Power is treated as a commodity, yet it is still vulnerable to fluctuations and failures. Once a part of the power system fails, damage to the rest of the electrical system could follow if it is not addressed quickly. To ensure this does not happen, basic types of protection schemes exist to ensure that the system is operational even in the face of a fault.
It is a usual practice in many industries to establish a system protection scheme that is relevant to the situation. For this reason, it is imperative that electrical engineers and related workers learn and understand a variety of scheme types.
In this article, we will discuss what system protection is and the protection schemes that can be appropriately applied to your business to ensure everything in the power system is up and running efficiently.
What is System Protection?
System protection is the branch of electrical engineering that deals with the science and art of detecting power problems in the system components. It enables engineers to isolate the faulty section so that the rest of the live electrical system remains operational and unaffected by damage.
According to the North American Electric Reliability Corp., a protection system consists of “protective relays, associated communication systems, voltage and current sensing devices, station batteries and DC control circuitry.”
Efficiency is a key parameter in designing, maintaining and fixing protection schemes. For this reason, engineers are constantly on the lookout for updates, new developments, and research to make protection schemes more efficient.
What is the purpose of system protection?
The main objective of system protection is to isolate faulty parts and guard the rest of the system from severe damage. Components or equipment that often need protection includes transformers and reactors, generators, power lines, capacitors and buses.
- Stabilizing the system
- Ensuring the safety of consumers
- Improving the reliability of electrical supply
- Preventing or minimizing damages to equipment
- Protecting the entirety of the system from overloads
- Prompting engineers and technicians to develop expertise in the field
The most common issues addressed by system protection schemes are short circuits, equipment failures and extraordinary conditions such as natural disasters.
Components of a system protection scheme
Protection schemes commonly have five components:
- Transformers – help decrease high voltage and current to manageable levels that relays can handle
- Protective relays – locate the fault and starts a disconnection order or trip
- Circuit breakers – obey auto-recloser or relay commands to close or open a system
- Batteries – provide an alternate source of power in case of disconnection
- Communication channels – enable staff to remotely proceed with analysis and tripping
What are the basic types of protection schemes?
True to its name, an adaptive protection scheme employs adaptive relays that can automatically adjust settings, logical functions and characteristics based on signals produced externally. Status changes of the system are made online, which showcase this scheme’s flexibility in answering power issues.
An adaptive scheme is highly reliable and is applied to modern digital systems. It typically uses microprocessors that adapt their settings in real-time to the actual power conditions. It is an online activity that considers changes in generation and topology to accommodate changes to the load and fault currents.
Differential current refers to the difference between input current and output current, and is the basis for the differential protection scheme. In this type, a piece of equipment or isolated zone is fixed with a differential relay that detects faults inside the specified zone.
This scheme operates on the fact that in normal situations, the current leaving a specified feeder should be equal to the current that has entered the same feeder. Once the system detects a difference, it activates the circuit breaker and trips the isolated zone immediately.
Distance or impedance relay protection happens as a result of a sag found in the system’s voltage level, which is caused by a fault. It is based on impedance or the ratio of voltage to the current within the relay terminals. This predetermined level will prompt the circuit breaker to commence.
The distance protection scheme is commonly used for lines that are more than 10 miles since the operative characteristic varies based on the line characteristic. If a rise in current and collapse in voltage is observed, this usually signals a fault on the line and operates the impedance relay.
There are instances when the protection relay in place or the circuit breaker itself fails to operate. In highly crucial systems, a backup protection scheme is necessary should the primary protection scheme fail to activate.
A backup works by removing the affected section and preventing the expansion of the disturbance in the system. It can either be remotely or locally done. In the remote backup, the response is generated from a different substation and protects both affected and unaffected portions of the specified zone. Local backup, on the other hand, refers to a device within the affected substation that senses each fault and initiates a trip.
Cybersecurity Protection Scheme
Interconnecting electrical systems including control centers and transmission are threatened by security attacks, especially now that protection systems can utilize microprocessors and be overseen online. For example, a grid could have a control system that is wired to the internet, which then exposes the entire system to hacking, sniffing, phishing, social engineering and other malicious threats.
Attacks on digital relays can happen, so a cybersecurity protection scheme should be established to insulate the entire system against data breach and equipment damage.
Find the Right Partner
Power is essential to modern-day living. It must be reliable and up-to-speed so that the industries that rely on it may continue to operate efficiently. With these system protection schemes, faults and other kinds of power failures can be resolved at the soonest possible time and that damages are little to none.
Are you looking for the right partner to implement protection schemes to your power system? Present Group has deep experience and expertise to help you. Send us a message today to learn more about our services.