Talk:Power-flow study

1. Some figures of the bus might be nice?
2. The term ybus is used twice without any definition, introduction or a link.
3. vdv — Preceding unsigned comment added by 115.111.52.227 (talk) 17:34, 29 January 2012 (UTC)Reply

Made some corrections to last section, Power Flow methods. The list of methods should be probably expanded, but these four are the general-purpose ones. Other possible ones could be the DC-approximation methods, Continuation methods, fuzzy/stochastic methods, etc., but all of them are not really general-purpose. --Gridquant (talk) 11:40, 1 October 2012 (UTC)Reply

Made some additions to one of the methods in the last section, Power Flow methods.Fast decoupled load flow method is widely adopted in the industry and it would be nice if we have more information on it. Basically I provided insights on why do we adopt such method and how FDLF is executed. =) --li.chenyang1990 (talk) 16:25, 23 November 2013 (PTC)

Made some additions to the Power Flow Problem Formulation section to highlight the relationship between voltage angle and real power, and between voltage magnitude and reactive power. --Jyho2 (talk) 08:44, 24 November 2013 (UTC)Reply

Suggest merge; the source article si quite short and would be better discussed in context. I'm also not sure that it is accurate, and it needs references. --Wtshymanski (talk) 17:56, 25 February 2013 (UTC)Reply

Done. --Wtshymanski (talk) 20:30, 17 February 2014 (UTC)Reply

If you want these, they cost extra...

As plant expansion and modification occurs, loads may be moved and larger ones added, leading to increased levels of available short-circuit currents. In addition, the power grid supplying the plant may have increased the available fault capacity due to the enlargement of its own system. The possibility of increasing the amount of short-circuit current available into a fault by these changes is the major reason for a periodic system study. If the short-circuit capacity of the system exceeds the capacity of the protective device, a dangerous situation exists for both plant personnel and system equipment. Under fault conditions, the protective devices would attempt to interrupt the fault current, which could cause a catastrophic failure. Therefore, the need and importance of determining the short-circuit capabilities of a system cannot be stressed enough.

There are many considerations to starting a motor other than effectively connecting it to the line voltage. Nuisance tripping and excessive running currents, as well as dimming of lights, are signs that a power system is not performing properly. The power system should be able to supply inrush to any motor on the system while supplying normal service for the rest of the system. If the system does not have sufficient capacity, there will be excessively low voltage drops and insufficient capacity for motor starting.

Protective device coordination is the ability of the closest upstream protective device to detect and clear the system fault without the operation of another protective device further upstream in the power system. As backup protection, if the closest device fails to operate for some reason, the next set of protective devices should be coordinated so they will operate before extensive damage results. Many cases of unexplained outages or heavily damaged equipment are accepted without question or knowledge that the real reason may be improper coordination of protective devices. A poorly coordinated system will result in nuisance outages during a fault condition. Damage to equipment are more likely under mis-coordinated protective devices hence, resulting in unplanned downtime and equipment repair or replacement.

Arc Flash studies are required and compliance with this standard is mandatory per OSHA. Companies will be cited and fined for not complying with these standards. A facility must provide, and be able to demonstrate, a safety program with defined responsibilities the following:

• Calculations for the degree of arc flash hazard
• Correct personal protective equipment (PPE) for workers
• Training for workers on the hazards of arc flash
• Appropriate tools for safe working
• Warning labels on equipment

System stability study is essential when adding, upgrading or evaluating existing generators within the facility. This study will evaluate overcurrent relay settings and or modifications to the protection scheme associated with the generators and utility. This time-based analysis will determine relay settings that will allow the generator out-of-step protection and overcurrent protections to operate for a disturbance prior to loss of system stability and damage to equipment's. In general, load shedding (LS) can be defined as the amount of load that must nearly instantly be removed from a power system to keep the remaining portion of the system operational. This load reduction is in response to a system disturbance that results in an unbalanced condition of the amount of system load exceeding the available electric generation. Common disturbances that can cause this condition to occur include faults, loss of generation, switching errors, lightning strikes, etc. Consequences of Improper Load Shed:

• Shedding too much load (Loss of Critical Process)
• Total loss of production
• Unsafe operating condition and environmental concerns
• Costly outages and equipment damage

In general, harmonic analysis is commonly used to predict distortion levels caused by the addition of a new harmonic-producing loads or capacitor banks. Consequences of excessive harmonic distortion include:

• Control / Computer system interference
• Overheating in rotating machinery
• Overheating / failure of capacitors
• Costly outages and equipment damage

--Wtshymanski (talk) 19:29, 22 September 2014 (UTC)Reply

The OpenElectrical wiki contains a list of some 50 software applications for power system analysis. The site is under a Creative Commons Attribution 3.0 license, compatible with Wikipedia. I think some of that information would be initially useful for this page. There needs to be some coverage of numerical tools, either here or in a stand-alone article. Best wishes. RobbieIanMorrison (talk) 00:07, 12 November 2016 (UTC)Reply