Power Systems - Who's in Charge Here
I hope you enjoyed that last one and the romp into mathematical equations. In this article we can take a break from math and talk about who the players are, and what they do. Let’s get started!
Power System operations are divided into two distinct areas, at least here in North America. We have largely been discussing things that operate on the “reliability side” of the grid. This is where the work is done to keep the machine moving, no one on the reliability side cares about money, in fact they are blocked by the FERC order 889 Standards of Conduct from discussing anything financial.
The other side is the “marketing side”, they are all things financial. The marketing side buys and sells power and arranges its delivery.
Per the Standards of Conduct these two functions cannot be in the same room and are often located across the property from each other. The reliability side is forbidden from sharing any information with the market side that might be used to leverage a profit or game the market. The Reliability to Marketing communications are literally, “I need you to buy this much energy and deliver it at this bus”, or “I have this much energy available to sell at this bus”, nothing else.
This picture shows the list of “reliability entities”, these are the functions a company registers to perform as a said entity and commits to fulfill the NERC Standards that apply to that entity. A utility can have several or all these functions in house, depending on what they do. Not all these functions have day-to-day duties but instead act more as place holders. The functions that do have active duties are generally given sperate areas of responsibilities to dedicated personnel. All of these functions are explained in the Glossary of Terms Used in NERC Reliability Standards.
We should still cover the important ones.
Balancing Area we have already covered in Power Systems - It's a Balancing Act.
Transmission Operator (TOP); if a BA controls frequency, a TOP controls voltage. Just to mention a Transmission Owner (TO) and a TOP do not need to be the same company, a TO can contract with a TOP to operate their lines. So, the TOP is literally responsible for operating the transmission lines, or the network of Transmission lines in his jurisdiction. You do actually have to operate a transmission line, they produce high voltage when they are lightly loaded, they pull the voltage down when they are heavily loaded. The operating limits may not be due to the size of the wire. Sometimes long lines have angular limits, you can literally twist the magnetic bond in two over the length of the line (called out of step). Some have voltage limits because the voltage at one end can collapse if you overload the line. Voltage is a relatively local occurrence on the power system. The job of making sure voltage stays within limits everywhere falls on the TOP. The TOP is also responsible for keeping lines, or groups of lines called paths, operating inside their load limits. Keep in mind it is Transmission lines that connect the BAs together. Jurisdiction between TOPs will usually change at a substation bus. Every transmission line is monitored on both ends. Any change in jurisdiction anywhere on the power system will always have watthour meters as well as other monitoring. It’s a big job.
Reliability Coordinator (RC); The RC is basically the policeman and the diplomat of his area of responsibility. The RC is responsible for a section of the Interconnection, usually containing several BAs and several TOPs. The RC has a wide view of the system, he receives data from the EMS and SCADA that are within his jurisdiction. It is his job to watch for conditions that may develop and threaten the integrity of the Interconnection. If needed, he can issue Operating Instructions to any entity in his jurisdiction that must be followed. Where two adjacent entities are having a disagreement, he can step in and issue a binding mitigation to the operational issue.
Generator Operator (GOP): Like the TOP, the GOP does not need to be the same company as the Generator Owner (GO). Probably more than half of the generation operating today is not owned by the utility. That responsibility has been spun off to companies like Calpine that specialize in owning and/or operating power plants. Because Power Plants are fundamental to a stable power system, they have their own set of rules they must follow, including reporting on the potential availability of their equipment, as well as immediately advising of a forced outage. Changes to the GOPs planned output must be reported to the host BA, the TOP issues the GOP a voltage schedule to follow for voltage output settings, if there is a deviation from schedule, the GOP needs to report it to the TOP. The GOP is pretty boxed in on how the power plant is operated, he just needs to follow instructions.
Distribution Provider (DP): The DP is generally the end of the line for NERC jurisdiction. The DP takes the power from the TOP at the point of delivery, then lowers the voltage to distribution level and delivers that power to the end users. It is not unusual for a DP to be a separate utility, like a co-op, or a municipal. It is generally accepted that once the voltage drops under 100kV, it is no longer considered part of the Bulk Electric System (BES), and NERC/FERC no longer have jurisdiction. An exception is given if an issue on a sub - 100kV line can marginally impact the BES. DP mostly falls under your Public Utilities Commision for rulemaking. NERC does have some applicable standards since the DPs actions can affect the BES.
Those are the major players on the reliability side. The marketing side is less defined. In the past, NERC had definitions for market functions, but it was decided that these functions were not related to reliability, and therefore not in their jurisdiction. Now it really depends on where you are doing business, what they call a marketing function. But it really comes down to three things:
I am a supplier; I have excess energy to sell.
I am a marketer; I am the middleman that buys and sells the energy and skims a little off the trade. Sometimes energy can pass through several marketers.
I have a load: I am buying energy to serve a load in my area. I might resell that energy as a distribution provider, but that’s out of the market.
So, the marketer makes the deal between the source, the place the energy is coming from, and the sync, the place the energy is going to. The market also has to provide the transmission rights to get it from the source to the point of receipt by the sync. The marketer may need to buy Transmission rights off a Transmission OASIS website to get the rights to move the energy. Both the source and the sync may also use some of their own transmission rights as part of the deal. It is the responsibility of the Sync to see that a NERC Etag is created for this transaction. The Etag will list the source of the energy, the transmission path that will be used to move the energy, and the final point of receipt by the sync. The transmission path will include information on what rights are used to move this energy. The market path of who was in the financial chain is also included. The Etag must be submitted before the close of the submission window for the next scheduling hour. The Etag then goes through an approval process on the reliability side to make sure the information is correct, the resources are adequate, and no rules are violated. One approved the Etag is used to help generate the NIs for the BA, and the transmission loading schedule for the TOP. If the Etag is not approved, the energy will not flow.
So, this was short and sweet, a bit of a yawner. But next time you hear Transmission Operator, it will be “aha, I know what that is”. Next let’s talk about how renewables play into all of this.
Thank you for this information. I request that you report on the California-specific legal euphemism, "Unspecified Power." This is the mechanism that moves considerable coal-fired power from Wyoming to California. The generation Etags get (ahem) "lost."