# US 10,483,762 B2 · Power transmission network

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- Number: US 10,483,762 B2
- Document ID: US10483762B2
- Status: Granted
- Kind: B2
- Application number: 15/316,522
- Filed: 2015-06-08
- Published: 2017-05-18
- Granted: 2019-11-19
- Earliest claimed: 2014-06-09
- Assignees: General Electric Technology GmbH
- Applicants: General Electric Technology GmbH
- Inventors: Omar Fadhel Jasim
- Web page: https://patentgrep.com/patent/US10483762B2

## CPC

- H02J 3/36: Arrangements for transfer of electric power between AC networks via high-voltage DC [HVDC] links; Arrangements for transfer of electric power between generators and networks via HVDC links
- H02J 3/06: Controlling the transfer of power between connected networks; Controlling load sharing between connected networks
- H02J 3/08: Synchronisation of networks
- H03L 7/087: using at least two phase detectors or a frequency and phase detector in the loop
- H03L 7/099: concerning mainly the controlled oscillator of the loop
- H02J 2003/365: {Reducing harmonics or oscillations in HVDC}
- Y02E 60/60: Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD]
- H02J: ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H03L: AUTOMATIC CONTROL, STARTING, SYNCHRONISATION OR STABILISATION OF GENERATORS OF ELECTRONIC OSCILLATIONS OR PULSES (generation of oscillations H03B)
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

A power transmission network is disclosed, which includes an AC electrical network connected to a point of common coupling, the point of common coupling being connectable to a further electrical device; and a processing circuit configured to receive and process a voltage of the point of common coupling to determine a phase difference between the voltages of the AC electrical network and the point of common coupling during an exchange of power between the AC electrical network and the point of common coupling.

## Claims

### Claim 1

A power transmission network comprising:
an AC electrical network connected to a point of common coupling, the AC electrical network having a voltage, the point of common coupling being connectable to a further electrical device; and
a processing circuit comprising a phase locked loop, the processing circuit configured to receive and process a voltage of the point of common coupling to determine a phase difference between the voltages of the AC electrical network and the point of common coupling during an exchange of power between the AC electrical network and the point of common coupling, the phase locked loop comprising:
a phase detector,
a loop filter, an output of the loop filter being configured to provide a phase difference signal corresponding to the phase difference;
a first voltage controlled oscillator; and
a second voltage controlled oscillator configured to lock the phases of the voltages of the AC electrical network and the point of common coupling prior to the exchange of power between the AC electrical network and the point of common coupling;
wherein the phase locked loop is configured to switch between the first voltage controlled oscillator and second voltage controlled oscillator.

### Claim 2 (depends on 1)

A power transmission network according to claim 1, wherein the voltages of the AC electrical network and the point of common coupling are in-phase prior to the exchange of power between the AC electrical network and the point of common coupling.

### Claim 3 (depends on 1)

A power transmission network according to claim 1, wherein the point of common coupling is connected to a converter.

### Claim 4 (depends on 3)

A power transmission network according to claim 3, wherein the processing circuit is configured to process the phase difference in combination with the voltage and current of the point of common coupling to determine a network impedance of the AC electrical network, to process the network impedance to define the operating requirements of the converter, and to operate the converter in accordance with the defined operating requirements.

### Claim 5 (depends on 4)

A power transmission network according to claim 4, wherein the processing circuit is configured to process the network impedance to define the real and/or reactive power exchange requirements of the exchange of power between the AC electrical network and the converter, and to operate the converter in accordance with the defined real and/or reactive power exchange requirements.

### Claim 6 (depends on 1)

A power transmission network according to claim 1, wherein the processing circuit further includes a frequency detector configured to receive and process a voltage of the point of common coupling to provide a frequency reference to at least one of the first voltage controlled oscillator and second voltage controlled oscillator.

### Claim 7 (depends on 6)

A power transmission network according to claim 6, wherein the frequency detector is or includes a frequency locked loop.

### Claim 8 (depends on 6)

A power transmission network according to claim 6, wherein the frequency detector is configured to clamp the frequency reference to correspond to a nominal frequency of the AC electrical network during the exchange of power between the AC electrical network and the point of common coupling.

### Claim 9 (depends on 1)

A power transmission network according to claim 1, wherein the phase detector is configured to perform a transformation of the received voltage of the point of common coupling to provide a voltage vector consisting of positive and negative sequence components.

### Claim 10 (depends on 9)

A power transmission network according to claim 9, wherein the loop filter is configured to receive and process only the positive sequence component of the positive and negative sequence components of the voltage vector to determine the phase difference between the voltages of the AC electrical network and the point of common coupling during an exchange of power between the AC electrical network and the point of common coupling.

### Claim 11 (depends on 1)

A power transmission network according to claim 1, wherein the processing circuit further includes a frequency detector configured to receive and process a voltage of the point of common coupling to provide a frequency reference to at least one of the first voltage controlled oscillator and second voltage controlled oscillator.

### Claim 12 (depends on 7)

A power transmission network according to claim 7, wherein the frequency detector is configured to clamp the frequency reference to correspond to a nominal frequency of the AC electrical network during the exchange of power between the AC electrical network and the point of common coupling.