The Digital Fault Recorder

The DDR function of the Model 9000 allows users to analyze complex power systems events and records the dynamic response of power systems to disturbances that have occurred within the same system. DDRs are extremely useful for disturbance analysis, investigating system oscillations, quantifying sudden changes in power system parameters, and obtaining data for verifying stability models. The DDR is normally used by utilities for low-speed disturbance recording and to capture records that are typically from 1 minute to 1 hour in length. The USI™ DDR function records frequency, phase angle, and RMS values of a power systems’ quantities. These quantities include voltage magnitude, current, MW, and MVAR, sampled and calculated at a rapid rate (i.e., 6 to 60 samples or more) per second. Recording duration is generally on the order of a minute or more.

The Model 9000 Sequence of Events Recorder (SER) application monitors external inputs and records status changes that occur in a power system. In order to accomplish this function, the SER samples and time stamps operational data in the chronological sequence in which the events take place. This operational data is monitored from substation equipment (i.e., relays, circuit breakers, etc.) and control schemes (automatic and manual) as they react to an event that takes place within the power systems the SER is monitoring. When collected, this data, which can be caused by several different individual events such as a switching operation, mis-operation, or fault, allows the chain of events to be analyzed and studied when searching for the cause of an event that took place within the power system, as well as the linkages between individual actions and effects. The SER can be ordered within the traditional, all-included Model 9000 DME Unit, or can also be ordered in a stand-alone, SER-only M9000 Unit for users who only need an SER function. Please contact USI for more details on this possible system configuration.

The Model 9000’s Phasor Measurement Unit optional application can be deployed to monitor a certain portion of a power system by recording phasor quantities and accurately referencing them to a standard time signal. To accomplish this task, the M9000’s PMU application extracts the parameters magnitude, phase angle, frequency, and rate of change of frequency from the signals appearing at its input terminals. Additionally, the PMU application allows M9000 Users to perform phasor measurement unit functions in addition to existing DME functions simultaneously. This add-on package requires no additional hardware or modification to an existing Model 9000 DME System installation. The PMU application features Syncrophasors available for each analog channel, positive sequence phasor calculated from any three-phase voltage or current inputs, analog values and digital input statues that can be added to the data stream, and user defined frame rate (60Hz, 30Hz, 20Hz, 15Hz, 10Hz), all while conforming to the IEEE PC37.118 standard. Additionally, the USI PhasorView™ software (see in accessories page), which allows real time monitoring of Syncrophasor data transmitted via the PC37.118 standard, comes with the USI PMU application at no additional cost.