IEEE C37.250-2020 pdf download

IEEE C37.250-2020 pdf download.IEEE Guide for Engineering,Implementation, and Management of System Integrity Protection Schemes.
—The type of problem the SiPS mitigates, for example, transient instability, thermal overload, transient or postevent voltage control, and so on.
—The geographic scale of the event that the SIPS is intended to mitigate. for example, “local” versus ‘wide area.”
—The electrical scale of the event that the SIPS is intended to mitigate, for example, the level of load or generation affected or at risk.
—Event-based versus condition-based SIPS operation, for example, taking action upon an unscheduled equipment outage event versus reacting to an overload condition.
—The type of action taken by the SIPS, for example, load shedding, generation rejection, and voltage control.
4.5.1 System conditions typically mitigated by System Integrity Protection Scheme actions
This subclause describes common abnormal power system conditions that are often intended to he mitigated by control actions of SIPS and control methods used to mitigate such phenomena.
Power system stability is the ability of an electric power system, for a given initial operating condition, to regain a state of operating equilibrium after being subjected to a physical disturbance, with most system variables bounded so that practically the entire system remains intact (Kundar, et al. [B25j). This general description covers essentially all power system conditions that result in stable operation. Conversely, the following individual phenomena are described as various causes of power system instability (rotor angle and voltage instability descriptions are adapted from Kundar, et al. [B25]):
a) Rotor angle instability refers to the loss of ability of synchronous machines of an interconnected power system to remain in synchronism after being subjected to a disturbance:
1) Small—disturbance (or sinal1—szgna) rotor angle instahthtv is concerned with the inability of the power system to maintain synchronism under small disturbances.
2) Laige—disturhance rotor angle instability or transient instahthtv, as it is commonly referred to, is the inability of the power system to maintain synchronism when subjected to a disturbance, such as a short circuit on a transmission line.
b) Frequency instability (overfrequency or underfrequency) is the movement of the system frequency outside of predefined limits that specif’ the maximum allowable magnitude and time duration of frequency excursions. Such instability is caused by a significant unresolved imbalance between supply and demand of the active power in the system.
c) Voltage instahiIit•’ refers to the loss of the ability of a power system to maintain steady voltages at all buses in the system after being subjected to a disturbance from a given initial operating condition. Power system voltage deviations from normal may be caused by power system faults, sudden increase in power demand, and so on.
1) Small-disturbance voltage instability refers to the system’s inability to maintain steady voltages when subjected to small perturbations such as incremental changes in system load.
2) Laige-disturhance voltage instability refers to the system’s inability to maintain steady voltages after large disturbances such as system faults, loss of generation, or circuit contingencies.
d) Abnormal voltages may include overvoltage. undcrvoltage, or voltage deviation (change from preevent to post-event). These conditions are typically caused by loss of major equipment due to faults or other switching events.
e) Overloads occur when the current flowing through power system facilities exceeds the rated capacity. This can be caused by powerfiowing through healthy facilities after the sudden unavailability of other power system facilities such as transmission lines and transformers that are isolated due to a fault.
Figure 8 summarizes the relationships among the most common power system problems where SIPS are applied and the mitigations for those problems. For example, frequency instability in the tbrm of overfrequency in excess of what would be expected to be controlled by the governor or AGC action may be addressed by generator rejection or braking resistor insertion, but it would not use load shedding. These are not the only system problems and mitigations fbr which SIPS may be applied. In addition, system studies may show that problem solutions that would not be classified as SIPS may also be appropriate for specific cases. For example, excessive overfrequency conditions may he monitored by local protective relays to trip generation faster, which is consistent with turbine damage curves, than would be expected for a SIPS application.