RESONANCE SUPPRESSION DEVICE

• US 20160028301A1
• Filed: 04/21/2014
• Published: 01/28/2016
• Est. Priority Date: 04/26/2013
• Status: Active Grant

• Current Assignee: Fuji Electric Company Limited (Fuji Electric Systems Company Limited)
• Original Assignee: Fuji Electric Company Limited (Fuji Electric Systems Company Limited)
• Inventors: Murakami, Kenya, Jintsugawa, Toru, Koike, Tomohiro, Kofuji, Kentaro
• Granted Patent: US 9,621,023 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H02J 2300/28 The renewable source being wind energy
• CPC Class Codes: H02J 3/01 Arrangements for reducing harmonics or ripples
• CPC Class Codes: H02J 3/381 Dispersed generators
• CPC Class Codes: H02M 1/12 Arrangements for reducing harmonics from ac input or output
• CPC Class Codes: H02M 7/44 by static converters
• CPC Class Codes: Y02E 10/76 Power conversion electric or electronic aspects
• CPC Class Codes: Y02E 40/40 Arrangements for reducing harmonics

Abstract

The present invention whose object is to reduce compensation current at the time when suppressing harmonic distortion caused by harmonic voltage, to reduce capacitance of an inverter, a resonance suppression device configured to suppress resonance which occurs when a power facility such as a wind power generator is connected to a power system includes: an inverter configured to supply alternating current to the power system, the inverter being in parallel with the power facility; a current command value generation unit in which voltage at a connection point between the power facility and the power system is inputted thereto and a current command value is obtained by multiplying, by a transfer function, a harmonic component contained in the voltage at the connection point; and a current control unit configured to control the alternating current outputted from the inverter based on the current command value.

Claims

1. A resonance suppression device configured to supply compensation current to a power system from a power conversion device connected to the power system, to suppress resonance which occurs with a power facility being connected to the power system, the resonance suppression device comprising:

a current command value generation unit whereto voltage of the power system is inputted, the current command value generation unit being configured to multiply, by a transfer function, a frequency component obtained by eliminating a fundamental wave component from frequency components contained in the inputted voltage, to generate a current command value with respect to the power conversion device,

the current command value generation unit being configured to output the current command value to the power conversion device, to supply the compensation current to the power system.

2. The resonance suppression device according to claim 1, wherein

the current command value generation unit includes

a first filter configured to extract a frequency component obtained by eliminating a fundamental wave component from frequency components contained in an inputted voltage, to output the resultant,

a second filter configured to extract a frequency component obtained by eliminating a fundamental wave component from frequency components contained in current supplied from the power facility to the power system, to output the resultant, and

a coefficient control unit configured to control a coefficient of the transfer function based on an output value of the second filter, and

voltage of the power system multiplied by the transfer function is inputted to the first filter and an output value thereof is used as the current command value, or voltage of the power system is inputted to the first filter;

an output value thereof is multiplied by the transfer function; and

the resultant output value is used as the current command value.

3. The resonance suppression device according to claim 1, wherein

the power system is a three-phase power system, and

the current command value generation unit includes

a first dq transformation unit configured to dq transform voltage of each phase of the power system,

a first filter configured to extract a frequency component obtained by eliminating a fundamental wave component from frequency components contained in each of a d-axis component and a q-axis component obtained by performing dq transformation in the first dq transformation unit, to output the resultant,

a second dq transformation unit configured to dq transform current of each phase supplied from the power facility to the power system,

a second filter configured to extract a frequency component obtained by eliminating a fundamental wave component from frequency components contained in each of a d-axis component and a q-axis component obtained by performing dq transformation in the second dq transformation unit, to output the resultant,

a coefficient control unit configured to control a coefficient of the transfer function based on an output value of the second filter, and

an inverse dq transformation unit configured to perform inverse dq transformation of a d-axis component and a q-axis component outputted from the first filter, to generate the current command value of each phase, and

any one of inputted values and output values of the first dq transformation unit, the first filter, and the inverse dq transformation unit is multiplied by the transfer function.

4. The resonance suppression device according to claim 2, wherein

the first filter and the second filter each are of any type of a high-pass filter, a bandpass filter, and a band elimination filter.

9. The resonance suppression device according to claim 2, wherein

the coefficient control unit is configured to control a coefficient of the transfer function so as to match an output value of the second filter with the current command value.

10. The resonance suppression device according to claim 9, wherein

the coefficient control unit includes a PI control unit whereto a deviation between the current command value and an output value of the second filter is inputted, and is configured to control a coefficient of the transfer function based on an output value of the PI control unit.

11. The resonance suppression device according to claim 10, wherein

the coefficient control unit includes a dead band with respect to the inputted deviation.

12. The resonance suppression device according to claim 2, wherein

the coefficient control unit is configured to control a coefficient of the transfer function so as to match a product of the current command value and an input value of the transfer function with a product of an output value of the second filter and an input value of the transfer function.

13. The resonance suppression device according to claim 12, wherein

the coefficient control unit includes

a first multiplication unit configured to multiply the current command value by an output value of the first filter,

a second multiplication unit configured to multiply an output value of the second filter by an output value of the first filter, and

a PI control unit whereto a deviation between an output value of the first multiplication unit and an output value of the second multiplication unit is inputted, the PI control unit being configured to control a coefficient of the transfer function based on the inputted deviation, and

the coefficient control unit is configured to control a coefficient of the transfer function based on an output value of the PI control unit.

14. The resonance suppression device according to claim 13, wherein

the coefficient control unit includes a dead band with respect to the inputted deviation.

15. The resonance suppression device according to claim 1, wherein

the current command value generation unit includes

a first filter configured to extract a frequency component obtained by eliminating a fundamental wave component from frequency components contained in the inputted voltage, to output the resultant, and

the transfer function in which a coefficient is a fixed value, and

voltage of the power system multiplied by the transfer function is inputted to the first filter and an output value thereof is used as the current command value, or voltage of the power system is inputted to the first filter;

an output value thereof is multiplied by the transfer function; and

the resultant output value is used as the current command value.

16. The resonance suppression device according to claim 15, wherein

the fixed value is a value that is set in advance according to the number of the power facilities in operation.

17. The resonance suppression device according to claim 1, wherein

the power facility is a wind power generation facility.

18. The resonance suppression device according to claim 1, wherein

the current command value generation unit includes a filter configured to extract a frequency component obtained by eliminating a fundamental wave component from frequency components contained in the inputted voltage, to output the resultant, and

voltage of the power system multiplied by the transfer function is inputted to the filter and an output value thereof is used as a current command value, or voltage of the power system is inputted to the filter;

an output value thereof is multiplied by the transfer function; and

a value corresponding to the resultant output value is used as the current command value, and

the current command value generation unit further includes a coefficient control unit configured to control a coefficient of the transfer function so that a value of the compensation current falls within a predetermined range, according to output capacity of the power conversion device.

5. A resonance suppression device configured to supply compensation current to a power system, to suppress resonance which occurs with a power facility being connected to the power system, the resonance suppression device comprising:

an inverter connected in parallel to the power system that is connected in parallel to the power facility, the inverter configured to supply the compensation current thereto, and

a current command value generation unit whereto voltage of the power facility is inputted, the current command value generation unit being configured to multiply, by a transfer function, a frequency component obtained by eliminating a fundamental wave component from frequency components contained in the inputted voltage, to generate a current command value with respect to the inverter,

the current command value generation unit being configured to output the current command value to the inverter, to supply the compensation current to the power system.

6. The resonance suppression device according to claim 5, wherein

the current command value generation unit includes

a first filter configured to extract a frequency component obtained by eliminating a fundamental wave component from frequency components contained in the inputted voltage, to output the resultant,

a second filter configured to extract a frequency component obtained by eliminating a fundamental wave component from frequency components contained in current supplied from the power facility to the power system, to output the resultant, and

a coefficient control unit configured to control a coefficient of the transfer function based on an output value of the second filter, and

voltage of the power system multiplied by the transfer function is inputted to the first filter, and an output value thereof is used as the current command value, or voltage of the power system is inputted to the first filter, an output value thereof is multiplied by the transfer function, and the resultant output value is used as the current command value.

7. The resonance suppression device according to claim 5, wherein

the power system is a three-phase power system, and

the current command value generation unit includes

a first dq transformation unit configured to dq transform voltage of each phase of the power system,

a first filter configured to extract a frequency component obtained by eliminating a fundamental wave component from frequency components contained in each of a d-axis component and a q-axis component obtained by performing dq transformation in the first dq transformation unit, to output the resultant,

a second dq transformation unit configured to dq transform current of each phase supplied from the power facility to the power system,

a second filter configured to extract a frequency component obtained by eliminating a fundamental wave component, from frequency components contained in a d-axis component and a q-axis component obtained by performing dq transformation in the second dq transformation unit, to output the resultant,

a coefficient control unit configured to control a coefficient of the transfer function based on an output value of the second filter, and

an inverse dq transformation unit configured to perform inverse dq transformation of a d-axis component and a q-axis component outputted from the first filter, to generate the current command value of each phase, and

any one of input values and output values of the first dq transformation unit, the first filter, and the inverse dq transformation unit is multiplied by the transfer function.

8. The resonance suppression device according to claim 6, wherein

the first filter and the second filter each are of any type of a high-pass filter, a bandpass filter, and a band elimination filter.

19. The resonance suppression device according to claim 5, wherein

the current command value generation unit includes a filter configured to extract a frequency component obtained by eliminating a fundamental wave component from frequency components contained in the inputted voltage, to output the resultant,

voltage of the power system multiplied by the transfer function is inputted to the filter and an output value thereof is used as a current command value, or voltage of the power system is inputted to the filter;

an output value thereof is multiplied by the transfer function; and

a value corresponding to the resultant output value is used as the current command value,

the current command value generation unit further includes a coefficient control unit configured to control a coefficient of the transfer function so that a value of the compensation current is falls within a predetermined range, according to output capacity of the inverter.