Discussion of "AGC logic based on NERCs new control performance standard and disturbance control standard" [and reply]

Abstract

The authors whole-heartedly agree that voltage sags are of critical concern to certain customers, and STSs are candidate solutions for voltage sag mitigation. In fact, since this paper 1 has been submitted, the authors have integrated comprehensive voltage sag analysis capabilities to their predictive reliability assessment tool. This includes the voltage sag impact of STSs.To model voltage sags, each customer is assigned a customized set of voltage sag levels (e.g., sag to 80%, sag to 70%, and sag to 60%). When a fault occurs on a component, the voltage profile is computed for the entire system (three-phase bolted faults are assumed). If a customer sags below a specified level and is not subsequently interrupted, that customer's "sag index" for that voltage level is incremented by the fault frequency. The sags results for a customer would look something like: 12.7 sags below 80%, 4.6 sags below 70%, and 2.8 sags below 60%.The impact of STSs on sags is handled in the same manner as interruptions. The only twist is that the voltage level at the STS secondary must be above a specified threshold for the transfer to occur. This provides a reasonable model of the STSs impact on a customer's complete voltage sag profile.As the discussers have correctly identified, a fault on a feeder will cause a voltage sag not only on itself, but on other feeders connected to the same bus at the substation. This means that all feeders on a low voltage bus need to be included to accurately model voltage sags. In addition, substation transformers must be modeled so that voltage sags can be computed accurately.

Implementation of Smart Grid Technologies in Pakistan under CPEC Project: Technical and Policy Implications

“…• To ensure balance in power generation and demand as power is directly coupled with frequency. Any difference of generation and demand leads to change in frequency which is detrimental for electrical appliances at home and in industries [20]. • Load distribution among generators to achieve minimum operational cost while considering the technical constraints like system security [21].…”

Automatic Power Generation Control Structure for Smart Electrical Power Grids

“…It means that matching control of the system frequency to the tie-line system frequency interchanged with the time period. ii)for security consideration [2]- [6] the changing the distributing loads among generators so as to reduced the operating costs subject…”

“…In expression(2), is the change in total unit economic desired generation at time step (k) (in seconds)based on the most advances execution of the EDC function at time instant kk (in minutes). The term (k) is calculated using Where PiAis the actual generation of unit i at time k, ACEis the area control error at time instant k, is the economic base point for unit i calculated by the most advances execution of the EDC at time kk, and N is the number of units operating in the APGC control system Nearly all of the APGC software systems have some kind of clean for avoiding the noise part of ACE which cannot be controlled [2]- [8]. It can be the EDC and ACE both control the task ofmatching the area for power generation to power consumed area load, such that the resultant of tie-line exchange and frequency of the area are their programmed values.…”