Optimizing voltage and VAR on the electric grid using distributed VAR sources
A plurality of edge of network grid volt ampere reactive (VAR) sources are provided in a power system in order to effectuate control at a customer level, which in turn effectuates control at a feeder level, which in turn effectuates control of an entire power system or wide area electric grid network. By optimally selecting voltage setpoints and applying such voltage setpoints to the plurality of edge of network grid VAR sources, the power system can be configured to self-balance, power factor compensation can be determined without the need for measuring load power factor. Moreover, traditionally volatile voltages at the feeder can be flattened, and VAR control can be realized.
1. A computer-implemented method for voltage and volt ampere reactive (VAR) control of a power system, comprising:
determining a transformer voltage setpoint;
setting a VAR voltage setpoint for a VAR device of a set of distributed VAR devices implemented in the power system, wherein the VAR voltage setpoint is within 2% of the transformer voltage setpoint in order to effectuate self-balancing of the power system, wherein the VAR device of the set of distributed VAR devices comprises a processor and is operatively connected to a secondary side of the transformer, the transformer comprising a service transformer of the power system, wherein each of the set of distributed VAR devices implement zero-droop control; and
controlling the VAR device of the set of distributed VAR devices by applying, with the processor, a distributed control algorithm comprising determining whether to activate the VAR device based on the VAR voltage setpoint independent of instructions from another VAR device or a central controller;
wherein the self-balancing occurs pursuant to at least a subset of the set of distributed VAR devices operating such that a primary side voltage equalizes with a secondary side voltage due to flow of VARs into the primary side, the flow of VARs automatically ceasing upon equalization of the primary side and the secondary side voltages resulting in zero net VARs, whereby a unity power factor is obtained at a feeder level by maintaining the VAR voltage setpoint at a value equal to the primary side voltage;
wherein a substation load tap changer transformer is operated in accordance with a secondary voltage setpoint distinct from the transformer voltage setpoint to enable a change in VARs drawn at a feeder level, wherein the secondary voltage setpoint of the load tap changer transformer is increased in response to at least one of the distributed VAR devices being below a minimum voltage limit and operating at a limit of the at least one distributed VAR device to provide VARs.
2. The computer-implemented method of claim 1 , further comprising dispatching VAR voltage setpoints to the set of distributed VAR devices, the set of distributed VAR devices being distributed along a feeder, wherein the dispatching of the VAR voltage setpoints is performed via at least one of wired and wireless communication mechanisms from a central command location.
3. The computer-implemented method of claim 1 , further comprising dispatching the transformer voltage setpoint to a transformer operatively connected to the set of distributed VAR devices, wherein the dispatching of the transformer voltage setpoint is performed via at least one of wired and wireless communication mechanisms from a central command location.
4. The computer-implemented method of claim 1 , further comprising determining whether any voltages associated with each of the set of distributed VAR devices exceed a voltage limit.
5. The computer-implemented method of claim 1 , wherein the VAR voltage setpoint for each VAR device of the set of distributed VAR device is different from the VAR voltage setpoint for other VAR devices of the set of distributed VAR devices.
6. The computer-implemented method of claim 1 , wherein the power system comprises a self-balancing power system such that the actual reactive power flow is reduced to zero subsequent to injecting reactive power into or pulling reactive power from a primary side of the power system.
7. The computer-implemented method of claim 1 , further comprising one of increasing or decreasing the transformer voltage setpoint and the secondary voltage setpoint in unison to increase or decrease, respectively, power draw by one or more loads, power change sensitivity being dependent upon a type of the one or more loads.
8. The computer-implemented method of claim 1 , further comprising one of increasing or decreasing the transformer voltage setpoint and the secondary voltage setpoint independently with respect to each other to at least one of provide centralized control for at least one of power and VARs drawn by a feeder of the power system, stabilize secondary voltage levels, reduce voltage drop across the service transformer, and increase voltage and VAR control predictability.
9. The computer-implemented method of claim 1 , wherein the self-balancing occurs independent of VAR measurements.
10. The computer-implemented method of claim 1 , wherein the self-balancing occurs independent of feeder topology information.
11. The computer-implemented method of claim 1 , wherein each of the set of distributed VAR devices comprises one of an edge of network grid optimization device, a dedicated VAR source, a static synchronous compensator (STATCOM), an inverter, a VAR-enhanced smart meter, or an electric vehicle charger.