Power Systems Studies

Power System Studies are comprehensive assessments of the electrical supply system in a given facility. These studies are essential for ensuring the safe and reliable operation of power systems, identifying potential problems and areas for improvement, and ensuring compliance with regulatory requirements. Power System Studies include Power System Analysis, which is the application of mathematical models and computational methods to analyze the performance of power systems.

Objective of Power System Studies

The objective of Power System Studies is to identify and analyze the electrical supply system’s potential issues and risks, develop recommendations for mitigating these issues, and optimize the system’s performance. These studies are typically conducted by electrical engineers with specialized knowledge and expertise in power supply design and power system design.

In the oil and gas industry, Power System Analysis is crucial due to the high levels of electrical demand and the safety risks associated with the industry’s operations. Power System Analysis helps identify and mitigate the risks associated with electrical supply systems in oil and gas facilities, including hazards such as electrical shock, arc flash, and equipment damage.

Power System Analysis is essential for a variety of reasons, including ensuring the safety of personnel and equipment, optimizing system performance, reducing downtime and maintenance costs, and complying with regulatory requirements. By identifying potential problems and developing solutions, Power System Analysis helps ensure the safe and reliable operation of power systems.

There are several standards for Power System Studies, including those set by the Institute of Electrical and Electronics Engineers (IEEE), the National Fire Protection Association (NFPA), and the Occupational Safety and Health Administration (OSHA). These standards provide guidelines and best practices for conducting Power System Studies, including the types of analysis to be used and the parameters to be evaluated.

What are the 3 types of power systems? 

The three types of distribution system designs are as follows  

• Radial Distribution System 
• Loop Distribution System 
• Network System 

Radial Distribution System 

The Radial distribution system is the most economical to build, and is commonly used in least populated areas. It has a single power source for a group of End users. A short-circuit or a power failure would interrupt power in the entire line which must be sorted out before power can be restored. 

Loop Distribution System 

A loop system loops across the service zone and comes back to the original place. The loop is tied to an alternate power source. Placement of switches in strategic locations, enables the utility to supply power End user from either direction. 

If one of the power source fails, switches are thrown either manually or automatically, and thereby power can be fed to End user from the other source. 

The loop system provides better continuity service when compared with the radial system. In the circumstance of power failures due to faults in the line, the utility has to find the fault and switch it around to put back service. The fault itself can then be put right by End user’s minimum interruptions. 

The loop system is more costly than the radial as more conductors and switches are required, but the resulting enhanced system reliability is worth the price paid. 

Network System 

Network systems are the most complex and are referred as interlocking loop systems. A End user can be provided with two, three, four, or more different power supplies. Therefore, the biggest advantage of such a system is increased reliability. Also, it is the most expensive. Citing this reason it is widely used only in high load density and congested areas. 

What are the significant parts of Power System? 

The significant parts of a power system are Generators, Transformers, Transmission lines, Busses and Loads. 

• Generators 

 Generators allow for power to be generated. 

• Transformers 

 Transforms one voltage level to another. 

• Transmission lines 

 Transmits the power with the required Voltage from one location to another. 

• Busses  & loads 

 Busses distribute Power among a number of transmission lines and power transformers which is later used by Customer and usually represented as loads.  

What is the Purpose of Power System? 

Power systems provide energy to utilities that perform a function in terms of Load. These loads varies from household devices to Industrial Equipment machineries. Usually loads expect a specific voltage and, for alternating current devices, a specific frequency and a certain number of phases which is ultimately served by the Power Systems. 

Importance of Stability analysis in Power System  

Power system stability incorporates the study of the dynamics of the power system under interruptions. Power system stability ensures the systems ability to resume to its stable or normal operations after been exposed to certain form of interruptions. Power system instability can be viewed as loss of synchronism  when the system is exposed to a certain interruption.  

The following are the three types of stability that needs to be analyzed 

• Steady state Stability 
• Transient state Stability 
• Dynamic state Stability 

Steady state Stability 

Steady state stability describes the response of synchronous machine to a moderately increasing load. It is related with the determination of the upper restraint of machine loading without synchronism loss, as long as the loading is increased moderately. 

Transient state Stability 

Transient stability describes the response to large interruptions that may result huge variations in power angles, rotor speeds, and power transfers. Transient stability is a quick occurrence which is evident within few seconds. Power system stability is usually related with rotor stability analysis. 

Dynamic state Stability 

Dynamic stability describes the response to minimal interruptions that take place on the system, creating oscillations. The system is considered to be dynamically stable if theses oscillations do not reach more than certain amplitude and gets exhausted quickly. In-case if these oscillations pick up pace gradually in amplitude, obviously the system becomes dynamically unstable. The origin of such type of instability is widely an interconnection that exists amidst control systems. 

Some of the analysis to be used in Power System Analysis include Load Flow Analysis, Short-Circuit Analysis, Protective Device Coordination, and Arc Flash Hazard Analysis.

Load Flow Analysis

Also known as Power Flow Analysis or load flow study is a fundamental power system study that analyzes the steady-state behavior of an electrical network under normal operating conditions. It determines the voltages, currents, and power flows throughout the system, providing valuable insights into system performance and helping ensure its reliable operation. The primary objective of a load flow analysis is to calculate the operating parameters of the power system, such as voltages, power factor, active power, reactive power, and line currents, under various load and generation conditions. This analysis is performed by solving a set of non-linear equations known as the power flow equations, which describe the electrical relationships and constraints in the network.

Short-Circuit Analysis

Used to determine the behavior and effects of electrical faults or short circuits in a power system. A short circuit occurs when an unintended connection is made between two points of different voltage potentials, resulting in a flow of excessive current. The purpose of a short circuit study is to assess the electrical system’s response to these fault conditions and determine the magnitude and distribution of fault currents. This information is crucial for designing protective devices, such as circuit breakers and relays, to detect and interrupt faults, ensuring the safety and reliability of the power system.

Protective Device Coordination

Protective Device Coordination, also known as protective device coordination study or selective coordination study, is a power system study that focuses on the coordination and selectivity of protective devices, such as relays and circuit breakers, within an electrical system. The purpose of protective device coordination is to ensure that only the nearest protective device to a fault or abnormal condition operates to isolate the faulted section while minimizing disruption to the rest of the system.

Arc Flash Hazard Analysis

Arc Flash Hazard Analysis, also known as arc flash study or arc flash risk assessment, is a power system study that focuses on assessing the potential for arc flash incidents and determining the associated hazards in an electrical system. An arc flash is a dangerous release of energy due to an electric arc, which can cause severe burns, injuries, and even fatalities to personnel working on or near energized equipment

Some advantages of conducting a power system Studies. 

• Reductions outage  time within the plant as a result of  the system style and instrumentation are changed to scale back  mean  time  between failures and mean time to repair. 
• Power Quality are considerably improved due to reduction in harmonic currents and voltages. 
• Reduction in outages due to unstable generator power swings following fault clearing. 
• Electrical Safety is conjointly improved as potential harmonic resonance conditions corrected and also because of identification and elimination of overvoltage and overcurrent things. 
• Improved operations with islanded conditions, thanks to implementation of load shedding scheme. 

Methodology 

Input Required 

• Overall key Single Line Diagram 
• List of switch gear-Plant wise 
• Protection single line diagram 

• Previous power system studies 
• Load schedules 
• Protective Relay Setting sheets type 
• And creation of relay 
• Data sheet and Name plate Details of all Generators, transformers, VFDs and HT motors 

Deliverables 

• Complete assessed input data report of all instrumentation 
• Load/power flow study 
• Report on Transformer/Generator size supported Load Flow Study 
• Short Circuit reports for  worst Case Scenario Conditions and its associated Results 
• Transient/Load Shedding report for the aforementioned worst case state of affairs for giant space distribution 
• Motor starting Current Analysis 
• Harmonics analysis on individual load clusters and harmonic Filter filler calculation 
• Coordination Study Report including computer generated time-current characteristics Curves(TCC) 
• Reliability study for major switchboards/Panels

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