A power system is made up of synchronous machines that work in unison. In order to ensure the continuity of the power system, they must maintain perfect synchronism under all steady-state conditions. When a disturbance occurs in the system, the system generates a force that causes it to return to normal or stable operation.
The power system is the most important component of power transmission, and it is subject to numerous disturbances. When this system is disrupted, it must be able to return to its original state, and this ability is referred to as the power system’s stability. System disturbances can be of various types, such as sudden changes in load, a sudden short circuit between line and ground, a line-to-line fault, all three line faults, switching, and so on. If the electric power system is unable to return to its previous state, it will cause a slew of power issues. Instabilities are caused by a lack of synchronization. The system integrity can be preserved when the entire power system remains intact with no tripping, except for those that are tripped to protect the power system due to the faulted elements.
In power plants, several synchronous generators are connected to a bus that has the same frequency and phase sequence as the generators. Therefore, for a stable operation, the generators must be synchronized with the bus during generation and transmission. As a result, power system stability is also known as synchronous stability, and it is defined as the system’s ability to return to synchronism after experiencing a disturbance such as switching on and off of load or line transience.
Another factor that must be considered in order to fully comprehend stability is the system’s stability limit. The stability limit specifies the maximum power that can flow through a specific part of the system that is subject to line disturbances or faulty power flow. We’ve covered the terminology associated with power system stability, so let’s look at the different types of stability.
The stability of a system is primarily determined by the behavior of the synchronous machines after a disturbance. The power system’s stability is classified into two types based on the magnitude of the disturbances.
- Steady-state Stability
- Temporary stability.
1. Stability of the steady-state :
It refers to the system’s ability to regain synchronism (the same speed and frequency across the network) after a slow and minor disturbance caused by gradual power changes. The ability of a power system to return to its stable configuration following a minor disturbance in the system is termed steady-state stability (such as the action of automatic voltage regulators). The assumption can only be made during very gradual and insignificant power changes. As a result, a machine or group of machines may cease to operate in synchronism if the power flowing through the circuit exceeds the maximum power permissible. In such a case, the system’s steady-state limit is said to have been reached. Another way of putting it is that steady-state stability is defined as the maximum power that can be passed through a system without it losing its stability.
There are two types of steady-state stability. a) Static stability b) Dynamic stability
- Static stability – It refers to the system’s stability that occurs without the assistance (benefit) of automatic control devices such as governors and voltage regulators.
- Stability under dynamic conditions – It denotes a system’s ability to return to its stable state following a very minor disturbance (disturbance occurs only for 10 to 30 seconds). It is also referred to as small signal stability. It is caused primarily by fluctuations in load or generation level.
2. Temporary Stability :
It is defined as the power system’s ability to return to normal operating conditions following a large disturbance. A large disturbance occurs in the system as a result of the sudden removal of the load, line switching operations; a fault occurs in the system, a line goes down, and so on. When a new transmitting and generating system is planned, transient stability is tested. The swing equation describes the synchronous machine’s behavior during transient disturbances.
Stability studies are useful for determining the critical clearing time of circuit breakers, voltage levels, and system transfer capability.
The significance of power system stability studies:
Power system engineering is a large and important part of electrical engineering studies. It is primarily concerned with the generation of electrical power and its transmission from the sending end to the receiving end in accordance with requirements while incurring the least amount of losses. Power fluctuates frequently as a result of load variations or disturbances.
Because of these reasons, the term “power system stability” is very important in this field. For stability correction, harmonic analysis is also necessary for conducting study and analysis of power quality. It is used to measure how quickly a system can return to a steady-state after experiencing any transience or disturbance. Since the mid-20th century, all major power stations have used the alternating current (AC) system mostly because it is the most efficient and cost-effective method of generating and distributing electricity.
The Electrical Power System Analysis is critical for the protection of power systems. A power systems study may be required to ensure the reliable operation of protective devices in the event of a short circuit or any fault current. However, no one performs a comprehensive suite of power system studies at the same time.
Typically, a complete Arc Flash study is required every 5 years over the life of a facility, as recommended by the latest NFPA 70E 2018 standard and OSHA requirements for the electrical safety of every employee in the field.
Generally, Arc flash studies include all of the major power systems studies that are required for any power systems facility (Hospitals, Power plants, Clubs, Industries, and so on), so if you perform an Arc flash study with the recommendations, it will cover the majority of the parts required in the power systems.
Benefits of going for Power System Stability Services
A well-designed power system ensures reliable performance and maximizes plant availability under all operating conditions, including transient conditions such as motor starting, non-linear loads, and generator failure. A poorly designed system can result in significant losses, such as outages, malfunctions, poor power quality, and Arc Flashover.
Power Systems Studies is an important study for ensuring a secure and safe electrical supply. Stability studies are useful for determining the critical clearing time of circuit breakers, voltage levels, and system transfer capability.
SAS Powertech provides exceptional Power System Stability services to its clients across all verticals to aid them in maintaining the stability of their power systems. SASPPL has been providing Power System Stability services to its clients across various verticals in India & South East Asia Region. We are known for sharing findings transparently & unbiased reporting. Our Power System Stability services and solutions are the most affordable, and we have helped clients achieve predicted results.