Physical Design of a Volt/Var Implementation

Transcription

1 1 Physical Design of a Volt/Var Implementation Hydro-Québec Distribution s approach Prepared by Bruno Fazio

2 2 Subjects Context Volt control Planning Control strategies and exploitation Var control Planning Control strategies and exploitation Future developments CVR

3 3 Context Quebec s energy board required that Hydro- Quebec economizes 11 TWh. The VVC program s (CATVAR) objective is to contribute 2 TWh annually as of Equipment needed: 150 substations and 2000 distribution lines 1000 remotely monitored voltage transformers 802 remote-controlled capacitor banks Infrastructure upgrades

4 4 Objective Dynamic management of customer demand Reduce voltage on the feeders to the lower limits allowed by the CSA-235 standard on PQ Use capacitor banks to improve voltage profile on the feeders

5 5 Planning Voltage Control

6 6 Planning substation selection Networks considered for voltage optimization Substations with a high loads, short lines, and large voltage gains Networks not considered Substations with completely underground lines* Substations without voltage regulators (tap changers) Substations with voltage controlled DG

7 7 Planning Retrofit of existing feeders Identify the lines with the lowest voltages Identify projects to increase voltage on the limiting lines as this limits VVC Increase the conductor size Balance the loads on each of the lines Install remote controlled capacitor banks* Install voltage regulators if needed* Install voltage measuring devices on feeders with lowest voltages Generally 3 per source

8 8 Control strategies Static Dynamic

9 Requirements 9

10 Control strategies and exploitation 10

11 11 Control strategies and exploitation New simulation - Significant load variations or network modifications Evaluate the lowest voltages Use of line measurements (if available) to validate simulations Calculation and modification of voltage targets if needed Fall back on lower complexity control systems if anomalies occur

12 Control strategies and exploitation 12

13 13 Energy Gains (GWh) , ,5 Permanent setpoint modifications Seasonal setpoint modifications 100 VVC control ,895 42,6 16,5 8,1 34,5 8, Other (CVR, etc)

14 14 Planning Var Control

15 15 Planning VVC project coincides with a transmission requirement to install 1000 Mvar on the network Benefits on distribution network Reduced losses Improved voltage profile (with VVC integration) Benefits on transmission network Reduced losses Improved voltage profile Increased stability limits Increased capacity limits

16 16 Planning Reactive power compensation per substation coordinated with Transport division Using planning software, the capacitors were placed in order to reduce line losses and improve the voltage profile Typically, placed on the lines with the lowest voltages Capacitors are remote controlled only no local control

17 17 Control strategies and exploitation Maintain Mvar in each substation within the realtime compensation limits provided by the Transport division Before switching capacitors, verify that it will not bring the tap of the substation transformers to an extreme position Verify that the switching of the capacitors will not cause the substation bus to be capacitive

18 18 Control strategies and exploitation Verify that the voltage is always within the normal operating limits. If not, a capacitor will be switched. Verified by real time load flow simulations If both volt & var control is deployed for a substation, the capacitors on the lines with the lowest voltages will be switched first in order to increase the voltage in these lines. This will permit the volt control system to lower the voltage more and increase energy gains.

19 19 Control strategies and exploitation Capacitor switching for volt/var control (1.5V gain for volt control) Feeder ID Phase Voltage min (cap offline) Voltage min (cap online) ART 238 A 120,8 121,4 ART 238 B 121,4 122,0 ART 238 C 119,6 120,2 ART 239 A 118,1 119,6 ART 239 B 120,5 121,2 ART 239 C 118,5 120,0

20 Control strategies and exploitation 20

21 21 Future developments Remote control the voltage regulators Use the AMI technology in order to determine the voltage drops on the BT network (worst case scenario voltage drops currently being used) Continue exploring the use of MV meters as measuring devices for clients in underground feeder networks Support VVC on lines with voltage controlled DG

22 22 CVR Approach: Lower the voltage on 4 substations by 3% on alternate days during a year Objective: Determine a CVR by season and customer class Substations with different customer types used : Industrial, commercial, residential Relationships were observed between the power, the voltage (weak correlation), the temperature (strong correlation) and the humidity (weak correlation)

23 23 CVR Preliminary results Summer CVR Preliminary results Substation CVR Residential Commercial Industrial % of load by customer type 1 0,66 60,6 31,9 7,5 2 0, ,7 4,2 3 0,48 39,1 19,4 41,5 4 0,64 64,5 30,3 5,2

24 24 Physical Design of a Volt/Var Implementation Thank you for your attention. Any questions?