 Good afternoon. This is Guillermo Salvatthied, your host for the show today on Perspectives on Energy and Welcome to Think Tech Hawaii. I am once again, I am the director of international services for the Health and Safety Institute industrial skills and I bid you welcome. So today we have these a third installment on our NERC test prep in the third in a series of NERC test prep exam review. We'll go over a few of the questions you're going to encounter on your NERC exam. Today's topic covers continuously analysis and reliability and we'll talk about some of the scenarios you see on there. Maybe go over like 10, 12 questions whatever we have time to do today in these like 26 minutes, but again thank you for tuning in and hopefully this gives you a I guess a teaser of what you would find if you took the drawn-off course offered by HSI industrial skills for the NERC RC certification test prep. So we have the online test preparation portion that gets you through all the modules and gets you prepared and then we also have a three and a half day instructor-led course that is like a final wrap-up of everything and usually these the questions that you're going to see today come from that class. So you get a lot more questions in that in that actual course, but this of course will give you an idea of what those exam questions look like. Mind you, we covered a few of them. The first session we did here, we talked about balancing and AC equation and things having to do with the area control error and related topics. The second one was something a little bit different. It was more about transmission topics and this one we're going to talk about continuous analysis and more about topics having to do with with the some of the distribution margins and what happens with scenarios where you lose a line and how that overloads the other lines. So without further ado, by the way also in our training, there is some simulation. So in another show, we'll hopefully have a demo of what we do with a simulation and how that demonstrates how things actually run in the system. It's a power flow tool which is very very powerful and helping you visualize what happens and how to react and give you some better training, usually initial training and of course also continuing education on how to manage a power system. So if we're further ado, let's go ahead and start on the first set of slides and we'll do the first question here. Okay, so here's an example, right? So transmission line C trips while carrying 800 megatons. Line A has 200 megatons of power flow, line B has a flow of 400 at the time of the outage. So that's before the other line trip. Line C has a loss line outage distribution factor of 0.25 and 0.1, we did it to the lines A and B respectively. So the reason the answer here is highlighted is 200 megawatts on A, 80 megawatts on B is simply you get those 800 megawatts, right? And simply multiply it times 0.25, which would be one fourth, right? I will say 800 megawatts, that would be 200 megawatts. And that's the impact the loss of that line carry 100 megawatts will have on line A. Now, what's the impact on line B? Well, line B, you read there, it says one tenth is a 0.1 line outage distribution factor, right? Really, it's a line B. So one tenth of 80 megawatts of 800 megawatts is 80 megawatts. So that is the effect that will have. And of course, it's a positive number. Notice that they give you answer C as a detractor, right? That's one thing you have to remember, right? And a lot of these questions is you have one or two really bad answers that are obvious, right? So what happens is on choice C, for example, if you're not paying attention, right? Especially if you think it's going, you may want to think that you're losing 200 megawatts, but really it's not what it is, right? So whenever you have three lines, for example, you lose one of the lines and they're all on a parallel path, that flow will have to go, it's still flowing from a source to a load. And that flow still has to find its way on the remaining lines. So, you know, it stands for a reason that whatever flow, you didn't lose a load and you didn't lose a source. So it's still pushing that energy across there somehow. So it's going to find its way through those two lines, potentially out through some other lines in the interconnected system. So that's why it's going to increase. And in this case, right, it's going to increase from 275 to 475 on line A and there will be an increase of 80 megawatts, right? From 400 to 480. And that will be the final result here. And they ask you that question, but what they're asking you here is what will be the impact on lines A and B due to the outage. So the impact is going to be 208, 280 megawatts. If you notice also that they're giving you another weird answer there, like 475 and 480. Again, another detractor and that's really, really wrong. So they're making you assume that it's going to go up by 400 to 400, which is again wrong, it's not going to be an even split at all for impedances, right? Based on how the flows are going. Clearly line A has a lot lower impedance than line B. And I say that because it's a lot more flow. So usually power lines will flow on a path at least resistance. So the sense again, line A has less resistance or impedance than line B in this case. Finally, 480, 475 is a really bad answer by detractor, meaning that they're going to flow in the opposite directions. So again, just remember in this case, you know, you need to eliminate some of the answers. But here it's A is meant to trick you. If you see, it's actually got the concepts correctly. And also if you read the question correctly, if you misread that question, you want to know what the final flow on those lines are. So if they ask the question here was, what will be the resulting flow after the outage? Then you might want to look at something else. And of course here, that answer is not even right anyway. So at least in this case, they did you a favor by not giving you that information. Let's see, take a look again here. So it'll be, oh, actually, no, yeah. It's definitely a detractor. So in this case, it would look like an A, right? If they had asked you that question. So like I said earlier, but either way, it's something to be very careful with. So let's go ahead and go to the next slide. And if you could, please. All right. So a powerful study indicates that a transmission line will reach its emergency overload rating within the hour. Okay, you got some time. A proud line is offer routine maintenance and can be placed in the service in 10 minutes. What is the first thing the operator should do, right? So what are the things you're going to consider, right? So they gave you some possible action items. That you could jump through, right? But mind you, it's the line where we choose emergency overload rating within the hour, which means right now it is not currently overloaded, right? It's going to be. And that, which probably tells me that load is increasing, which means that it's, load is inflated this time of the day. If it were, you know, over the peak of the day and then load is kind of like winding down, say it's after five o'clock, for example, where everybody now is quitting time every day, everybody goes home, then this may impact your decision, right? Because they say, well, maybe at this point, but of course you do a powerful, right? But so, and one of the things that you have to understand as when you're running system operations, everything you do has to, has to be run by a powerful. You don't want to do anything. You don't want to be in a state which you haven't studied, right? And part of that involves being able to understand where you're going to be and being able to understand or predict what will be the next contingency. So if I, if I show this line, it's going to be out of service, right? For the next hour or so, but it can be returned to service, right? The parallel line offer routine maintenance. At this point, if you show it back in service, then that, that over node magically goes away. Of course, because the parallel line, similar to what we were talking about earlier. So if it takes 10 minutes to get this line back in service, by the time you get everybody mobilized and they usually call that a clear up time, by the time you get everybody mobilized and make the calls and everything else, they can get it back in 10 minutes, then he should have everybody prepared to go ahead and put that line back in service within that time, right? So let's talk about why A, B, and C are the wrong answers in this case and why D is the best answer. So shed load of the downstream bus. Yeah, that'll certainly get rid of the overload, right? But we don't want to shed load to keep from shedding load, right? You want to make sure that shedding load will be the last resort and you will do, you will shed load if you had to, right? That's usually if you're already in an overloaded state or say, for example, something happened right now and you have a problem where, you know, because the analysis tells you that this line right now will then overload and to begin to cascade and have a cascading out, this could lead to a blackout. So yes, that will be an event where you actually shed load and they told you that your line is currently overloaded and exceeding an IRL limit, then you will consider doing that. But you're not there. You're not even overloaded now. You're not even overloaded until an hour from now. So you have time. So there A is not an answer you want to do right now. Redispatch generation. They didn't give you any choices for generation. Normally that happens a lot, right? And in utilities where they own both generation and transmission oftentimes that happens. The problem with that is that through redispatch generation, you know, you have to consider where the generator is at. Which one do you ramp up? Which one do you ramp down? And in this question, they gave you no such indication. They don't give you the scenario where the generators were at. You'll see it as another question. But it isn't on this book. So B isn't really an adequate answer at this time. Now, the worst thing you could do in this case is open that line. Because in this case, that means that power is still flowing. If you open that line, it's going to force that power somewhere else. And more than likely now you've caused a worse problem. So you're already down one line. Then now you're going to get rid of another line. Which of course is going to further aggravate overload somewhere else. So in this case, right, we are going to do is initiate the restoration of that power in parallel line that's out for routine maintenance. That should take 10 minutes. Normally you don't want to wait to like, you know, 10 minutes till to get the line, you know, back in service. You want to do it way ahead of time. So you give yourself some kind of margin because and that's usually what the industry does. In my experience, having gone through this sort of thing quite a lot, usually the clear up time, they say it takes an hour. Sometimes it takes a little longer. Other times it's a lot quicker. I mean, I've had that happen. But you want to give yourself a cushion of time because in a lot of cases, right, you don't want to run up against that clock and actually have an overload. You got to remember to contingency analysis is looking at what ifs, what could happen. So that contingency analysis relies on state estimator. So state estimator tries to estimate your state where you're going to be five minutes from now, 10 minutes from now. And so then when you grab, for example, you're a snapshot of your system and you try and forecast where you're going to be an hour from now, you're estimated. So again, estimates are known to be off by some percentage points. I don't know how good you are, but you might end up having a problem with that estimate. You may be late, you may be early. So that's why you want to give yourself enough time. So that's why you would initiate restoration of the parallel line now, even if it only takes 10 minutes and you're going to have an extra 50 minutes to even contemplate what you did after the line comes back in service. So again, D is the best answer. All right. Let's go ahead and jump to the next question in this case. All right. You are a system operator and the load forecast is for an all-time summer peak load day. It's going to be hot, right? Now we have a lot of those right now. Generation and reactive resources will be tight. Okay. Which scheduled job would you allow to proceed? So in this particular case, right, one of the things that we realize is that what do you not need during such a day of high load, high heat, high demand, right? Every generator is maxed out. So capacitors are normally used to support voltage. So a capacitor back is something you normally switch out at night. Usually that's when you have access to voltage. So you don't need voltage support at night. In fact, you want to keep voltage down at night because usually that's when everything is lightly loaded and voltage tends to creep up. So that's why A is not an edge. Relay testing, and I used to be a relay engineer. Myself out in the field. I can tell you that relay testing on a carrier on a heavy load of 345 kV line is the last thing you want to do because I mean, most relay, most relay techs, most relay engineers, PNC, protection and control engineers are great, great personnel, but accidents happen and somebody can just simply bump a one of the cabinets and you can pick up a relay. So you don't want to have anything being tested at the time, especially when you could accidentally trip something. So at this point, keep your hands in your pockets, no testing at this time. Time to catch up on paperwork. C, so B's not a good answer at this time. I mean, I would definitely hold off on relay testing. C, oh, especially if the line's hot. If the line's on a service and you got scheduled testing, then okay, fine. Then a scheduled service lines out, you can't do much damage. Oh, we lost the slide. There we go. Now, so, but if the line's in service carrying load on a heavily loaded day, yeah, you don't want to do it. Number C, letter C, breaker bushing cleaning on a generator breaker. Wow. So in this case, usually they clean breakers with distilled water, high pressure, high pressure hose. There's always that risk that you're going to, there's some contamination somewhere, you're going to have a flash over somehow and you could trip a generator. You could trip the, you could trip a, you lose a lot of, a lot of generation in that particular incident. Again, not a good thing because you're already, you're already maxed out. You have a lot of your generating resources are online. And if you lose that, you may get close to a problem in this case. So D, finally, we arrive at D, maintenance and a 735 KV Shunt Reactor is a really big one. So you're not going to be needing a Shunt Reactor in the middle of the day when you have, in the summer on a heavily loaded day with every single generating resource online and trying to serve a lot of load. That's something you normally use at night on very, on a very lightly loaded system. So in this case, you can afford to take a Shunt Reactor out of service because likely, likelihood is you're not going to need it until maybe midnight or beyond that. So that's why D is a good answer in this case, the best edge. So that's it. Right. The next one, what? Which condition is likely to lead to a potential voltage collapse? Remember we talked about cab banks, right? Okay. So in this case, the answer here is insufficient dynamic reactor resources, right? So let's talk about what the way the other ones are wrong, right? So the man is higher than expected. That happens all the time, right? So voltage collapse, I mean, that wouldn't necessarily lead to a voltage collapse, right? It's usually that there may be a component, right? They got you there, but usually a lot more things have to go wrong, right? B, too many planned outages? No. I mean, that could have also gotten you there, but the fact of the matter is that usually it involves voltage collapse and then a lot of voltage collapse happens because you don't have anything to support the voltage. The lack of right-of-way maintenance is also not a good answer because at this point it's very far-fetched, right? In the sense that you may have had an issue with vegetation, you may have had an issue with problems, but if you have lack of right-of-way maintenance, that would more likely indicate that you had a tree made contact with one of the lines. At that point, that will be more like a line fault, right? Also with budget management, you have a lot of FAC standards that have strict vegetation management rules. So right now, budget management is very well maintained when it comes to transmission systems, especially 100 kV and above. So the last one, right? C, which is the correct answer, insufficient dynamic reactive resources, right? So dynamic reactive resources means either a, the generation, for example, is a dynamic resource, that can provide reactive support, meaning they can put bars into the system, they can absorb bars. So in a lot of cases, right, usually the best resource you've got to help you manage your voltage, of course, is the generator itself. So once you begin to lose, once your generator's already maxed out and you know they're giving you everything they can on those reactive resources, they've done all they can. Anything beyond that, the voltage begins to decline. Now you're relying on your, your, your, your, your capbines, your, your capacitors to give you, but that becomes a static resource. The problem with capbines is that, those are very finite, right? And they are, need to get them in service early, but not too early, because if you wait too long, you reduce their capability. And that's the other issue. Now you got starting for compensators or synchronous condensers. Those are a really great resource, right? So to help you with your, with your dynamic reactive support, problem is you get to the point where if you run out of those as well, those are dynamic resource, right? You will have an issue supporting voltage. So especially if the load continues to climb. So in this case, right, the things that can really get you into that problem to a voltage collapse, of course, would be insufficient dynamic reactive resources. All right. Next question, please. Okay. Given the data on the image below, what would be the result if the load at bus B increased by 200 megawatts? So mind you, notice that everything's flowing from bus A to bus B. And so it's going from, I guess, left to right, right? And then there's lines one, two, three and four. And of course, all these lines have different impedances. If you notice, they are, except for the last line, three and four are the same impedance. Because you can tell that because they have an equal distribution factor. It's the same flow. Even though the SOM is a little different, right? 260 and 280. So given the data image below, what would be the result of the load at bus B increased 200 megawatts? So by 200 megawatt increase, it means the distribution factors are on each of the lines, right? So 200 megawatts times 0.2. And really what you're doing is calculate, right? 200 megawatts times 0.3. So the math here is really quick. So one tenth of 200 megawatts would be 20 times three will be 60. So if you add 240 plus 60, that puts you at 300. That right there will put you over the SOL, right? Now, if you did the same thing, you ran the math. So the SOL is 290. So the resulting flow on that line would be 300 megawatts. You're already over the SOL. That's why two is correct. Now, if you try and calculate the other lines, right? For example, distribution factor of 0.2, two tenths. 200 megawatts, it's 40 megawatts. So you add 40 to 160. That'll be right at 200 megawatts. So you're not exceeding your SOL. You're right at the SOL. So you're not exceeding it yet. Line three and four, for example, is both a quarter. So a quarter of 200 is 50. So that'll be 250 and 250. So the wall will end the limit. So at that point, so that is not an answer. And of course, D is not the answer either. So really, in this case, it's not exceeding the SOL. If line one will be at the SOL, then that would also be a good response. But, you know, here they give you the most correct answer's line. It's answer B. Hopefully that makes sense. This is a distribution factor, right? For each of the lines in this case. All right, let's go ahead and do the next question. A firm transaction is at the start at the top of the hour. That will overload line Z by 10 megawatts above its identified SOL. System operating limit, right? Meaning it's 100%. Non-firm transactions are running and they have power transfer distribution factors of 0.2 on line Z. How much non-firm when a hero, they mean how much non-firm flow will have to be cut in order to stay within the SOL? Meaning that you got to cut back you got to cut back somewhere on all these transactions to reduce that line by 10 megawatts, right? So here, the way you figure this out is multiply 10 times 0.2 you end up with 50. And that's how you figure out that I'm sorry, you divide you divide 10 by 0.2 and that's how you get that 50 in this case. And that's how you get it, okay? So you end up with 50. So you would have to cut 50 megawatts around that area just to alleviate the flow on that line by 10 megawatts. That's the distribution factors, right? When you actually schedule a line you schedule a flow on that line the impact of that is so significant in the sense that you have to come there's some flow that's flowing through that line that you will cut but it's also surrounding schedules that will also be impacted. So in this case, right, dividing dividing 10 by 0.2 you end up with 50 megawatts and so you have to cut 50 megawatts to give yourself 10 megawatts for relief on that line. Pretty interesting. Let's do one more. Okay, so this is we can't see the formula here but it is the distribution factor for the generation shift factor in this case. One thing you got to remember here is that transmission line A, B has a system operating limit of 375 megawatts and it's currently loaded at 450. So you go over this line by about 75 megawatts. So with the below information how would you read this batch to relieve the loading while maintaining system bounds? So right now the way that works is you have, for example, generator A is a shift factor of negative 0.54 line A to B. Generator B is a shift factor of positive 0.25 for line A and B. So they want you to it's basically 75 megawatts in this case. So what they want you to do is go ahead and increase generation A by 100 megawatts and decrease generation B by 100 megawatts and that'll give you the relief you need on that line to get you back down so that's 375. So answer C is the correct answer in this case. And I think we have time for one more. A transmission line conductor is rated at 180 megawatts. The line side current transformer is rated at 160. And the boss is rated at 200 MVA, these raw MVA units. What is the MVA limit of the transmission line? So in this case, 160 because it is the weakest link. It is the lowest rated element in that particular set of components. So 160 is a current line side current transformer in this case. All right, I think that is all time we have today for questions. Again, there's more of these in our training and training that we have for the online test prep course and we have of course a lot of really useful last minute training that we have in a three and a half day instructor leg course. Those usually that course you attend once you've completed all of the online modules and you've done all the exams and you're pretty much ready to kind of wrap things up and then you're just about ready to go ahead and schedule your exam at that point. So usually the pass rate for this exam when you take it unaided is about 63, 65%. For us, we've seen in a pass rate between 80 85% after taking our online courses and our preparation program. So definitely worth actually investing in the time and the effort and of course expense of going through this online test prep program. It's not to mention the fact that it's rather expensive to sign up for the exam. $700 I think it is and then now you only want to do that one time and I have to retake it again. So I definitely encourage you to go ahead and go to our website hsi.com industrial skills and I think that we're going to pull something up there that's a little longer talks about the FIA right there it is. Okay, so a little long, but if you go to the actual HSI solutions that you'll be able to draw down and find Merck exam prep and they'll get you all the information you need. Then again, if you're taking it lots of luck if you have any other questions just put them in the comments or try and get to it as soon as we can but definitely always encourage you to go ahead and join our program to get your NERC test prep training done so you can succeed and only able to take the exam one time. Okay, and then hopefully just keep up your certification with continuing education hours. So anyway, thank you again for joining us and I look forward to seeing you on the next session which will probably be the fourth and final installment of this whole NERC test prep series and we'll talk to you soon. Have a great day and take care. Goodbye now.