ABB Summary: ABB Suite of Power Transmission Test Cases Mats Larsson Corporate Research ABB Switzerland Ltd. Jan 19, 2004

Collapse Scenario  Line tripping (L3) after 100 s  Inherent Load Recovery  Tap Changer Tries to Restore Voltage  Generator field limit activated at 286 s  Collapse Tap Controlled LoadGenerator Voltage Overload limit reached Tap Changer Control

Control Objectives  Stabilize all voltages within p.u.  Use minimal amount of load shedding  Control voltage at bus 4 as close as possible to 1 p.u.  Capacitor and tap changer control can be used freely

“ Medium Scale” ABB Test Case Three copies of small case Similar control objectives Recovery dynamics in : load (continuous) Transformers (discrete) Inputs: Line impedances (disturbance) 3 Capacitors 3 Voltage Refs. Transformer (optional) 3 Load shedding Outputs: 3 Load voltages 2 Generator field voltages

Case 1 – Tripping of Lines Vload[2]Vload[3] GEfd[2]GEfd[3] pos[2]pos[3]  Collapse in 400 secs

Case 2 – Cap Switch in Area Vload[2]Vload[3] GEfd[2]GEfd[3] pos[2]pos[3] System.C2.step  Cap switch at 100 secs stabilizes

Case 3 – Tap Reference Change (-5%) Vload[2]Vload[3] GEfd[1]GEfd[2] pos[2]pos[3]  Tap reference at 100 secs stabilizes

Case 4 – Second line trip Vload[2]Vload[3] GEfd[1]GEfd[2] pos[2]pos[3]  No longer stable...

Case 5 – Added load shedding at bus Vload[2]Vload[3] GEfd[1]GEfd[2] pos[2]pos[3]  Additional load shedding stabilizes

Model Complexity  6 disturbance inputs - (0,1,2) Control inputs:  3 capacitors - (0,1)  3 load shedding – (0,1,2,3)  3 tap voltage refs – (0.8–1.2) Continuous dynamics:  3 loads (2 dynamic states each) Discrete dynamics:  3 transformers (3 states each)  2 generator limiters (2 states each)

Possible work on new model  Scaling of Model-predictive approaches (ETH, Grenoble?)  Testing of decentralized schemes (Lund, Grenoble)  Requests for customized versions welcome...

Large scale case – CIGRE Nordic 32  52 Discrete control inputs  Load shedding  Generator voltage setpoints  Tap changers  10 Controlled outputs  Load voltages  67 Constrained outputs  All voltages, generator currents  State-space ~ nodes

 At 10 s – Gen 4062 Trips Lost generation compensated by hydro units in the north Increased losses in transmission corridor, lower voltage in southern region Generators in the south increase reactive power production Generator Trip – No Emergency Control  At 30 s – Gen 1043 and 4042 at limit Voltage support lost in middle and southern parts  At 50+ s – Tap changers restore load Further voltage decrease Collapse at 180 s

Generator Trip – Model Predictive Control Time (sec) Voltage (p.u.) V1043 V4012 V4042 Generator trip

Constraint Management Armature Currents