Collection of electric power from renewable energy sources via high voltage, direct current systems with conversion and supply to an alternating current transmission network

• US 8,212,408 B2
• Filed: 08/18/2009
• Issued: 07/03/2012
• Est. Priority Date: 12/24/2008
• Status: Active Grant

• Current Assignee: Schneider Electric USA, Inc. (Schneider Electric SE)
• Original Assignee: Alencon Acquisition Co. LLC
• Inventors: Fishman, Oleg S.
• Primary Examiner(s): Amrany, Adi
• Application Number:
  US12/543,338
• Publication Number:
  US 20100156189A1
• Time in Patent Office: 1,050 Days
• Field of Search: 307/43, 307/77, 307 82- 84
• US Class Current: 307/77
• CPC Class Codes: H02J 2300/26 involving maximum power point tracking control for photovoltaic sources maximum power point systems in particular G05F1/67
• CPC Class Codes: H02J 2300/28 The renewable source being wind energy wind motors F03D
• CPC Class Codes: H02J 2300/40 wherein a plurality of decentralised, dispersed or local energy generation technologies are operated simultaneously
• CPC Class Codes: H02J 3/36 Arrangements for transfer of electric power between ac networks via a high-tension dc link
• CPC Class Codes: H02J 3/381 Dispersed generators
• CPC Class Codes: H02J 3/44 with means for ensuring correct phase sequence
• CPC Class Codes: H02M 1/0074 Plural converter units whose inputs are connected in series
• CPC Class Codes: H02M 7/493 the static converters being arranged for operation in parallel
• CPC Class Codes: Y02E 10/56 Power conversion systems, e.g. maximum power point trackers
• CPC Class Codes: Y02E 10/76 Power conversion electric or electronic aspects
• CPC Class Codes: Y02E 60/60 Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD]

Abstract

Wind-generated electric power is collected in a multiple nodal arrangement where the DC output current of each node can be held constant while the DC output node voltage is allowed to vary. The DC outputs from the wind-generated power collection nodes are connected together in series and fed to a plurality of regulated current source inverters via a high voltage DC transmission link. Each inverter converts input DC power into a three phase AC output. The AC outputs of the regulated current source inverters are connected to a phase shifting transformation network that supplies three phase electric power to a conventional AC electrical transmission system. Alternatively wind-generated and photovoltaic-generated electric power is commonly collected in a nodal arrangement and transported at high voltage DC to a plurality of regulated current source inverters for supply to the conventional AC electrical transmission system.

Claims

1. Apparatus for collecting at least one megawatt of wind-generated electric power and delivering the at least one megawatt of wind-generated power to an AC transmission network, the apparatus comprising:

a plurality of wind-generated power collection nodes, each one of the plurality of wind-generated power collection nodes comprising a wind turbine driven generator assembly having an AC synchronous generator with a generator output connected to an input of an AC to DC rectifier having a DC rectifier output;

a plurality of node isolated step-down current regulators, each one of the plurality of node isolated step-down current regulators having a node isolated step-down current regulator input connected exclusively to the DC rectifier output of one of the plurality of wind-generated power collection nodes;

a series string high voltage DC series circuit formed from a serial interconnection of a node isolated step-down current regulator output from each one of the plurality of wind-generator power collection nodes, the series string high voltage DC series circuit having an electric potential of at least 15 kilovolts;

a high voltage DC power transmission link having a first and a second end high voltage DC power transmission link terminations, the first end high voltage DC power transmission link termination connected across the series string high voltage DC series circuit;

a plurality of regulated current source inverters, each one of the plurality of regulated current source inverters having an inverter DC input and an inverter three phase AC output, the inverter DC input of each one of the plurality of regulated current source inverters series interconnected to form a series string inverter DC input circuit, the second end high voltage DC power transmission link termination connected across the series string inverter DC input circuit, the inverter three phase AC output of each one of the plurality of regulated current source inverters in voltage synchronization with the voltage of the AC transmission network, and each phase current of the inverter three phase AC output of each one of the plurality of regulated current source inverters having a stepped current waveform; and

at least one phase shifting transformation network, each one of the at least one phase shifting transformation networks connecting the inverter AC outputs of the plurality of regulated current source inverters to the AC transmission network.

2. The apparatus of claim 1 wherein each of the at least one phase shifting transformation networks comprises one or more transformers, each one of the one or more transformers comprising a plurality of secondary and primary phase shifting windings, the plurality of secondary phase shift windings connected to the inverter AC output of the plurality of regulated current source inverters, and the plurality of primary phase shifting windings connected to the AC transmission network.

3. A method of collecting at least one megawatt of wind-generated DC electric power and delivering the at least one megawatt of wind-generated DC electric power to an AC transmission network, the method comprising the steps of:

generating the at least one megawatt of wind-generated DC electric power from a plurality of wind-generated power collection nodes, each one of the plurality of wind-generated power collection nodes comprising a wind turbine driven generator assembly having an AC synchronous generator with a generator output connected to an input of an AC to DC rectifier having a DC rectifier output;

connecting a plurality of node isolated step-down regulators to the DC rectifier outputs of each one of the plurality of wind-generated power collection nodes, a node isolated step-down current regulator input from each one of the plurality of node isolated step-down regulators connected exclusively to one of the DC rectifier outputs of the plurality of node isolated step-down regulators;

serially interconnecting a node isolated step-down current regulator output from each one of the plurality of wind-generated power collection nodes to form an interconnected high voltage DC series circuit having an electric potential of at least 15 kilovolts;

serially interconnecting an inverter DC input of each one of a plurality of regulated current source inverters to form a high voltage DC series string inverter DC input circuit;

transporting the at least one megawatt of wind-generated DC electric power from the interconnected high voltage DC series circuit to the high voltage DC series string inverter DC input circuit to form a high voltage DC power loop circuit;

converting the at least one megawatt of wind-generated DC electric power to AC electric power in each one of the plurality of regulated current source inverters to produce an inverter three phase AC output from each of the plurality of regulated current source inverters in voltage synchronization with the voltage of the AC transmission network, and each phase current of the inverter three phase AC output of each one of the plurality of regulated current source inverters having a stepped current waveform;

phase shifting the inverter three phase AC outputs from all of the plurality of regulated current source inverters to form an inverter phase shifted AC output current; and

injecting the inverter phase shifted AC output current from the plurality of regulated current source inverters into the AC transmission network.

4. A method of delivering a megawatt quantity of DC electric power from a DC high voltage wind-generated electric power source to an AC transmission network, the method comprising the steps of:

generating the megawatt quantity of wind-generated DC electric power from a plurality of wind-generated power collection nodes, each one of the plurality of wind-generated power collection nodes comprising a wind turbine driven generator assembly having an AC synchronous generator with a generator output connected to an input of an AC to DC rectifier having an AC to DC rectifier output;

individually electrically isolating and step-down current regulating the AC to DC rectifier output of each one of the plurality of wind-generated power collection nodes;

forming an interconnected high voltage DC series circuit from all of the electrically isolated and step-down current regulated AC to DC rectifier outputs of the plurality of wind-generated power collection nodes, the interconnected high voltage DC series circuit having an electric potential of at least 15 kilovolts;

transporting the megawatt quantity of wind-generated DC electric power from the interconnected high voltage DC series circuit to a high voltage DC series string inverter DC input circuit formed from a serial interconnection of an inverter DC input of each one of a plurality of regulated current source inverters;

converting the megawatt quantity of wind-generated DC electric power to AC electric power in each one of the plurality of regulated current source inverters to produce an inverter three phase AC output from each of the plurality of regulated current source inverters in voltage synchronization with the voltage of the AC transmission network, and each phase current of the inverter three phase AC output from each one of the plurality of regulated current source inverters having a stepped current waveform;

phase shifting the inverter three phase AC outputs from all of the plurality of regulated current source inverters to form an inverter phase shifted AC output current; and

injecting the inverter phase shifted AC output current from the plurality of regulated current source inverters into the AC transmission network whereby the megawatt quantity of DC electric power is delivered to the AC transmission network.

5. Apparatus for collecting at least one megawatt quantity of DC electric power from a combination of solar photovoltaic power and wind-generated power, and delivering the at least one megawatt quantity of DC electric power to an AC transmission network, the apparatus comprising:

a combination of a plurality of solar photovoltaic power collection nodes and a plurality of wind-generated power collection nodes, each one of the plurality of solar photovoltaic power collection nodes comprising a plurality of solar photovoltaic power collectors, each one of the plurality of solar photovoltaic power collectors comprising a plurality of solar photovoltaic modules interconnected in a series string circuit to an input of a dedicated solar collector step-up voltage regulator having a solar collector step-up voltage regulator output and each one of the plurality of wind-generated power collection nodes comprising a wind turbine driven generator assembly having an AC synchronous generator with a generator output connected to an input of an AC to DC rectifier having a DC rectifier output;

a plurality of node isolated step-down current regulators, each one of the plurality of node isolated step-down current regulators having a node isolated step-down current regulator input connected exclusively to the solar collector step-up voltage regulator output of each one of the plurality of solar photovoltaic power collection nodes and the DC rectifier output of one of the plurality of wind-generated power collection nodes;

a series string high voltage DC series circuit formed from a serial interconnection of a node isolated step-down current regulator output from each one of the plurality of solar photovoltaic power collection nodes and each one of the plurality of wind-generator power collection nodes, the series string high voltage DC series circuit having an electric potential of at least 15 kilovolts;

a high voltage DC power transmission link having a first and a second end high voltage DC power transmission link terminations, the first end high voltage DC power transmission link termination connected across the series string high voltage DC series circuit;

a plurality of regulated current source inverters, each one of the plurality of regulated current source inverters having an inverter DC input and an inverter three phase AC output, the inverter DC input of each one of the plurality of regulated current source inverters series interconnected to form a series string inverter DC input circuit, the second end high voltage DC power transmission link termination connected across the series string inverter DC input circuit, the inverter three phase AC output of each one of the plurality of regulated current source inverters in voltage synchronization with the voltage of the AC transmission network, and each phase current of the inverter three phase AC output of each one of the plurality of regulated current source inverters having a stepped current waveform; and

at least one phase shifting transformation network, each of the at least one phase shifting transformation networks connecting the inverter AC outputs of the plurality of regulated current source inverters to the AC transmission network.

6. A method of collecting at least one megawatt quantity of DC electric power from a combination of solar photovoltaic power and wind-generated power and delivering the at least one megawatt quantity of DC electric power to an AC transmission network, the method comprising the steps of:

generating the at least one megawatt quantity of DC electric power from a combination of one or more solar photovoltaic power collection nodes and one or more wind-generated power collection nodes, each of the one or more solar photovoltaic power collection nodes comprising a plurality of solar photovoltaic power collectors, each one of the plurality of solar photovoltaic power collectors comprising a plurality of solar photovoltaic modules interconnected in a series string circuit to an input of a dedicated solar collector step-up voltage regulator having a solar collector step-up voltage regulator output, and each one of the one or more wind-generated power collection nodes comprising a wind turbine driven generator assembly having an AC synchronous generator with a generator output connected to an input of an AC to DC rectifier having a DC rectifier output;

connecting a plurality of node isolated step-down regulators to the solar collector step-up voltage regulator outputs of each one of the one or more solar photovoltaic power collection nodes and the DC rectifier outputs of each one of the one or more wind-generated power collection nodes, a node isolated step-down current regulator input from each one of the plurality of node isolated step-down regulators connected exclusively to one of the solar collector step-up voltage regulator outputs of the one or more solar photovoltaic power collection nodes and exclusively to one of the DC rectifier outputs of the one or more wind-generated power collection nodes;

serially interconnecting a node isolated step-down current regulator output from each of the one or more solar photovoltaic power collection nodes and the one or more wind-generated power collection nodes to form an interconnected high voltage DC series circuit having an electric potential of at least 15 kilovolts;

serially interconnecting an inverter DC input of each one of a plurality of regulated current source inverters to form a high voltage DC series string inverter DC input circuit; and

transporting the at least one megawatt quantity of solar photovoltaic and wind-generated DC electric power from the interconnected high voltage DC series circuit to the high voltage DC series string inverter DC input circuit to form a high voltage DC power loop circuit;

converting the at least one megawatt quantity of solar photovoltaic and wind-generated DC power to AC electric power in each one of the plurality of regulated current source inverters to produce an inverter three phase AC output from each of the plurality of regulated current source inverters in voltage synchronization with the voltage of the AC transmission network, and each phase current of the inverter three phase AC output of each one of the plurality of regulated current source inverters having a stepped current waveform;

phase shifting the inverter three phase AC outputs from all of the plurality of regulated current source inverters to form a phase shifted AC output current; and

injecting the phase shifted AC output current from the plurality of regulated current source inverters into the AC transmission network.