Understanding Transmission System Power Flow

[rockman7892]

I have recently been trying to gain a better understanding of the electrical transmission grid and wanted to particular gain a better understanding of how power flow between different locations on the grid. I have found that the US is broken up into 3 main NERC interconnections ( Eastern, Western & ERCOT)with each interconnection consisting of many utilities and generation sites which are all interconnected to make up a transmission system within each interconnection.

I see that each interconnected system is subdivided into "control area" which essentially represent and area made up of local generation sites and loads. Between these control areas there are "tie Lines" in order to allow the flow of power between these different control areas. Can anyone offer any good references for gaining better insight for how power is shared between these control areas or offer a general explanation of the concept?

From what I can tell each control area is responsible for balancing a scheduled net interchange (local area power consumptions vs import/export between other control areas) as well as maintaining a given system frequency measured as the "area control error" (ACE).

Some Questions

1) It appears that each control area has a specific "balancing authority" which is the utility or entity responsible for maintaining the power flow between adjacent control area?

2) Are there only transmission ties between balancing authorities in different control areas? In other words there will never be a transmission tie between a balancing authority and non-balancing authority in different control area?

3) Does each control area consist of local utilities or generating sites that are controlled by a single balancing authority in that area?

4) How do Regional Transmission organizations or independent system operators play into this power flow scheme?

5) Is there a way to track a particular power flow that originates in area of the country and is consumed in another area of the country by the patch of which it takes between various control areas?

I appreciate any help in gaining better insight into some of these concepts.

 

[Gianoli]

Check out this link:

http://energy.gov/sites/prod/files/oeprod/DocumentsandMedia/BlackoutFinal-Web.pdf

It's a lengthy read but gives some good insights into the operation of the electrical power transmission grid.

 

[marks1080]

1) FERC is the main entity in North America. It sets the rules for its sub agencies, like NERC for example. NERC will then set the rules a more local level, eventually dictating some procedures for utilities or operating entities. These agencies add bureaucracy, but it really is necessary for overall system stability, seeing that they are all connected together.

2) transmission lines know no borders!

3) Generally, yes. Each region will have some overlord type controlling/operating authority. This is different from a typical utility operations center as they are usually the ones also doing the buying and selling between jurisdictions. This type of authority would deal directly with an agency like NERC for example, and they would then push policy to the regional utilities/operators/generators, etc...

4) Generally in North America they participate by entering the market. Private generators can bid on blocks of generation. Private transmission operators have to play by the rules like everyone else.

5) You can track the metering of the tie lines. So you know in total what's coming in and what's going out. But, you can't really track power coming in one tie line and trace it through the system and see those same electrons pass out of another tie line. Think of each local jurisdiction as a bucket of water. Power coming in is the same as water being poured into the bucked. Power going out to another jurisdiction is water being siphoned out of the bucket. I can track each individual drop in and out of the bucket, but once a water drop goes into the bucket I can't ever separate those specific water molecules out again. The best you can do is use modeling software if you're really interested in this, but there's no reason to be.