CN113949053A - Direct-current micro-grid system of pumping unit well group and cooperative control method thereof - Google Patents

Direct-current micro-grid system of pumping unit well group and cooperative control method thereof Download PDF

Info

Publication number
CN113949053A
CN113949053A CN202010694382.8A CN202010694382A CN113949053A CN 113949053 A CN113949053 A CN 113949053A CN 202010694382 A CN202010694382 A CN 202010694382A CN 113949053 A CN113949053 A CN 113949053A
Authority
CN
China
Prior art keywords
converter
direct
power generation
generation unit
current
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN202010694382.8A
Other languages
Chinese (zh)
Inventor
孙东
齐光峰
周亮
张强
范路
李炜
董伟佳
郑炜博
王晓东
林强
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
China Petroleum and Chemical Corp
Technology Inspection Center of Sinopec Shengli Oilfield Co
Shengli Oilfield Testing and Evaluation Research Co Ltd
Original Assignee
China Petroleum and Chemical Corp
Technology Inspection Center of Sinopec Shengli Oilfield Co
Shengli Oilfield Testing and Evaluation Research Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by China Petroleum and Chemical Corp, Technology Inspection Center of Sinopec Shengli Oilfield Co, Shengli Oilfield Testing and Evaluation Research Co Ltd filed Critical China Petroleum and Chemical Corp
Priority to CN202010694382.8A priority Critical patent/CN113949053A/en
Publication of CN113949053A publication Critical patent/CN113949053A/en
Pending legal-status Critical Current

Links

Images

Classifications

    • 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
    • H02J1/00—Circuit arrangements for dc mains or dc distribution networks
    • 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
    • H02J1/00—Circuit arrangements for dc mains or dc distribution networks
    • H02J1/10—Parallel operation of dc sources
    • 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
    • H02J1/00—Circuit arrangements for dc mains or dc distribution networks
    • H02J1/10—Parallel operation of dc sources
    • H02J1/106—Parallel operation of dc sources for load balancing, symmetrisation, or sharing
    • 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
    • H02J1/00—Circuit arrangements for dc mains or dc distribution networks
    • H02J1/14—Balancing the load in a network
    • 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
    • H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
    • H02J2300/20—The dispersed energy generation being of renewable origin
    • H02J2300/22—The renewable source being solar energy
    • H02J2300/24—The renewable source being solar energy of photovoltaic origin
    • 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
    • H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
    • H02J2300/20—The dispersed energy generation being of renewable origin
    • H02J2300/28—The renewable source being wind energy
    • 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
    • H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
    • H02J2300/40—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation wherein a plurality of decentralised, dispersed or local energy generation technologies are operated simultaneously
    • 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
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy
    • Y02E10/56—Power conversion systems, e.g. maximum power point trackers

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Supply And Distribution Of Alternating Current (AREA)
  • Control Of Eletrric Generators (AREA)

Abstract

The invention provides a direct-current micro-grid system of a pumping unit well group and a cooperative control method thereof, belonging to the technical field of direct-current micro-grid systems. The technical scheme is as follows: the high-voltage side of the step-down transformer is connected with a three-phase power grid, the low-voltage side of the step-down transformer is connected to the alternating current input end of the first AC/DC converter, the direct current output end of the first AC/DC converter serves as a common direct current bus, the output end of the photovoltaic cell panel is connected to the low-voltage input end of the unidirectional DC/DC converter, the high-voltage output end of the unidirectional DC/DC converter is connected to the common direct current bus in parallel, the stator outlet end of the permanent magnet wind generating set is connected to the alternating current input end of the second AC/DC converter, the direct current output end of the second AC/DC converter is connected to the common direct current bus in parallel, and the pumping unit and the third DC/AC converter are connected to the common direct current bus in parallel respectively. The invention has the beneficial effects that: the voltage fluctuation of the direct current bus can be effectively reduced, and the stability of a power supply system is improved.

Description

Direct-current micro-grid system of pumping unit well group and cooperative control method thereof
Technical Field
The invention relates to a direct-current micro-grid system, in particular to a direct-current micro-grid system of a pumping unit well group and a cooperative control method thereof.
Background
The oil fields in China are mostly low-permeability low-energy and low-yield oil fields, the power consumption is large compared with that of a self-blowing oil well, and the existing network system for supplying power to the oil pumping unit in the oil field mainly depends on a national power grid or a distributed power generation unit or network power supply extracted and adjusted from the national power grid, so that the problems of long-distance power transmission consumption and poor stability exist.
In recent years, distributed renewable energy represented by wind power and photovoltaic power generation is popularized and applied in a large quantity in order to solve the structural contradiction and environmental pollution problems of traditional energy and achieve energy conservation and consumption reduction of oil fields and green coordinated sustainable development. However, as distributed renewable energy sources such as wind energy and solar energy continuously permeate into the power grid, the distributed renewable energy sources have the characteristics of obvious randomness, intermittency, dispersity and the like, and have adverse effects on the aspects of stable operation, safety control, electric energy quality and the like of a power system.
The direct-current micro-grid system is an electric network topology which can maximally accept distributed power supplies, improve power supply reliability and improve emergency power supply capacity of a power grid. The direct-current micro-grid is used as an autonomous operation system, and the tide in the system can be actively regulated by using a flexible control technology of power electronic equipment, such as an improved control method of distributed energy storage equipment and the coordination control of a plurality of energy storage power supplies, so that the stability of a power distribution system is enhanced, and the efficiency of the power distribution system is improved. Therefore, the application of the direct-current micro-grid system can promote effective consumption of various renewable energy sources in an oil extraction area, improve the power supply reliability of an oil well, and realize wind-solar complementary, efficient, energy-saving, safe and reliable direct-current micro-grid power supply system.
At present, the stability and the power balance of a direct-current micro-grid system are mainly controlled by an energy storage battery and a super capacitor, the investment cost of installation engineering is high, and the difficulty of later maintenance is high. Meanwhile, the control method of the direct current micro-grid system is mainly a centralized control method. The centralized control method needs to set a microgrid central controller to send a control instruction to a controlled unit after complex calculation processing, so as to realize the control target of the system. This control requires a complex and costly communication network.
Disclosure of Invention
The invention aims to provide a dynamic power balance control method of a direct-current micro-grid, aiming at the defects of the existing topological structure and control method of a direct-current micro-grid system of a pumping unit well group and the adverse effects of intermittent new energy output characteristics and pumping unit load fluctuation characteristics on the stability of a three-phase power grid, so that the voltage fluctuation of a direct-current bus is effectively reduced, and the stability of a power supply system is improved.
The invention is realized by the following measures: a direct-current micro-grid system of a pumping unit well group is characterized by comprising a step-down transformer, a photovoltaic power generation unit, a wind power generation unit and a pumping unit load, wherein the photovoltaic power generation unit comprises a photovoltaic cell panel and a unidirectional DC/DC converter, the wind power generation unit comprises a permanent magnet wind power generation unit and an AC/DC converter II, and the pumping unit load comprises a pumping unit and a DC/AC converter III;
the high-voltage side of the step-down transformer is connected with a three-phase power grid, the low-voltage side of the step-down transformer is connected to the alternating current input end of the first AC/DC converter, the direct current output end of the first AC/DC converter serves as a common direct current bus, the output end of the photovoltaic cell panel is connected to the low-voltage input end of the unidirectional DC/DC converter, the high-voltage output end of the unidirectional DC/DC converter is connected to the common direct current bus in parallel, the stator outlet end of the permanent magnet wind generating set is connected to the alternating current input end of the second AC/DC converter, the direct current output end of the second AC/DC converter is connected to the common direct current bus in parallel, and the oil pumping unit and the third DC/AC converter are connected to the common direct current bus in parallel respectively;
the direct current unloading circuit further comprises a direct current unloading resistor and a direct current voltage-stabilizing capacitor which are respectively connected to the common direct current bus in parallel, and the direct current unloading resistor is controlled by a controllable switch.
And a reactor is connected in series between the step-down transformer and the first AC/DC converter.
The cooperative control method of the direct-current micro-grid system of the pumping unit well group specifically comprises a rectification energy consumption mode, an inversion derating mode and an island droop mode;
in the rectification energy consumption mode, the first AC/DC converter works in a rectification state, the voltage of the public direct current bus is maintained to be stable, the general voltage is stabilized at 750V, and the photovoltaic power generation unit and the fan power generation unit are controlled to work in a maximum power tracking state;
in the inversion derating mode, the AC/DC converter works in an inversion feedback state to control the photovoltaic power generation unit and the fan power generation unit to reduce power to operate;
and in the island droop mode, the AC/DC converter is locked to control the photovoltaic power generation unit and the fan power generation unit to output power according to a droop control coefficient.
And under the inversion derating mode, the power instructions P of the photovoltaic power generation unit and the fan power generation unitPV、PwindRespectively setting as follows:
Figure BDA0002590265470000021
Figure BDA0002590265470000022
in the formula: pGSC_RT、PloadRespectively representing rated power of the AC/DC converter I and power of the pumping unit load; k is PPV/PwindThe power sharing coefficient is shown, and k is more than or equal to 0 and less than or equal to 10.
In the island droop mode, when the power of the load of the oil pumping unit is larger than zero, namely PloadWhen the power is more than 0, the power instruction P of the photovoltaic power generation unit and the power instruction P of the fan power generation unitPV、PwindRespectively setting as follows:
PPV＝α1Pload+ΔPdc1 (1)
Pwind＝α2Pload+ΔPdc2 (2)
in the formula: alpha is alpha1、α2Droop control coefficients of the photovoltaic power generation unit and the fan power generation unit respectively, and has alpha1＝k/(1+k)，α2＝1/(1+k)；ΔPdc1、ΔPdc1Compensation power respectively output by the photovoltaic power generation unit and the fan power generation unit participating in bus voltage regulation and having delta Pdc1≥0，ΔPdc2≥0；
When the power of the load of the oil pumping unit is less than or equal to zero, namely PloadAnd when the current is less than or equal to 0, locking trigger pulses of converters of the photovoltaic power generation unit and the fan power generation unit, and absorbing the power fed into the common direct current bus by the load of the oil pumping unit through the direct current unloading resistor.
When the secondary side voltage value of the step-down transformer is normal (general line)The effective value of the voltage is not lower than 340V), and the load power of the oil pumping unit is greater than zero (namely P)loadMore than 0), the direct current micro-grid system of the pumping well group operates in the rectification energy consumption mode;
when the voltage value of the secondary side of the step-down transformer is normal (the effective value of the common line voltage is not lower than 340V) and the load power of the pumping unit is less than or equal to zero (namely P)loadLess than or equal to 0), and the direct-current microgrid system of the pumping well group is switched to the inversion derating mode;
when the voltage value of the secondary side of the step-down transformer is abnormal (the effective value of the general line voltage is lower than 340V), the direct-current micro-grid system of the pumping unit well group is switched to an island droop mode.
The method for controlling the AC/DC converter I in each mode comprises the following specific steps: firstly, the line voltage U of the three-phase power grid isgabcPhase current IgabcPerforming synchronous coordinate transformation to obtain d-axis and q-axis components U under a synchronous rotating coordinate systemgdq、Igdq(ii) a Then adding IgdqAnd a current reference value
Figure BDA0002590265470000031
Difference value Δ I ofgdqSending into Proportional Integral Resonance (PIR) controller, adding feed forward compensation term to obtain control vector V under synchronous rotation coordinate systemgdq(ii) a Will control vector VgdqPerforming inverse synchronous coordinate transformation to obtain a control vector V under a two-phase static coordinate systemgαβWill VgαβAnd sending the signal into a space vector modulation module to obtain a pulse signal of the AC/DC converter I. The method specifically comprises the following steps: measuring three-phase network side line voltage U by the prior artgabcPhase current I of three-phase network sidegabc(ii) a The measured three-phase network side line voltage U is measuredgabcPhase current I of three-phase network sidegabcPerforming stationary coordinate transformation to obtain alpha and beta axis components U in a stationary coordinate systemgαβ、IgαβThe coordinate transformation expression is (voltage and current expressions are identical):
Figure BDA0002590265470000032
will UgαβObtaining fundamental wave power grid angular frequency omega and a power grid angular signal theta through a phase-locked loop module;
will UgabcAnd IgabcPerforming synchronous coordinate transformation according to the power grid angle signal theta to obtain d-axis and q-axis components U under a synchronous rotating coordinate systemgdq、Igdq(ii) a The coordinate transformation expression is:
Figure BDA0002590265470000041
will IgdqAnd a current reference value
Figure BDA0002590265470000042
Difference value Δ I ofgdqSending into Proportional Integral Resonance (PIR) controller, adding feed forward compensation term to obtain control vector V under synchronous rotation coordinate systemgdq(ii) a The feedforward compensation term is calculated as follows:
Figure BDA0002590265470000043
wherein a transfer function of a proportional-integral-resonance (PIR) controller is:
Figure BDA0002590265470000044
in the formula: kp and Ki are respectively proportional and integral coefficients of the PI controller; kr0 is the resonance coefficient of a 2-frequency doubling resonator; ω c0 is the cutoff frequency of the 2-fold frequency resonator.
Will control vector VgdqPerforming inverse synchronous coordinate transformation to obtain a control vector V under a two-phase static coordinate systemgαβWill VgαβAnd sending the signal into a space vector modulation module to obtain a pulse signal for controlling the network side converter.
Compared with the prior art, the invention has the beneficial effects that: an energy storage battery unit and a super capacitor unit are not required to be installed in the direct-current micro-grid system of the pumping well group, the stability of a direct-current bus and the balance of source load power are adjusted by a control system of a photovoltaic and fan power generation unit, the engineering investment cost is obviously reduced, and the later maintenance difficulty is small; the cooperative control method of the direct-current micro-grid system of the pumping unit well group can work normally in the load-reversed power generation or island operation state of the pumping unit, and can quickly and stably realize the grid-off switching process, so that the load of the pumping unit is not influenced; the switching of the control method is judged by each unit control system, the dynamic power balance of the direct-current micro-grid can be realized without arranging a central controller and a communication module for real-time communication and unified control, the system operation reliability is high, and the investment cost is effectively reduced.
Drawings
Fig. 1 is a topological structure diagram of the present invention.
FIG. 2 is a control flow chart of the present invention.
Fig. 3 is a simulation result diagram of the pumping unit well group direct current micro grid under the grid-connected operation condition when the traditional control mode is adopted.
Fig. 4 is a simulation result diagram of the pumping well group direct current microgrid under the grid-connected operation condition when the control method of the invention is adopted.
FIG. 5 is a simulation result diagram of the switching of parallel operation and off-grid operation of the pumping well group direct current micro-grid using the control method of the present invention.
Fig. 6 is a simulation result diagram of the pumping well group dc microgrid operating in an island droop mode.
Fig. 7 is a control block diagram of a grid-side fully-controlled rectifier of the direct-current micro-grid system of the pumping well group.
Wherein the reference numerals are: 1. a step-down transformer; 2. an AC/DC converter I; 3. a photovoltaic cell panel; 4. a unidirectional DC/DC converter; 5. a permanent magnet wind generating set; 6. an AC/DC converter II; 7. a direct current unloading resistor; 8. a third DC/AC converter; 9. a pumping unit; 10. a reactor; 11. a common DC bus; 12. and (4) loading the oil pumping unit.
Detailed Description
In order to clearly illustrate the technical features of the present solution, the present solution is explained below by way of specific embodiments.
The first embodiment is as follows:
referring to fig. 1, a direct-current microgrid system of a pumping unit well group comprises a step-down transformer 1, a photovoltaic power generation unit, a wind power generation unit and a pumping unit load 12, wherein the photovoltaic power generation unit comprises a photovoltaic cell panel 3 and a unidirectional DC/DC converter 4, the wind power generation unit comprises a permanent magnet wind power generation unit 5 and an AC/DC converter two 6, and the pumping unit load 12 comprises a pumping unit 9 and a DC/AC converter three 8;
the high-voltage side of the step-down transformer 1 is connected with a three-phase power grid, the low-voltage side of the step-down transformer 1 is connected to an alternating current input end of an AC/DC converter I2, a direct current output end of the AC/DC converter I2 serves as a common direct current bus 11, an output end of the photovoltaic cell panel 3 is connected to a low-voltage input end of a unidirectional DC/DC converter 4, a high-voltage output end of the unidirectional DC/DC converter 4 is connected to the common direct current bus 11 in parallel, a stator outlet end of the permanent magnet wind generating set 5 is connected to an alternating current input end of an AC/DC converter II 6, a direct current output end of the AC/DC converter II 6 is connected to the common direct current bus 11 in parallel, and the oil pumping unit 9 and the DC/AC converter III 8 are respectively connected to the common direct current bus 11 in parallel;
the direct-current unloading circuit further comprises a direct-current unloading resistor 7 and a direct-current voltage-stabilizing capacitor which are respectively connected to the common direct-current bus 11 in parallel, and the direct-current unloading resistor 7 is controlled by a controllable switch.
A reactor 10 is connected in series between the step-down transformer 1 and the first AC/DC converter 2.
Example two:
referring to fig. 1, 2 and 7, the direct-current microgrid system of the pumping unit well group comprises a step-down transformer 1, a photovoltaic power generation unit, a wind power generation unit and a pumping unit load 12, wherein the photovoltaic power generation unit comprises a photovoltaic cell panel 3 and a unidirectional DC/DC converter 4, the wind power generation unit comprises a permanent magnet wind power generator set 5 and an AC/DC converter two 6, and the pumping unit load 12 comprises a pumping unit 9 and a DC/AC converter three 8;
the high-voltage side of the step-down transformer 1 is connected with a three-phase power grid, the low-voltage side of the step-down transformer 1 is connected to an alternating current input end of an AC/DC converter I2, a direct current output end of the AC/DC converter I2 serves as a common direct current bus 11, an output end of the photovoltaic cell panel 3 is connected to a low-voltage input end of a unidirectional DC/DC converter 4, a high-voltage output end of the unidirectional DC/DC converter 4 is connected to the common direct current bus 11 in parallel, a stator outlet end of the permanent magnet wind generating set 5 is connected to an alternating current input end of an AC/DC converter II 6, a direct current output end of the AC/DC converter II 6 is connected to the common direct current bus 11 in parallel, and the oil pumping unit 9 and the DC/AC converter III 8 are respectively connected to the common direct current bus 11 in parallel;
the direct-current unloading circuit further comprises a direct-current unloading resistor 7 and a direct-current voltage-stabilizing capacitor which are respectively connected to the common direct-current bus 11 in parallel, and the direct-current unloading resistor 7 is controlled by a controllable switch.
A reactor 10 is connected in series between the step-down transformer 1 and the first AC/DC converter 2.
The cooperative control method of the direct-current micro-grid system of the pumping unit well group specifically comprises a rectification energy consumption mode, an inversion derating mode and an island droop mode;
in the rectification energy consumption mode, the first AC/DC converter works in a rectification state, the voltage of the public direct current bus is maintained to be stable, the general voltage is stabilized at 750V, and the photovoltaic power generation unit and the fan power generation unit are controlled to work in a maximum power tracking state;
in the inversion derating mode, the AC/DC converter works in an inversion feedback state to control the photovoltaic power generation unit and the fan power generation unit to reduce power to operate;
and in the island droop mode, the AC/DC converter is locked to control the photovoltaic power generation unit and the fan power generation unit to output power according to a droop control coefficient.
And under the inversion derating mode, the power instructions P of the photovoltaic power generation unit and the fan power generation unitPV、PwindRespectively setting as follows:
Figure BDA0002590265470000061
Figure BDA0002590265470000062
in the formula: pGSC_RT、PloadRespectively representing rated power of the AC/DC converter I and power of the pumping unit load; k is PPV/PwindThe power sharing coefficient is shown, and k is more than or equal to 0 and less than or equal to 10.
In the island droop mode, when the power of the load of the oil pumping unit is larger than zero, namely PloadWhen the power is more than 0, the power instruction P of the photovoltaic power generation unit and the power instruction P of the fan power generation unitPV、PwindRespectively setting as follows:
PPV＝α1Pload+ΔPdc1 (1)
Pwind＝α2Pload+ΔPdc2 (2)
in the formula: alpha is alpha1、α2Droop control coefficients of the photovoltaic power generation unit and the fan power generation unit respectively, and has alpha1＝k/(1+k)，α2＝1/(1+k)；ΔPdc1、ΔPdc1Compensation power respectively output by the photovoltaic power generation unit and the fan power generation unit participating in bus voltage regulation and having delta Pdc1≥0，ΔPdc2≥0；
When the power of the load of the oil pumping unit is less than or equal to zero, namely PloadAnd when the current is less than or equal to 0, locking trigger pulses of converters of the photovoltaic power generation unit and the fan power generation unit, and absorbing the power fed into the common direct current bus by the load of the oil pumping unit through the direct current unloading resistor.
When the voltage value of the secondary side of the step-down transformer is normal (the effective value of the common line voltage is not lower than 340V) and the load power of the pumping unit is more than zero (namely P)loadMore than 0), the direct current micro-grid system of the pumping well group operates in the rectification energy consumption mode;
when the voltage value of the secondary side of the step-down transformer is normal (the effective value of the common line voltage is not lower than 340V) and the load power of the pumping unit is less than or equal to zero (namely P)loadLess than or equal to 0), and the direct-current microgrid system of the pumping well group is switched to the inversion derating mode;
when the voltage value of the secondary side of the step-down transformer is abnormal (the effective value of the general line voltage is lower than 340V), the direct-current micro-grid system of the pumping unit well group is switched to an island droop mode.
The method for controlling the AC/DC converter I in each mode comprises the following specific steps: firstly, the line voltage U of the three-phase power grid isgabcPhase current IgabcPerforming synchronous coordinate transformation to obtain d-axis and q-axis components U under a synchronous rotating coordinate systemgdq、Igdq(ii) a Then adding IgdqAnd a current reference value
Figure BDA0002590265470000071
Difference value Δ I ofgdqSending into Proportional Integral Resonance (PIR) controller, adding feed forward compensation term to obtain control vector V under synchronous rotation coordinate systemgdq(ii) a Will control vector VgdqPerforming inverse synchronous coordinate transformation to obtain a control vector V under a two-phase static coordinate systemgαβWill VgαβAnd sending the signal into a space vector modulation module to obtain a pulse signal of the AC/DC converter I. The method specifically comprises the following steps: measuring three-phase network side line voltage U by the prior artgabcPhase current I of three-phase network sidegabc(ii) a The measured three-phase network side line voltage U is measuredgabcPhase current I of three-phase network sidegabcPerforming stationary coordinate transformation to obtain alpha and beta axis components U in a stationary coordinate systemgαβ、IgαβThe coordinate transformation expression is (voltage and current expressions are identical):
Figure BDA0002590265470000072
will UgαβObtaining fundamental wave power grid angular frequency omega and a power grid angular signal theta through a phase-locked loop module;
will UgabcAnd IgabcPerforming synchronous coordinate transformation according to the power grid angle signal theta to obtain d-axis and q-axis components U under a synchronous rotating coordinate systemgdq、Igdq(ii) a The coordinate transformation expression is:
Figure BDA0002590265470000073
will IgdqAnd a current reference value
Figure BDA0002590265470000074
Difference value Δ I ofgdqSending into Proportional Integral Resonance (PIR) controller, adding feed forward compensation term to obtain control vector V under synchronous rotation coordinate systemgdq(ii) a The feedforward compensation term is calculated as follows:
Figure BDA0002590265470000081
wherein a transfer function of a proportional-integral-resonance (PIR) controller is:
Figure BDA0002590265470000082
in the formula: kp and Ki are respectively proportional and integral coefficients of the PI controller; kr0 is the resonance coefficient of a 2-frequency doubling resonator; ω c0 is the cutoff frequency of the 2-fold frequency resonator.
Will control vector VgdqPerforming inverse synchronous coordinate transformation to obtain a control vector V under a two-phase static coordinate systemgαβWill VgαβAnd sending the signal into a space vector modulation module to obtain a pulse signal for controlling the network side converter.
Example three:
referring to fig. 1-7, wherein in fig. 3-6, Vabc is the three-phase voltage of the grid output; vdc is the dc bus voltage; ppv is the output power of the photovoltaic power generation unit; pwind is the output power of the wind power generation unit; pload and Qload are respectively the active power and the reactive power of the load of the oil pumping unit.
A direct-current micro-grid system of a pumping unit well group comprises a step-down transformer 1, a photovoltaic power generation unit, a wind power generation unit and a pumping unit load 12, wherein the photovoltaic power generation unit comprises a photovoltaic cell panel 3 and a unidirectional DC/DC converter 4, the wind power generation unit comprises a permanent magnet wind power generator set 5 and an AC/DC converter II 6, and the pumping unit load 12 comprises a pumping unit 9 and a DC/AC converter III 8;
the high-voltage side of the step-down transformer 1 is connected with a three-phase power grid, the low-voltage side of the step-down transformer 1 is connected to an alternating current input end of an AC/DC converter I2, a direct current output end of the AC/DC converter I2 serves as a common direct current bus 11, an output end of the photovoltaic cell panel 3 is connected to a low-voltage input end of a unidirectional DC/DC converter 4, a high-voltage output end of the unidirectional DC/DC converter 4 is connected to the common direct current bus 11 in parallel, a stator outlet end of the permanent magnet wind generating set 5 is connected to an alternating current input end of an AC/DC converter II 6, a direct current output end of the AC/DC converter II 6 is connected to the common direct current bus 11 in parallel, and the oil pumping unit 9 and the DC/AC converter III 8 are respectively connected to the common direct current bus 11 in parallel;
the direct-current unloading circuit further comprises a direct-current unloading resistor 7 and a direct-current voltage-stabilizing capacitor which are respectively connected to the common direct-current bus 11 in parallel, and the direct-current unloading resistor 7 is controlled by a controllable switch.
A reactor 10 is connected in series between the step-down transformer 1 and the first AC/DC converter 2.
The cooperative control method of the direct-current micro-grid system of the pumping unit well group specifically comprises a rectification energy consumption mode, an inversion derating mode and an island droop mode;
in the rectification energy consumption mode, the first AC/DC converter works in a rectification state, the voltage of the public direct current bus is maintained to be stable, the general voltage is stabilized at 750V, and the photovoltaic power generation unit and the fan power generation unit are controlled to work in a maximum power tracking state;
in the inversion derating mode, the AC/DC converter works in an inversion feedback state to control the photovoltaic power generation unit and the fan power generation unit to reduce power to operate;
and in the island droop mode, the AC/DC converter is locked to control the photovoltaic power generation unit and the fan power generation unit to output power according to a droop control coefficient.
And under the inversion derating mode, the power instructions P of the photovoltaic power generation unit and the fan power generation unitPV、PwindRespectively setting as follows:
Figure BDA0002590265470000091
Figure BDA0002590265470000092
in the formula: pGSC_RT、PloadRespectively representing rated power of the AC/DC converter I and power of the pumping unit load; k is PPV/PwindThe power sharing coefficient is shown, and k is more than or equal to 0 and less than or equal to 10.
In the island droop mode, when the power of the load of the oil pumping unit is larger than zero, namely PloadWhen the power is more than 0, the power instruction P of the photovoltaic power generation unit and the power instruction P of the fan power generation unitPV、PwindRespectively setting as follows:
PPV＝α1Pload+ΔPdc1 (1)
Pwind＝α2Pload+ΔPdc2 (2)
in the formula: alpha is alpha1、α2Droop control coefficients of the photovoltaic power generation unit and the fan power generation unit respectively, and has alpha1＝k/(1+k)，α2＝1/(1+k)；ΔPdc1、ΔPdc1Compensation power respectively output by the photovoltaic power generation unit and the fan power generation unit participating in bus voltage regulation and having delta Pdc1≥0，ΔPdc2≥0；
When the power of the load of the oil pumping unit is less than or equal to zero, namely PloadAnd when the current is less than or equal to 0, locking trigger pulses of converters of the photovoltaic power generation unit and the fan power generation unit, and absorbing the power fed into the common direct current bus by the load of the oil pumping unit through the direct current unloading resistor.
When the voltage value of the secondary side of the step-down transformer is normal (the effective value of the common line voltage is not lower than 340V) and the load power of the pumping unit is more than zero (namely P)loadMore than 0), the direct current micro-grid system of the pumping well group operates in the rectification energy consumption mode;
when the voltage value of the secondary side of the step-down transformer is normal (the effective value of the general line voltage is not lower than 34)0V) and the load power of the pumping unit is less than or equal to zero (namely P)loadLess than or equal to 0), and the direct-current microgrid system of the pumping well group is switched to the inversion derating mode;
when the voltage value of the secondary side of the step-down transformer is abnormal (the effective value of the general line voltage is lower than 340V), the direct-current micro-grid system of the pumping unit well group is switched to an island droop mode.
The following is compared with the control method in the present application according to the conventional control method:
fig. 3 shows a simulation result of the pumping well group dc micro grid under the grid-connected operation condition when the conventional control method is adopted. In the simulation process, the oil pumping unit is in a reverse power generation state at 0.3s, the wind turbine generator and the photovoltaic module continue to transmit power to the direct-current bus, the oil pumping unit does not need a power grid to provide power at the moment, the power generated by the motor, the fan and the photovoltaic module is fed back to the direct-current bus, so that the voltage of the direct-current bus rises more rapidly, the direct-current unloading resistor protection action is triggered when the voltage reaches 600V, and the voltage of the direct-current bus is gradually recovered to 540V after the motor is in an up stroke at 0.6 s. Therefore, in the traditional control mode, the power fluctuation of the load of the oil pumping unit is not considered, and when the downstroke of the oil pumping unit reverses the power generation, the direct-current bus voltage is easily increased in a surge mode, so that the operation safety of the system is endangered.
Fig. 4 shows a simulation result of the pumping well group dc microgrid under the grid-connected operation condition when the control method of the present invention is adopted. And in the simulation initial stage, the power required by the load of the oil pumping unit is larger than zero, the micro-grid is in a rectification energy consumption mode, the oil pumping unit gradually enters a reverse power generation state after 1.2s, and the micro-grid is gradually switched to an inversion derating mode. Comparing with fig. 3, it can be seen that the control method of the present invention not only can meet the power requirement of the load, but also can ensure the relative stability of the quality bus voltage (the bus voltage fluctuation is less than 30V in the whole process, and the protection action of the direct current unloading resistor is not triggered).
Fig. 5 shows a simulation result of the pumping well group direct-current microgrid which adopts the control method of the invention and is switched between on-grid operation and off-grid operation. As shown in the figure, at the time of 1s, a short-circuit fault occurs in a power grid, the system detects that the voltage value of the secondary side of the transformer is abnormal, namely the effective value of the line voltage is lower than 340V, and the system automatically switches to an island droop operation mode; and (5) after 1.4s, removing the power grid fault, and re-putting the system into the network for operation. Simulation test results show that the control method can realize automatic switching of the grid-connected and off-grid running states of the micro-grid, and cannot cause large electromagnetic transient impact.
Fig. 6 shows a simulation result of the pumping well group dc microgrid operating in the island droop mode. As shown in the figure, in the operation mode, the load power is increased steeply when being 1.2s, and when the load power is larger than the maximum power output by photovoltaic and wind power, the voltage of the direct current bus begins to drop rapidly; when the voltage of the direct current bus drops to 520V, the system automatically cuts off part of the load, the source load power balance is maintained, and the voltage of the direct current bus is transited to a stable state again. Simulation test results show that the control method can effectively improve the voltage stability level of the direct current bus and ensure the safe and stable operation of the system.
The technical features of the present invention which are not described in the above embodiments may be implemented by or using the prior art, and are not described herein again, of course, the above description is not intended to limit the present invention, and the present invention is not limited to the above examples, and variations, modifications, additions or substitutions which may be made by those skilled in the art within the spirit and scope of the present invention should also fall within the protection scope of the present invention.

Claims (8)

1. A direct-current micro-grid system of a pumping unit well group is characterized by comprising a step-down transformer, a photovoltaic power generation unit, a wind power generation unit and a pumping unit load, wherein the photovoltaic power generation unit comprises a photovoltaic cell panel and a unidirectional DC/DC converter, the wind power generation unit comprises a permanent magnet wind power generation unit and an AC/DC converter II, and the pumping unit load comprises a pumping unit load and a DC/AC converter III;
the high-voltage side of the step-down transformer is connected with a three-phase power grid, the low-voltage side of the step-down transformer is connected to the alternating current input end of the first AC/DC converter, the direct current output end of the first AC/DC converter serves as a public direct current bus, the output end of the photovoltaic cell panel is connected to the low-voltage input end of the unidirectional DC/DC converter, the high-voltage output end of the unidirectional DC/DC converter is connected to the public direct current bus in parallel, the stator outlet end of the permanent magnet wind generating set is connected to the alternating current input end of the second AC/DC converter, the direct current output end of the second AC/DC converter is connected to the public direct current bus in parallel, and the oil pumping unit and the third DC/AC converter are connected to the public direct current bus in parallel respectively.
2. The direct-current microgrid system of a pumping well group is characterized by further comprising a direct-current unloading resistor and a direct-current voltage-stabilizing capacitor which are respectively connected to the common direct-current bus in parallel, wherein the direct-current unloading resistor is controlled by a controllable switch.
3. The direct-current microgrid system for the pumping unit well group is characterized in that a reactor is connected in series between the step-down transformer and the first AC/DC converter.
4. The cooperative control method of the direct-current microgrid system of the pumping unit well group is characterized by specifically comprising a rectification energy consumption mode, an inversion derating mode and an island droop mode;
in the rectification energy consumption mode, the first AC/DC converter works in a rectification state, the voltage of the public direct current bus is maintained to be stable, and the photovoltaic power generation unit and the fan power generation unit are controlled to work in a maximum power tracking state;
in the inversion derating mode, the AC/DC converter works in an inversion feedback state to control the photovoltaic power generation unit and the fan power generation unit to reduce power to operate;
and in the island droop mode, the AC/DC converter is locked to control the photovoltaic power generation unit and the fan power generation unit to output power according to a droop control coefficient.
5. The cooperative control method for the direct-current microgrid system of the pumping well group according to claim 4, characterized in that in the inversion derating mode, the power of the photovoltaic power generation units and the fan power generation units refers to power of the wind turbine generator unitsLet PPV、PwindRespectively setting as follows:
Figure FDA0002590265460000011
Figure FDA0002590265460000012
in the formula: pGSC_RT、PloadRespectively representing rated power of the AC/DC converter I and power of the pumping unit load; k is PPV/PwindThe power sharing coefficient is shown, and k is more than or equal to 0 and less than or equal to 10.
6. The cooperative control method for the direct-current microgrid system of a pumping unit well group according to claim 4, characterized in that in the island droop mode, when the power of the pumping unit load is greater than zero, P isloadWhen the power is more than 0, the power instruction P of the photovoltaic power generation unit and the power instruction P of the fan power generation unitPV、PwindRespectively setting as follows:
PPV＝α1Pload+ΔPdc1 (1)
Pwind＝α2Pload+ΔPdc2 (2)
in the formula: alpha is alpha1、α2Droop control coefficients of the photovoltaic power generation unit and the fan power generation unit respectively, and has alpha1＝k/(1+k)，α2＝1/(1+k)；ΔPdc1、ΔPdc1Compensation power respectively outputted by the photovoltaic power generation unit and the fan power generation unit participating in bus voltage regulation and having delta Pdc1≥0，ΔPdc2≥0；
When the power of the load of the oil pumping unit is less than or equal to zero, namely PloadWhen the current is less than or equal to 0, locking the trigger pulse of the converters of the photovoltaic power generation unit and the fan power generation unit, and absorbing the trigger pulse by the direct current unloading resistorThe oil engine load feeds the power of the common dc bus.
7. The cooperative control method for the direct current micro-grid system of the pumping unit well group according to claim 4,
when the voltage value of the secondary side of the step-down transformer is normal and the load power of the pumping unit is greater than zero, the direct-current micro-grid system of the pumping unit well group operates in the rectification energy consumption mode;
when the voltage value of the secondary side of the step-down transformer is normal and the load power of the pumping unit is less than or equal to zero, the direct-current micro-grid system of the pumping unit well group is switched to the inversion derating mode;
and when the voltage value of the secondary side of the step-down transformer is abnormal, the direct-current micro grid system of the pumping well group is switched to an island droop mode.
8. The cooperative control method of the direct-current microgrid system of the pumping unit well group is characterized by further comprising a control method of the first AC/DC converter in each mode, and specifically comprises the following steps: firstly, the line voltage U of the three-phase power grid isgabcPhase current IgabcPerforming synchronous coordinate transformation to obtain d-axis and q-axis components U under a synchronous rotating coordinate systemgdq、Igdq(ii) a Then adding IgdqAnd a current reference value
Figure FDA0002590265460000021
Difference value Δ I ofgdqSending into Proportional Integral Resonance (PIR) controller, adding feed forward compensation term to obtain control vector V under synchronous rotation coordinate systemgdq(ii) a Will control vector VgdqPerforming inverse synchronous coordinate transformation to obtain a control vector V under a two-phase static coordinate systemgαβWill VgαβAnd sending the signal into a space vector modulation module to obtain a pulse signal of the AC/DC converter I.
CN202010694382.8A 2020-07-17 2020-07-17 Direct-current micro-grid system of pumping unit well group and cooperative control method thereof Pending CN113949053A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202010694382.8A CN113949053A (en) 2020-07-17 2020-07-17 Direct-current micro-grid system of pumping unit well group and cooperative control method thereof

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202010694382.8A CN113949053A (en) 2020-07-17 2020-07-17 Direct-current micro-grid system of pumping unit well group and cooperative control method thereof

Publications (1)

Publication Number Publication Date
CN113949053A true CN113949053A (en) 2022-01-18

Family

ID=79326851

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202010694382.8A Pending CN113949053A (en) 2020-07-17 2020-07-17 Direct-current micro-grid system of pumping unit well group and cooperative control method thereof

Country Status (1)

Country Link
CN (1) CN113949053A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115510684A (en) * 2022-10-25 2022-12-23 中国石油天然气股份有限公司 Optimization method of independent light-storage integrated oil well interval pumping production system
US11955782B1 (en) 2022-11-01 2024-04-09 Typhon Technology Solutions (U.S.), Llc System and method for fracturing of underground formations using electric grid power

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115510684A (en) * 2022-10-25 2022-12-23 中国石油天然气股份有限公司 Optimization method of independent light-storage integrated oil well interval pumping production system
US11955782B1 (en) 2022-11-01 2024-04-09 Typhon Technology Solutions (U.S.), Llc System and method for fracturing of underground formations using electric grid power

Similar Documents

Publication Publication Date Title
AU2019419383B2 (en) Virtual synchronous generator system and method
CN110581565B (en) Control method and device in photovoltaic power generation grid-connected system
CN110086198B (en) Multi-terminal hybrid direct-current power transmission system control method for offshore wind power grid connection
CN107947221B (en) Power electronic transformer direct-current fault ride-through method
CN110690731A (en) Power electronic transformer applicable to hybrid micro-grid and coordination control and mode switching method thereof
CN104113077A (en) Coordination control method for double-fed asynchronous wind driven generator high voltage ride through
CN104079007A (en) Distributed grid-connected photovoltaic power generation control method for inhibiting overvoltage of low-voltage feeder line
US11641109B2 (en) Grid-forming wind turbine control method for diode rectifier unit-based offshore wind power transmission system
CN105978008A (en) Flow battery energy storage system with wind field black-start function and work method thereof
CN108923450B (en) Control and operation method of current source type high-voltage direct-current transmission system
CN110707719A (en) Dynamic control method for voltage of bus on additional high-voltage side of high-capacity phase modulator
CN113949053A (en) Direct-current micro-grid system of pumping unit well group and cooperative control method thereof
Bhaskar et al. Transient stability enhancement by using fuel cell as STATCOM
CN114640141A (en) Network-building type fan control method for offshore wind power diode rectification unit sending-out system
Othmane Dynamic modeling and control of a wind turbine with MPPT control connected to the grid by using PMSG
CN115241919A (en) SLCC commutation system for novel power system and control method thereof
Dayo et al. LVRT enhancement of a grid-tied PMSG-based wind farm using static VAR compensator
AU2021101279A4 (en) Fuzzy logic based grid connected hybrid energy system with modified luo converter
CN114481179A (en) Medium-voltage direct-current collection type renewable energy power generation and hydrogen production system and working method thereof
Eslahi et al. A comparative study of control methods for grid side converters in PMSG-based wind energy conversion systems
CN110011354B (en) Method for rapid voltage regulating system based on virtual synchronous generator
Zhang et al. Constraints and control strategies of quasi-Z-source cascaded multilevel inverter
Abdelkhalek et al. A reduced cost wind energy conversion system based on permanent magnet synchronous generator with a parallel connected AC-DC buck-boost converter
Ma et al. Simulation research on fault ride through for permanent magnet synchronous generator wind power system
Liu et al. Improved droop control for parallel inverters in microgrids

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination