Short Answer:

Incremental fuel cost in power generation is the additional cost required to produce one more unit of electricity (usually one megawatt-hour or MWh). It shows how much the fuel cost increases when the power output of a generating unit is slightly raised.

It is an important concept used in economic load dispatch (ELD) to decide which generator should supply more power. Generators with lower incremental fuel costs are usually given priority in generation to minimize overall fuel cost in the power system.

Detailed Explanation:

Incremental fuel cost in power generation

Incremental fuel cost refers to the rate at which fuel cost increases with a small increase in power generation. It tells how much extra money is spent on fuel when the output of a generating unit is increased by a very small amount. This concept is especially important in thermal power plants, where the fuel cost is a major part of the operating cost.

It is also called the marginal fuel cost and is expressed in units like ₹/MW or $/MWh. Power system operators use this value to compare different generators and make decisions about which ones should supply more or less power at a given time.

How It Is Calculated:

If C(P) is the total fuel cost as a function of power output P, then the incremental fuel cost is calculated as the derivative of this function with respect to P:

Incremental Fuel Cost = dC/dP

In practical terms, the fuel cost function is often represented as a quadratic equation:

C(P) = a + bP + cP²

Where:

• C(P) is the fuel cost in ₹ or $
• P is the power generated in MW
• a, b, c are cost coefficients

Then the incremental fuel cost becomes:

dC/dP = b + 2cP

This means the incremental fuel cost increases with the output of the generator.

Importance in Power System Operations:

1. Economic Load Dispatch (ELD):
   The incremental fuel cost is used in ELD to find the most economical way to allocate load among different generating units. The generator with the lowest incremental cost is given more load.
2. Cost Optimization:
   By comparing the incremental cost of all running units, the system ensures that the total generation cost is minimized.
3. Generator Scheduling:
   Helps in deciding the most efficient generator mix for current demand.
4. Real-Time Control:
   Incremental cost values can be updated in real-time based on fuel price and generator performance, allowing dynamic decision-making.
5. Environmental Considerations:
   Some advanced models include emission cost along with fuel cost to optimize generation based on environmental limits.

Factors Affecting Incremental Fuel Cost:

• Fuel Price: Higher fuel prices increase the incremental cost.
• Efficiency of Generator: More efficient generators have lower incremental costs.
• Generator Condition: Wear and maintenance condition can affect heat rate and cost.
• Operating Load: At higher loads, fuel usage per unit may increase due to reduced efficiency.

Conclusion:

Incremental fuel cost in power generation indicates the additional fuel expense needed to increase power output slightly. It is calculated as the derivative of the fuel cost function and plays a vital role in economic dispatch and generator scheduling. By using incremental cost values, power systems can achieve cost-effective and optimized electricity generation while maintaining system stability and meeting demand.