TWI730649B - Power conversion system and method - Google Patents

Power conversion system and method Download PDF

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TWI730649B
TWI730649B TW109106939A TW109106939A TWI730649B TW I730649 B TWI730649 B TW I730649B TW 109106939 A TW109106939 A TW 109106939A TW 109106939 A TW109106939 A TW 109106939A TW I730649 B TWI730649 B TW I730649B
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power conversion
power
voltage
energy storage
command
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TW202037029A (en
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陳麗
王長永
邱愛斌
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台達電子企業管理（上海）有限公司
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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
    • H02J1/00—Circuit arrangements for dc mains or dc distribution networks
    • H02J1/10—Parallel operation of dc sources
    • H02J1/12—Parallel operation of dc generators with converters, e.g. with mercury-arc rectifier
    • 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
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/60—Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD]

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  • Power Engineering (AREA)
  • Inverter Devices (AREA)
  • Supply And Distribution Of Alternating Current (AREA)

Abstract

The present disclosure provides a power conversion system. The power conversion system includes at least one power conversion device and a controller. The power conversion device is connected to a DC grid. Each power conversion device includes a power generating unit, an inverting unit, an intermediate-frequency transformer and a rectifying device. The inverting unit is electrically connected to the corresponding power generating unit and is configured for converting an output voltage of the power generating unit into a first AC voltage. The intermediate-frequency transformer is electrically connected to the inverting unit for boosting the first AC voltage to a second AC voltage. The rectifying device is electrically connected to the intermediate-frequency transformer and the DC grid and is configured for rectifying the second AC voltage and outputting a DC voltage. The controller receives the high-level control command and controls the power conversion operation of the power conversion device accordingly.

Description

電力變換系統及方法Power conversion system and method

本公開涉及一種電力變換系統及方法，特別涉及一種耦合至直流電網的電力變換系統及方法。The present disclosure relates to a power conversion system and method, and more particularly to a power conversion system and method coupled to a DC power grid.

隨著新能源發電的快速發展，各種發電及儲能系統逐步接入電網中。在接入交流電網前，需要進行長距離輸電，現有技術中多利用交流電纜進行輸電。然而，長距離的交流電纜效率較低且成本較高。此外，長距離交流電纜與大量變換器耦合，易發生寬頻域震盪，不利於系統穩定。With the rapid development of new energy power generation, various power generation and energy storage systems are gradually connected to the grid. Before being connected to the AC power grid, long-distance power transmission is required. In the prior art, AC cables are often used for power transmission. However, long-distance AC cables are less efficient and costly. In addition, long-distance AC cables are coupled with a large number of converters, which is prone to wide-band oscillations, which is not conducive to system stability.

因此，如何發展一種可改善上述現有技術的電力變換系統及方法，實為目前迫切的需求。Therefore, how to develop a power conversion system and method that can improve the above-mentioned prior art is actually an urgent need at present.

本公開的目的在於提供一種電力變換系統及方法，通過並聯耦接於直流電網的電力變換裝置，可提供高壓直流電至直流電網。此外，可依據上級控制命令來協調電力變換裝置的電能轉換操作。借此，本公開的電力變換系統及方法是採用高壓直流輸電，可降低成本並減小輸電過程中的損耗。The purpose of the present disclosure is to provide a power conversion system and method, which can provide high-voltage DC power to the DC power grid through power conversion devices coupled in parallel to the DC power grid. In addition, the power conversion operation of the power conversion device can be coordinated according to upper-level control commands. Therefore, the power conversion system and method of the present disclosure adopts high-voltage direct current transmission, which can reduce the cost and reduce the loss in the power transmission process.

為達上述目的，本公開提供一種電力變換系統，耦接於直流電網，電力變換系統包含至少一電力變換裝置及主控制器。電力變換裝置並聯耦接於直流電網，其中每一電力變換裝置包含至少一發電單元、至少一逆變單元、中頻變壓器及整流裝置。逆變單元電連接於對應的發電單元，並架構於將發電單元的輸出電壓轉換為第一交流電壓。中頻變壓器電連接於逆變單元，並將第一交流電壓升壓為第二交流電壓。整流裝置電連接於中頻變壓器及直流電網，以對第二交流電壓進行整流並輸出直流電壓。主控制器被配置為接收上級控制命令，以基於上級控制命令協調電力變換裝置的電能轉換操作。To achieve the above objective, the present disclosure provides a power conversion system coupled to a DC power grid. The power conversion system includes at least one power conversion device and a main controller. The power conversion device is coupled to the DC grid in parallel, and each power conversion device includes at least one power generation unit, at least one inverter unit, an intermediate frequency transformer, and a rectifier device. The inverter unit is electrically connected to the corresponding power generation unit, and is configured to convert the output voltage of the power generation unit into a first AC voltage. The intermediate frequency transformer is electrically connected to the inverter unit and boosts the first AC voltage to the second AC voltage. The rectifying device is electrically connected to the intermediate frequency transformer and the DC power grid to rectify the second AC voltage and output the DC voltage. The main controller is configured to receive an upper-level control command to coordinate the power conversion operation of the power conversion device based on the upper-level control command.

為達上述目的，本公開更提供一種電力變換方法，適用於電力變換系統，其中電力變換系統耦接於直流電網並包含至少一電力變換裝置及主控制器，電力變換裝置並聯耦接於直流電網，每一電力變換裝置包含至少一發電單元、至少一逆變單元、一中頻變壓器及一整流裝置。電力變換方法包含下列步驟：(a) 利用逆變單元將對應的發電單元的輸出電壓轉換為第一交流電壓；(b) 利用中頻變壓器將第一交流電壓升壓為第二交流電壓；(c) 利用整流裝置對第二交流電壓進行整流並產生直流電壓；以及(d) 利用主控制器接收上級控制命令，並基於上級控制命令協調電力變換裝置的電能轉換操作。To achieve the above objective, the present disclosure further provides a power conversion method suitable for a power conversion system, wherein the power conversion system is coupled to a DC power grid and includes at least one power conversion device and a main controller, and the power conversion device is coupled in parallel to the DC power grid Each power conversion device includes at least one power generation unit, at least one inverter unit, an intermediate frequency transformer, and a rectifier device. The power conversion method includes the following steps: (a) Use an inverter unit to convert the output voltage of the corresponding power generation unit into a first AC voltage; (b) Use an intermediate frequency transformer to boost the first AC voltage to a second AC voltage; c) Utilizing the rectifying device to rectify the second AC voltage and generating a DC voltage; and (d) Utilizing the main controller to receive upper-level control commands, and coordinate the power conversion operation of the power conversion device based on the upper-level control commands.

體現本公開特徵與優點的一些典型實施例將在後段的說明中詳細敘述。應理解的是本公開能夠在不同的實施方式上具有各種的變化，其皆不脫離本公開的範圍，且其中的說明及圖示在本質上是當作說明之用，而非架構於限制本公開。Some typical embodiments embodying the features and advantages of the present disclosure will be described in detail in the following description. It should be understood that the present disclosure can have various changes in different implementations, which do not depart from the scope of the present disclosure, and the descriptions and illustrations therein are essentially for illustrative purposes, rather than being constructed to limit the present disclosure. public.

圖1A為本公開優選實施例的電力變換系統的電路架構示意圖。如圖1A所示，電力變換系統2耦接於直流電網1，且包含至少一電力變換裝置21及主控制器20。電力變換裝置21皆並聯耦接於直流電網1。主控制器20被配置為接收上級控制指令，並基於上級控制命令協調電力變換裝置21的電能轉換操作，其中主控制器20可為例如但不限於被配置為控制電力變換裝置21的輸出功率為固定值。進一步地，上級控制命令可由上級直流電網調度中心發送給主控制器，例如功率指令，但本公開不以此為限。每一電力變換裝置21包含至少一發電單元22、至少一逆變單元23、中頻變壓器24及整流裝置25。每一逆變單元23均電連接於對應的發電單元22，逆變單元23架構於將發電單元22的輸出電壓轉換為第一交流電壓。中頻變壓器24電連接於所有逆變單元23，且架構於將每一逆變單元輸出的第一交流電壓升壓為第二交流電壓。於一些實施例中，中頻變壓器24包含多個低壓繞組及一個高壓繞組，其中低壓繞組電連接於對應的逆變單元23。整流裝置25電連接於中頻變壓器24及直流電網1，整流裝置25對第二交流電壓進行整流，並輸出高壓直流電至直流電網1。借此，本公開的電力變換系統2耦合至直流電網，可採用高壓直流輸電，降低成本並減小輸電過程中的損耗。FIG. 1A is a schematic diagram of a circuit structure of a power conversion system according to a preferred embodiment of the present disclosure. As shown in FIG. 1A, the power conversion system 2 is coupled to the DC power grid 1 and includes at least one power conversion device 21 and a main controller 20. The power conversion devices 21 are coupled to the DC power grid 1 in parallel. The main controller 20 is configured to receive an upper-level control command and coordinate the power conversion operation of the power conversion device 21 based on the upper-level control command. The main controller 20 may be, for example, but not limited to, configured to control the output power of the power conversion device 21 as Fixed value. Further, the upper-level control command may be sent to the main controller by the upper-level DC grid dispatching center, such as a power command, but the present disclosure is not limited to this. Each power conversion device 21 includes at least one power generating unit 22, at least one inverter unit 23, an intermediate frequency transformer 24 and a rectifying device 25. Each inverter unit 23 is electrically connected to the corresponding power generation unit 22, and the inverter unit 23 is configured to convert the output voltage of the power generation unit 22 into a first AC voltage. The intermediate frequency transformer 24 is electrically connected to all the inverter units 23, and is configured to boost the first AC voltage output by each inverter unit into a second AC voltage. In some embodiments, the intermediate frequency transformer 24 includes a plurality of low-voltage windings and one high-voltage winding, wherein the low-voltage winding is electrically connected to the corresponding inverter unit 23. The rectifying device 25 is electrically connected to the intermediate frequency transformer 24 and the DC power grid 1, and the rectifying device 25 rectifies the second AC voltage and outputs high-voltage DC power to the DC power grid 1. In this way, the power conversion system 2 of the present disclosure is coupled to the DC power grid, and high-voltage DC power transmission can be adopted, which reduces the cost and the loss in the power transmission process.

於一些實施例中，在任一電力變換裝置21中，逆變單元23依據中頻變壓器24的工作頻率ω而將對應的發電單元22的輸出電壓轉換為第一交流電壓，其中第一交流電壓的頻率等於中頻變壓器24的工作頻率ω。In some embodiments, in any power conversion device 21, the inverter unit 23 converts the output voltage of the corresponding power generating unit 22 into a first AC voltage according to the operating frequency ω of the intermediate frequency transformer 24, wherein The frequency is equal to the operating frequency ω of the intermediate frequency transformer 24.

須注意的是，對於電力變換系統2中的電力變換裝置，電力變換裝置可為例如但不限於採用風力發電或光伏發電，例如圖2C及圖2D所示。當然，若電力變換系統2包含多個電力變換裝置中，亦可分別採用不同的發電來源，例如圖2A所示，多個電力變換裝置中可部分採用風力發電，部分採用光伏發電。以下將分別示例說明採用風力發電及光伏發電的電力變換裝置 (21a、21b) 的電路結構。It should be noted that, for the power conversion device in the power conversion system 2, the power conversion device may be, for example, but not limited to, wind power generation or photovoltaic power generation, as shown in FIG. 2C and FIG. 2D, for example. Of course, if the power conversion system 2 includes multiple power conversion devices, different power generation sources may be used respectively. For example, as shown in FIG. 2A, some of the multiple power conversion devices may use wind power generation, and some of the power conversion devices may use photovoltaic power generation. The following examples illustrate the circuit structures of power conversion devices (21a, 21b) that use wind power generation and photovoltaic power generation.

圖3A為本公開優選實施例的採用風力發電的電力變換裝置的電路結構示意圖。如圖3A所示，電力變換裝置21a採用風力發電，電力變換裝置21a的發電單元為風力發電單元22a，風力發電單元22a包括風機28和機側變換器26。電力變換裝置21a的逆變單元為網側變換器23a，電連接於機側變換器26與中頻變壓器24之間，並架構於穩定直流母線電壓及控制輸出電壓頻率。機側變換器26將風機28發出的頻率和幅值變化的交流電變換為直流電，網側變換器23a將直流電轉換為中頻三相交流電(即第一交流電壓)。中頻三相交流電經過高升壓比的中頻變壓器24升壓後得到第二交流電，最後通過不控整流裝置25將第二交流電變換為直流電並輸出至高壓直流輸電網（即直流電網1）。其中，中頻變壓器24具有高升壓比將低壓三相交流電（例如690V）升為高壓三相交流電（例如26KV），採用中頻變壓器可減小變壓器體積，降低成本。進一步地，高壓三相交流電通過一個高耐壓的不控整流裝置25轉換為直流電，本發明的整流裝置25也可採用半控器件。直流電網1的母線電壓為35KV，但本發明不以此為限。3A is a schematic diagram of a circuit structure of a power conversion device using wind power generation according to a preferred embodiment of the present disclosure. As shown in FIG. 3A, the power conversion device 21a uses wind power generation, the power generation unit of the power conversion device 21a is a wind power generation unit 22a, and the wind power generation unit 22a includes a wind turbine 28 and a machine-side converter 26. The inverter unit of the power conversion device 21a is a grid-side converter 23a, which is electrically connected between the machine-side converter 26 and the intermediate frequency transformer 24, and is constructed to stabilize the DC bus voltage and control the output voltage frequency. The machine-side converter 26 converts the alternating current with varying frequency and amplitude generated by the fan 28 into direct current, and the grid-side converter 23a converts the direct current into intermediate frequency three-phase alternating current (ie, the first alternating voltage). The intermediate frequency three-phase alternating current is boosted by the intermediate frequency transformer 24 with a high step-up ratio to obtain the second alternating current, and finally the second alternating current is converted into direct current by the uncontrolled rectifier device 25 and output to the high voltage direct current transmission grid (ie, direct current grid 1) . Among them, the intermediate frequency transformer 24 has a high step-up ratio to convert low-voltage three-phase alternating current (for example, 690V) to high-voltage three-phase alternating current (for example, 26KV). The use of an intermediate frequency transformer can reduce the volume of the transformer and reduce the cost. Further, the high-voltage three-phase alternating current is converted into direct current through a high withstand voltage uncontrolled rectifier device 25, and the rectifier device 25 of the present invention can also adopt a semi-controlled device. The bus voltage of the DC power grid 1 is 35KV, but the present invention is not limited to this.

於一些實施例中，風力發電單元22a的輸出電壓為小於1KV的低壓或大於1KV的高壓，逆變單元對應為低壓逆變單元或高壓逆變單元。於一些實施例中，電力變換裝置21a還包含濾波器27，濾波器27電連接於網側變換器23a與中頻變壓器24之間，濾波器27是架構於對網側變換器23a的輸出電流進行濾波。In some embodiments, the output voltage of the wind power generation unit 22a is a low voltage less than 1KV or a high voltage greater than 1KV, and the inverter unit corresponds to a low voltage inverter unit or a high voltage inverter unit. In some embodiments, the power conversion device 21a further includes a filter 27. The filter 27 is electrically connected between the grid-side converter 23a and the intermediate frequency transformer 24. The filter 27 is constructed to output current from the grid-side converter 23a. Perform filtering.

整流裝置25包含多個橋臂，本實施例中，整流裝置包含3個橋臂，每一橋臂具有節點，節點電連接於中頻變壓器24並將橋臂分為兩個支路，每一支路由多個整流元件串聯構成。借此，可降低對整流元件的耐壓性能要求。整流元件可為例如但不限於二極體或半控器件。針對直流電網1的電壓等級（例如35KV），需要選取高耐壓的二極體或半控器件，每半個橋臂由大於等於兩個的二極體或半控器件串聯構成，可降低每一整流元件的耐壓等級，降低成本。The rectifier device 25 includes a plurality of bridge arms. In this embodiment, the rectifier device includes 3 bridge arms. Each bridge arm has a node. The node is electrically connected to the intermediate frequency transformer 24 and the bridge arm is divided into two branches. Route multiple rectifier elements connected in series. In this way, the requirements for the withstand voltage of the rectifier element can be reduced. The rectifying element can be, for example, but not limited to, a diode or a semi-control device. For the voltage level of DC grid 1 (for example, 35KV), a diode or semi-control device with high withstand voltage needs to be selected. Each half of the bridge arm is composed of two or more diodes or semi-control devices in series, which can reduce The withstand voltage level of a rectifier element reduces the cost.

於一些實施例中，風機28為高壓風機（例如10KV），對應的機側變換器26和網側變換器23a為高壓變換器，如圖3B所示，機側變換器26及網側變換器23a均為多電平變換器，但亦不以此為限，借此可降低中頻變壓器24的匝比。例如，採用10KV等級的風力發電機和變流器（包括機側變換器和網側變換器），和常規的690V風力發電系統相比，選用的中頻變壓器24的匝比可降低十幾倍，針對35KV的直流輸電系統，中頻變壓器24匝比由26KV/690V降低為26KV/10KV。In some embodiments, the fan 28 is a high-pressure fan (for example, 10KV), and the corresponding machine-side converter 26 and the grid-side converter 23a are high-voltage converters. As shown in FIG. 3B, the machine-side converter 26 and the grid-side converter 23a are all multi-level converters, but not limited to this, so that the turns ratio of the intermediate frequency transformer 24 can be reduced. For example, using 10KV grade wind turbines and converters (including machine-side converters and grid-side converters), compared with the conventional 690V wind power generation system, the turns ratio of the selected intermediate frequency transformer 24 can be reduced by more than ten times For the 35KV DC transmission system, the 24 turns ratio of the intermediate frequency transformer is reduced from 26KV/690V to 26KV/10KV.

此外，風力發電單元22a及逆變單元 (即網側變換器23a) 的個數並不限於一，例如於圖3C所示，電力變換裝置21a可包含兩個風力發電單元22a及兩個網側變換器23a，其中兩個網側變換器23a分別電連接於兩個風力發電單元22a，中頻變壓器24電連接於兩個網側變換器23a。於此實施例中，中頻變壓器24為雙繞組升壓變壓器，相較於採用兩個獨立變壓器分別連接於兩個網側變換器23a的方案，可有效節省成本。當然，風機28也可採用具有多輸出繞組的風機，如圖3D所示，風機28包括兩組輸出繞組，其中每一組輸出繞組電連接對應的機側變換器26，構成一個風力發電單元22a。In addition, the number of wind power generation units 22a and inverter units (ie, grid-side converters 23a) is not limited to one. For example, as shown in FIG. 3C, the power conversion device 21a may include two wind power generation units 22a and two grid-side converters. In the converter 23a, the two grid-side converters 23a are electrically connected to the two wind power generation units 22a, respectively, and the intermediate frequency transformer 24 is electrically connected to the two grid-side converters 23a. In this embodiment, the intermediate frequency transformer 24 is a dual-winding step-up transformer, which can effectively save costs compared to a solution in which two independent transformers are respectively connected to two grid-side converters 23a. Of course, the wind turbine 28 can also be a wind turbine with multiple output windings. As shown in FIG. 3D, the wind turbine 28 includes two sets of output windings, and each set of output windings is electrically connected to the corresponding machine-side converter 26 to form a wind power generation unit 22a. .

為了對電力變換裝置21a中的電能轉換進行控制，其中於本實施例中，電力變換裝置21a為風力發電系統，機側變換器26控制風機28的輸出功率，網側變換器23a穩定直流母線29的母線電壓同時控制輸出的第一交流電壓的頻率，第一交流電壓的幅值由直流電網1和整流裝置25鉗位住。如圖4所示，電力變換裝置21a的逆變單元包含第一控制電路200a，第一控制電路200a依據中頻變壓器24的工作頻率ω及逆變單元的多個電信號而產生一開關信號，並通過開關信號控制逆變單元的轉換操作。第一控制電路200a包含計算器201、座標變換器202、電壓調節器203、電流調節器204及PWM (Pulse Width Modulation) 調製器205。計算器201依據中頻變壓器24的工作頻率ω產生角度信號θ，即對頻率ω積分產生角度信號。中頻頻率常規取400HZ，為中頻變壓器24的額定工作頻率，但本發明不以此為限。座標變換器202依據逆變單元 (即網側變換器23a) 的交流端的三相電流量Iabc 及角度信號θ產生有功電流Id 及無功電流Iq 。電壓調節器203採樣直流母線29的直流母線電壓Udc ，並依據直流母線電壓Udc 及其指令值Udcr 產生有功電流指令Idr 。電流調節器204依據有功電流指令Idr 、無功電流指令Iqr 、有功電流Id 、無功電流Iq 及角度信號θ產生三相控制電勢Eabc 。PWM調製器205依據三相控制電勢Eabc 產生開關信號，其中第一控制電路200a通過開關信號控制網側變換器23a的轉換操作。PWM調製器205可為例如但不限於通過SPWM (Sinusoidal PWM) 或SVPWM (Space Vector PWM) 技術產生開關信號。其中，無功電流指令通過對無功功率進行閉環調節得到。In order to control the conversion of electric energy in the power conversion device 21a, in this embodiment, the power conversion device 21a is a wind power generation system, the machine-side converter 26 controls the output power of the wind turbine 28, and the grid-side converter 23a stabilizes the DC bus 29 At the same time, the frequency of the output first AC voltage is controlled by the bus voltage of, and the amplitude of the first AC voltage is clamped by the DC power grid 1 and the rectifier 25. As shown in FIG. 4, the inverter unit of the power conversion device 21a includes a first control circuit 200a. The first control circuit 200a generates a switching signal according to the operating frequency ω of the intermediate frequency transformer 24 and a plurality of electrical signals of the inverter unit. And through the switch signal to control the conversion operation of the inverter unit. The first control circuit 200a includes a calculator 201, a coordinate converter 202, a voltage regulator 203, a current regulator 204, and a PWM (Pulse Width Modulation) modulator 205. The calculator 201 generates an angle signal θ according to the operating frequency ω of the intermediate frequency transformer 24, that is, integrates the frequency ω to generate an angle signal. The intermediate frequency frequency is conventionally taken as 400 Hz, which is the rated operating frequency of the intermediate frequency transformer 24, but the present invention is not limited to this. The coordinate converter 202 generates an active current I d and a reactive current I q according to the three-phase current I abc and the angle signal θ at the AC end of the inverter unit (ie, the grid-side converter 23 a ). The voltage regulator 203 samples the DC bus voltage U dc of the DC bus 29, and generates an active current command I dr according to the DC bus voltage U dc and its command value U dcr . The current regulator 204 generates a three-phase control potential E abc according to the active current command I dr , the reactive current command I qr , the active current I d , the reactive current I q and the angle signal θ. The PWM modulator 205 generates a switching signal according to the three-phase control potential E abc , wherein the first control circuit 200a controls the switching operation of the grid-side converter 23a through the switching signal. The PWM modulator 205 may be, for example, but not limited to, generating a switching signal through SPWM (Sinusoidal PWM) or SVPWM (Space Vector PWM) technology. Among them, the reactive current command is obtained by closed-loop adjustment of the reactive power.

圖5A為本公開優選實施例的採用光伏發電的電力變換裝置的電路結構示意圖。如圖5A所示，電力變換裝置21b採用光伏發電，電力變換裝置21b的發電單元為光伏發電單元22b，逆變單元23b將光伏發電單元22b的輸出電壓轉換為中頻三相交流電(即第一交流電壓)。中頻三相交流電經過高升壓比的中頻變壓器24升壓後得到第二交流電，最後通過不控整流裝置25將第二交流電變換為直流電並輸出至高壓直流輸電網（即直流電網1）。其中與圖3A中類似的電路元件是以相同的標號表示，類似電路元件具有類似的功能，具體請參考上述描述，於此不再贅述。此外，光伏發電單元22b及逆變單元23b的個數並不限於一，例如於圖5B所示，電力變換裝置21b可包含兩個光伏發電單元22b及兩個逆變單元23b，其中兩個逆變單元23b分別電連接於兩個光伏發電單元22b，中頻變壓器24電連接於兩個逆變單元23b。FIG. 5A is a schematic diagram of a circuit structure of a power conversion device using photovoltaic power generation according to a preferred embodiment of the present disclosure. As shown in Figure 5A, the power conversion device 21b uses photovoltaic power generation, the power generation unit of the power conversion device 21b is a photovoltaic power generation unit 22b, and the inverter unit 23b converts the output voltage of the photovoltaic power generation unit 22b into intermediate frequency three-phase AC power (ie, the first AC voltage). The intermediate frequency three-phase alternating current is boosted by the intermediate frequency transformer 24 with a high step-up ratio to obtain the second alternating current, and finally the second alternating current is converted into direct current by the uncontrolled rectifier device 25 and output to the high voltage direct current transmission grid (ie, direct current grid 1) . The circuit elements similar to those in FIG. 3A are denoted by the same reference numerals, and the similar circuit elements have similar functions. For details, please refer to the above description, which will not be repeated here. In addition, the number of photovoltaic power generation units 22b and inverter units 23b is not limited to one. For example, as shown in FIG. 5B, the power conversion device 21b may include two photovoltaic power generation units 22b and two inverter units 23b. The transformation unit 23b is electrically connected to the two photovoltaic power generation units 22b, and the intermediate frequency transformer 24 is electrically connected to the two inverter units 23b.

為了對電力變換裝置21b中的電能轉換進行控制，其中於本實施例中，電力變換裝置21b為光伏發電系統，逆變單元23b控制輸出的第一交流電壓的頻率，第一交流電壓的幅值由直流電網1和整流裝置25鉗位住。如圖6所示，電力變換裝置21b的逆變單元23b包含第二控制電路200b，第二控制電路200b依據中頻變壓器24的工作頻率ω及逆變單元23b的多個電信號而產生一開關信號，並通過開關信號控制逆變單元23b的轉換操作。第二控制電路200b包含計算器201、座標變換器202、MPPT (Maximum power point tracking) 控制器206、電壓調節器203、電流調節器204及PWM調製器205。計算器201依據中頻變壓器24的工作頻率ω產生角度信號θ，即對頻率ω積分產生角度信號。中頻頻率常規取400HZ，為中頻變壓器24的額定工作頻率，但本發明不以此為限。座標變換器202依據逆變單元23b的交流端的三相電流量Iabc 及角度信號θ產生有功電流Id 及無功電流Iq 。MPPT控制器206獲取光伏發電單元22的輸出電壓Uo 及輸出電流Io ，並根據輸出電壓Uo 及輸出電流Io 計算直流功率，以根據MPPT演算法獲取輸出電壓指令Uor 。電壓調節器203依據光伏發電單元22b的輸出電壓Uo 及輸出電壓指令Uor 產生有功電流指令Idr 。電流調節器204依據有功電流指令Idr 、無功電流指令Iqr 、有功電流Id 、無功電流Iq 及角度信號θ產生三相控制電勢Eabc 。PWM調製器205依據三相控制電勢Eabc 產生開關信號，其中第二控制電路200b通過開關信號控制逆變單元23b的轉換操作。PWM調製器205可為例如但不限於通過SPWM (Sinusoidal PWM) 或SVPWM (Space Vector PWM) 技術調製產生開關信號。其中，無功電流指令通過對無功功率進行閉環調節得到。In order to control the conversion of electric energy in the power conversion device 21b, in this embodiment, the power conversion device 21b is a photovoltaic power generation system, and the inverter unit 23b controls the frequency of the output first AC voltage, and the amplitude of the first AC voltage It is clamped by the DC grid 1 and the rectifier 25. As shown in FIG. 6, the inverter unit 23b of the power conversion device 21b includes a second control circuit 200b. The second control circuit 200b generates a switch according to the operating frequency ω of the intermediate frequency transformer 24 and a plurality of electrical signals from the inverter unit 23b. Signal, and the switching operation of the inverter unit 23b is controlled by the switch signal. The second control circuit 200b includes a calculator 201, a coordinate converter 202, an MPPT (Maximum power point tracking) controller 206, a voltage regulator 203, a current regulator 204, and a PWM modulator 205. The calculator 201 generates an angle signal θ according to the operating frequency ω of the intermediate frequency transformer 24, that is, integrates the frequency ω to generate an angle signal. The intermediate frequency frequency is conventionally taken as 400 Hz, which is the rated operating frequency of the intermediate frequency transformer 24, but the present invention is not limited to this. The coordinate converter 202 generates an active current I d and a reactive current I q according to the three-phase current I abc and the angle signal θ at the AC end of the inverter unit 23 b. The MPPT controller 206 obtains the output voltage U o and the output current I o of the photovoltaic power generation unit 22, and calculates the DC power according to the output voltage U o and the output current I o to obtain the output voltage command U or according to the MPPT algorithm. The voltage regulator 203 generates an active current command I dr according to the output voltage U o and the output voltage command U or of the photovoltaic power generation unit 22 b. The current regulator 204 generates a three-phase control potential E abc according to the active current command I dr , the reactive current command I qr , the active current I d , the reactive current I q and the angle signal θ. The PWM modulator 205 generates a switching signal according to the three-phase control potential E abc , wherein the second control circuit 200b controls the switching operation of the inverter unit 23b through the switching signal. The PWM modulator 205 can be, for example, but not limited to, modulating and generating a switching signal through SPWM (Sinusoidal PWM) or SVPWM (Space Vector PWM) technology. Among them, the reactive current command is obtained by closed-loop adjustment of the reactive power.

於一些實施例中，電力變換裝置21包括第一電力變換裝置和第二電力變換裝置，第一電力變換裝置和第二電力變換裝置並聯耦接於直流電網1。其中第一電力變換裝置為風力發電系統，第二電力變換裝置為光伏發電系統。In some embodiments, the power conversion device 21 includes a first power conversion device and a second power conversion device, and the first power conversion device and the second power conversion device are coupled to the DC power grid 1 in parallel. The first power conversion device is a wind power generation system, and the second power conversion device is a photovoltaic power generation system.

於一些實施例中，除電力變換裝置21之外，電力變換系統2還包含儲能裝置3，如圖1B所示，儲能裝置3與所有電力變換裝置21一同並聯耦接於直流電網1。進一步地，如圖2B所示，電力變換系統2包括採用風力發電的電力變換裝置21a、採用光伏發電的電力變換裝置21b及儲能裝置3，形成大型的風光儲混合發電系統。當然本發明不以此為限，如圖2C所示，電力系統2包括採用風力發電的電力變換裝置21a和儲能裝置3，形成風儲發電系統；如圖2D所示，電力系統2包括採用光伏發電的電力變換裝置21b和儲能裝置3，形成光儲發電系統。In some embodiments, in addition to the power conversion device 21, the power conversion system 2 further includes an energy storage device 3. As shown in FIG. 1B, the energy storage device 3 and all the power conversion devices 21 are coupled to the DC grid 1 in parallel. Furthermore, as shown in FIG. 2B, the power conversion system 2 includes a power conversion device 21a that uses wind power generation, a power conversion device 21b that uses photovoltaic power generation, and an energy storage device 3, forming a large-scale wind-solar hybrid power generation system. Of course, the present invention is not limited to this. As shown in FIG. 2C, the power system 2 includes a power conversion device 21a that uses wind power generation and an energy storage device 3 to form a wind storage power generation system; as shown in FIG. 2D, the power system 2 includes The photovoltaic power conversion device 21b and the energy storage device 3 form a light storage power generation system.

基於上述各實施例及其變形，本公開提出一種高壓直流耦合系統，至少一個電力變換裝置（如風力發電裝置、光伏發電裝置）和/或儲能裝置之間獨立並聯耦接在直流電網上，方便擴展；各發電單元通過各自的逆變單元將發出的電能轉換為中頻交流電，並經過各自的升壓變壓器和整流裝置變換為高壓直流電接入高壓直流輸電網，儲能裝置通過直流變換器將低壓直流電變換為高壓直流電接入高壓直流輸電網，採用直流輸電技術將電能輸送至遠端電網或使用者端，同樣電壓等級下輸送能力更強，損耗更小；由主控制器進行統一控制，實現發電，電網調節和調度功能。Based on the foregoing embodiments and their variants, the present disclosure proposes a high-voltage DC coupling system, in which at least one power conversion device (such as a wind power generation device, a photovoltaic power generation device) and/or an energy storage device are independently coupled in parallel to the DC power grid, Convenient expansion; each power generation unit converts the generated electric energy into intermediate frequency alternating current through its own inverter unit, and converts it into high-voltage direct current through its respective step-up transformer and rectifier device to connect to the high-voltage direct current transmission grid, and the energy storage device through the DC converter Convert low-voltage direct current to high-voltage direct current and connect it to the high-voltage direct current transmission grid, and use direct current transmission technology to transmit the electric energy to the remote grid or user end. Under the same voltage level, the transmission capacity is stronger and the loss is smaller; it is controlled by the main controller. , To achieve power generation, grid regulation and dispatch functions.

圖2B示意性示出一種高壓直流耦合系統，其包含採用風力發電的電力變換裝置21a、採用光伏發電的電力變換裝置21b、儲能裝置3和主控制器20。其中電力變換裝置21a、電力變換裝置21b和儲能裝置3分別作為獨立的裝置並聯耦接於直流電網1，實現風機或者光伏發電的高壓直流輸電，並且各裝置可隨時併入直流電網1或與直流電網1斷開，方便擴展。主控制器20檢測電力變換裝置21a和電力變換裝置21b的輸出功率，並根據電網調度命令計算儲能裝置3的功率指令，以控制儲能裝置3的充放電運行，使電力變換系統2實現固定功率輸出；或者主控制器20根據上級控制命令計算儲能裝置3的功率指令，以控制儲能裝置3的充放電運行，實現削峰填谷，平滑新能源等目標。需要說明的是，上述描述僅用於示意性說明，並不構成對本公開的限制。當然，本實施例的系統可以同時包含多個風力發電裝置，多個光伏發電裝置和多個儲能裝置。2B schematically shows a high-voltage direct current coupling system, which includes a power conversion device 21a that uses wind power generation, a power conversion device 21b that uses photovoltaic power generation, an energy storage device 3, and a main controller 20. The power conversion device 21a, the power conversion device 21b, and the energy storage device 3 are respectively connected in parallel to the DC grid 1 as independent devices to realize high-voltage DC transmission of wind turbines or photovoltaic power generation, and each device can be integrated into the DC grid 1 or connected at any time. The DC grid 1 is disconnected to facilitate expansion. The main controller 20 detects the output power of the power conversion device 21a and the power conversion device 21b, and calculates the power command of the energy storage device 3 according to the grid dispatch command to control the charging and discharging operation of the energy storage device 3, so that the power conversion system 2 is fixed Power output; or the main controller 20 calculates the power command of the energy storage device 3 according to the upper-level control command to control the charging and discharging operation of the energy storage device 3, and achieve goals such as peak shaving and valley filling and smoothing of new energy. It should be noted that the above description is only used for schematic description, and does not constitute a limitation to the present disclosure. Of course, the system of this embodiment may include multiple wind power generation devices, multiple photovoltaic power generation devices, and multiple energy storage devices at the same time.

圖2C示意性示出另一種高壓直流耦合系統，其包含採用風力發電的電力變換裝置21a、儲能裝置3和主控制器20。其中電力變換裝置21a和儲能裝置3分別作為獨立的裝置並聯耦接於直流電網1，實現風機發電的高壓直流輸電，並且各裝置可隨時併入直流電網1或與直流電網1斷開，方便擴展。主控制器20檢測電力變換裝置21a的輸出功率，並根據電網調度命令計算儲能裝置3的功率指令，以控制儲能裝置3的充放電運行，使電力變換系統2實現固定功率輸出；或者主控制器20根據上級控制命令計算儲能裝置3的功率指令，以控制儲能裝置3的充放電運行，實現削峰填谷，平滑新能源等目標。需要說明的是，上述描述僅用於示意性說明，並不構成對本公開的限制。當然，本實施例的系統可以包含多個風力發電裝置，即對應一個風力發電廠，且該風力發電裝置可以是陸上風電，也可以是海上風電。FIG. 2C schematically shows another high-voltage direct current coupling system, which includes a power conversion device 21a that uses wind power generation, an energy storage device 3, and a main controller 20. The power conversion device 21a and the energy storage device 3 are separately coupled to the DC grid 1 in parallel as independent devices to realize high-voltage DC transmission of wind power generation, and each device can be integrated into the DC grid 1 or disconnected from the DC grid 1 at any time, which is convenient Extension. The main controller 20 detects the output power of the power conversion device 21a, and calculates the power command of the energy storage device 3 according to the grid dispatch command to control the charging and discharging operation of the energy storage device 3, so that the power conversion system 2 achieves a fixed power output; or The controller 20 calculates the power command of the energy storage device 3 according to the superior control command, so as to control the charging and discharging operation of the energy storage device 3, so as to achieve goals such as peak shaving and valley filling, and smoothing of new energy. It should be noted that the above description is only used for schematic description, and does not constitute a limitation to the present disclosure. Of course, the system of this embodiment may include multiple wind power generation devices, that is, corresponding to one wind power plant, and the wind power generation device may be onshore wind power or offshore wind power.

圖2D示意性示出又一種高壓直流耦合系統，其包含採用光伏發電的電力變換裝置21b、儲能裝置3和主控制器20。其中電力變換裝置21b和儲能裝置3分別作為獨立的裝置並聯耦接於直流電網1，實現光伏發電的高壓直流輸電，並且各裝置可隨時併入直流電網1或與直流電網1斷開，方便擴展。主控制器20檢測光伏發電裝置21b的輸出功率，並根據電網調度命令計算儲能裝置3的功率指令，以控制儲能裝置3的充放電運行，電力變換系統2實現固定功率輸出；或者主控制器20根據上級控制命令計算儲能裝置3的功率指令，以控制儲能裝置3的充放電運行，實現削峰填谷，平滑新能源等目標。需要說明的是，上述描述僅用於示意性說明，並不構成對本公開的限制。當然，本實施例的系統可以包含多個光伏發電裝置，即對應一個光伏發電廠。FIG. 2D schematically shows another high-voltage direct current coupling system, which includes a power conversion device 21b that uses photovoltaic power generation, an energy storage device 3, and a main controller 20. The power conversion device 21b and the energy storage device 3 are separately coupled to the DC grid 1 in parallel as independent devices to realize high-voltage DC transmission of photovoltaic power generation, and each device can be integrated into the DC grid 1 or disconnected from the DC grid 1 at any time, which is convenient Extension. The main controller 20 detects the output power of the photovoltaic power generation device 21b, and calculates the power command of the energy storage device 3 according to the grid dispatch command to control the charging and discharging operation of the energy storage device 3, and the power conversion system 2 realizes a fixed power output; or the main control The device 20 calculates the power command of the energy storage device 3 according to the superior control command, so as to control the charging and discharging operation of the energy storage device 3, so as to achieve goals such as peak shaving and valley filling, and smoothing of new energy. It should be noted that the above description is only used for schematic description, and does not constitute a limitation to the present disclosure. Of course, the system of this embodiment may include multiple photovoltaic power generation devices, that is, one photovoltaic power plant corresponds to one.

圖7為本公開優選實施例的儲能裝置的電路結構示意圖。如圖7所示，儲能裝置3包含多個儲能單元30，每一儲能單元30包含相連接的儲能元件31及直流變換器32，其中多個直流變換器32串聯連接以形成直流輸出端耦接至直流電網1。於此實施例中，主控制器20可為例如但不限於被配置為控制多個電力變換裝置21的輸出功率及儲能裝置3的輸出功率之和為固定值。於一些實施例中，主控制器20接收多個儲能元件31的荷電狀態，並自直流電網1接收上級控制命令，主控制器20基於上級控制命令及荷電狀態產生該多個直流變換器32的功率指令，借此可根據實際需求調整各儲能單元30的輸出功率。FIG. 7 is a schematic diagram of a circuit structure of an energy storage device according to a preferred embodiment of the present disclosure. As shown in FIG. 7, the energy storage device 3 includes a plurality of energy storage units 30, and each energy storage unit 30 includes a connected energy storage element 31 and a DC converter 32, wherein the plurality of DC converters 32 are connected in series to form a DC The output terminal is coupled to the DC power grid 1. In this embodiment, the main controller 20 may be, for example, but not limited to, configured to control the sum of the output power of the plurality of power conversion devices 21 and the output power of the energy storage device 3 to a fixed value. In some embodiments, the main controller 20 receives the state of charge of the plurality of energy storage elements 31, and receives an upper-level control command from the DC grid 1, and the main controller 20 generates the plurality of DC converters 32 based on the upper-level control command and the state of charge. According to the actual demand, the output power of each energy storage unit 30 can be adjusted.

為了對儲能裝置3的電能轉換進行控制，於一些實施例中，如圖8所示，儲能單元30還包含第三控制電路300，第三控制電路300包含計算器301、功率調節器302、電流調節器303及PWM調製器304。計算器301依據儲能元件的電流I及電壓U計算儲能元件功率P。功率調節器302接收主控制器20提供的該儲能單元30的功率指令Pr ，依據儲能元件的功率P及功率指令Pr 產生儲能元件的電流指令Ir 。其中，主控制器20根據各儲能元件的荷電狀態分配儲能裝置總的功率指令，得到每一儲能單元的功率指令Pr ，各儲能單元根據功率指令自動分配高壓側直流電壓。電流調節器303依據儲能元件的電流I及電流指令Ir 產生直流電勢E。PWM調製器304依據直流電勢E產生開關信號，其中第三控制電路300通過開關信號控制直流變換器32的轉換操作。In order to control the electric energy conversion of the energy storage device 3, in some embodiments, as shown in FIG. 8, the energy storage unit 30 further includes a third control circuit 300, and the third control circuit 300 includes a calculator 301 and a power regulator 302. , Current regulator 303 and PWM modulator 304. The calculator 301 calculates the power P of the energy storage element according to the current I and the voltage U of the energy storage element. The power regulator 302 receives the power command P r of the energy storage unit 30 provided by the main controller 20, and generates a current command I r of the energy storage element according to the power P and the power command P r of the energy storage element. The main controller 20 allocates the total power command of the energy storage device according to the state of charge of each energy storage element to obtain the power command P r of each energy storage unit, and each energy storage unit automatically allocates the high-voltage side DC voltage according to the power command. The current regulator 303 generates a direct current potential E according to the current I of the energy storage element and the current command Ir. The PWM modulator 304 generates a switching signal according to the DC potential E, and the third control circuit 300 controls the switching operation of the DC converter 32 through the switching signal.

通過設置儲能裝置3，主控制器20可通過控制儲能裝置3靈活調整電力變換系統2中的功率輸出的分配。舉例而言，主控制器20檢測電力變換裝置21的發電功率，並對發電功率進行濾波平滑處理後得到目標功率，進而將目標功率減去發電功率，並依據其差值調整儲能裝置3中各儲能單元的功率指令以控制儲能單元的充放電運作，平滑功率波動，借此使電力變換系統2的實際輸出功率與目標功率一致。此外，主控制器20可依據直流電網1的負荷需求及電力變換裝置21的發電情況進行能量調度，例如在電力變換裝置21的發電量較多且直流電網1的負荷需求較小時，可將多餘的能量存儲於儲能裝置3的儲能元件31中，而在電力變換裝置21的發電量較少且直流電網1的負荷需求較大時，則可將儲能元件31所存儲的能量釋出並供給至直流電網1。By providing the energy storage device 3, the main controller 20 can flexibly adjust the distribution of power output in the power conversion system 2 by controlling the energy storage device 3. For example, the main controller 20 detects the generated power of the power conversion device 21, filters and smoothes the generated power to obtain the target power, and then subtracts the generated power from the target power, and adjusts the energy storage device 3 according to the difference. The power command of each energy storage unit controls the charging and discharging operation of the energy storage unit to smooth power fluctuations, thereby making the actual output power of the power conversion system 2 consistent with the target power. In addition, the main controller 20 can perform energy dispatch based on the load demand of the DC grid 1 and the power generation situation of the power conversion device 21. For example, when the power conversion device 21 has a large amount of power generation and the DC grid 1 has a small load demand, it can Excess energy is stored in the energy storage element 31 of the energy storage device 3. When the power conversion device 21 generates less power and the load demand of the DC grid 1 is large, the energy stored in the energy storage element 31 can be released. Output and supply to the DC grid 1.

主控制器20與每一電力變換裝置21通信，可根據直流電網1的實際需求實現不同功能。當直流電網1要求電力變換系統2輸出固定功率時，若電力變換系統2不包括儲能裝置，主控制器20檢測每一電力變換裝置21的輸出功率，對至少一電力變換裝置21進行限功率運行，以輸出目標功率至直流電網1，滿足直流電網1的實際需求；若電力變換系統2包括儲能裝置3，主控制器20檢測每一電力變換裝置21的輸出功率，如光伏發電裝置和/或風力發電裝置的輸出功率，固定功率輸出的目標功率減去電力變換裝置21的輸出功率，得到儲能裝置3的功率指令，根據儲能元件31的荷電狀態將儲能裝置3的功率指令分配給每一儲能單元30，通過控制儲能裝置3的充放電運行實現固定功率輸出。The main controller 20 communicates with each power conversion device 21 and can implement different functions according to the actual needs of the DC power grid 1. When the DC grid 1 requires the power conversion system 2 to output fixed power, if the power conversion system 2 does not include an energy storage device, the main controller 20 detects the output power of each power conversion device 21 and limits the power of at least one power conversion device 21 Run to output target power to the DC grid 1 to meet the actual needs of the DC grid 1. If the power conversion system 2 includes an energy storage device 3, the main controller 20 detects the output power of each power conversion device 21, such as photovoltaic power generation devices and / Or the output power of the wind power generation device, the target power of the fixed power output minus the output power of the power conversion device 21 to obtain the power command of the energy storage device 3, and the power command of the energy storage device 3 according to the state of charge of the energy storage element 31 Allocate to each energy storage unit 30, and achieve a fixed power output by controlling the charging and discharging operation of the energy storage device 3.

於一些實施例，主控制器20檢測風力發電裝置和/或光伏發電裝置的發電功率，通過儲能裝置3對此功率進行濾波平滑處理，具體地，平滑後的目標功率減去實際發電功率，得到需要儲能裝置3平滑的波動的功率指令。 於一些實施例，主控制器20根據電網調度和各發電裝置發電情況，控制儲能裝置3實現能量時移，例如當發電裝置發出的電能較多而需求較小時，將能量存儲在儲能元件31中；當發電裝置發出的電能較少而需求較大時，將儲能元件31中的能量輸出，滿足實際需求。In some embodiments, the main controller 20 detects the power generated by the wind power generation device and/or the photovoltaic power generation device, and performs filtering and smoothing processing on the power through the energy storage device 3. Specifically, the smoothed target power minus the actual generated power, Obtain a fluctuating power command that needs to be smoothed by the energy storage device 3. In some embodiments, the main controller 20 controls the energy storage device 3 to implement energy time shift according to the grid dispatch and the power generation conditions of each power generation device. For example, when the power generation device generates more electric energy and the demand is small, the energy is stored in the energy storage device. In the element 31; when the power generation device generates less electric energy and the demand is greater, the energy in the energy storage element 31 is output to meet the actual demand.

圖9為本公開優選實施例的電力變換方法的步驟示意圖。電力變換方法可適用於圖1A及圖1B所示的電力變換系統2中。如圖9所示，電力變換方法包含下列步驟S1、S2、S3及S4。Fig. 9 is a schematic diagram of steps of a power conversion method according to a preferred embodiment of the present disclosure. The power conversion method can be applied to the power conversion system 2 shown in FIGS. 1A and 1B. As shown in FIG. 9, the power conversion method includes the following steps S1, S2, S3, and S4.

於步驟S1中，利用逆變單元23將對應的發電單元22的輸出電壓轉換為第一交流電壓。於一些實施例中，逆變單元23是依據中頻變壓器24的工作頻率ω將對應的發電單元22的輸出電壓轉換為第一交流電壓，其中第一交流電壓的頻率等於工作頻率ω。In step S1, the inverter unit 23 is used to convert the output voltage of the corresponding power generation unit 22 into a first AC voltage. In some embodiments, the inverter unit 23 converts the output voltage of the corresponding power generating unit 22 into the first AC voltage according to the operating frequency ω of the intermediate frequency transformer 24, wherein the frequency of the first AC voltage is equal to the operating frequency ω.

於步驟S2中，利用中頻變壓器24將第一交流電壓升壓為第二交流電壓。In step S2, the intermediate frequency transformer 24 is used to boost the first AC voltage to the second AC voltage.

於步驟S3中，利用整流裝置25對第二交流電壓進行整流並產生直流電壓。In step S3, the rectifying device 25 is used to rectify the second AC voltage and generate a DC voltage.

於步驟S4中，利用主控制器20接收上級控制命令，並基於上級控制命令協調多個電力變換裝置21的電能轉換操作。於一些實施例中，是利用主控制器20控制多個電力變換裝置21的輸出功率為固定值。於另一些實施例中，是利用主控制器20控制多個電力變換裝置21的輸出功率及儲能裝置3的輸出功率之和為固定值。In step S4, the main controller 20 is used to receive the upper-level control command, and the power conversion operation of the plurality of power conversion devices 21 is coordinated based on the upper-level control command. In some embodiments, the main controller 20 is used to control the output power of the plurality of power conversion devices 21 to a fixed value. In other embodiments, the main controller 20 is used to control the sum of the output power of the multiple power conversion devices 21 and the output power of the energy storage device 3 to a fixed value.

於一些實施例中，為了對採用風力發電的電力變換裝置21a進行控制，電力變換方法還包含下列步驟。首先，依據中頻變壓器24的工作頻率ω產生角度信號θ。接著，依據風力發電單元22a所對應的逆變單元 (即網側變換器23a) 的交流端的三相電流量Iabc 及角度信號θ產生有功電流Id 及無功電流Iq 。接著，採樣直流母線29的母線電壓Udc ，並依據直流母線電壓Udc 及其指令值Udcr 產生有功電流指令Idr 。而後，依據有功電流指令Idr 、無功電流指令Iqr 、有功電流Id 、無功電流Iq 及角度信號θ產生三相控制電勢Eabc 。最後，依據三相控制電勢Eabc 產生開關信號，並通過開關信號控制風力發電單元22a所對應的逆變單元 (即網側變換器23a) 的運行。In some embodiments, in order to control the power conversion device 21a using wind power generation, the power conversion method further includes the following steps. First, the angle signal θ is generated according to the operating frequency ω of the intermediate frequency transformer 24. Next, the active current I d and the reactive current I q are generated according to the three-phase current I abc and the angle signal θ of the AC end of the inverter unit (ie, the grid-side converter 23 a) corresponding to the wind power generation unit 22 a. Then, the bus voltage U dc of the DC bus 29 is sampled, and the active current command I dr is generated according to the DC bus voltage U dc and its command value U dcr . Then, a three-phase control potential E abc is generated according to the active current command I dr , the reactive current command I qr , the active current I d , the reactive current I q and the angle signal θ. Finally, a switching signal is generated according to the three-phase control potential E abc , and the operation of the inverter unit (ie, the grid-side converter 23a) corresponding to the wind power generation unit 22a is controlled by the switching signal.

於一些實施例中，為了對採用光伏發電的電力變換裝置21b進行控制，電力變換方法還包含下列步驟。首先，依據中頻變壓器24的工作頻率ω產生角度信號θ。接著，依據光伏發電單元22b所對應的逆變單元23b的交流端的三相電流量Iabc 及角度信號θ產生有功電流Id 及無功電流Iq 。接著，獲取光伏發電單元22的輸出電壓Uo 及輸出電流Io ，並根據輸出電壓Uo 及輸出電流Io 計算直流功率，並根據MPPT演算法獲取輸出電壓指令Uor 。接著，依據光伏發電單元22b的輸出電壓Uo 及輸出電壓指令Uor 產生有功電流指令Idr 。而後，依據有功電流指令Idr 、無功電流指令Iqr 、有功電流Id 、無功電流Iq 及角度信號θ產生三相控制電勢Eabc 。最後，依據三相控制電勢Eabc 產生開關信號，並通過開關信號控制光伏發電單元22b所對應的逆變單元23b的運行。In some embodiments, in order to control the power conversion device 21b using photovoltaic power generation, the power conversion method further includes the following steps. First, the angle signal θ is generated according to the operating frequency ω of the intermediate frequency transformer 24. Then, the active current I d and the reactive current I q are generated according to the three-phase current I abc and the angle signal θ at the AC end of the inverter unit 23 b corresponding to the photovoltaic power generation unit 22 b. Then, the output voltage U o and the output current I o of the photovoltaic power generation unit 22 are obtained, the DC power is calculated according to the output voltage U o and the output current I o , and the output voltage command U or is obtained according to the MPPT algorithm. Then, the active current command I dr is generated according to the output voltage U o and the output voltage command U or of the photovoltaic power generation unit 22 b. Then, a three-phase control potential E abc is generated according to the active current command I dr , the reactive current command I qr , the active current I d , the reactive current I q and the angle signal θ. Finally, a switching signal is generated according to the three-phase control potential E abc , and the operation of the inverter unit 23b corresponding to the photovoltaic power generation unit 22b is controlled by the switching signal.

於一些實施例中，為了對儲能裝置3進行控制，電力變換方法還包含下列步驟。首先，依據儲能元件電流I及電壓U計算儲能元件功率P。接著，接收主控制器20提供的該儲能單元30的功率指令Pr ，依據儲能元件的功率P及功率指令Pr 產生儲能元件的電流指令Ir 。而後，依據儲能元件的電流I及電流指令Ir 產生直流電勢E。最後，依據電勢E產生開關信號，並通過開關信號控制直流變換器32的運行。In some embodiments, in order to control the energy storage device 3, the power conversion method further includes the following steps. First, calculate the power P of the energy storage element according to the current I and the voltage U of the energy storage element. Then, the power command P r of the energy storage unit 30 provided by the main controller 20 is received , and the current command I r of the energy storage element is generated according to the power P and the power command P r of the energy storage element. Then, a direct current potential E is generated according to the current I of the energy storage element and the current command Ir. Finally, a switching signal is generated according to the potential E, and the operation of the DC converter 32 is controlled by the switching signal.

綜上所述，本公開提供一種電力變換系統及方法，通過並聯耦接於直流電網的至少一電力變換裝置，可提供高壓直流電至直流電網。此外，可依據直流電網的上級控制命令來協調多個電力變換裝置的電能轉換操作。借此，本公開的電力變換系統及方法是採用高壓直流輸電，可降低成本並減小輸電過程中的損耗。再者，通過設置儲能裝置，主控制器可通過控制儲能裝置靈活調整電力變換系統中的功率輸出的分配，實現控制目標。更甚者，主控制器可依據直流電網的供給負荷及電力變換裝置的發電情況進行能量調度，例如在電力變換裝置的發電量較多且直流電網的供給負荷較小時，可將多餘的能量存儲於儲能裝置的儲能元件中，而在電力變換裝置的發電量較少且直流電網的供給負荷較大時，則可將儲能元件所存儲的能量釋出而供給予直流電網。In summary, the present disclosure provides a power conversion system and method, which can provide high-voltage DC power to the DC power grid through at least one power conversion device coupled in parallel to the DC power grid. In addition, the power conversion operations of multiple power conversion devices can be coordinated according to the upper-level control commands of the DC grid. Therefore, the power conversion system and method of the present disclosure adopts high-voltage direct current transmission, which can reduce the cost and reduce the loss in the power transmission process. Furthermore, by setting the energy storage device, the main controller can flexibly adjust the distribution of power output in the power conversion system by controlling the energy storage device to achieve the control target. What's more, the main controller can perform energy dispatch according to the supply load of the DC grid and the power generation situation of the power conversion device. For example, when the power conversion device has a large amount of power generation and the supply load of the DC grid is small, the excess energy can be It is stored in the energy storage element of the energy storage device, and when the power conversion device generates less power and the supply load of the DC grid is large, the energy stored in the energy storage element can be released and supplied to the DC grid.

須注意，上述僅是為說明本公開而提出的優選實施例，本公開不限於所述的實施例，本公開的範圍由申請專利範圍決定。且本公開得由熟習此技術的人士任施匠思而為諸般修飾，然皆不脫申請專利範圍所欲保護者。It should be noted that the foregoing are only preferred embodiments proposed for explaining the present disclosure, and the present disclosure is not limited to the described embodiments, and the scope of the present disclosure is determined by the scope of the patent application. Moreover, the present disclosure can be modified in many ways by those who are familiar with this technology, but it does not deviate from those who wish to protect the scope of the patent application.

1:直流電網 2:電力變換系統 20:主控制器 21、21a、21b:電力變換裝置 22:發電單元 22a:風力發電單元 22b:光伏發電單元 23、23b:逆變單元 23a:網側變換器 24:中頻變壓器 25:整流裝置 26:機側變換器 27:濾波器 28:風機 29:直流母線 200a:第一控制電路 200b:第二控制電路 201:計算器 202:座標變換器 203:電壓調節器 204:電流調節器 205:PWM調製器 206:MPPT控制器 3:儲能裝置 30:儲能單元 31:儲能元件 32:直流變換器 300:第三控制電路 301:計算器 302:功率調節器 303:電流調節器 304:PWM調製器 ω:工作頻率 θ:角度信號 Iabc:三相電流量 Id:有功電流 Idr:有功電流指令 Iq:無功電流 Iqr:無功電流指令 Uo:輸出電壓 Udc:直流母線電壓 Udcr:指令值 Io:輸出電流 I:電流 U:電壓 P:功率 Pr:功率指令 Eabc、E:電勢1: DC grid 2: Power conversion system 20: Main controller 21, 21a, 21b: Power conversion device 22: Power generation unit 22a: Wind power generation unit 22b: Photovoltaic power generation unit 23, 23b: Inverter unit 23a: Grid-side converter 24: Intermediate frequency transformer 25: Rectifier 26: Machine-side converter 27: Filter 28: Fan 29: DC bus 200a: First control circuit 200b: Second control circuit 201: Calculator 202: Coordinate converter 203: Voltage Regulator 204: Current regulator 205: PWM modulator 206: MPPT controller 3: Energy storage device 30: Energy storage unit 31: Energy storage element 32: DC converter 300: Third control circuit 301: Calculator 302: Power Regulator 303: current regulator 304: PWM modulator ω: operating frequency θ: angle signal I abc : three-phase current I d : active current I dr : active current command I q : reactive current I qr : reactive current Command U o : output voltage U dc : DC bus voltage U dcr : command value I o : output current I: current U: voltage P: power P r : power command E abc , E: electric potential

圖1A為本公開優選實施例的電力變換系統的電路架構示意圖。FIG. 1A is a schematic diagram of a circuit structure of a power conversion system according to a preferred embodiment of the present disclosure.

圖1B為本公開另一優選實施例的電力變換系統的電路架構示意圖。FIG. 1B is a schematic diagram of a circuit structure of a power conversion system according to another preferred embodiment of the present disclosure.

圖2A為圖1A的電力變換系統的變化例的電路架構示意圖。FIG. 2A is a schematic diagram of a circuit structure of a variation of the power conversion system of FIG. 1A.

圖2B、圖2C及圖2D為圖1B的電力變換系統的變化例的電路架構示意圖。FIG. 2B, FIG. 2C, and FIG. 2D are schematic diagrams of the circuit structure of a modification of the power conversion system of FIG.

圖3A為本公開優選實施例的採用風力發電的電力變換裝置的電路結構示意圖。3A is a schematic diagram of a circuit structure of a power conversion device using wind power generation according to a preferred embodiment of the present disclosure.

圖3B、圖3C及圖3D為圖3A的電力變換裝置的變化例的電路結構示意圖。3B, 3C, and 3D are schematic diagrams of the circuit structure of a modified example of the power conversion device of FIG. 3A.

圖4為圖3A的電力變換裝置及其控制電路的電路結構示意圖。4 is a schematic diagram of the circuit structure of the power conversion device and its control circuit of FIG. 3A.

圖5A為本公開優選實施例的採用光伏發電的電力變換裝置的電路結構示意圖。FIG. 5A is a schematic diagram of a circuit structure of a power conversion device using photovoltaic power generation according to a preferred embodiment of the present disclosure.

圖5B為圖5A的電力變換裝置的變化例的電路結構示意圖。FIG. 5B is a schematic diagram of a circuit structure of a modification of the power conversion device of FIG. 5A.

圖6為圖5A的電力變換裝置及其控制電路的電路結構示意圖。6 is a schematic diagram of the circuit structure of the power conversion device and its control circuit of FIG. 5A.

圖7為本公開優選實施例的儲能裝置的電路結構示意圖。FIG. 7 is a schematic diagram of a circuit structure of an energy storage device according to a preferred embodiment of the present disclosure.

圖8為圖7的儲能裝置及其控制電路的電路結構示意圖。FIG. 8 is a schematic diagram of the circuit structure of the energy storage device and its control circuit of FIG. 7.

圖9為本公開優選實施例的電力變換方法的步驟示意圖。Fig. 9 is a schematic diagram of steps of a power conversion method according to a preferred embodiment of the present disclosure.

1:直流電網 1: DC grid

2:電力變換系統 2: Power conversion system

20:主控制器 20: main controller

21:電力變換裝置 21: Power conversion device

22:發電單元 22: power generation unit

23:逆變單元 23: Inverter unit

24:中頻變壓器 24: Intermediate frequency transformer

25:整流裝置 25: Rectifier

Claims (22)

一種電力變換系統，耦接於一直流電網，且包含： 至少一電力變換裝置，並聯耦接於該直流電網，其中每一該電力變換裝置包含： 至少一發電單元； 至少一逆變單元，其中每一該逆變單元電連接於對應的該發電單元，將該發電單元的一輸出電壓轉換為一第一交流電壓； 一中頻變壓器，電連接於該至少一逆變單元，並將該第一交流電壓升壓為一第二交流電壓；以及 一整流裝置，電連接於該中頻變壓器及該直流電網，對該第二交流電壓進行整流並輸出一直流電壓；以及 一主控制器，被配置為接收一上級控制命令，以基於該上級控制命令協調該至少一電力變換裝置的電能轉換操作。A power conversion system, coupled to a DC power grid, and including: At least one power conversion device is coupled to the DC grid in parallel, and each of the power conversion devices includes: At least one power generation unit; At least one inverter unit, each of the inverter units is electrically connected to the corresponding power generation unit, and an output voltage of the power generation unit is converted into a first AC voltage; An intermediate frequency transformer, electrically connected to the at least one inverter unit, and boosting the first AC voltage to a second AC voltage; and A rectifier device, electrically connected to the intermediate frequency transformer and the DC grid, to rectify the second AC voltage and output a DC voltage; and A main controller is configured to receive an upper-level control command to coordinate the power conversion operation of the at least one power conversion device based on the upper-level control command. 如請求項1所述的電力變換系統，其中該整流裝置包含多個橋臂，每一該橋臂具有一節點，該節點電連接於該中頻變壓器並將該橋臂分為兩個支路，每一該支路由多個整流元件串聯構成。The power conversion system according to claim 1, wherein the rectifying device includes a plurality of bridge arms, each of the bridge arms has a node, the node is electrically connected to the intermediate frequency transformer and the bridge arm is divided into two branches Each branch is composed of multiple rectifier elements connected in series. 如請求項1或2所述的電力變換系統，其中該中頻變壓器包含多個低壓繞組和一個高壓繞組，每一該低壓繞組電連接於對應的該逆變單元。The power conversion system according to claim 1 or 2, wherein the intermediate frequency transformer includes a plurality of low-voltage windings and a high-voltage winding, and each of the low-voltage windings is electrically connected to the corresponding inverter unit. 如請求項1所述的電力變換系統，其中於任一該電力變換裝置中，該逆變單元依據該中頻變壓器的一工作頻率將對應的該發電單元的該輸出電壓轉換為該第一交流電壓，且該第一交流電壓的頻率等於該工作頻率。The power conversion system according to claim 1, wherein in any of the power conversion devices, the inverter unit converts the output voltage of the corresponding power generation unit into the first AC according to an operating frequency of the intermediate frequency transformer Voltage, and the frequency of the first AC voltage is equal to the operating frequency. 如請求項4所述的電力變換系統，其中於至少一個該電力變換裝置中，該發電單元為風力發電單元；每一該逆變單元包含一第一控制電路，其中該第一控制電路依據該工作頻率及該逆變單元的多個電信號而產生一開關信號，並通過該開關信號控制該逆變單元的轉換操作。The power conversion system according to claim 4, wherein in at least one of the power conversion devices, the power generation unit is a wind power generation unit; each of the inverter units includes a first control circuit, wherein the first control circuit is based on the The operating frequency and the multiple electrical signals of the inverter unit generate a switching signal, and the switching operation of the inverter unit is controlled by the switching signal. 如請求項5所述的電力變換系統，其中該第一控制電路包含： 一計算器，依據該工作頻率產生一角度信號； 一座標變換器，依據該逆變單元的交流端的一三相電流量及該角度信號產生一有功電流及一無功電流； 一電壓調節器，採樣一直流母線的一直流母線電壓，依據該直流母線電壓及其指令值產生一有功電流指令； 一電流調節器，依據該有功電流指令、一無功電流指令、該有功電流、該無功電流及該角度信號產生一電勢；以及 一PWM調製器，依據該電勢產生該開關信號，其中該第一控制電路通過該開關信號控制該逆變單元的運行。The power conversion system according to claim 5, wherein the first control circuit includes: A calculator to generate an angle signal according to the operating frequency; A standard converter generates an active current and a reactive current according to a three-phase current of the AC terminal of the inverter unit and the angle signal; A voltage regulator, sampling the DC bus voltage of the DC bus, and generating an active current command based on the DC bus voltage and its command value; A current regulator that generates an electric potential according to the active current command, a reactive current command, the active current, the reactive current, and the angle signal; and A PWM modulator generates the switching signal according to the electric potential, wherein the first control circuit controls the operation of the inverter unit through the switching signal. 如請求項5所述的電力變換系統，其中該風力發電單元的該輸出電壓為小於1KV的低壓或大於1KV的高壓，該逆變單元對應為低壓逆變單元或高壓逆變單元。The power conversion system according to claim 5, wherein the output voltage of the wind power generation unit is a low voltage less than 1KV or a high voltage greater than 1KV, and the inverter unit corresponds to a low voltage inverter unit or a high voltage inverter unit. 如請求項4所述的電力變換系統，其中於至少一個該電力變換裝置中，該發電單元為光伏發電單元，每一該逆變單元包含一第二控制電路，其中該第二控制電路依據該工作頻率及該逆變單元的多個電信號而產生一開關信號，並通過該開關信號控制該逆變單元的轉換操作。The power conversion system according to claim 4, wherein in at least one of the power conversion devices, the power generation unit is a photovoltaic power generation unit, and each of the inverter units includes a second control circuit, wherein the second control circuit is based on the The operating frequency and the multiple electrical signals of the inverter unit generate a switching signal, and the switching operation of the inverter unit is controlled by the switching signal. 如請求項8所述的電力變換系統，其中該第二控制電路包含： 一計算器，依據該工作頻率產生一角度信號； 一座標變換器，依據該逆變單元的交流端的一三相電流量及角度信號產生一有功電流及一無功電流； 一MPPT控制器，依據該光伏發電單元的該輸出電壓及一輸出電流獲取一輸出電壓指令； 一電壓調節器，依據該光伏發電單元的該輸出電壓及該輸出電壓指令產生一有功電流指令； 一電流調節器，依據該有功電流指令、一無功電流指令、該有功電流、該無功電流及該角度信號產生一電勢；以及 一PWM調製器，依據該電勢產生該開關信號，其中該第二控制電路通過該開關信號控制該逆變單元的運行。The power conversion system according to claim 8, wherein the second control circuit includes: A calculator to generate an angle signal according to the operating frequency; A standard converter generates an active current and a reactive current according to a three-phase current and angle signal at the AC terminal of the inverter unit; An MPPT controller, which obtains an output voltage command according to the output voltage and an output current of the photovoltaic power generation unit; A voltage regulator, which generates an active current command according to the output voltage of the photovoltaic power generation unit and the output voltage command; A current regulator that generates an electric potential according to the active current command, a reactive current command, the active current, the reactive current, and the angle signal; and A PWM modulator generates the switching signal according to the electric potential, wherein the second control circuit controls the operation of the inverter unit through the switching signal. 如請求項4所述的電力變換系統，其中至少一個該電力變換裝置包括一第一電力變換裝置及一第二電力變換裝置，並聯耦接於該直流電網；於該第一電力變換裝置中，該發電單元為風力發電單元；於該第二電力變換裝置中，該發電單元為光伏發電單元。The power conversion system according to claim 4, wherein at least one of the power conversion devices includes a first power conversion device and a second power conversion device, coupled to the DC grid in parallel; in the first power conversion device, The power generation unit is a wind power generation unit; in the second power conversion device, the power generation unit is a photovoltaic power generation unit. 8及10中任一項所述的電力變換系統，還包含一儲能裝置，其中該儲能裝置與該電力變換裝置並聯耦接於該直流電網，該儲能裝置包含多個儲能單元，每一該儲能單元包含相連接的一儲能元件及一直流變換器，多個該直流變換器串聯連接形成一直流輸出端耦接至該直流電網。The power conversion system according to any one of 8 and 10, further comprising an energy storage device, wherein the energy storage device and the power conversion device are coupled to the DC grid in parallel, and the energy storage device includes a plurality of energy storage units, Each of the energy storage units includes an energy storage element and a DC converter connected to each other, and a plurality of the DC converters are connected in series to form a DC output terminal coupled to the DC power grid. 如請求項11所述的電力變換系統，其中該主控制器接收該多個儲能元件的荷電狀態，並基於該上級控制命令及該荷電狀態產生該多個直流變換器的功率指令。The power conversion system according to claim 11, wherein the main controller receives the state of charge of the plurality of energy storage elements, and generates power commands of the plurality of DC converters based on the upper-level control command and the state of charge. 如請求項12所述的電力變換系統，其中該儲能單元還包含一第三控制電路，其中該第三控制電路包含： 一計算器，依據該儲能元件的一電流及一電壓計算獲得該儲能元件的一功率； 一功率調節器，依據該功率及一功率指令產生一電流指令； 一電流調節器，依據該電流指令及該電流產生一電勢；以及 一PWM調製器，依據該電勢產生一開關信號，其中該第三控制電路通過該開關信號控制該直流變換器的運行。The power conversion system according to claim 12, wherein the energy storage unit further includes a third control circuit, wherein the third control circuit includes: A calculator for calculating and obtaining a power of the energy storage element according to a current and a voltage of the energy storage element; A power regulator, which generates a current command according to the power and a power command; A current regulator that generates an electric potential according to the current command and the current; and A PWM modulator generates a switching signal according to the electric potential, wherein the third control circuit controls the operation of the DC converter through the switching signal. 如請求項11所述的電力變換系統，其中該主控制器被配置為控制該至少一個電力變換裝置的輸出功率為一固定值；或該主控制器被配置為控制該至少一個電力變換裝置的輸出功率及該儲能裝置的輸出功率之和為該固定值。The power conversion system according to claim 11, wherein the main controller is configured to control the output power of the at least one power conversion device to a fixed value; or the main controller is configured to control the output power of the at least one power conversion device The sum of the output power and the output power of the energy storage device is the fixed value. 一種電力變換方法，適用於一電力變換系統，其中該電力變換系統耦接於一直流電網並包含至少一電力變換裝置及一主控制器，該至少一電力變換裝置並聯耦接於該直流電網，每一該電力變換裝置包含至少一發電單元、至少一逆變單元、一中頻變壓器及一整流裝置，該電力變換方法包含： (a) 利用該逆變單元將對應的該發電單元的一輸出電壓轉換為一第一交流電壓； (b) 利用該中頻變壓器將該第一交流電壓升壓為一第二交流電壓； (c) 利用該整流裝置對該第二交流電壓進行整流並產生一直流電壓；以及 (d) 利用該主控制器接收一上級控制命令，並基於該上級控制命令協調該至少一電力變換裝置的電能轉換操作。A power conversion method is suitable for a power conversion system, wherein the power conversion system is coupled to a DC power grid and includes at least one power conversion device and a main controller, the at least one power conversion device is coupled in parallel to the DC power grid, Each power conversion device includes at least one power generation unit, at least one inverter unit, an intermediate frequency transformer, and a rectifier device, and the power conversion method includes: (a) Using the inverter unit to convert an output voltage of the corresponding power generation unit into a first AC voltage; (b) Using the intermediate frequency transformer to boost the first AC voltage into a second AC voltage; (c) Using the rectifying device to rectify the second AC voltage and generate a DC voltage; and (d) Using the main controller to receive an upper-level control command, and coordinate the power conversion operation of the at least one power conversion device based on the upper-level control command. 如請求項15所述的電力變換方法，其中於該步驟 (a) 中，該逆變單元是依據該中頻變壓器的一工作頻率將對應的該發電單元的該輸出電壓轉換為該第一交流電壓，其中該第一交流電壓的頻率等於該工作頻率。The power conversion method according to claim 15, wherein in the step (a), the inverter unit converts the output voltage of the corresponding power generating unit into the first AC according to an operating frequency of the intermediate frequency transformer Voltage, wherein the frequency of the first AC voltage is equal to the operating frequency. 如請求項16所述的電力變換方法，其中至少一個該電力變換裝置的該發電單元為風力發電單元，該電力變換方法還包含步驟： (e1) 依據該工作頻率產生一角度信號； (e2) 依據該風力發電單元所對應的該逆變單元的交流端的一三相電流量及該角度信號產生一有功電流及一無功電流； (e3) 採樣一直流母線的一直流母線電壓，依據該直流母線電壓及其指令值產生一有功電流指令； (e4) 依據該有功電流指令、一無功電流指令、該有功電流、該無功電流及該角度信號產生一電勢；以及 (e5) 依據該電勢產生一開關信號，並通過該開關信號控制該風力發電單元所對應的該逆變單元的運行。The power conversion method according to claim 16, wherein the power generation unit of at least one of the power conversion devices is a wind power generation unit, and the power conversion method further includes the steps: (e1) Generate an angle signal according to the operating frequency; (e2) Generate an active current and a reactive current according to a three-phase current and the angle signal of the AC terminal of the inverter unit corresponding to the wind power unit; (e3) Sampling the DC bus voltage of the DC bus, and generate an active current command based on the DC bus voltage and its command value; (e4) Generate an electric potential based on the active current command, a reactive current command, the active current, the reactive current, and the angle signal; and (e5) A switch signal is generated according to the electric potential, and the operation of the inverter unit corresponding to the wind power unit is controlled by the switch signal. 如請求項16所述的電力變換方法，其中至少一個該電力變換裝置的該發電單元為光伏發電單元，該電力變換方法還包含步驟： (f1) 依據該工作頻率產生一角度信號； (f2) 依據該光伏發電單元所對應的該逆變單元的交流端的一三相電流量及該角度信號計算一有功電流及一無功電流； (f3) 依據該光伏發電單元的該輸出電壓及一輸出電流獲取一輸出電壓指令； (f4) 依據該光伏發電單元的該輸出電壓及該輸出電壓指令產生一有功電流指令 (f5) 依據該有功電流指令、一無功電流指令、該有功電流、該無功電流及該角度信號產生一電勢；以及 (f6) 依據該電勢產生一開關信號，並通過該開關信號控制該光伏發電單元所對應的該逆變單元的運行。The power conversion method according to claim 16, wherein the power generation unit of at least one of the power conversion devices is a photovoltaic power generation unit, and the power conversion method further includes the steps: (f1) Generate an angle signal according to the operating frequency; (f2) Calculate an active current and a reactive current according to a three-phase current and the angle signal of the AC terminal of the inverter unit corresponding to the photovoltaic power generation unit; (f3) Obtain an output voltage command according to the output voltage and an output current of the photovoltaic power generation unit; (f4) Generate an active current command based on the output voltage of the photovoltaic power generation unit and the output voltage command (f5) Generate an electric potential based on the active current command, a reactive current command, the active current, the reactive current, and the angle signal; and (f6) A switch signal is generated according to the electric potential, and the operation of the inverter unit corresponding to the photovoltaic power generation unit is controlled by the switch signal. 如請求項15-18中任一項所述的電力變換方法，其中該電力變換系統還包含一儲能裝置，該儲能裝置與該至少一電力變換裝置並聯耦接於該直流電網，該儲能裝置包含多個儲能單元，每一該儲能單元包含相連接的一儲能元件及一直流變換器，多個該直流變換器串聯連接形成一直流輸出端以耦接至該直流電網。The power conversion method according to any one of claim 15-18, wherein the power conversion system further includes an energy storage device, the energy storage device and the at least one power conversion device are coupled to the DC grid in parallel, and the storage The energy device includes a plurality of energy storage units, each of the energy storage units includes an energy storage element and a DC converter connected in series, and a plurality of the DC converters are connected in series to form a DC output terminal to be coupled to the DC power grid. 如請求項19所述的電力變換方法，還包含步驟：利用該主控制器接收該多個儲能元件的荷電狀態，並基於該上級控制命令及該荷電狀態產生該多個直流變換器的功率指令。The power conversion method according to claim 19, further comprising the step of: receiving the state of charge of the plurality of energy storage elements by the main controller, and generating the power of the plurality of DC converters based on the superior control command and the state of charge instruction. 如請求項19所述的電力變換方法，還包含步驟： (g1) 依據該儲能元件的一電流及一電壓計算獲得該儲能元件的一功率； (g2) 依據該功率及一功率指令產生一電流指令； (g3) 依據該電流指令及該電流產生一電勢；以及 (g4) 依據該電勢產生一開關信號，並通過該開關信號控制該直流變換器的運行。The power conversion method according to claim 19, further comprising the steps: (g1) Calculate and obtain a power of the energy storage element based on a current and a voltage of the energy storage element; (g2) Generate a current command based on the power and a power command; (g3) Generate an electric potential based on the current command and the current; and (g4) A switching signal is generated according to the electric potential, and the operation of the DC converter is controlled by the switching signal. 如請求項19所述的電力變換方法，還包含步驟：利用主控制器控制該至少一電力變換裝置的輸出功率為一固定值，或利用該主控制器控制該至少一電力變換裝置的輸出功率及該儲能裝置的輸出功率之和為該固定值。The power conversion method according to claim 19, further comprising the step of: using a main controller to control the output power of the at least one power conversion device to a fixed value, or using the main controller to control the output power of the at least one power conversion device The sum of the output power of the energy storage device is the fixed value.
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