This sample project demonstrates IQ's capability to integrating Synergi database, process the data and generating distribution system models seamlessly. Results presented here provide a comparison between Synergi and IQ to validate the results generated by IQ.
Project Description
A 2,000 kW PV interconnection application (Project PV) was filed for a distribution feeder with the following loading conditions. The feeder has 2,065.4 kW online PV and 4 PV system in construction (previously approved but not) and 2,065.4 kW online PV systems.
Load Condition | Phase A | Phase B | Phase C | Total |
|---|---|---|---|---|
Peak Load (07/20 @ 7 p.m.) | 1,567.001 kW &
5,63.546 kVAr | 1,645.192 kW & 588.693 kVAr | 1,573.711 kW & 575.027 kVAr | 4,785.905 kW & 1,728.265 kVAr |
Light Load (30% of peak load) | 470.100 kW &
169.064 kVAr | 493.558 kW & 176.608 kVAr | 472.113 kW & 172.508 kVAr | 1,435.771 kW & 518.180 kVAr |
Generation Status | Generation Type | Generation Size |
|---|---|---|
In Construction | PV (@ Location 1) | 1,000 kW |
In Construction | PV (@ Location 2) | 1,250 kW |
In Construction | PV ( 2 units @ Location 3) | 5,000 kW |
In Construction | PV (@ Location 4) | 1,992 kW |
Online | PV | 2,065.4 kW |
System Modeling with IQ
The Synergi database file was integrated into the IQ database. Upon the integration, the feeder model was automatically generated by only identifying the substation and feeder ID. The system layout generated by IQ is shown here. The locations for existing generations, Project PV and the substation are marked in the layout.
Power Flow Analysis with IQ
The power flow analysis conducted by IQ showed that Project PV would cause thermal limit violation on a section of the feeder with 336 Al conductor (as shown in the figure). Upgrading the conductor to 447 ACSR would mitigate the thermal overload risk. The reverse power flow at the substation calculated by IQ matches the values calculated by Synergi.
Load Condition | Reverse Power in Synergi | Reverse Power in IQ |
|---|---|---|
Peak Load | 6,674 kW | 6,586 kW |
Light Load | 9,458 kW | 9,432 kW |
The system has a LTC at substation and two voltage regulations downstream of the substation. The changes in the taps due to the addition of Project PV is listed in the table below. The results from Synergi and IQ match.
Load Condition | Voltage Regulating Equipment | Max Change in Taps Due to Project PV in Synergi | Max Change in Taps Due to Project PV in IQ |
|---|---|---|---|
Peak Load | Substation LTC | 0 | 0 |
Peak Load | REG_89/41 | 1 | 1 |
Peak Load | REG_90/246 | 1 | 1 |
Light Load | Substation LTC | 0 | 0 |
Light Load | REG_89/41 | 1 | 1 |
Light Load | REG_90/246 | 1 | 1 |
Voltage Flicker Analysis
A load swing equal to rated Project PV generation output reduction by 95% was used to calculate the maximum voltage flicker caused by normal operation of a PV systems. The values calculated by Synergi and IQ are listed in the following table.
Load Condition | Without Project PV | With Project PV in Synergi | With Project PV in IQ |
|---|---|---|---|
Light Load | 2.90% | 2.30% | 2.44% |
Peak Load | 3.87% | 3.11% | 3.19% |
Another way to investigate the impact of PV intermittency on voltage levels is quasi-static time series (QSTS) analysis which captures time-dependent aspects of power flow, including the interaction between the daily changes in load and PV output and control actions by feeder devices and advanced inverters. A year-long 5-minute interval QSTS was performed for the entire feeder including all loads and PV units. The entire analysis was performed in 43 minutes. Table below presents the results. The following graph demonstrates the voltage variations at the point of interconnection (POI) of each PV unit for a sample day in March.
Voltage at PVs POI on a weekday in March
Impact | Value |
|---|---|
Long-Term Flicker (Plt) | 0.040 |
Short-Term Flicker (Pst) | 0.102 |
Voltage Variation | 1.95% |
Max Tap Change | 1 Due to Project PV and 3 Due to Existing PVs |
A closer look at short-term flicker analysis demonstrates the value of QSTS in capturing the impact of PVs on distribution systems as opposed to methods relying on a snap-shot of the system. While those methods might be sufficient for distribution systems with low penetration of renewables, they may fail to provide a realistic picture of the system with high renewables.
Short-term flicker at Project PV POI
Fault Analysis
Fault study performed by IQ showed the increase in fault currents caused by Project PV. The fault currents calculated by IQ matches the values calculated by Synergi (see tables below).
Fault Location | LLL | LLG | LL | LG | LLL | LLG | LL | LG |
|---|---|---|---|---|---|---|---|---|
Project PV POI | 4,565 | 4,175 | 4,032 | 3,169 | 4,734 | 4,347 | 4,201 | 3,267 |
CB at Substation | 9,680 | 9,685 | 8,462 | 9,587 | 9,849 | 9854 | 8,631 | 9,685 |
Fault Analysis in Synergi |
|---|
Fault Without Project PV | Fault With Project PV |
|---|
Fault Location | LLL | LLG | LL | LG | LLL | LLG | LL | LG |
|---|---|---|---|---|---|---|---|---|
Project PV POI | 4,512 | 4,092 | 3,986 | 3,083 | 4,703 | 4,267 | 4,176 | 3,139 |
CB at Substation | 9,642 | 9,646 | 8,433 | 9,512 | 9,816 | 9,820 | 8,608 | 9,621 |
Fault Without Project PV | Fault With Project PV |
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Fault Analysis in IQ |
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