Considerations for the Application of Synchrophasors to Predict Voltage Instability

Growth in electric load, without a corresponding growth in service infrastructure, results in systems operating closer to voltage and frequency instability. While rotor angle stability, or real power stability, can be determined by balancing load and generation, until recent advances in technology, it was difficult to quantify or predict voltage stability. Synchronized phasor measurements (synchrophasors) are a new technology that provides a tool for system operators and planners to measure the state of the electrical system. Synchrophasors measure voltages and currents, at diverse locations on a power grid, and can output accurately time-stamped voltage and current phasors. Implementing a synchrophasor system involves a number of discrete stages. Implementation may involve using phasor measurement and control units (PMCUs) at locations suitable to provide the desired inputs to predictive algorithms, then establishing communication from those sites to a central location for data processing. At the central location, the data from the different locations must be correlated, displayed, and recorded. This paper discusses the completion of these steps for a unique R&D demonstration project installed by Long Island Power Authority. Long Island Power Authority will use data collected from this project to determine future steps to continue work to improve system reliability by testing a predictive model to preempt steady-state voltage collapse. We discuss concerns, trade-offs made, lessons learned during installation, and initial operation of the system