# US 11,451,062 B2 · Method and system for controlling a renewable energy plant

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- Number: US 11,451,062 B2
- Document ID: US11451062B2
- Status: Granted
- Kind: B2
- Application number: 17/040,564
- Filed: 2019-04-09
- Published: 2021-11-25
- Granted: 2022-09-20
- Earliest claimed: 2018-04-14
- Assignees: Merit Si, LLC
- Applicants: Merit Si, LLC
- Inventors: Dmitriy Anichkov
- Web page: https://patentgrep.com/patent/US11451062B2

## CPC

- H02J 3/381: {Dispersed generators}
- H02J 3/06: Controlling the transfer of power between connected networks; Controlling load sharing between connected networks
- H02J 3/16: by adjustment of reactive power
- H02J 3/48: Controlling the sharing of active power
- H02J 13/12: Monitoring network conditions, e.g. electrical magnitudes or operational status
- H02J 2101/24: Photovoltaics
- H02J 2101/28: Wind energy
- H02J 2103/30: Simulating, planning, modelling, reliability check or computer assisted design [CAD] of electric power networks
- Y02E 40/70: Smart grids as climate change mitigation technology in the energy generation sector
- Y02E 60/00: Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y04S 10/123: the energy generation units being or involving renewable energy sources
- Y04S 10/30: State monitoring, e.g. fault, temperature monitoring, insulator monitoring, corona discharge
- Y04S 10/50: Systems or methods supporting the power network operation or management, involving a certain degree of interaction with the load-side end user applications
- Y04S 40/20: Information technology specific aspects, e.g. CAD, simulation, modelling, system security
- H02J: ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y04S: SYSTEMS INTEGRATING TECHNOLOGIES RELATED TO POWER NETWORK OPERATION, COMMUNICATION OR INFORMATION TECHNOLOGIES FOR IMPROVING THE ELECTRICAL POWER GENERATION, TRANSMISSION, DISTRIBUTION, MANAGEMENT OR USAGE, i.e. SMART GRIDS

## Abstract

A method for controlling power flow between a renewable energy plant and an electric power grid, the plant having an intermittent energy source, the method comprising: using a control system, measuring power output from the plant and determining a first difference between the measured power output from the plant and a power reference; measuring frequency deviation of the power output from the plant and determining a second difference between the measured frequency deviation and a frequency deviation reference; generating a first error by limiting a sum of the first and second differences between predetermined minimum and maximum power error limits; modelling power output from the source and determining a second error between the modelled power output from the source and a control signal applied to the source to control the power output therefrom; and, generating the control signal by applying the first and second errors to a PI loop.

## Claims

### Claim 1

A method for controlling power flow between a renewable energy plant and an electric power grid, the renewable energy plant having an intermittent energy source, the method comprising:
using a renewable energy plant control system, measuring power output from the renewable energy plant and determining a first difference signal between the measured power output from the renewable energy plant and a power reference;
measuring frequency deviation of the power output from the renewable energy plant and determining a second difference signal between the measured frequency deviation and a frequency deviation reference;
generating a first error signal by limiting a sum of the first and second difference signals between predetermined minimum and maximum power error limits;
modelling power output from the intermittent energy source and determining a second error signal between the modelled power output from the intermittent energy source and a control signal applied to the intermittent energy source to control the power output therefrom; and,
generating the control signal by applying the first and second error signals to a proportional-integral loop.

### Claim 2 (depends on 1)

The method of claim 1, wherein the modelling power output from the intermittent energy source includes measuring power output from the intermittent energy source to generate the modelled power output from the intermittent energy source.

### Claim 3 (depends on 1)

The method of claim 1, wherein the modelling power output from the intermittent energy source includes measuring electrical properties of the renewable energy plant and applying the measured electrical properties to a model of the intermittent energy source to generate the modelled power output from the intermittent energy source.

### Claim 4 (depends on 3)

The method of claim 3, wherein the electrical properties are measured at a point of metering of the renewable energy plant.

### Claim 5 (depends on 4)

The method of claim 4, wherein the electrical properties include one or more of current, voltage, and power.

### Claim 6 (depends on 3)

The method of claim 3, wherein the model is at least one of a power flow model and a line drop compensation model.

### Claim 7 (depends on 1)

The method of claim 1, wherein the modelling power output from the intermittent energy source includes measuring electrical properties of the renewable energy plant and applying the measured electrical properties and the control signal to an adaptive model of the intermittent energy source to generate the modelled power output from the intermittent energy source.

### Claim 8 (depends on 7)

The method of claim 7, wherein the electrical properties are measured at a point of metering of the renewable energy plant.

### Claim 9 (depends on 8)

The method of claim 8, wherein the electrical properties include one or more of current, voltage, and power.

### Claim 10 (depends on 9)

The method of claim 9, wherein the adaptive model adjusts a resistive component of line impedance.

### Claim 11 (depends on 10)

The method of claim 10, further comprising adjusting the adaptive model to minimize a difference between modeled intermittent energy source power output and measure intermittent energy source power output.

### Claim 12 (depends on 1)

The method of claim 1, wherein the power reference is a minimum of the power reference and a power reference corresponding to a current limit for existing operating parameters.

### Claim 13 (depends on 1)

The method of claim 1, wherein the power output from the renewable energy plant is an active power output, wherein the power reference is an active power reference, wherein the minimum and maximum power error limits are minimum and maximum active power error limits, and wherein the power output from the intermittent energy source is an active power output.

### Claim 14 (depends on 1)

The method of claim 1, wherein the intermittent energy source includes a photovoltaic energy source.

### Claim 15 (depends on 1)

The method of claim 1, wherein the intermittent energy source includes a wind turbine.

### Claim 16 (depends on 1)

The method of claim 1, wherein the intermittent energy source is one or more intermittent energy sources.

### Claim 17 (depends on 1)

The method of claim 1, wherein the renewable energy plant has at least one energy load coupled thereto.

### Claim 18 (depends on 1)

The method of claim 1, wherein the renewable energy plant has at least one controllable load coupled thereto.

### Claim 19 (depends on 1)

The method of claim 1, wherein the renewable energy plant has at least one energy storage coupled thereto.

### Claim 20 (depends on 1)

A control system for controlling power flow between a renewable energy plant and an electric power grid, the renewable energy plant having an intermittent energy source, the control system comprising:
a processor coupled to memory; and,
at least one of hardware and software modules within the memory and controlled or executed by the processor, the modules including computer readable instructions executable by the processor for causing the control system to implement the method of claim 1.