Integrated Volt/VAR Control (IVVC)

Cooper Power Systems has now extended its Capacitor Bank Control (CBC) application to include Integrated Volt/VAR Control (IVVC). IVVC continuously analyzes and controls load tap changers (LTCs), capacitor banks, and voltage regulators to manage system power factor and voltage. This allows utilities to flatten each feeder’s voltage profile and to lower average voltages. It often results in significant energy savings while simultaneously maintaining unity power factor to eliminate technical losses.

IVVC provides all of the benefits of power factor correction, voltage optimization, and condition-based maintenance in a single, optimized package. In addition, IVVC enables conservation voltage reduction (CVR) on a utility’s system. CVR is a process by which the utility systematically reduces voltages in its distribution network, resulting in a proportional reduction of load on the network. A 1% reduction in voltage typically results in a 0.5% to 0.7% reduction in load.

Cooper Power Systems’ IVVC improves system reliability, efficiency, and productivity by managing voltage profile and power factor, reducing line losses, deferring the costs of new installations, and reducing equipment maintenance costs.

Cooper Power Systems has over 11 years of experience delivering CBC systems to electric utilities in North America and Hawaii and has deployed tens of thousands capacitor bank controllers during that time.

How Integrated Volt/VAR Control works

IVVC analyzes real-time feeder voltages from regulators, LTCs, capacitors, medium-voltage sensors, and any additional monitoring points, such as customer meters. It also incorporates historical data that helps to determine the effect of each operation. IVVC analyzes real-time feeder voltages from regulators, LTCs, capacitors, medium-voltage sensors, and customer meters. It also analyzes and incorporates historical data to determine the effect of each operation.

IVVC includes an optimization engine to meet a utility’s desired power factor and voltage targets and resolve any conflicts between the two parameters. The application evaluates and controls LTC and regulator set points and tap positions, as well as capacitor bank states, in order to maintain target voltages in the distribution grid. It also evaluates and controls capacitor bank states to manage feeder and substation VAR flows; this allows the utility to maintain a power factor as close to unity as possible. This optimization of resources enables a utility to defer new installation costs by making the most of equipment already in place.

IVVC does the following:

• Integrates with SCADA, DMS, or OMS systems to support reconfiguration of switches off-nominal switching. (Note: IVVC typically integrates with SCADA, DMS, or OMS systems in order to associate the correct capacitor banks and voltage monitoring points with the correct feeder.)
• Permits SCADA operators to maintain operational control, but requires less need for operational intervention when IVVC is deployed.
• Alerts operators of devices that are non-functional or near a routine maintenance threshold, which helps facilitate condition-based maintenance schedules.
• Supports failover and recovery schemes, which ensures voltage quality when communications fail from the application to the controls.
• Communicates only when necessary, thus reducing message traffic in the communications network.

What IVVC looks like

Voltage curve for regulated distribution line with feeder capacitors

The Integrated Volt/VAR Control scheme combines both voltage regulation and power factor correction in real time, ensuring the optimum performance from the system to which IVVC is applied.

Feeder voltage profile

Notice that the voltage curve with IVVC has been flattened to 1-volt delta between all three phases. Voltage and VARs are optimized in real time with Yukon’s IVVC application. This voltage optimization, combined with an improved power factor, results in better reliability and greater efficiency of the distribution system.

Yukon IVVC application

The Yukon screen shown in Figure 2 represents the optimization of one substation with two feeders. Notice the power factor at the bus: it is 99.6% while maintaining the flattest possible voltage profile shown in Figure 1. Yukon also shows the current state of the capacitor bank.

Hardware Requirements

To operate at maximum efficacy, the Volt/VAR Control scheme requires certain system hardware. This presents an opportunity to upgrade systems and save on future costs. The required system hardware for optimal performance is as follows:

• Substation LTCs
• Substation Regulators
• Substation Capacitor Banks
• Feeder Capacitors
• Down-line (Feeder) Regulators
• Capacitor Bank Controls
• Regulator Controls
• Medium Voltage Sensors

Benefits

The IVVC solution is specifically designed to deliver the following benefits to utilities, ensuring that capacitors are operational and effective:

• Reduce generation requirements
• Reduced carbon footprint
• Unity power factor 24/7 in all weather and load conditions
• Flat feeder voltage profile
• Conservation Voltage Reduction (CVR) to reduce demand during peak hours
• Immediate notification of a capacitor operation malfunction such as a blown fuse
• Remote activation of regulators and capacitors, plus change the CBC-7000 controller settings without sending a field crew
• Real-time alarms from capacitor sites such as neutral current voltage threshold violations

More IVVC Management Benefits

• Global and regional views of available and unavailable VARs
• Improves System Reliability
• Improves feeder voltage profile
• Reduces line losses
• Releases system capacity
• Defers construction costs
• Eliminates PF Penalties
• Adapts to changing system needs
• Adapts to system reconfiguration
• Offers Conservation Voltage Reduction
• Increases KWh sales
• Increases productivity
• Provides O&M savings

Overall, IVVC further improves a utility by providing:

• Reliability
• Efficiency
• O&M Savings