to temperature control mode then we decrease TNR manually by pressing the manual frequency decrease button.
Now I want to know, Can we change the decrement rate of TNR for only Turbine operating at Temperature Control mode? Is the decrement rate available in control constant?