Interconnecting power generation system

• US 7,233,082 B2
• Filed: 12/09/2003
• Issued: 06/19/2007
• Est. Priority Date: 12/10/2002
• Status: Expired due to Fees

• Current Assignee: Ebara Corporation, Ebara Densan Ltd. (Ebara Corporation)
• Original Assignee: Ebara Densan Ltd. (Ebara Corporation)
• Inventors: Ishihara, Seiichi, Kataoka, Tadashi, Sato, Motoyasu, McKelvey, Terence, Marui, Eishi, Furuya, Tai, Kinoshita, Noboru, Zheng, Shaojun, Ozawa, Takahide
• Primary Examiner(s): Jackson; Stephen W.
• Assistant Examiner(s): AMAYA, CARLOS DAVID
• Application Number:
  US10/731,879
• Publication Number:
  US 20040264089A1
• Time in Patent Office: 1,288 Days
• Field of Search: 307/64
• US Class Current: 307/64
• CPC Class Codes: H02J 3/38 Arrangements for parallely feeding a single network by two or more generators, converters or transformers
• CPC Class Codes: H02J 3/388 Islanding, i.e. disconnection of local power supply from the network

Abstract

To provide an interconnecting power generation system which can detect an abnormality in the utility power supply and can be isolated from a utility power system and can prevent damage to a turbogenerator.

An interconnecting power generation system comprises: an interconnecting inverter 14; a voltage phase shift circuit 20 which synchronizes the output voltage phase of the interconnecting inverter 14 with the utility power voltage phase and monitors zero crossings of the utility power voltage, and which shifts the output voltage phase from the utility power voltage phase and shifts the shifted output voltage phase to the utility power voltage phase; a phase comparator 24 for comparing the voltage phase of the utility power system 10 and the output voltage phase of the interconnecting inverter; and an interconnection control unit 30 which detects a power outage caused by an interruption of power supply from the utility power system 10 based on a series of a predetermined number of matching signals outputted from the phase comparator 24 and sends a control signal to a circuit breaker 22 to shut off the output of the interconnecting inverter 14 from the utility power system 10.

Claims

1. An interconnecting power generation system connected in parallel to a utility power system for supplying electrical power to an interconnecting load, comprising:

an interconnecting inverter for linking generated electrical power to said utility power system;

a voltage phase shift circuit which synchronizes the output voltage phase of said interconnecting inverter with the utility power voltage phase and monitors zero crossings of said utility power voltage, and which, when a predetermined number of zero crossings have been detected, to detect a power outage actively, shifts said output voltage phase from said utility power voltage phase during one cycle and shifts the shifted output voltage phase to said utility power voltage phase during the following cycle;

a circuit breaker for shutting off the output of said interconnecting inverter from said utility power system;

a phase comparator for comparing the voltage phase of said utility power system and said output voltage phase of said interconnecting inverter; and

an interconnection control unit which detects a power outage caused by an interruption of power supply from said utility power system based on a series of a predetermined number of matching signals outputted from said phase comparator and sends a control signal to said circuit breaker to shut off the output of said interconnecting inverter from said utility power system.

2. An interconnecting power generation system connected in parallel to a utility power system for supplying electrical power to an interconnecting load, comprising:

an interconnecting inverter for linking generated electrical power to said utility power system;

a voltage phase shift circuit which synchronizes the output voltage phase of said interconnecting inverter with the utility power voltage phase and monitors zero crossings of said utility power voltage, and which, when a predetermined number of zero crossings have been detected, shifts said output voltage phase from said utility power voltage phase during one cycle and shifts the shifted output voltage phase to said utility power voltage phase during the following cycle;

a circuit breaker for shutting off the output of said interconnecting inverter from said utility power system;

a phase comparator for comparing the voltage phase of said utility power system and said output voltage phase of said interconnecting inverter; and

an interconnection control unit which detects a power outage caused by an interruption of power supply from said utility power system based on a series of a predetermined number of matching signals outputted from said phase comparator and sends a control signal to said circuit breaker to shut off the output of said interconnecting inverter from said utility power system;

wherein, when no matching signal is outputted from said phase comparator within a period during which said output voltage phase is to be matched with said utility power voltage phase, said interconnection control unit detects variations in the frequency of said utility power system and sends a control signal to said circuit breaker to shut off the output of said interconnecting inverter from said utility power system.

3. An interconnecting power generation system connected in parallel to a utility power system and for supplying electrical power to an interconnecting load, comprising:

a turbogenerator for generating electrical power,

an interconnecting inverter for linking electrical power generated by said turbogenerator to said utility power system;

a voltage phase shift circuit which synchronizes the output voltage phase of said interconnecting inverter with the utility power voltage phase and monitors zero crossings of said utility power voltage, and which, when a predetermined number of zero crossings have been detected, shifts said output voltage phase from said utility power voltage phase during one cycle and shifts the shifted output voltage phase to said utility power voltage phase during the following cycle;

a circuit breaker for shutting off the output of said interconnecting inverter from said utility power system;

a phase comparator for comparing the voltage phase of said utility power system and said output voltage phase of said interconnecting inverter; and

an interconnection control unit which detects a power outage caused by an interruption of power supply from said utility power system based on a series of a predetermined number of matching signals outputted from said phase comparator and sends a control signal to said circuit breaker to shut off the output of said interconnecting inverter from said utility power system, and which decreases the rotational speed of said turbogenerator to a predetermined speed during the period between the detection of said power outage and the shutoff of said utility power system.

4. The interconnecting power generation system according to claim 3, wherein said turbogenerator recharges a battery within said predetermined period of time in response to said shutoff command.

5. An interconnecting power generation system connected in parallel to a utility power system and for supplying electrical power to an interconnecting load, comprising:

a turbogenerator for generating electrical power,

an interconnecting inverter for linking electrical power generated by said turbogenerator to said utility power system;

a voltage phase shift circuit which synchronizes the output voltage phase of said interconnecting inverter with the utility power voltage phase and monitors zero crossings of said utility power voltage, and which, when a predetermined number of zero crossings have been detected, shifts said output voltage phase from said utility power voltage phase during one cycle and shifts the shifted output voltage phase to said utility power voltage phase during the following cycle;

a circuit breaker for shutting off the output of said interconnecting inverter from said utility power system;

a phase comparator for comparing the voltage phase of said utility power system and said output voltage phase of said interconnecting inverter; and

an interconnection control unit which detects a power outage caused by an interruption of power supply from said utility power system based on a series of a predetermined number of matching signals outputted from said phase comparator and sends a control signal to said circuit breaker to shut off the output of said interconnecting inverter from said utility power system, and sends a shutoff command to said turbogenerator to stop the operation of said turbogenerator after allowing the turbine to rotate at the rated rotational speed for a predetermined period of time.

6. The interconnecting power generation system according to claim 5, wherein said turbogenerator recharges a battery within said predetermined period of time in response to said shutoff command.