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- Nachgewiesen in: USPTO Patent Grants
- Sprachen: English
- Patent Number: 11616,369
- Publication Date: March 28, 2023
- Appl. No: 17/061343
- Application Filed: October 01, 2020
- Assignees: STATE GRID JIANGSU ELECTRIC POWER CO., LTD. (Nanjing, CN), STATE GRID JIANGSU ELECTRIC POWER CO., LTD. ECONOMIC RESEARCH INSTITUTE (Nanjing, CN), STATE GRID JIANGSU ELECTRIC POWER DESIGN CONSULTING INSTITUTE CO., LTD. (Nanjing, CN), STATE GRID CORPORATION OF CHINA (Beijing, CN), STATE GRID JIANGSU ELECTRIC POWER CO., LTD. MARKETING CENTER (Nanjing, CN)
- Claim: 1. A control method for a parallel Modular Multilevel Converter (MMC) unit of a Line Commutated Converter (LCC)-MMC hybrid cascade converter station, comprising following steps: (1) numbering all MMC units connected in parallel in a MMC valve manifold of the LCC-MMC hybrid cascade converter station according to a control manner and a rated capacity of each MMC unit of the MMC units, wherein a specific implementation process of the step (1) is as follows: firstly, dividing all MMC units in the MMC valve manifold into two types, that is, MMC units controlled in the constant direct-current voltage control manner and counted to be N 1 , and MMC units controlled in the constant active power control manner and counted to be N 2 ; and numbering the MMC units controlled in the constant direct-current voltage control manner from 1 to N 1 according to an order of rated capacities from small to large, and numbering the MMC units controlled by the constant active power from N 1 +1 to N 1 +N 2 according to an order of rated capacities from small to large; (2) in a case where a MMC unit of the all MMC units connected in parallel uses a constant direct-current voltage control manner, calculating a direct-current instruction value of the MMC unit according to a direct-current measurement value; (3) in a case where a MMC unit of the all MMC units connected in parallel uses a constant active power control manner, calculating an active power instruction value of the MMC unit according to the rated capacity of the MMC unit and a direct-current instruction value of a system rectifier station; (4) in a case where the MMC unit of the all MMC units connected in parallel uses the constant direct-current voltage control manner, correcting a direct-current voltage instruction value of the MMC unit by using the direct-current instruction value and the direct-current measurement value, and further controlling the MMC unit according to the corrected direct-current voltage instruction value; and (5) in a case where the MMC unit of the all MMC units connected in parallel uses the constant active power control manner, controlling the MMC unit according to the active power instruction value.
- Claim: 2. The control method of claim 1 , wherein in the step (2), the direct-current instruction value of the MMC unit is calculated by using a following formula: [mathematical expression included] wherein i dcref_k is a direct-current instruction value of a k-th MMC unit in the MMC valve manifold, S k is a rated capacity of the k-th MMC unit, S i is a rated capacity of an i-th MMC unit, i dci and i dcba_i are a direct-current measured value and a direct-current reference value of the i-th MMC unit respectively, i dcba_k is a direct-current reference value of the k-th MMC unit, i and k are natural numbers, 1≤i≤N 1 , 1≤k≤N 1 , and N 1 is a number of MMC units controlled in the constant direct-current voltage control manner in the MMC valve manifold.
- Claim: 3. The control method of claim 1 , wherein in the step (3), the active power instruction value of the MMC unit is calculated by using a following formula; [mathematical expression included] wherein P ref_r is an active power instruction value of an r-th MMC unit in the MMC valve manifold, i ba_rec and i ref_rec are a direct-current instruction value and a direct-current reference value of a rectifier station respectively, S r is a rated capacity of the r-th MMC unit, S j is a rated capacity of a j-th MMC unit, i dcba_r is a direct-current reference value of the r-th MMC unit, N 1 is a number of MMC units controlled in the constant direct-current voltage control manner in the MMC valve manifold, N 2 is a number of MMC units controlled in the constant active power control manner in the MMC manifold, r and j are natural numbers, 1≤j≤N 1 +N 2 , and N 1 +1≤r≤N 1 +N 2 .
- Claim: 4. The control method of claim 1 , wherein a specific implementation process of the step (4) is as follows: firstly, subtracting a direct-current instruction value i dcref_k from a direct-current measurement value i dck of a k-th MMC unit to obtain a corresponding current error value; then, introducing the current error value into a proportional control stage and an amplitude limiting stage in turn to obtain a direct-current voltage correct value of the k-th MMC unit; and finally, adding the direct-current voltage correct value to an original direct-current voltage instruction value of the k-th MMC unit to obtain a corrected direct-current voltage instruction value, and controlling the k-th MMC unit in the constant direct-current voltage control manner according to the corrected direct-current voltage instruction value, wherein 1≤k≤N 1 , and N 1 is a number of MMC units controlled in the constant direct-current voltage control manner in the MMC valve manifold.
- Claim: 5. The control method of claim 4 , wherein a proportional coefficient of the proportional control stage is set to 0.1, and a maximum output limit value and a minimum output limit value of the amplitude limiting stage are set to 0.1 p.u. and −0.1 p.u. respectively.
- Claim: 6. The control method of claim 1 , wherein according to the control strategy, active power of a MMC unit for controlling active power is calculated, and a direct-current voltage instruction value correction stage is added in a constant direct-current voltage MMC unit, a direct-current is reasonably distributed in the MMC units connected in parallel.
- Patent References Cited: 8867241 October 2014 Asplund ; 9515565 December 2016 Gupta ; 9602021 March 2017 Chaudhuri ; 20140146582 May 2014 Gupta ; 20150145252 May 2015 Lin ; 20170331390 November 2017 Xu ; 20210165034 June 2021 Lu ; 3028231 June 2019 ; 103178539 June 2013 ; 105634257 June 2016 ; 107994597 May 2018 ; 108829989 November 2018 ; 109617112 April 2019 ; 110311400 October 2019
- Other References: X. Li et al., “Study on Main Circuit Configuration and Control Modes for a New LCC-MMC Hybrid HVDC System,” 2019 IEEE PES Asia-Pacific Power and Energy Engineering Conference (APPEEC), 2019, pp. 1-5, doi: 10.1109/APPEEC45492.2019.8994570. (Year: 2019). cited by examiner ; F. Xu et al., “Control of hybrid tripole HVDC based on LCC and F-MMC,” 2014 IEEE PES T&D Conference and Exposition, 2014, pp. 1-5, doi: 10.1109/TDC.2014.6863557. (Year: 2014). cited by examiner ; Chinese Office Action dated Nov. 16, 2021, Chinese Application No. 202011165213.1, international filing date Oct. 27, 2020. 10 pages. cited by applicant ; Xu Zheng et al., Inverter Station Connection Modes and Control Strategies of LCC-MMC Hybrid HVDC Systems, Electric Power Construction, Jul. 2018, vol. 39 No. 7, China Academic Journal Electronic Publishing House. cited by applicant
- Primary Examiner: Finch, III, Fred E
- Attorney, Agent or Firm: ArentFox Schiff LLP
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