CN113949089A - Electrochemical energy storage commutation system and method with harmonic suppression capability - Google Patents
Electrochemical energy storage commutation system and method with harmonic suppression capability Download PDFInfo
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- CN113949089A CN113949089A CN202111200074.6A CN202111200074A CN113949089A CN 113949089 A CN113949089 A CN 113949089A CN 202111200074 A CN202111200074 A CN 202111200074A CN 113949089 A CN113949089 A CN 113949089A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/28—Arrangements for balancing of the load in a network by storage of energy
- H02J3/32—Arrangements for balancing of the load in a network by storage of energy using batteries with converting means
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/01—Arrangements for reducing harmonics or ripples
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
- H02J3/48—Controlling the sharing of the in-phase component
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/40—Arrangements for reducing harmonics
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Abstract
The invention discloses an electrochemical energy storage commutation system with harmonic suppression capability and a method thereof, wherein the system comprises a 6kV auxiliary power unit, a commutation transformation unit and an electrochemical energy storage battery unit; the converter transformer unit and the electrochemical energy storage battery unit jointly form an electrochemical energy storage system, and power exchange is carried out between the electrochemical energy storage system and the 6kV auxiliary power unit, so that AGC frequency modulation of the thermal power unit is assisted; a harmonic compensation voltage link is added into a voltage control system of an MMC multi-circuit topology converter in the converter transformer unit, 5-order and 7-order higher harmonics are suppressed by adopting a harmonic injection method, and the quality of power supply of the electrochemical energy storage battery unit to the converter transformer unit is improved. The invention can improve the quality of the electric energy supplied by the storage battery to the station service.
Description
Technical Field
The invention relates to an electrochemical energy storage commutation system with harmonic suppression capability and a method thereof, wherein an MMC multi-circuit topology commutation device is adopted to realize power bidirectional flow, and a harmonic injection method is adopted in a control system of the MMC multi-circuit topology commutation device to suppress higher harmonics generated in a power transmission process and improve the quality of power supply and electric energy.
Background
Along with the increase of the grid-connected quantity of wind power and photovoltaic power, the rapid development of interconnected large power grids, large-capacity power generation and long-distance power transmission, the frequency modulation task of a power system is heavier. At present, the Chinese frequency modulation power supply mainly comprises a thermal power generating unit and a hydroelectric generating unit, and the working principle is that the active output of the units is adjusted and the frequency change of the system is tracked. However, the thermal power generating unit generally has the problems of long response time lag, low unit climbing speed and the like, the power grid dispatching instruction cannot be accurately tracked, the phenomena of adjusting time delay, adjusting deviation, adjusting reverse and the like are exposed, the thermal power generating unit frequently changes power to operate, fatigue and abrasion of unit equipment are aggravated to a certain extent, and the operation life of the unit is influenced.
The electrochemical energy storage battery as an energy storage component with high power density and energy density can participate in the response AGC frequency modulation of a thermal power plant, but the transformation of the energy storage battery is more complex, and the workload of the transformation of the original system is larger. The energy storage battery is connected to the side of the service Power through a bidirectional Power Conversion System (PCS). The IGBT adopted by the PCS device of the electrochemical energy storage battery is too high in manufacturing cost and easy to damage, and the application of the electrochemical energy storage battery in the field of AGC frequency modulation of a thermal power generating unit is influenced.
Disclosure of Invention
The invention aims to provide an electrochemical energy storage commutation system with harmonic suppression capability and a method thereof, and the system adopts an MMC multi-circuit topology commutation device to realize bidirectional power flow. A harmonic injection method is adopted in the MMC multi-circuit topology converter control system to inhibit higher harmonics generated in the inversion process of the MMC multi-circuit topology converter, and the quality of electric energy supplied by a storage battery to station power is improved.
In order to achieve the purpose, the invention adopts the following technical scheme to realize the purpose:
an electrochemical energy storage commutation system with harmonic suppression capability comprises a 6kV auxiliary power unit, a commutation transformation unit and an electrochemical energy storage battery unit;
the converter transformer unit and the electrochemical energy storage battery unit jointly form an electrochemical energy storage system, and power exchange is carried out between the electrochemical energy storage system and the 6kV auxiliary power unit, so that AGC frequency modulation of the thermal power unit is assisted; and a harmonic compensation voltage link is added into a voltage control system of the MMC multi-circuit topology converter device in the converter transformer unit, 5-order and 7-order higher harmonics are inhibited by adopting a harmonic injection method, and the quality of electric energy supplied by the electrochemical energy storage battery unit to the converter transformer unit is improved.
A further improvement of the invention is that the 6kV service unit comprises: the system comprises a 6kV factory split transformer, a 6kV factory A-section bus breaker, a 6kV factory B-section bus breaker, a 6kV factory A-section bus and a 6kV factory B-section bus;
6kV house-service split-winding transformer connects in the generator export, 6kV house-service A section generating line circuit breaker connect in 6kV house-service split-winding transformer low pressure side A section, through closed 6kV house-service A section generating line circuit breaker, 6kV house-service split-winding transformer to 6kV house-service A section generating line power supply, 6kV house-service B section generating line circuit breaker connect in 6kV house-service split-winding transformer low pressure side B section, through closed 6kV house-service B section generating line circuit breaker, 6kV house-service split-winding transformer to 6kV house-service B section generating line power supply.
A further improvement of the present invention is that the converter transformer unit comprises: the system comprises an A-section energy storage grid-connected switch, a B-section energy storage grid-connected switch, an A-section energy storage step-up transformer, a B-section energy storage step-up transformer, an A-section energy storage MMC multi-circuit topology converter and a B-section energy storage MMC multi-circuit topology converter;
a section energy storage grid-connected switch connect in 6kV mill is with A section generating line, A section energy storage step-up transformer connect in A section energy storage grid-connected switch, A section energy storage MMC multi-circuit topology conversion equipment connect in A section energy storage step-up transformer, B section energy storage grid-connected switch connect in 6kV mill is with B section generating line, B section energy storage step-up transformer connect in B section energy storage grid-connected switch, B section energy storage MMC multi-circuit topology conversion equipment connect in B section energy storage step-up transformer.
In a further development of the invention, the electrochemical energy storage cell comprises: the electrochemical energy storage battery comprises a section A and a section B;
the A-section electrochemical energy storage battery is connected to the A-section energy storage MMC multi-circuit topology converter, and electric energy transmission between the A-section electrochemical energy storage battery and the 6kV station A-section bus is realized by closing the A-section energy storage grid-connected switch; when the A-section electrochemical energy storage battery transmits electric energy to the A-section bus of the 6kV plant, the A-section energy storage MMC multi-circuit topology converter works in an inversion state at the moment, an AGC frequency modulation instruction of thermal power load rising is responded, and when the 6kV plant A-section bus transmits electric energy to the A-section electrochemical energy storage battery, the A-section energy storage MMC multi-circuit topology converter works in a rectification state at the moment, and an AGC frequency modulation instruction of thermal power load falling is responded;
the B-section electrochemical energy storage battery is connected with the B-section energy storage MMC multi-circuit topology converter, electric energy transmission between the B-section electrochemical energy storage battery and a 6kV station B-section bus is achieved by closing a B-section energy storage grid-connected switch, when the B-section electrochemical energy storage battery transmits electric energy to the 6kV station B-section bus, the B-section energy storage MMC multi-circuit topology converter works in an inversion state at the moment, responds to an AGC frequency modulation instruction of a thermal power load, when the 6kV station B-section bus transmits electric energy to the B-section electrochemical energy storage battery, and at the moment, the B-section energy storage MMC multi-circuit topology converter works in a rectification state and responds to the AGC frequency modulation instruction of the thermal power load reduction.
The invention has the further improvement that the A-section energy storage MMC multi-circuit topology converter and the B-section energy storage MMC multi-circuit topology converter comprise an upper bridge arm and a lower bridge arm, wherein the upper bridge arm and the lower bridge arm are respectively formed by connecting N sub-modules SM with the same structure in series with a filter reactor L, and the on-off of an upper thyristor and a lower thyristor in the SM are controlled to control the on-off of an SM capacitor, so that the A-section energy storage MMC multi-circuit topology converter and the B-section energy storage MMC multi-circuit topology converter work in a rectification or inversion state, and the AGC frequency modulation of an electrochemical energy storage response thermal power generating unit is realized.
An electrochemical energy storage commutation method with harmonic suppression capability, which is based on the electrochemical energy storage commutation system with harmonic suppression capability, includes:
a harmonic compensation voltage link is added into the voltage control system of the A-section energy storage MMC multi-circuit topology converter and the B-section energy storage MMC multi-circuit topology converter, and the method comprises the following steps:
1) under an abc three-phase static coordinate system, establishing an output voltage equation of alternating current sides of the A-section energy storage MMC multi-circuit topology converter and the B-section energy storage MMC multi-circuit topology converter;
2) obtaining 5-order and 7-order harmonic steady-state voltage equations in a dq coordinate system according to the A-section energy storage MMC multi-circuit topology converter and the B-section energy storage MMC multi-circuit topology converter output voltage equation obtained in the step 1);
3) under the dq synchronous rotating coordinate system, the fundamental wave is a direct current component, and 5 th harmonic and 7 th harmonic are alternating current components, and according to 5 th harmonic and 7 th harmonic steady-state voltage equations under the dq coordinate system obtained in the step 2), i is extracted through a 5-order low-pass filterd5、iq5、ed5、eq5Extract i by 7 low pass filtersd7、iq7、ed7、eq7And the signs are all inverted to obtain the injected harmonic voltage compensation component;
4) and introducing the voltage compensation components injected with the 5 th order harmonic and the 7 th order harmonic obtained in the step 3) into the voltage control system of the MMC multi-circuit topology converter device in the converter transformer unit 2 to play a role in inhibiting the 5 th order harmonic and the 7 th order harmonic.
In a further development of the invention, step 1): under an abc three-phase static coordinate system, establishing an output voltage equation of the A-section energy storage MMC multi-circuit topology converter 2-5 and the B-section energy storage MMC multi-circuit topology converter on the alternating current side:
wherein: u. ofa、ub、ucOutputting three-phase alternating-current voltage for the A-section energy storage MMC multi-circuit topology converter and the B-section energy storage MMC multi-circuit topology converter; omega is the electrical angular velocity; t represents a time; theta1、θ1、θ7The corresponding power factor angles for fundamental, 5 th harmonic, 7 th harmonic; u. of1、u5、u5The voltage amplitudes of fundamental wave, 5 th harmonic wave and 7 th harmonic wave.
In a further development of the invention, the step 2): obtaining a 5-order harmonic steady-state voltage equation under a dq coordinate system according to the A-section energy storage MMC multi-circuit topology converter and the B-section energy storage MMC multi-circuit topology converter output voltage equation obtained in the step 1):
wherein: u. ofd5、uq5The components of 5-th harmonic voltage on a d axis and a q axis respectively; i.e. id5、iq5Outputting components of 5-order harmonic current of three-phase current on a d axis and a q axis for the A-section energy storage MMC multi-circuit topology converter and the B-section energy storage MMC multi-circuit topology converter respectively; e.g. of the typed5、eq5The components of the voltage 5 times of the low-voltage side of the energy storage boosting transformer at the section A and the energy storage boosting transformer at the section B on the d axis and the q axis respectively; steady state voltage equation for the 7 th harmonic:
wherein: u. ofd7、uq7The components of the harmonic voltage of the 7 th order on the d axis and the q axis respectively; i.e. id7、iq7The A-section energy storage MMC multi-circuit topology converter and the B-section energy storage MMC multi-circuit topology converter output components of 7-order harmonic voltage of three-phase current on a d axis and a q axis respectively; e.g. of the typed7、eq7The components of the low-voltage side voltage 7 times of the A-section energy storage boosting transformer and the B-section energy storage boosting transformer on the d axis and the q axis respectively.
In a further development of the invention, step 3): under the dq synchronous rotating coordinate system, the fundamental wave is a direct current component, and 5 th harmonic and 7 th harmonic are alternating current components, and according to 5 th harmonic and 7 th harmonic steady-state voltage equations under the dq coordinate system obtained in the step 2), i is extracted through a 5-order low-pass filterd5、iq5、ed5、eq5Extract i by 7 low pass filtersd7、iq7、ed7、eq7And the signs are all inverted to obtain the injected harmonic voltage compensation component:
in a further development of the invention, the step 4): compensating the voltage compensation component of the injected 5 th and 7 th harmonic waves obtained in the step 3)
And the MMC multi-circuit topology converter device voltage control system introduced into the converter transformer unit 2 plays a role in inhibiting 5-order and 7-order higher harmonics.
Compared with the prior art, the invention has at least the following beneficial technical effects:
1. the invention can realize that the electrochemical energy storage battery assists the thermal power generating unit to participate in AGC frequency modulation, and improve AGC frequency modulation benefit of the thermal power plant.
2. The invention adopts the MMC multi-circuit topology converter, has good expansibility, can realize flexible control of active power and reactive power by power four-quadrant operation, can respond to the AGC frequency modulation instruction of load rise/fall of the thermal power generating unit in real time, can stabilize the direct-current bus voltage of the storage battery pack, and avoids the circulation phenomenon of the electrochemical energy storage battery caused by voltage unbalance.
3. According to the invention, a harmonic compensation voltage link is added in the voltage control system of the MMC multi-circuit topology converter device, and 5-order and 7-order higher harmonics are inhibited by adopting a harmonic injection method, so that the higher harmonics generated in the inversion process of the MMC multi-circuit topology converter device can be effectively inhibited, and the quality of electric energy supplied by the electrochemical energy storage battery to station power is improved.
Drawings
FIG. 1 is an electrochemical energy storage converter system of a thermal power plant.
Description of reference numerals:
1-6 kV service power unit; 2-a current conversion voltage transformation unit; 3-electrochemical energy storage cell; 1-6 kV house service split transformers; 1-2-6 kV factory A-section bus circuit breaker; 1-3-6 kV factory B-section bus circuit breaker; 1-4-6 kV factory A section bus; 1-5-6 kV factory B section bus; 2-1-A section of energy storage grid-connected switch; 2-B section energy storage grid-connected switch; 2-3-A section of energy storage boosting transformer; 2-4-B section energy storage boosting transformation; 2-5-A section energy storage MMC multi-circuit topology converter; 2-6-B section energy storage MMC multi-circuit topology converter; 3-1-A section electrochemical energy storage battery; 3-2-B segment electrochemical energy storage battery.
Detailed Description
Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict. The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.
As shown in fig. 1, the electrochemical energy storage converter system with harmonic suppression capability provided by the present invention includes a 6kV auxiliary power unit 1, a converter transformer unit 2 and an electrochemical energy storage battery unit 3; the converter transformer unit 2 and the electrochemical energy storage battery unit 3 jointly form an electrochemical energy storage system, and power exchange is carried out between the electrochemical energy storage system and the 6kV auxiliary power unit 1, so that AGC frequency modulation of the auxiliary thermal power unit is realized; and a harmonic compensation voltage link is added into a voltage control system of the MMC multi-circuit topology converter device in the converter transformer unit 2, 5-order and 7-order higher harmonics are inhibited by adopting a harmonic injection method, and the quality of electric energy supplied by the electrochemical energy storage battery unit 3 to the converter transformer unit 2 is improved.
The 6kV auxiliary power unit 1 comprises: 1-1 part of a 6kV factory split transformer, 1-2 parts of a 6kV factory A-section bus breaker, 1-3 parts of a 6kV factory B-section bus breaker, 1-4 parts of a 6kV factory A-section bus and 1-5 parts of a 6kV factory B-section bus; 6kV house-service split-winding transformer 1-1 connects in the generator export, 6kV house-service A section generating line circuit breaker 1-2 connect in 6kV house-service split-winding transformer 1-1 low pressure side A section, through closed 6kV house-service A section generating line circuit breaker 1-2, 6kV house-service split-winding transformer 1-1 to 6kV house-service A section generating line 1-4 supplies power, 6kV house-service B section generating line circuit breaker 1-3 connect in 6kV house-service split-winding transformer 1-1 low pressure side B section, through closed 6kV house-service B section generating line circuit breaker 1-3, 6kV house-service split-winding transformer 1-1 to 6kV house-service B section generating line 1-5 supplies power.
The converter transformer unit 2 includes: the system comprises an A-section energy storage grid-connected switch 2-1, a B-section energy storage grid-connected switch 2-2, an A-section energy storage step-up transformer 2-3, a B-section energy storage step-up transformer 2-4, an A-section energy storage MMC multi-circuit topology converter 2-5 and a B-section energy storage MMC multi-circuit topology converter 2-6; the A section energy storage grid-connected switch 2-1 is connected to a 6kV factory A section bus 1-4, the A section energy storage boost transformer 2-3 is connected to the A section energy storage grid-connected switch 2-1, the A section energy storage MMC multi-circuit topology converter 2-5 is connected to the A section energy storage boost transformer 2-3, the A section electrochemical energy storage battery 3-1 is connected to the A section energy storage MMC multi-circuit topology converter 2-5, and electric energy transmission between the A section electrochemical energy storage battery 3-1 and the 6kV factory A section bus 1-4 is achieved by closing the A section energy storage grid-connected switch 2-1. When the A-section electrochemical energy storage battery 3-1 transmits electric energy to the 6kV plant A-section bus 1-4, the A-section energy storage MMC multi-circuit topology converter 2-5 works in an inversion state at the moment, and responds to an AGC frequency modulation instruction of thermal power load rise. When the 6kV factory-used A-section bus 1-4 transmits electric energy to the A-section electrochemical energy storage battery 3-1, the A-section energy storage MMC multi-circuit topology converter 2-5 works in a rectification state and responds to an AGC frequency modulation instruction of thermal power load reduction.
The electrochemical energy storage cell 3 comprises: the section A of the electrochemical energy storage battery 3-1 and the section B of the electrochemical energy storage battery 3-2; the B-section energy storage grid-connected switch 2-2 is connected to a B-section bus 1-5 for the 6kV plant, the B-section energy storage boost transformer 2-4 is connected to the B-section energy storage grid-connected switch 2-2, the B-section energy storage MMC multi-circuit topology converter 2-6 is connected to the B-section energy storage boost transformer 2-4, the B-section electrochemical energy storage battery 3-2 is connected to the B-section energy storage MMC multi-circuit topology converter 2-6, and electric energy transmission between the B-section electrochemical energy storage battery 3-2 and the 6kV plant B-section bus 1-5 is realized by closing the B-section energy storage grid-connected switch 2-2. When the B-section electrochemical energy storage battery 3-2 transmits electric energy to the 6kV station B-section bus 1-5, the B-section energy storage MMC multi-circuit topology converter 2-6 works in an inversion state and responds to an AGC frequency modulation instruction of thermal power load rise. When the 6kV station B section bus 1-5 transmits electric energy to the B section electrochemical energy storage battery 3-2, the B section energy storage MMC multi-circuit topology converter 2-6 works in a rectification state and responds to an AGC frequency modulation instruction of thermal power load reduction.
The A-section energy storage MMC multi-circuit topology converter 2-5 and the B-section energy storage MMC multi-circuit topology converter 2-6 comprise upper and lower bridge arms, the upper and lower bridge arms are formed by connecting N sub-modules (SM) with the same structure in series with a filter reactor (L), and the SM capacitors are controlled to be switched in and out by controlling the on-off of an upper thyristor and a lower thyristor in the SM, so that the A-section energy storage MMC multi-circuit topology converter 2-5 and the B-section energy storage MMC multi-circuit topology converter 2-6 work in a rectification or inversion state, and the electrochemical energy storage response thermal power generating unit AGC frequency modulation is realized.
The invention adds a harmonic compensation voltage link in the voltage control system of the A-section energy storage MMC multi-circuit topology converter 2-5 and the B-section energy storage MMC multi-circuit topology converter 2-6, firstly, under an abc three-phase static coordinate system, an output voltage equation of the A-section energy storage MMC multi-circuit topology converter 2-5 and the B-section energy storage MMC multi-circuit topology converter 2-6 at the alternating current side is established:
in formula (1): u. ofa、ub、ucOutputting three-phase alternating-current voltage for the A-section energy storage MMC multi-circuit topology converter 2-5 and the B-section energy storage MMC multi-circuit topology converter 2-6; omega is the electrical angular velocity; t represents a time; theta1、θ1、θ7The corresponding power factor angles for fundamental, 5 th harmonic, 7 th harmonic; u. of1、u5、u5The voltage amplitudes of fundamental wave, 5 th harmonic wave and 7 th harmonic wave. The 5 th harmonic steady state voltage equation in dq coordinates can be written as:
in formula (2): u. ofd5、uq5The components of 5-th harmonic voltage on a d axis and a q axis respectively; i.e. id5、iq5Outputting components of 5-th harmonic current of three-phase current on a d axis and a q axis for the A-section energy storage MMC multi-circuit topology converter 2-5 and the B-section energy storage MMC multi-circuit topology converter 2-6 respectively; e.g. of the typed5、eq5The components of the voltage 5 times of the low-voltage side of the energy storage boosting transformer 2-3 of the section A and the energy storage boosting transformer 2-4 of the section B on the d axis and the q axis respectively.
The steady state voltage equation for the 7 th harmonic in dq coordinate system can be written as:
in formula (3): u. ofd7、uq7Respectively at 7 th harmonic voltageComponents on d-axis, q-axis; i.e. id7、iq7The components of 7-order harmonic voltages of three-phase currents output by the A-section energy storage MMC multi-circuit topology converter 2-5 and the B-section energy storage MMC multi-circuit topology converter 2-6 on a d axis and a q axis respectively; e.g. of the typed7、eq7The components of the low-voltage side voltage 7 times of the A-section energy storage boosting transformer 2-3 and the B-section energy storage boosting transformer 2-4 on the d axis and the q axis respectively.
In the dq synchronous rotation coordinate system, the fundamental wave is a direct current component, and the 5 th harmonic and the 7 th harmonic are alternating current components. Extract i by 5 low pass filtersd5、iq5、ed5、eq5And the signs are all inverted, and the injected harmonic voltage compensation component is obtained in the formula (2)
Comprises the following steps:
extract i by 7 low pass filtersd7、iq7、ed7、eq7. And the signs are all inverted, and the injected harmonic voltage compensation component is obtained in the formula (3)
Comprises the following steps:
the harmonic injection method is adopted to inhibit 5-order and 7-order higher harmonics, so that the higher harmonics generated in the inversion process of the A-section energy storage MMC multi-circuit topology converter 2-5 and the B-section energy storage MMC multi-circuit topology converter 2-6 can be effectively inhibited, and the quality of the electric energy supplied by the electrochemical energy storage battery to the station power is improved.
Although the invention has been described in detail hereinabove with respect to a general description and specific embodiments thereof, it will be apparent to those skilled in the art that modifications or improvements may be made thereto based on the invention. Accordingly, such modifications and improvements are intended to be within the scope of the invention as claimed.
Claims (10)
1. An electrochemical energy storage commutation system with harmonic suppression capability is characterized by comprising a 6kV auxiliary power unit (1), a commutation transformation unit (2) and an electrochemical energy storage battery unit (3);
the converter transformer unit (2) and the electrochemical energy storage battery unit (3) jointly form an electrochemical energy storage system, and power exchange is carried out between the electrochemical energy storage system and the 6kV auxiliary power unit (1) so as to assist the thermal power unit to carry out AGC frequency modulation; a harmonic compensation voltage link is added into a voltage control system of the MMC multi-circuit topology converter device in the converter transformer unit (2), 5-order and 7-order higher harmonics are suppressed by adopting a harmonic injection method, and the quality of power supply energy of the electrochemical energy storage battery unit (3) to the converter transformer unit (2) is improved.
2. An electrochemical energy storage converter system with harmonic suppression capability according to claim 1, characterized in that the 6kV service unit (1) comprises: the system comprises a 6kV factory split transformer (1-1), a 6kV factory A-section bus breaker (1-2), a 6kV factory B-section bus breaker (1-3), a 6kV factory A-section bus (1-4) and a 6kV factory B-section bus (1-5);
6kV house-service split-winding transformer (1-1) is connected in the generator export, 6kV house-service A section generating line circuit breaker (1-2) connect in 6kV house-service split-winding transformer (1-1) low pressure side A section, through closed 6kV house-service A section generating line circuit breaker (1-2), 6kV house-service split-winding transformer (1-1) to 6kV house-service A section generating line (1-4) power supply, 6kV house-service B section generating line circuit breaker (1-3) connect in 6kV house-service split-winding transformer (1-1) low pressure side B section, through closed 6kV house-service B section generating line circuit breaker (1-3), 6kV house-service split-winding transformer (1-1) to 6kV house-service B section generating line (1-5) power supply.
3. An electrochemical energy storage converter system with harmonic suppression capability according to claim 2, characterized in that the converter transformer unit (2) comprises: the power supply comprises an A-section energy storage grid-connected switch (2-1), a B-section energy storage grid-connected switch (2-2), an A-section energy storage step-up transformer (2-3), a B-section energy storage step-up transformer (2-4), an A-section energy storage MMC multi-circuit topology converter (2-5) and a B-section energy storage MMC multi-circuit topology converter (2-6);
a section energy storage grid-connected switch (2-1) connect in 6kV mill is with A section generating line (1-4), A section energy storage step-up change (2-3) connect in A section energy storage grid-connected switch (2-1), A section energy storage MMC multi-circuit topology converter (2-5) connect in A section energy storage step-up change (2-3), B section energy storage grid-connected switch (2-2) connect in 6kV mill is with B section generating line (1-5), B section energy storage step-up change (2-4) connect in B section energy storage grid-connected switch (2-2), B section MMC energy storage multi-circuit topology converter (2-6) connect in B section energy storage step-up change (2-4).
4. An electrochemical energy storage converter system with harmonic suppression capability according to claim 3, characterized in that the electrochemical energy storage cell (3) comprises: the A section of electrochemical energy storage battery (3-1) and the B section of electrochemical energy storage battery (3-2);
the A-section electrochemical energy storage battery (3-1) is connected to the A-section energy storage MMC multi-circuit topology converter device (2-5), and electric energy transmission between the A-section electrochemical energy storage battery (3-1) and the 6kV factory A-section bus (1-4) is realized by closing the A-section energy storage grid-connected switch (2-1); when the A-section electrochemical energy storage battery (3-1) transmits electric energy to the 6kV plant A-section bus (1-4), the A-section energy storage MMC multi-circuit topological converter device (2-5) works in an inversion state at the moment, an AGC frequency modulation instruction of a thermal power load rise is responded, when the 6kV plant A-section bus (1-4) transmits electric energy to the A-section electrochemical energy storage battery (3-1), the A-section energy storage MMC multi-circuit topological converter device (2-5) works in a rectification state at the moment, and an AGC frequency modulation instruction of a thermal power load drop is responded;
the B-section electrochemical energy storage battery (3-2) is connected with the B-section energy storage MMC multi-circuit topology converter device (2-6), electric energy transmission between the B-section electrochemical energy storage battery (3-2) and the 6kV plant B-section bus (1-5) is realized by closing the B-section energy storage grid-connected switch (2-2), when the B-section electrochemical energy storage battery (3-2) transmits electric energy to the 6kV plant B-section bus (1-5), the B-section energy storage MMC multi-circuit topology converter device (2-6) works in an inversion state, a frequency modulation AGC instruction of thermal power load rise is responded, when the 6kV plant B-section bus (1-5) transmits electric energy to the B-section electrochemical energy storage battery (3-2), the B-section energy storage MMC multi-circuit topology converter device (2-6) works in a rectification state, responding to an AGC frequency modulation instruction of the thermal power load reduction.
5. The electrochemical energy storage converter system with harmonic suppression capability according to claim 4, wherein the A-section energy storage MMC multi-circuit topology converter device (2-5) and the B-section energy storage MMC multi-circuit topology converter device (2-6) comprise an upper bridge arm and a lower bridge arm, the upper bridge arm and the lower bridge arm are formed by connecting N sub-modules SM with the same structure in series and a filter reactor L, and the SM capacitors are controlled to be switched in and out by controlling the on-off of an upper thyristor and a lower thyristor in the SM, so that the A-section energy storage MMC multi-circuit topology converter device (2-5) and the B-section MMC energy storage multi-circuit topology converter device (2-6) work in a rectification or inversion state, and the frequency modulation of the electrochemical energy storage response thermal power generating unit AGC is realized.
6. An electrochemical energy storage commutation method with harmonic suppression capability, which is based on the electrochemical energy storage commutation system with harmonic suppression capability of claim 5, and comprises:
a harmonic compensation voltage link is added into the voltage control system of the A-section energy storage MMC multi-circuit topology converter device (2-5) and the B-section energy storage MMC multi-circuit topology converter device (2-6), and the method comprises the following steps:
1) under an abc three-phase static coordinate system, establishing an output voltage equation of the alternating current side of the A-section energy storage MMC multi-circuit topology converter device (2-5) and the B-section energy storage MMC multi-circuit topology converter device (2-6);
2) obtaining 5-order and 7-order harmonic steady-state voltage equations under a dq coordinate system according to the A-section energy storage MMC multi-circuit topology converter device (2-5) and the B-section energy storage MMC multi-circuit topology converter device (2-6) alternating-current side output voltage equation obtained in the step 1);
3) under the dq synchronous rotating coordinate system, the fundamental wave is a direct current component, and 5 th harmonic and 7 th harmonic are alternating current components, and according to 5 th harmonic and 7 th harmonic steady-state voltage equations under the dq coordinate system obtained in the step 2), i is extracted through a 5-order low-pass filterd5、iq5、ed5、eq5Extract i by 7 low pass filtersd7、iq7、ed7、eq7And the signs are all inverted to obtain the injected harmonic voltage compensation component;
4) and introducing the voltage compensation components injected with the 5 th order harmonic and the 7 th order harmonic obtained in the step 3) into the voltage control system of the MMC multi-circuit topology converter device in the converter transformer unit 2 to play a role in inhibiting the 5 th order harmonic and the 7 th order harmonic.
7. The method for converting electrochemical energy storage with harmonic suppression capability according to claim 6, wherein the step 1): under an abc three-phase static coordinate system, establishing an output voltage equation of the alternating current side of the A-section energy storage MMC multi-circuit topology converter 2-5 and the B-section energy storage MMC multi-circuit topology converter (2-6):
wherein: u. ofa、ub、ucOutputting three-phase alternating-current voltage for the A-section energy storage MMC multi-circuit topology converter device (2-5) and the B-section energy storage MMC multi-circuit topology converter device (2-6); omega is the electrical angular velocity; t represents a time; theta1、θ1、θ7The corresponding power factor angles for fundamental, 5 th harmonic, 7 th harmonic; u. of1、u5、u5The voltage amplitudes of fundamental wave, 5 th harmonic wave and 7 th harmonic wave.
8. The method for converting electrochemical energy storage with harmonic suppression capability according to claim 7, wherein the step 2): obtaining the A-section energy storage MMC multi-circuit topology obtained in the step 1)The converter (2-5) and the B-section energy storage MMC multi-circuit topology converter (2-6) output voltage equation at the alternating current side are used for obtaining a 5-order harmonic steady-state voltage equation under a dq coordinate system:
wherein: u. ofd5、uq5The components of 5-th harmonic voltage on a d axis and a q axis respectively; i.e. id5、iq5The components of 5-th harmonic current of three-phase current on a d axis and a q axis are output by the A-section energy storage MMC multi-circuit topology converter device (2-5) and the B-section energy storage MMC multi-circuit topology converter device (2-6) respectively; e.g. of the typed5、eq5The components of the voltage 5 times of the low-voltage side of the energy storage boosting transformer (2-3) at the section A and the energy storage boosting transformer (2-4) at the section B on the d axis and the q axis respectively; steady state voltage equation for the 7 th harmonic:
wherein: u. ofd7、uq7The components of the harmonic voltage of the 7 th order on the d axis and the q axis respectively; i.e. id7、iq7The components of 7-order harmonic voltages of three-phase currents output by the A-section energy storage MMC multi-circuit topology converter device (2-5) and the B-section energy storage MMC multi-circuit topology converter device (2-6) on a d axis and a q axis respectively; e.g. of the typed7、eq7The components of the low-voltage side voltage 7 times of the A-section energy storage boosting transformer (2-3) and the B-section energy storage boosting transformer (2-4) on the d axis and the q axis respectively.
9. The method for converting electrochemical energy storage with harmonic suppression capability according to claim 8, wherein the step 3): under the dq synchronous rotating coordinate system, the fundamental wave is a direct current component, and 5 th harmonic and 7 th harmonic are alternating current components, and according to 5 th harmonic and 7 th harmonic steady-state voltage equations under the dq coordinate system obtained in the step 2), i is extracted through a 5-order low-pass filterd5、iq5、ed5、eq5Extract i by 7 low pass filtersd7、iq7、ed7、eq7And the signs are all inverted to obtain the injected harmonic voltage compensation component:
10. the method for converting electrochemical energy storage with harmonic suppression capability according to claim 9, wherein the step 4): compensating the voltage compensation component of the injected 5 th and 7 th harmonic waves obtained in the step 3)
And the MMC multi-circuit topology converter device voltage control system introduced into the converter transformer unit 2 plays a role in inhibiting 5-order and 7-order higher harmonics.
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