Power Transfer Capability ? Concepts of TTC, NTC,ATC,TRM in Power Transfer ?

Long distance bulk power transfers are essential for an economic and secure supply of electric power. Power system transfer capability indicates how much inter area power transfers can be increased without compromising system security. Accurate identification of this capability provides vital information for both planning and operation of the bulk power market. (Planners need to know the system bottlenecks and system operators must not implement transfers which exceed the calculated transfer capability.)

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Power transfer capability is a measure of the maximum amount of power that can be transferred over a transmission network under certain assumptions and conditions. It is important for ensuring the security and efficiency of power systems, especially in a deregulated environment where power transactions are based on market forces. There are different types of power transfer capability, depending on the criteria and methods used to calculate them. Some of the common types are:

?Total Transfer Capability (TTC): This represents the maximum amount of power transfer that the transmission network can accommodate while meeting the pre-specified and post-specified contingency system conditions.

?Available Transfer Capability (ATC): This is the difference between TTC and the sum of existing transmission commitments (including retail customer service) and a capacity margin to allow for uncertainties.

?Transfer Capability Margin (TRM): This is an amount of transmission transfer capability necessary to provide reasonable assurance that the interconnected transmission network will be secure.

?Capacity Benefit Margin (CBM): This is an amount of transmission transfer capability reserved by load-serving entities to ensure access to generation from interconnected systems to meet generation reliability requirements.

Repeated estimates of transfer capabilities are needed to ensure that the combined effects of power transfers do not cause an undue risk of system overloads, equipment damage, or blackouts. However, an overly conservative estimate of transfer capability unnecessarily limits the power transfers and is a costly and inefficient use of the network.

Power transfers are increasing both in amount and in variety as deregulation proceeds. Indeed, such power transfers are necessary for a competitive market for electric power. There is a very strong economic incentive to improve the accuracy and effectiveness of transfer capability computations for use by system operators, planners and power marketers.

Term “transfer capability” refers to the amount of electric power that can be passed through a transmission network from one place to another. The concept of transfer capability is useful for several reasons. A system which can accommodate large inter-area transfers is generally more robust and flexible than a system with limited ability to accommodate inter-area transfers.

Thus, transfer capability can be used as a rough indicator of relative system security. Transfer capability is also useful for comparing the relative merits of planned transmission improvements. A transmission expansion that increases transfer capability between two areas of the grid might be more beneficial for increasing both reliability and economic efficiency than an alternate improvement that provides a lesser increase in transfer capability

TOTAL TRANSFER CAPABILITY (TTC)

Total Transfer Capability (TTC) is the maximum amount of power that can be transferred over a transmission line or a group of transmission lines while maintaining system stability. It is a crucial parameter in power system operation and planning, as it helps to ensure that the transmission system is operated within safe and reliable limits.

TTC takes into account various factors such as the capacity of the transmission lines, the voltage limits of the system, and the available generation capacity. The calculation of TTC involves a complex analysis of the power system, which considers the impact of various contingencies such as line outages, generator outages, and load variations.

In practice, TTC is typically calculated by power system operators using sophisticated computer models that simulate the behavior of the power system under different operating conditions. These models take into account the physical characteristics of the transmission system, as well as the dynamic behavior of the generators and loads.

TTC is an important parameter for power system planning, as it helps to ensure that the transmission system is capable of meeting the future demand for electricity. By calculating the TTC, system operators can identify potential bottlenecks in the transmission system and plan for the construction of new transmission lines or the expansion of existing ones.

TTC is a critical parameter for ensuring the safe and reliable operation of the power system, and it plays a key role in maintaining the balance between supply and demand of electricity.

NET TRANSFER CAPABILITY (NTC)

Net Transfer Capability (NTC) is the maximum amount of power that can be transferred over an interconnection between two power systems while maintaining the reliability of the systems. It is the difference between the transfer limit and the scheduled transfer. The transfer limit is the maximum amount of power that can be transferred over the interconnection without violating system reliability criteria, while the scheduled transfer is the amount of power that has been scheduled to be transferred over the interconnection.

The NTC is determined by various factors such as the capacity of the transmission lines, the stability of the power systems, and the availability of the generation resources. It is calculated using complex mathematical models that take into account the various parameters of the power system.

The NTC is an important parameter in the operation of power systems, as it helps ensure the reliability of the interconnected systems. It is used by system operators to manage the flow of power between different regions and to prevent overloading of transmission lines. The NTC also plays a critical role in the planning of new transmission lines and the expansion of the power grid.

For example, suppose there are two power systems A and B, which are interconnected through a transmission line. The maximum amount of power that can be transferred from system A to system B without causing any reliability issues is the NTC. If the NTC between systems A and B is 500 MW, then the maximum amount of power that can be transferred from system A to system B is 500 MW. If the transfer of power exceeds this limit, it may cause overloading of transmission lines, voltage instability, and other issues that can lead to blackouts or other disruptions in the power system. Therefore, NTC is an important factor in ensuring the reliable and efficient operation of the power system.

AVAILABLE TRANSMISSION CAPABILITY (ATC)

Available Transmission Capability (ATC) is the amount of power that can be transmitted over a transmission line or a group of transmission lines while maintaining the reliability of the power system. It is the maximum amount of power that can be transferred after taking into account the transmission system's physical limitations, voltage limits, and other operational constraints. ATC is an important parameter for power system operation and planning, as it helps to ensure that the transmission system is operated within safe and reliable limits.

The calculation of ATC takes into account various factors such as the capacity of the transmission lines, the available generation capacity, and the system's operating conditions. ATC considers the impact of various contingencies such as line outages, generator outages, and load variations. It is calculated by power system operators using sophisticated computer models that simulate the behavior of the power system under different operating conditions.

ATC is a critical parameter for power system planning, as it helps to ensure that the transmission system is capable of meeting the current and future demand for electricity. By calculating the ATC, system operators can identify potential bottlenecks in the transmission system and plan for the construction of new transmission lines or the expansion of existing ones.

Available transfer capability is defined as:

Available Transfer Capability (ATC) = Total Transfer Capability (TTC) ? Existing Transmission Commitments (ETC) ?Transmission Reliability Margin (TRM) ?Capacity Benefit Margin (CBM)

ATC= TTC-ETC-TRM-CBM

ATC is a crucial parameter for ensuring the safe and reliable operation of the power system, and it plays a key role in maintaining the balance between supply and demand of electricity.

TRANSMISSION RELIABILITY MARGIN (TRM)

Transmission Reliability Margin (TRM) is the amount of available transmission capacity that is held in reserve to ensure the reliable operation of the power system. It is a measure of the transmission system's ability to handle unexpected events such as equipment failures, extreme weather conditions, and sudden changes in power demand. TRM is calculated by subtracting the forecasted peak demand from the available transmission capacity, leaving a margin of capacity that can be used to maintain the reliability of the system.

TRM is an important parameter for power system planning and operation, as it helps to ensure that the transmission system is operated within safe and reliable limits. TRM provides a buffer of available capacity that can be used to maintain the reliability of the system during periods of high demand or unexpected events. By maintaining a sufficient TRM, power system operators can ensure that the system can handle unexpected events without compromising the reliability of the system.

TRM is calculated using complex computer models that simulate the behavior of the power system under different operating conditions. The models take into account various factors such as the capacity of the transmission lines, the available generation capacity, and the system's operating conditions. The models also consider the impact of various contingencies such as line outages, generator outages, and load variations.

TRM is a critical parameter for ensuring the safe and reliable operation of the power system. By maintaining a sufficient TRM, power system operators can ensure that the transmission system can handle unexpected events without compromising the reliability of the system.

CAPACITY BENEFIT MARGIN

Capacity Benefit Margin (CBM) is a measure of the reliability of a power system. It represents the amount of excess capacity available in the system over and above the expected peak demand. CBM is expressed as a percentage of the expected peak demand and is typically used by system planners to ensure that there is enough capacity to meet future demand growth and to maintain a reliable power supply.

CBM is calculated by subtracting the expected peak demand from the available capacity and then dividing the result by the expected peak demand. The available capacity includes all of the generating units, transmission lines, and other system components that are expected to be available during the peak demand period. The expected peak demand is the highest level of demand that is expected to occur during a given period, typically a year.

For example, if the expected peak demand is 10,000 MW and the available capacity is 12,000 MW, the CBM would be 20% ((12,000 - 10,000) / 10,000 x 100%). This means that there is a 20% excess capacity available to meet unexpected demand or to cover the loss of a generating unit or transmission line.

CBM is an important metric for system planners because it helps to ensure that there is enough capacity available to maintain a reliable power supply. A CBM of 15% or higher is generally considered to be adequate, while a CBM of less than 10% is considered to be a potential risk to the reliability of the system.

BENEFIT's OF POWER TRANSFER CAPABILITY

Benefits of Power Transfer Capability (PTC) include:

1. Increased Reliability: PTC allows for the transfer of power between different regions, which can help to balance supply and demand and reduce the risk of blackouts or other power outages.

2. Improved Market Efficiency: PTC enables market participants to access a wider range of power sources, which can help to reduce costs and increase competition in the energy market.

3. Better Resource Utilization: PTC can help to optimize the use of existing power generation resources by allowing excess power to be transferred to areas with higher demand.

4. Increased Renewable Energy Integration: PTC can help to facilitate the integration of renewable energy sources into the power grid by allowing excess power generated by wind or solar farms to be transferred to other regions.

5. Enhanced Grid Stability: PTC can help to maintain grid stability by allowing for the quick and efficient transfer of power in response to changes in demand or supply.