IEEE Chapter Symposium Possible Applications of PMUs for Detecting Angle Instability in Power Systems Nima Farkhondeh Jahromi Zongyu Liu March 28, 2017

Angle Stability Classification First Proposed PMU-Based Algorithm Outline Problem Formulation Angle Stability Classification First Proposed PMU-Based Algorithm Second Proposed PMU-Based Algorithm Conclusion and Remarks March 28, 2017

Contradictory combination Problem Formulation Centralized Power plants Small number of large scale gen. units Traditional generator design/const. Not so high efficiency Popularity of renewable energy Large number of small scale gen. units Newer Technology in generator design Higher efficiency Power networks (due to power transfer capacity) get closer to their stability margin Less tolerance Regulated electricity market Deregulated electricity market Various power flow directions More congestions Contradictory combination Stability control (instability detection) is (will be) the key challenge March 28, 2017

[Real-time] small disturbance angle stability assessment Angle Stability Classification [Real-time] Angle Stability Assessment in future Power Systems Axis 1 [Real-time] large disturbance angle stability (transient stability) assessment Axis 2: [Real-time] small disturbance angle stability assessment March 28, 2017

1st Proposed PMU-based Algorithm Detection of transient instability based on the real-time COA Concept of Centre Of Angles (COA) Difficult to directly measure Difficult to access in real time. Number of units being dispatched can vary March 28, 2017

1st Proposed PMU-based Algorithm (1) Substitution of the internal angle with the phase angle of the high side bus voltage Substitution of the inertia time constant with the high side active power injection G T Phase Measurement Unit (PMU) Approximation! (could be a source of error) March 28, 2017

1st Proposed PMU-based Algorithm (2) Illustration of substitution of the inertia time constant with the high side active power injection March 28, 2017

1st Proposed PMU-based Algorithm (3) Real-time Centre of Inertia for area i Real-time Centre of Inertia for the whole system March 28, 2017

1st Proposed PMU-based Algorithm (4) Taking the appropriate remedial action(s) based on the value of If > “pre-specified benchmark” (continuously) 1) Area i (in a detailed analysis each gen. can be an area) is speeding up 2) Suitable remedial action is to trip some generators If < “pre-specified benchmark” (continuously) 1) Area i (in a detailed analysis each gen. can be an area) is slowing down 2) Suitable remedial action is load shedding March 28, 2017

1st Proposed PMU-based Algorithm (5) Alarm mode based on comparing the real-time signals A real-time signal for area i A signal to be used as a reference: Critically-stable response March 28, 2017

1st Proposed PMU-based Algorithm (6) Rescue-time definition Permanent decline March 28, 2017

1st Proposed PMU-based Algorithm (7) The method (the reference signal) is fault-location (and also fault-type) dependent. The method is dependent on the inertia time constant of the generators (Perhaps in future; lighter machines have higher output) March 28, 2017

2nd Proposed PMU-based Algorithm Principal idea is to have a real-time energy function (by means of PMUs) for a system divided into two clusters. The main question: Based on the real-time energy function, will the system split to more clusters or not? Area 1 M1 ω1 Area 2 M2 ω2 New [temporary] steady-state March 28, 2017

2nd Proposed PMU-based Algorithm (2) March 28, 2017

Conclusion and Remarks It might be possible to perform an on-line transient instability detection and mitigation for a multi-area power systems By improving (generalizing) the proposed algorithm, it might be possible to avoid some blackouts happen due to islanding Designing the appropriate remedial action, is very much dependent on the system capabilities and is difficult to be generalized March 28, 2017

Discussions Suggestions Questions Criticisms Ideas Compliments March 28, 2017