Parallel Method for Two Electrical Generators

Abstract

The present invention provides a parallel method for two electrical generators, more particularly, a parallel method for controlling a Micro-turbine Generator (MTG) in parallel with a traditional Reciprocating Generator (RG). A parallel protection equipment is designed to connect with both the Micro-turbine Generator (MTG) and the traditional Reciprocating Generator (RG) in parallel operation during the Micro-turbine Generator (MTG) regular inspection and maintenance without the power shutoff under the safe condition. The parallel protection equipment comprises a plurality of power resistors, terminal blocks, a breaker, a 24V control relay and a bypass contactor. In addition, the present invention provides bypass contactor control through a monitoring signal contributed by the traditional Reciprocating Generator (RG) working in parallel or by a customer control panel.

Claims

1. A method of connecting a Micro-turbine generator and a traditional reciprocating generator in parallel with a parallel protection equipment comprising: (1) providing a plurality of resistors in the parallel protection equipment connected between the Micro-turbine generator and the traditional reciprocating generator to limit current flow between two generators; (2) controlling the main current flow from the Micro-turbine generator to the load with a bypass contactor; (3) limiting current flow passing through the plurality of resistors to a safe value by a protective breaker.

2. The method of claim 1 can also be applied to any two generators in parallel operation, if the current flow between these two generators is found larger than their maximum allowable value.

Description

[0008] FIG. 1 shows a color photograph of the parallel protection equipment. In FIG. 2, the components of the parallel protection equipment are shown, the parallel protection equipment includes a plurality of power resistors, terminal blocks, a breaker, a 24V control relay and a bypass contactor. In FIG. 3, the schematic diagram shows the concept of the MTG and the traditional RG in parallel operation with the parallel protection equipment. For all applications, there is a customer control panel to monitor the RG status. When the RG output power is switched off, the control signal is read as one (1) from the customer control panel, the bypass contactor K.sub.1 is closed based on this signal. The MTG is now supplying full current through contactor K.sub.1 to the load. When the RG output power is switched on, the control signal is read as zero (0) from the customer control panel, the bypass contactor K.sub.1 is disconnected based on this signal. When K.sub.1 opens, the MTG only takes small current passing through a set of resistors and the breaker to the load, the major current requested by customer load will be transferred to the RG. Then, the MTG can be shut off for inspection and maintenance while the RG is taking major load. There is no power gap during this transfer operation. Maximum current flowing between two none-identical voltage sources, MTG and RG, is limited to a safe value by the set of resistors, thus the MTG and RG parallel operation is achieved successfully. In abnormal conditions, if the current passing through resistors exceeds the breaker's maximum limit value, the breaker will trip off and disconnect the MTG from the RG and the load. This is to prevent high current causing resistors overheat in abnormal conditions. FIG. 4 shows the complete circuit diagram of the parallel protection equipment designed for MTG and RG parallel operation. If the control signal of the customer panel is equal or less than 24V DC voltage, the bypass contactor will be controlled by the relay. Otherwise the control signal is required to be 230V AC, to directly control the bypass contactor coil.

[0009] This parallel protection equipment enables parallel operations between MTG and RG in various applications where zero power interruption is required during load transferring between MTG and RG.

REFERENCE

[0010] 1. U.S. Pat. No. 6,410,992B1, Aug. 23, 2000-Jun. 25, 2002. Capstone Turbine Corp. System and method for dual mode control of a turbogenerator/motor. [0011] 2. U.S. Pat. No. 7,078,825B2, Jun. 18, 2002-Jul. 18, 2006. Ingersoll-Rand Energy Systems Corp. Micro-turbine engine system having stand-alone and grid-parallel operating modes.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The accompanying drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component that is illustrated in various figures is represented by a like numeral. For purposes of clarity, not every component may be labeled in every drawing. In the drawings:

[0013] FIG. 1 shows a color photograph of the parallel protection equipment.

[0014] FIG. 2 shows a schematic view of components of the parallel protection equipment.

[0015] FIG. 3 shows a single-line schematic view of concept of Micro-turbine generator and traditional reciprocating generator in parallel operation with the parallel protection equipment.

[0016] FIG. 4 shows a schematic view of circuit diagram of the parallel protection equipment.