1 / 21

210 likes | 360 Vues

Complex Flow-Based Non-Linear ATC Screening. Santiago Grijalva The Power Affiliates Program Urbana, May 23, 2002. Motivation. Electricity markets have to deal with the effect of network constraints. Transfer capability: Flow-based transmission rights Transmission operations

Télécharger la présentation
## Complex Flow-Based Non-Linear ATC Screening

**An Image/Link below is provided (as is) to download presentation**
Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.
Content is provided to you AS IS for your information and personal use only.
Download presentation by click this link.
While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.
During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

**Complex Flow-Based Non-Linear ATC Screening**Santiago Grijalva The Power Affiliates Program Urbana, May 23, 2002**Motivation**• Electricity markets have to deal with the effect of network constraints. • Transfer capability: • Flow-based transmission rights • Transmission operations • Generation and transmission planning**1st Limiter**Thermal @Line X 2nd Limiter Thermal @ Line Y 3rd Limiter Low Voltage @ Bus Z 0 700 950 1300 Static ATC • Supervises: • Line Thermal Limits • Bus High and Low Voltage Limits • Static Collapse • Exact determination requires non-linear continuation algorithms • Transfer limiter sequences are required Transfer size (MW)**Static ATC**• Contingency conditions • Several directions • System patterns Contingency Pattern Need Fast Methods Linear ATC Direction**Linear ATC**• Thermal limits only • Often thermal limits appear as first limiters • Distribution Factors (PTDF’s) • Good for large combinatorial studies • Drawback: • No Bus Voltage Supervision • No Static Collapse Supervision**ATC Cases**Cases correctly assessed with Linear ATC Cases that need Non-Linear ATC Linear and Non-linear ATC Cases • Unexpected non-linear constraints can have a significant impact in security • We don’t know which cases until we run the full non-linear simulation • ATC Screening**Non-Linear ATC Screening**• Research on new methods to estimate the distance to security constraints • Methods based on the state variables: • Bus high and low voltage • Methods based on branch complex flow: • Thermal limits • Generator reactive power limits • Static collapse**Estimated**Thermal Actual Low Voltage Reactive Support Collapse 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 Transfer Size (p.u.) Non-Linear ATC Screening**1. Linear ATC with Reactive Flows**Qjk Line is Overloaded Limiting Circle: (0,0,MVA rating) Operating Circle: (Pjk,0,Qjk,0,Sjk,0) Pjk Pjk0 MVA rating Pjkmax**Change in system state:**• Mismatches in rectangular coordinates: • Corrected state change: Can get transfer size p from here 2. Bus Voltage Constraints Transfer Direction T=Tsell+TBuy • Define a transfer: pT Transfer Size in (MW) or p.u.**Transfer #**32 28 24 20 16 12 8 4 0 0 5 10 15 20 25 30 35 Transfer Size, p (p.u.) 2. Bus Voltage Constraints**3. Static Collapse** Line Static Transfer Stability Limit (STSL) • Complex flow trajectory. At least one line must hit the STSL before collapse**3. Static Collapse**Typical Simulation Result Qjk/Yjk First STSL Pjk/Yjk**32**Transfer # 28 24 20 16 12 8 4 0 35 40 25 30 20 15 0 5 10 Transfer Size, p (p.u) 3. Static Collapse**Reactive Support Qj**2.25 2 Actual 1.75 1.5 Circle 1.25 1 Vcrit 0.75 Fourth Order 0.5 0.25 0 0.25 0.5 0.75 1 1.25 1.5 1.75 2 2.25 0 Transfer Size, p (p.u.) 4. Generator Reactive Power Limits • PV bus supports voltage for changes in complex flows due to the transfer.**32**Transfer # 28 24 20 16 12 8 4 0 18 20 12 14 16 10 4 0 2 6 8 Transfer Size, p (p.u.) 4. Generator Reactive Power Limits**Estimated**Thermal Actual Low Voltage Reactive Support Collapse 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 Screening Logic • Decision Rule • Statistical • Adaptive • Heuristic If the first limiter is thermal and limiters of other type occur beyond +%, then linear ATC is sufficient. Otherwise non-linear simulation is required.**Transfer Limiter Sequences**Transfer # 15 V L Q C 14 L V Q C L V Q C 13 L Q V C V Q L C 12 V L Q C L V Q C 11 L Q V C V Q L C 10 V L Q C V Q C L 9 V Q L C V Q L C 8 V Q L C V C L Q 7 V C L V C Q 6 V L Q C L V Q C 5 L V Q C V L C Q 4 V L Q C L V Q C 3 L V Q C L V C Q 2 L V Q C V L C Q 1 V L Q C 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Transfer Size, p (p.u.)**Result**• Screening based on the decision rule was successful in 95% of cases. • Less than 5% of cases that did require non-linear simulation were classified as linear.**Conclusions**• Linear ATC is enhanced by estimating the effect of reactive power flows. • A consistent prediction of the point of collapse is obtained with indicators based on the complex-flow of individual elements. • The distance to non-linear security constraints can be estimated with information from the base case. • ATC cases that require non-linear simulation are identified with high significance by the ATC screening algorithm.

More Related