- Figure 1
A wind farm integrated into a transmission grid is subject to curtailment due to temporary or long-term insufficient capacity on the transmission lines. Maintenance outage of a nearby line, dispatch of competing wind farms and availability of other generators are examples of system events that may limit injection capacity. In general, events that increase transmission utilization present potential curtailment conditions for wind farms, and so the daily and seasonal load cycles, and changes to interchange and import/export patterns can influence injection capacity.
In measuring the potential curtailment of a wind farm for, say, the incoming year, it is important to take into account the wind availability as well. It may seem likely that curtailment will occur when the load is highest and transmission use is greatest; however, this condition may occur in summer when wind availability is low. Hence, we have the common situation that at summer peak, the available transmission is low, but the wind capacity is also low, resulting in no or minimal curtailment. Some operating wind farms have observed that most curtailments occur in the spring and fall periods where grid use may be low but wind farm capacities are higher.
One approach to estimating potential wind farm curtailment is to simulate the hourly chronological performance of the combined generation and transmission system taking into account outages, unit commitment, least cost dispatch and load variations. This method is widely known as production simulation. In addition to being data intensive and laborious to setup, the simulation duration can be significant, especially if one chooses to run multiple years in a Monte Carlo simulation. This Blog presents a methodology that is based on an analytical model that is generally much simpler to develop than production simulation models and provides some unique insight into how and how often curtailments come about. Read the rest of this entry »
Tags: curtailment, power flow, pslf, psse, pterra, transmission, wind farm, wind power
Oklahoma was certainly a welcoming place as we held our first two courses of the fall season there. We thank our hosts for their hospitality and for setting up the two courses. And thanks for the barbecue and salsa lunches! Yum! The one thing that the instructors forgot was to take a picture, so we will make do with Dr. Gutierrez’ mug as our graphic for this blog. Ratings and comments on the courses are as follows: Read the rest of this entry »
Tags: blackout, collapse, courses, dynamics, fall 2010, oklahoma, pterra, seminar, simulation, stability, voltage, voltage ledge
There has been a change in the schedule for two courses this month as follows:
- Aug 17-14, 2010 – Dynamic Simulations Analysis and Applications Course
- Aug 24-26, 2010 – Voltage Stability Analysis and Applications Course
We will be travelling offsite for these courses. Read the rest of this entry »
Tags: blackout, collapse, courses, distribution, dynamics, HVDC, interconnection, underground cables, voltage, wind
The upcoming schedule of courses for Fall of 2010 includes a number of mainstay application courses, and a new course on underground cables, offered by Pterra jointly with Electrical Consulting Engineers, Inc. The lineup:
- Aug 10-12, 2010 – Dynamic Simulations Analysis and Applications Course
- Aug 24-26, 2010 – Voltage Stability Analysis and Applications Course
- Sept 21-23, 2010 – HVDC Transmission Analysis and Applications Course
- Oct 19-21, 2010 – Applications in Wind Power Interconnection Course
- Nov 2-4, 2010 – Aspects of Underground Power Cable Systems Course
- Nov 16-18, 2010 – Power Flow Analysis and Applications Course
Tags: courses, dynamics, HVDC, LVRT, power flow, pslf, psse, pterra, seminar, stability, system impact, training, transmission, voltage, wind, wind farm, wind power
What can we say? We had all the windy people together and spent the next 3 days blowing air. Seriously, we did get into some serious technical discussions about wind modeling specifics and the energy market in general, including:
- How best to model a wind farm – lumped as one equivalent, lumped per feeder or detailed representation? Some further thoughts on this can be found in Wind Farm Integration: On the Use of Agreggate Models.
- Trend of cost allocation for system upgrades. This was not on the course outline but the discussion led in this direction.
- What is the fair way to represent wind farms in integration studies – 100% capacity for summer peak load conditions or some lower capacity or alternate system loading condition. More on this in The Coincidence of Wind
.
Tags: courses, interconnection, LVRT, seminar, transmission, wind, wind farm, wind power
If we think about wind turbines as induction generators, one would assume that these would be VAR (reactive power) sinks, demanding vars from the grid to be able to deliver watts. However, that may be true from the point of view of only the wind turbines themselves. In reality, wind farms are far more than a group of small generators. Electrically, wind farms that deliver at bulk power levels to the grid behave more like a small urban subtransmission grid with characteristics that are far removed from those of a large power facility such as a coal, oil, nuclear or natural gas plant. Read the rest of this entry »
Tags: control, interconnection, power flow, voltage, wind, wind farm, wind power
Held in Albany, NY
We had a full class, with active participants. It was fun to teach and hopefully it was also fun to have been a participant in the course! The participants gave an overall rating for the course of 4.86 out of a possible 5.0. Thanks! Also, everyone did a great job on the test reviews. Thanks for the effort! Read the rest of this entry »
Tags: blackout, collapse, convergence, courses, LVRT, pterra, seminar, stability, transmission, voltage
by Pterra Consulting
In this Blog, we discuss the amazing story of how a lowly 2,000 MW HVDC line was able to support a transmission capacity increase of 3,200 MW. Read on … Read the rest of this entry »
Tags: CREZ, ERCOT, HVDC, interconnection, power flow, pterra, system impact, Texas, transmission, wind farm, wind power
Albany in Spring
Here is the updated schedule for power systems analysis courses for Spring 2010. All courses are to be held at the Pterra Training Facility in Albany, New York.
- April 20-22, 2010 – Voltage Stability Analysis and Applications Course
- May 11-13, 2010 – HVDC Transmission Analysis and Applications Course
- May 25-27, 2010 – Dynamic Simulations Analysis and Applications Course
- June 8-10, 2010 – Power Flow Analysis and Applications Course
- June 15-17, 2010 – Applications in Wind Power Interconnection Course
For early birds, all the above courses are being offered at 2005 prices ($295 per seat). So sign up now at the Cvent registration site!
Links: Pterra Training - more info on Pterra courses, including course descriptions, logistics, customization, offsite courses and other training matters. Pterra Home Page - business site for Pterra Consulting. Pterra’s Facebook Page - for general stuff such as class photos, picnics, news on energy matters, etc.
Tags: convergence, courses, dynamics, HVDC, interconnection, LVRT, power flow, pslf, psse, pterra, seminar, transmission, wind farm, wind power
(This Blog is an introductory discussion of the AC power flow at a beginner level. Other Blogs on this site discuss more advanced aspects of the power flow, including convergence and alternative solution methods.)
The Power Flow is a steady-state representation of a meshed three-phase electrical network. It is sometimes characterized as a “snapshot” of electrical operating conditions given a set of assumed electrical customers (loads) and supplies (generators) linked together through a transmission system (grid). A single-phase equivalent of the positive sequence network is used since balanced three-phase conditions are assumed.
Power Flow Model of the Electrical Grid
A graphical illustration of a sample electrical network is shown below. This diagram shows only the positive sequence electrical connections.
- Sample Electrical Network
Tags: convergence, power flow, pslf, psse, pterra, transmission, voltage, wind farm, wind power
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