Interconnected Power System: Advantages, Disadvantages, and Problems

Interconnected Power System_ Advantages, Disadvantages, and Problems

The power system network is an interconnected network. It means all generators are connected with the grid. Therefore, if one generator is overloaded the load can be transferred on other generators.

There are many advantages and disadvantages of the interconnected system. In this article, we will explain briefly on this topic.

Advantages of the Interconnected Power System

  • Use of older plants
  • Economical operation
  • Increase the reliability of power supply
  • Exchange of peak load
  • Increase the diversity factor
  • Reduce plant reserve capacity
  • Reduce capital and operating cost

Use of Older Plants

In the power system network, there are some old and insufficient generating stations. These stations have the capacity to carry short peaks of the load. But these generating stations are not sufficient to run on a continuous basis.

If the system is interconnected than these plants are also connected in a system with a transmission line and we can use these plants to meet the peak load demand. So, to achieve this purpose, these generating stations are used with modern plants.

In this way, we can meet peak load demand without giving extra burden on modern plants with the help of old and insufficient generating station.

Economic Operation

All the generating stations are working on the same frequency and same voltage level. Because of the sharing of load among the power plants are done in such a way that all generating stations can work continuously with high efficiency and high-power factor.

The less efficient and old generating stations are not used continuously and these plants are used only at peak hours. Therefore, in an interconnected system makes the economical operation of the power stations.

Increase the Reliability of Power Supply

In the interconnected power system, all the load has more than one supply. If one supply is failed or in maintenance, in this condition load is supplied by another source.

So, if a major breakdown occurred in the power station, then the load is transferred to other healthy power station. Hence, the load is always connected with an uninterrupted power supply and increases the reliability of the system.

Exchange of Peak Load

In the summer season, the use of inductive load like air-conditioner is increase. Therefore, in this season, the load curve of the power station shows a peak demand.

This peak demand is more than the capacity of that power system. In this condition, an extra load must be shared by other power station, otherwise, overload relay may operate and load shedding will be done to reduce the burden on a power station.

In the interconnected system, the peak load is transferred to the old generating station. So, the load curve will remain flat in peak demand conditions.

Increase Diversity Factor

It is a ratio of the sum of the individual maximum load of various plants of the system to the maximum demand of the entire system.

The load curve is not the same for all generating stations connected in the interconnected power system. In this way, the maximum demand for the system is reduced as compared to the sum of individual maximum demands on various power stations. And the diversity factor of the system is improved. Therefore, the effective capacity of plants is increased.

Reduce Plant Reserve Capacity

Every power plant has a standby unit for emergencies. In the interconnected system, all plants are connected in parallel. So, the reserve capacity of the system is reduced and it increases the efficiency of the system.

Reduce Capital and Operating Cost

In an interconnected system, the efficiency of plants is increased and the cost of power generation is reduced. In this system, capital cost and operating cost is reduced. So, per kW price is also reduced.

Disadvantages of Interconnected System

  • Expensive tie line
  • Expensive circuit breaker
  • Synchronizing problem
  • Metering and instrumentation

Problems Associated with the Interconnected system

The interconnected system has more advantages than disadvantages. That is the reason, the actual power system is the interconnected network. But there are some problems that are associated with satisfactory implementation.

  • Voltage control
  • Communication
  • Frequency control
  • Metering and instrumentation
  • Shortage of reserve capacity
  • Synchronizing problem

Voltage Control

In the interconnected system, the voltage is an important parameter and it must remain constant at any point of the network. The system voltage may decrease due to high inductive load demand.

Generally, this problem is occurring in the summer season because of the use of air-conditioners, water pumps, and fans. This problem can be solved by meeting the reactive power requirement. For this purpose, the shunt capacitance is used at the load centers.

Communication

The communication facility is not sufficient to provide better operation in the interconnected power system because of the available frequency spectrum is congested.

This problem is occurring in the present communication technique that is the Power Line Carrier Communication (PLCC) technique. To overcome this problem, we have to use other communication techniques like fiber optics and multiple system digital microwave system.

Frequency Control

The frequency is inversely proportional to the load demand. If load demand is increasing frequency is decreased and vice versa. In the case of peak load demand, the frequency is very low. The system frequency should maintain between 48.5 to 50.5 Hz.

If system frequency is not in this range, in this condition frequency relay will operate and disconnect the load.

Metering and Instrumentation

At a different stage of power system network, meters and sensors placed to measure the quantities like voltage, current, frequency, active power, reactive power, etc.

These meters and instruments are very costly. For load forecasting and future calculation, a record of this measurement we required. So, it is necessary to install a sequential recorder, disturbance recorder, etc.

Shortage of Reserve Capacity

In the case of peak load, the load demand is more than the power generation. In this condition, if every power station has a certain amount of reserve power then it can be used to meet demand. This is also useful to meet minute to minute variation in load and load forecasting error.

This can be classified into two types: clod reserve and an operating reserve.

Synchronizing Problem

In an interconnected power system, all the generators are connected in parallel and it must operate at the same frequency.

If this does not happen than any generator of the system may go to out of step condition because of the synchronization breakup.

In the worst condition, the blackout condition may create. So, it is a necessary condition to operate all the generating stations in the synchronized manner.

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