Connecting circuit and method for connecting a generator to the electricity grid making use thereof

• US 20040130216A1
• Filed: 03/11/2004
• Published: 07/08/2004
• Est. Priority Date: 03/12/2001
• Status: Active Grant

• Current Assignee: Enatec Micro-Cogen B.V.
• Original Assignee: Enatec Micro-Cogen B.V.
• Inventors: Beckers, Gerardus Jacobus Josephine, Maria Zutt, Jacobus Gerardus, Van Kampen, Berend Jan, Van Kampen, Willem Antoon, Bekkering, Dirk Lucas, Ribberdink, Johannes Sjoerd
• Granted Patent: US 7,078,830 B2
• Time in Patent Office: Days
• US Class Current: 307/112
• CPC Class Codes: H02J 3/42 with automatic parallel connection when synchronisation is achieved

Abstract

The present invention relates to a connecting circuit for connecting to an electricity grid an electric generator for generating electrical energy, comprising: a measuring circuit for measuring the current through the connecting circuit; a storage element for storing charge supplied by the generator for at least some period of time; a second measuring circuit for measuring the amount of stored charge, which circuit is connected to a storage element; and a first controllable switch for connecting the generator to the electricity grid subject to the measured current intensity, voltage and stored charge.

Claims

1. Connecting circuit for connecting to an electricity grid an electric generator for generating electrical energy, comprising:

a measuring circuit for measuring the current through the connecting circuit;

a storage element for storing charge supplied by the generator for at least some period of time;

a second measuring circuit for measuring the amount of stored charge, which circuit is connected to a storage element; and

a first controllable switch for connecting the generator to the electricity grid subject to the measured current intensity, voltage and stored charge.

2. Connecting circuit as claimed in claim 1, wherein the first measuring circuit comprises a transformer.

3. Connecting circuit as claimed in claim 1 or 2, wherein the second measuring circuit comprises a differential amplifier.

4. Connecting circuit as claimed in claim 1, 2 or 3, further comprising a circuit for generating a voltage of a predetermined value.

5. Connecting circuit as claimed in any of the claims 1-4, further comprising a phase circuit for determining and shifting the phase of the measured signals.

6. Connecting circuit as claimed in claim 4, wherein the circuit comprises a microprocessor, an EPROM in which the signal of predetermined value is stored in digital form, and a DA-converter.

7. Connecting circuit as claimed in claim 6, wherein a counter is connected to the EPROM for phase-shifting of the output of the EPROM.

8. Connecting circuit as claimed in claim 5, wherein the phase circuit comprises a phase comparator, a phase-locking and a return loop.

9. Connecting circuit as claimed in one or more of the claims 1-8, wherein a dissipative element and a second controllable switch are arranged parallel to the storage element.

11. Method as claimed in claim 9, wherein a connecting circuit according to one or more of the claims 1-8 is applied.

12. Method as claimed in claim 10 or 11, wherein the measured values according to claims 1-10 are used to postpone or cause the connection to the electricity grid not to take place or to interrupt an existing connection and to return to dissipation of the generated electric power in such a short time that mechanical, electromechanical or electrical damage will be avoided.

10. Method for connecting an electric generator to an electricity grid, wherein using a connecting circuit wherein the current through the connecting circuit is measured, the amount of stored charge in a storage element of the measuring circuit is measured, and wherein the generator is connected to the electricity grid as soon as measurement shows that the phase of the voltage generated by the generator and the voltage of the electricity grid are roughly equal.