Voltage controller for minimizing the utility power provided to a local load site having a local power source

• US 6,329,798 B1
• Filed: 12/11/1999
• Issued: 12/11/2001
• Est. Priority Date: 12/11/1998
• Status: Expired due to Fees

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Huggett, Colin, Kalman, Gabor
• Primary Examiner(s): STERRETT, JEFFREY L
• Application Number:
  US09/460,188
• Time in Patent Office: 731 Days
• Field of Search: 323/205, 323/207
• US Class Current: 323/207
• CPC Class Codes: G05F 1/70 Regulating power factor; Regulating reactive current or power
• CPC Class Codes: H02M 1/44 Circuits or arrangements for compensating for electromagnetic interference in converters or inverters

Abstract

A load site voltage regulation control system. The load site receives electrical power from a utility over transmission lines. The load site also receives electrical power from a local generator unit operating with an inverter. The local generator unit and inverter arc coupled to the load by an EMI filter and a transformer. Voltage at the load is controlled by adjusting the inverter voltage using an inverter voltage command. The inverter voltage command is based on load voltage, inverter voltage, EMI filter voltage, utility supplied current, and inverter current. In one embodiment, the inverter voltage is adjusted to minimize utility supplied reactive and real power and to actively dampen EMI filter voltage, with the inverter voltage command being developed though a multi-loop PPI control system.

Claims

1. A method for regulating the voltage at a load site, the load site receiving power signals from a distant power source and having a load site source and a load, the load site source having a maximum power producing capability including a maximum real and reactive power producing capability, and the load having a real and a reactive power requirement, the method comprising the steps of:

dynamically monitoring the real power required by the load;

allowing the load site source to provide a predetermined portion of the real power required by the load up to the maximum real power producing capability of the load site source; and

allowing the distance power source to provide any remaining real power required by the load.

2. A method according to claim 1 wherein the load site source is allowed to provide all of the real power required by the load up to the maximum real power producing capability of the load site source.

3. A method according to claim 1 further comprising the step of using any excess power producing capability of the local site source to minimize the reactive power required from the distant power source.

4. A power controller adapted for load site voltage regulation, the load site receiving power from a distant power source and the load site including a load site source and a load, the power including current and voltage signals from the distance power source which are either directly or indirectly coupled to the load, the load site source having a maximum power producing capability including a maximum real and reactive power producing capability, and the load having a real and a reactive power requirement, the power controller comprising:

a regulator controller coupled between the local site source and the load, the regulator controller allowing any excess power producing capability of the local site source to minimize the reactive power required from the distant power source.

5. A power controller according to claim 4 wherein the regulator controller causes the load site source to provide substantially all of the real power required by the load up to the maximum real power producing capability of the load site source, after which the regulator controller causes the distance power source to provide any remaining real power required by the load.

6. A power controller according to claim 4 wherein the regulator controller attempts to match the real power provided by the load site source with the real power required by the load when the real power required by the load is less than the power producing capability of the local site source.

7. The power controller according to claim 4, wherein the regulator controller adjusts the angle of the power provided to the load by the local site source such that the reactive power required from the distant power source is minimized.

8. The power controller according to claim 4, wherein the regulator controller uses any excess power producing capability of the local site source to adjust the angle of the power provided to the load by the local site source such that the reactive power required from the distant power source is minimized.

9. A method for regulating the voltage at a load site connected to a utility power source over transmission lines, the load site including a power generator unit operatively coupled to an inverter operatively coupled to a load by a path including a filter, the method comprising:

determining an indication of load voltage;

determining an indication of utility current provided by the utility power source to the load;

determining an indication of inverter current;

forming a commanded current signal using the indication of load voltage and the indication of utility current;

determining a real component of utility current;

comparing the real component of utility current to a reference signal to form a commanded amplitude of current;

determining a reactive component of utility current;

comparing the reactive component of utility current to an indication of load voltage for form a commanded angle of current; and

combining the commanded amplitude of current and the commanded angle of current to produce a commanded current signal; and

forming an inverter voltage command using the indication of inverter current and the commanded current signal.