TW202341604A - Power conversion system - Google Patents

Power conversion system Download PDF

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TW202341604A
TW202341604A TW112111901A TW112111901A TW202341604A TW 202341604 A TW202341604 A TW 202341604A TW 112111901 A TW112111901 A TW 112111901A TW 112111901 A TW112111901 A TW 112111901A TW 202341604 A TW202341604 A TW 202341604A
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Taiwan
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power
preset
frequency
conversion system
power conversion
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TW112111901A
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Chinese (zh)
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TWI829573B (en
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劉偉霖
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達方電子股份有限公司
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Priority to JP2023056822A priority Critical patent/JP2023155188A/en
Priority to US18/131,380 priority patent/US20230327449A1/en
Publication of TW202341604A publication Critical patent/TW202341604A/en
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/66—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/04—Circuit arrangements for ac mains or ac distribution networks for connecting networks of the same frequency but supplied from different sources
    • H02J3/06—Controlling transfer of power between connected networks; Controlling sharing of load between connected 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
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/28—Arrangements for balancing of the load in a network by storage of energy
    • H02J3/32—Arrangements for balancing of the load in a network by storage of energy using batteries with converting means
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/381—Dispersed generators
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/388—Islanding, i.e. disconnection of local power supply from the 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
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/0047—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with monitoring or indicating devices or circuits
    • H02J7/0048—Detection of remaining charge capacity or state of charge [SOC]
    • 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
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/34—Parallel operation in networks using both storage and other dc sources, e.g. providing buffering
    • H02J7/35—Parallel operation in networks using both storage and other dc sources, e.g. providing buffering with light sensitive cells

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Supply And Distribution Of Alternating Current (AREA)
  • Charge And Discharge Circuits For Batteries Or The Like (AREA)
  • Inverter Devices (AREA)

Abstract

A power conversion system (PCS), in which the microcontroller unit determines current charged ratio of a rechargeable battery according to a state-of-charge (SOC) signal received from the rechargeable battery, and obtains an output power of the PCS according to the voltage and current detected by a voltmeter-and-current meter of the PCS. When the microcontroller unit detects a grid disconnection, it adjusts a frequency of an output alternating current of the power conversion system based on the output power and the current charged ratio of the charging battery, causing the frequency of the alternating current to switch between no less than three different frequencies. The greater current charged ratio of the charging battery, the lower the frequency the alternating current is switched to.

Description

功率轉換系統Power conversion system

本發明係有關於一種功率轉換系統（Power conversion system；PCS），尤指一種可依據充電電池的已充電比例調整其輸出的交流電頻率之功率轉換系統。The present invention relates to a power conversion system (PCS), and in particular, to a power conversion system that can adjust the output alternating current frequency of a rechargeable battery according to its charged ratio.

功率轉換系統（Power conversion system；PCS）是一種雙向的電力轉換逆變器，可用於併網(on-grid)和離網(off-grid)的電能儲存應用。如何有效地操作功率轉換系統，一直是本技術領域的一項重要課題。A power conversion system (PCS) is a bidirectional power conversion inverter that can be used for on-grid and off-grid electrical energy storage applications. How to effectively operate a power conversion system has always been an important issue in this technical field.

本發明的功率轉換系統中包含交流電電源埠、直流電電源埠、電壓電流計以及微控制單元。直流電電源埠耦接於充電電池。電壓電流計耦接於交流電電源埠，用以偵測功率轉換系統從交流電電源埠所輸出的電壓及電流。微控制單元用以控制功率轉換系統的操作，並從充電電池接收荷電狀態信號。其中微控制單元根據荷電狀態信號而得知充電電池的目前已充電比例，並依據電壓電流計所偵測到的電壓及電流，進而計算出功率轉換系統的對外輸出功率。當微控制單元偵測到發生市電離網時，微控制單元則執行下述步驟：當判斷出充電電池的目前已充電比例大於第一預設比例時，將功率轉換系統從交流電電源埠所輸出的交流電的頻率調整至第一頻率，以使耦接於交流電電源埠的太陽光電變流器停止輸出電能；當判斷出充電電池的目前已充電比例小於第一預設比例且大於第二預設比例，且對外輸出功率的負值大於第一預設功率時，將交流電電源埠所輸出的交流電的頻率調升第一預設值；以及當判斷出充電電池的目前已充電比例小於第三預設比例時，將交流電電源埠所輸出的交流電的頻率調降第二預設值。The power conversion system of the present invention includes an AC power supply port, a DC power supply port, a voltage ammeter and a micro control unit. The DC power port is coupled to the rechargeable battery. The voltage and ammeter is coupled to the AC power port for detecting the voltage and current output by the power conversion system from the AC power port. The microcontrol unit controls the operation of the power conversion system and receives the state-of-charge signal from the rechargeable battery. The micro control unit learns the current charging ratio of the rechargeable battery based on the state-of-charge signal, and calculates the external output power of the power conversion system based on the voltage and current detected by the voltage and ammeter. When the micro-control unit detects that the mains power is off-grid, the micro-control unit performs the following steps: when it is determined that the current charged ratio of the rechargeable battery is greater than the first preset ratio, the power conversion system outputs the power from the AC power port. The frequency of the alternating current is adjusted to the first frequency so that the solar photovoltaic converter coupled to the alternating current power supply port stops outputting electric energy; when it is determined that the current charged proportion of the rechargeable battery is less than the first preset proportion and greater than the second preset proportion, and when the negative value of the external output power is greater than the first preset power, the frequency of the AC power output by the AC power port is increased to the first preset value; and when it is determined that the current charged proportion of the rechargeable battery is less than the third preset value When setting the ratio, the frequency of the AC power output by the AC power port is reduced by a second preset value.

第1圖是本發明一實施例之功率轉換系統（Power conversion system；PCS）100與所耦接的市電10、負載60、充電電池70、太陽光電變流器（Photovoltaic inverter；PV inverter）50及太陽能板80之功能方塊圖。太陽光電變流器50用以將太陽能板80所產生的直流電轉換成交流電，並將轉換後的交流電饋入負載60及/或功率轉換系統100。Figure 1 shows a power conversion system (PCS) 100 and the coupled mains 10, load 60, rechargeable battery 70, photovoltaic inverter (PV inverter) 50 and Functional block diagram of solar panel 80. The solar photovoltaic converter 50 is used to convert the DC power generated by the solar panel 80 into AC power, and feed the converted AC power into the load 60 and/or the power conversion system 100 .

功率轉換系統100包含市電連接埠12、交流電電源埠14、直流電電源埠16、電壓電流計30以及微控制單元（microcontroller unit；MCU）40。功率轉換系統100可通過市電連接埠12連接於市電10，並從市電10接收電力。直流電電源埠16耦接於充電電池70，而功率轉換系統100可透過直流電電源埠16對充電電池70進行充電或從充電電池70接收電力。電壓電流計30耦接於交流電電源埠14，用以偵測功率轉換系統100從交流電電源埠14所輸出的電壓Va及電流Ia。其中，電壓Va及電流Ia分別為交流電電壓及交流電電流。微控制單元40用以控制功率轉換系統的操作，並從充電電池70接收荷電狀態信號SOC。微控制單元40可根據荷電狀態信號SOC得到充電電池70的目前已充電比例，並依據電壓電流計30所偵測到的電壓Va及電流Ia，得到功率轉換系統100的對外輸出功率P_Inv。當對外輸出功率P_Inv為正時，表示功率轉換系統100透過交流電電源埠14對外輸出電能；而當對外輸出功率P_Inv為負時，表示功率轉換系統100透過交流電電源埠14從外部接收電能。The power conversion system 100 includes a mains connection port 12 , an AC power port 14 , a DC power port 16 , a voltage and ammeter 30 and a microcontroller unit (MCU) 40 . The power conversion system 100 can be connected to the mains 10 through the mains connection port 12 and receive power from the mains 10 . The DC power port 16 is coupled to the rechargeable battery 70 , and the power conversion system 100 can charge the rechargeable battery 70 or receive power from the rechargeable battery 70 through the DC power port 16 . The voltage and ammeter 30 is coupled to the AC power port 14 for detecting the voltage Va and current Ia output by the power conversion system 100 from the AC power port 14 . Wherein, voltage Va and current Ia are alternating current voltage and alternating current current respectively. The micro control unit 40 is used to control the operation of the power conversion system and receive the state of charge signal SOC from the rechargeable battery 70 . The micro control unit 40 can obtain the current charging ratio of the rechargeable battery 70 based on the state of charge signal SOC, and obtain the external output power P_Inv of the power conversion system 100 based on the voltage Va and current Ia detected by the voltage and ammeter 30 . When the external output power P_Inv is positive, it means that the power conversion system 100 outputs electric energy to the outside through the AC power port 14 ; and when the external output power P_Inv is negative, it means that the power conversion system 100 receives electric energy from the outside through the AC power port 14 .

功率轉換系統100還可包含直流轉換器20以及電源逆變器22。直流轉換器20用以將充電電池70所輸出的直流電壓Vb轉換成數值不同的直流電壓Vd，而電源逆變器22則是用以將直流電壓Vd轉換成交流電形式的電壓Va。The power conversion system 100 may also include a DC converter 20 and a power inverter 22 . The DC converter 20 is used to convert the DC voltage Vb output by the rechargeable battery 70 into a DC voltage Vd with different values, and the power inverter 22 is used to convert the DC voltage Vd into an alternating current voltage Va.

當微控制單元40偵測到發生市電離網（off-grid）時（例如：市電連接埠12與市電10之間的連接被切斷或市電10發生斷電時），微控制單元40會調整功率轉換系統100從交流電電源埠14所輸出的交流電的頻率F，進而控制功率轉換系統100所輸出的對外輸出功率P_Inv。請參考第2圖，第2圖是第1圖之太陽光電變流器50的對外輸出功率比值與功率轉換系統100所輸出的交流電的頻率F之間的關係圖。第2圖的橫軸表示功率轉換系統100從交流電電源埠14所輸出的交流電的頻率F，而第2圖的縱軸表示太陽光電變流器50的對外輸出功率比值。第2圖的縱軸標示100之處表示太陽光電變流器50以最大值（即100%）進行輸出，而而縱軸標示0之處表示太陽光電變流器50停止輸出。此外，當頻率F介於F_Start和F_Stop之間時，對外輸出功率比值與頻率F呈現線性的反向關係，亦即此時的外輸出功率比值越大，則交流電的頻率F會越低。其中，F_min＜F_normal＜F_Start＜F_Stop，而F_min表示功率轉換系統100所輸出的交流電之頻率F的最小值，F_normal為功率轉換系統100一般正常操作的頻率，F_Start所對應的對外輸出功率比值等於100%，而F_Stop所對應的對外輸出功率比值等於0%。其中，F_min可簡稱為「最小頻率」，F_normal可簡稱為「一般頻率」，F_Start可簡稱為「啟始頻率」，而F_Stop可簡稱為「停止頻率」。啟始頻率F_Start例如是60赫茲（Hz），而停止頻率F_Stop例如是60.5赫茲（Hz）。此外，另有一截止頻率F_trip，用以強制太陽光電變流器50停止輸出電能，而使功率轉換系統100進入過頻保護（F_Trip例如是60.6赫茲（Hz）。由於交流電的頻率F一旦到達F_Trip以上，太陽光電變流器50就會停止輸出電能，故頻率F_trip可稱為「截止頻率」）。When the micro-control unit 40 detects that the mains power is off-grid (for example, the connection between the mains connection port 12 and the mains 10 is cut off or the mains 10 is out of power), the micro-control unit 40 will adjust The frequency F of the AC power output by the power conversion system 100 from the AC power port 14 further controls the external output power P_Inv output by the power conversion system 100 . Please refer to Figure 2. Figure 2 is a relationship diagram between the external output power ratio of the solar photovoltaic converter 50 in Figure 1 and the frequency F of the alternating current output by the power conversion system 100. The horizontal axis of FIG. 2 represents the frequency F of the AC power output by the power conversion system 100 from the AC power port 14 , and the vertical axis of FIG. 2 represents the external output power ratio of the solar photovoltaic converter 50 . The vertical axis marked 100 in Figure 2 indicates that the solar photovoltaic converter 50 outputs at the maximum value (ie, 100%), and the vertical axis marked 0 indicates that the solar photovoltaic converter 50 stops outputting. In addition, when the frequency F is between F_Start and F_Stop, the external output power ratio has a linear inverse relationship with the frequency F. That is, the greater the external output power ratio at this time, the lower the frequency F of the alternating current will be. Among them, F_min＜F_normal＜F_Start＜F_Stop, and F_min represents the minimum value of the frequency F of the alternating current output by the power conversion system 100, F_normal is the general normal operating frequency of the power conversion system 100, and the external output power ratio corresponding to F_Start is equal to 100 %, and the external output power ratio corresponding to F_Stop is equal to 0%. Among them, F_min can be referred to as "minimum frequency", F_normal can be referred to as "general frequency", F_Start can be referred to as "start frequency", and F_Stop can be referred to as "stop frequency". The start frequency F_Start is, for example, 60 Hz, and the stop frequency F_Stop is, for example, 60.5 Hz. In addition, there is a cut-off frequency F_trip, which is used to force the solar photovoltaic converter 50 to stop outputting electric energy, so that the power conversion system 100 enters over-frequency protection (F_Trip is, for example, 60.6 Hz). Since the frequency F of the alternating current reaches above F_Trip , the solar photovoltaic converter 50 will stop outputting electric energy, so the frequency F_trip can be called the "cut-off frequency").

第3A圖和第3B圖是第1圖之微控制單元40控制功率轉換系統100的流程圖。當微控制單元40偵測到發生市電離網（off-grid）時（例如：市電連接埠12與市電10之間的連接被切斷或市電10發生斷電時））或重新連線併網饋電時，微控制單元40會執行第3A圖和第3B圖的流程，此流程包含下述步驟：Figures 3A and 3B are flow charts of the micro control unit 40 in Figure 1 controlling the power conversion system 100. When the micro control unit 40 detects that the mains power is off-grid (for example: the connection between the mains connection port 12 and the mains 10 is cut off or the mains 10 is out of power)) or reconnects to the grid. When feeding power, the micro control unit 40 will execute the process of Figure 3A and Figure 3B. This process includes the following steps:

步驟S200：微控制單元40判斷功率轉換系統100是否重新連網？其中，當轉換系統100重新連上市電10或太陽光電變流器50開始供電時，即表示功率轉換系統100重新連網。當微控制單元40判斷出功率轉換系統100並未重新連網時，執行步驟S201；反之，則執行步驟S210；Step S200: The micro control unit 40 determines whether the power conversion system 100 is reconnected to the network? When the conversion system 100 is reconnected to the mains 10 or the solar photovoltaic converter 50 starts to provide power, it means that the power conversion system 100 is reconnected to the network. When the micro control unit 40 determines that the power conversion system 100 has not been reconnected to the network, step S201 is executed; otherwise, step S210 is executed;

步驟S201：微控制單元40根據荷電狀態信號SOC判斷充電電池70的目前已充電比例是否大於預設比例S2？其中，預設比例S2可介於20％至90％，而當微控制單元40判斷出充電電池70的目前已充電比例大於預設比例S2時，執行步驟S202；反之，則執行步驟S203；Step S201: The micro control unit 40 determines whether the current charged ratio of the rechargeable battery 70 is greater than the preset ratio S2 according to the state of charge signal SOC. The preset ratio S2 may be between 20% and 90%. When the micro control unit 40 determines that the currently charged ratio of the rechargeable battery 70 is greater than the preset ratio S2, step S202 is executed; otherwise, step S203 is executed;

步驟S202：微控制單元40將功率轉換系統100從交流電電源埠14所輸出的交流電的頻率F提高至（F_Trip + Max_Step），以使耦接於交流電電源埠14的太陽光電變流器50停止輸出電能，而進入過頻保護。其中，F_Trip例如是62赫茲（Hz），而Max_step例如是0.3赫茲。更進一步地說，一旦交流電的頻率F到達F_Trip以上，太陽光電變流器50就會停止輸出電能，頻率F_Trip可稱為「截止頻率」。因此，當交流電的頻率F等於（F_Trip + Max_step）時，則可更加確保太陽光電變流器50會停止輸出電能；此外，Max_Step可以等於（（F_Stop－F_Start）/2），而F_Trip大於F_Stop；當微控制單元40執行完步驟S202後，即回到步驟S200；Step S202: The micro control unit 40 increases the frequency F of the AC power output by the power conversion system 100 from the AC power port 14 to (F_Trip + Max_Step), so that the solar photovoltaic converter 50 coupled to the AC power port 14 stops outputting power, and enters over-frequency protection. Among them, F_Trip is, for example, 62 Hertz (Hz), and Max_step is, for example, 0.3 Hz. Furthermore, once the frequency F of the alternating current reaches above F_Trip, the solar photovoltaic converter 50 will stop outputting electric energy, and the frequency F_Trip can be called the "cutoff frequency". Therefore, when the frequency F of the alternating current is equal to (F_Trip + Max_step), it is more ensured that the solar photovoltaic converter 50 will stop outputting electric energy; in addition, Max_Step can be equal to ((F_Stop-F_Start)/2), and F_Trip is greater than F_Stop; After the micro control unit 40 finishes executing step S202, it returns to step S200;

步驟S203：微控制單元40根據荷電狀態信號SOC判斷充電電池70的目前已充電比例是否大於預設比例S3？其中，預設比例S3小於預設比例S2，並可介於15％至85％。當微控制單元40判斷出充電電池70的目前已充電比例大於預設比例S3時，執行步驟S204；反之，則執行步驟S207；Step S203: The micro control unit 40 determines whether the current charged ratio of the rechargeable battery 70 is greater than the preset ratio S3 according to the state of charge signal SOC. The preset ratio S3 is smaller than the preset ratio S2 and can range from 15% to 85%. When the micro control unit 40 determines that the current charged ratio of the rechargeable battery 70 is greater than the preset ratio S3, step S204 is executed; otherwise, step S207 is executed;

步驟S204：微控制單元40判斷對外輸出功率P_Inv的負值（即：－P_Inv）是否大於預設功率P2？其中，當對外輸出功率P_Inv的負值為正時，即表示功率轉換系統100從外部接收電力，而預設功率P2例如是1000瓦，但並不以此為限。當微控制單元40並未判斷出對外輸出功率P_Inv的負值大於預設功率P2時，執行步驟S205；而當微控制單元40判斷出對外輸出功率P_Inv的負值大於預設功率P2時，執行步驟S209；Step S204: The micro control unit 40 determines whether the negative value of the external output power P_Inv (ie: -P_Inv) is greater than the preset power P2? When the negative value of the external output power P_Inv is positive, it means that the power conversion system 100 receives power from the outside, and the preset power P2 is, for example, 1000 watts, but is not limited thereto. When the micro control unit 40 does not determine that the negative value of the external output power P_Inv is greater than the preset power P2, step S205 is executed; and when the micro control unit 40 determines that the negative value of the external output power P_Inv is greater than the preset power P2, step S205 is executed. Step S209;

步驟S205：微控制單元40判斷對外輸出功率P_Inv是否小於預設功率P1？其中，預設功率P1小於預設功率P2，而預設功率P1例如是500瓦，但並不以此為限。當判斷出對外輸出功率P_Inv小於預設功率P1時，執行步驟S206；反之，則回到步驟S201；Step S205: The micro control unit 40 determines whether the external output power P_Inv is less than the preset power P1? The preset power P1 is smaller than the preset power P2, and the preset power P1 is, for example, 500 watts, but is not limited to this. When it is determined that the external output power P_Inv is less than the preset power P1, step S206 is executed; otherwise, step S201 is returned;

步驟S206：微控制單元40將頻率F調升一預設值Min_Step（即：F=F+Min_Step），並回到步驟S201；其中，預設值Min_Step可以等於（（F_Stop－F_Start）/8），而頻率F在此步驟中最高被調高至F_Stop，亦即頻率F在此步驟中的最大值F_Max為F_Stop。步驟S206的作用在於：當充電電池70的目前已充電比例大於預設比例S3，且對外輸出功率P_Inv小於預設功率P1時，藉由調升頻率F，而降低太陽光電變流器50的輸出功率；Step S206: The micro control unit 40 increases the frequency F by a preset value Min_Step (ie: F=F+Min_Step), and returns to step S201; where the preset value Min_Step can be equal to ((F_Stop-F_Start)/8) , and the frequency F is adjusted up to F_Stop in this step, that is, the maximum value F_Max of the frequency F in this step is F_Stop. The function of step S206 is to: when the current charged ratio of the rechargeable battery 70 is greater than the preset ratio S3 and the external output power P_Inv is less than the preset power P1, the output of the solar photovoltaic converter 50 is reduced by increasing the frequency F. power;

步驟S207：微控制單元40根據荷電狀態信號SOC判斷充電電池70的目前已充電比例是否小於預設比例S1？其中，預設比例S1小於預設比例S2及S3，並可介於10％至80％，而當微控制單元40判斷出充電電池70的目前已充電比例小於預設比例S1時，執行步驟S208；反之，則回到步驟S201；Step S207: The micro control unit 40 determines whether the current charged ratio of the rechargeable battery 70 is less than the preset ratio S1 according to the state of charge signal SOC. The preset ratio S1 is smaller than the preset ratios S2 and S3, and can be between 10% and 80%. When the micro control unit 40 determines that the currently charged ratio of the rechargeable battery 70 is smaller than the preset ratio S1, step S208 is executed. ; Otherwise, return to step S201;

步驟S208：微控制單元40將頻率F調降一預設值Min_Step（即：F = F － Min_Step），並回到步驟S201；其中，頻率F在此步驟中最低被調至F_Start，亦即頻率F在此步驟中的最小值F_Min為F_Start。步驟S208的作用在於：當充電電池70的目前已充電比例小於預設比例S1時，藉由調降頻率F，而調升太陽光電變流器50的輸出功率；Step S208: The micro control unit 40 decreases the frequency F by a preset value Min_Step (ie: F = F - Min_Step), and returns to step S201; in this step, the frequency F is adjusted to the lowest value F_Start, which is the frequency The minimum value of F in this step, F_Min, is F_Start. The function of step S208 is to: when the current charged ratio of the rechargeable battery 70 is less than the preset ratio S1, increase the output power of the solar photovoltaic converter 50 by lowering the frequency F;

步驟S209：微控制單元40將頻率F調升一預設值Mid_Step（即：F = F + Mid_Step），並回到步驟S201；其中，預設值Mid_Step可以等於（（F_Stop－F_Start）/4），而頻率F在此步驟中最高被調至F_Stop，亦即頻率F在此步驟中的最大值F_Max為F_Stop。步驟S209的作用在於：當充電電池70的目前已充電比例大於預設比例S3，且功率轉換系統100從外部所接收電力大於預設功率P2時，藉由調升頻率F，而降低太陽光電變流器50的輸出功率；Step S209: The micro control unit 40 increases the frequency F by a preset value Mid_Step (ie: F = F + Mid_Step), and returns to step S201; where the preset value Mid_Step can be equal to ((F_Stop-F_Start)/4) , and the frequency F is adjusted to the highest value F_Stop in this step, that is, the maximum value F_Max of the frequency F in this step is F_Stop. The function of step S209 is to: when the current charged ratio of the rechargeable battery 70 is greater than the preset ratio S3, and the power received by the power conversion system 100 from the outside is greater than the preset power P2, the frequency F is increased to reduce the solar power variation. The output power of the current converter 50;

步驟S210：微控制單元40根據荷電狀態信號SOC判斷充電電池70的目前已充電比例是否小於預設比例S1？若微控制單元40判斷充電電池70的目前已充電比例並未小於預設比例S1時，則執行步驟S211；反之，則執行步驟S212；Step S210: The micro control unit 40 determines whether the current charged ratio of the rechargeable battery 70 is less than the preset ratio S1 according to the state of charge signal SOC. If the micro control unit 40 determines that the current charged ratio of the rechargeable battery 70 is not less than the preset ratio S1, step S211 is executed; otherwise, step S212 is executed;

步驟S211：微控制單元40將頻率F設定為截止頻率F_Trip，以使太陽光電變流器50停止輸出電能，而進入過頻保護，並回到步驟S210；以及Step S211: The micro control unit 40 sets the frequency F to the cutoff frequency F_Trip, so that the solar photovoltaic converter 50 stops outputting electric energy and enters over-frequency protection, and returns to step S210; and

步驟S212：微控制單元40將頻率F調整至（F_Stop － Min_Step），並回到步驟S200。Step S212: The micro control unit 40 adjusts the frequency F to (F_Stop - Min_Step) and returns to step S200.

當太陽光電變流器50偵測到電壓或頻率超出正常工作範圍會啟動保護（例如：過壓、欠壓、過頻、欠頻、孤島運轉（Islanding）...等情況），進而不再輸出功率饋網，此時微控制單元40會判斷太陽光電變流器50是否跳脫，以依據狀態來調控功率轉換系統100的交流輸出頻率F，進而決定太陽光電變流器50是否可再重新連線併網饋電。若太陽光電變流器50偵測市電端的電壓與頻率符合正常的工作範圍時，則會判定可重新連網饋電的條件成立，而太陽光電變流器50計數特定秒數（例如：併網法規規範的300秒）後就會饋網輸出。When the solar photovoltaic converter 50 detects that the voltage or frequency exceeds the normal operating range, it will activate protection (for example: overvoltage, undervoltage, overfrequency, underfrequency, islanding, etc.), and then no longer The output power is fed into the network. At this time, the micro control unit 40 will determine whether the solar photovoltaic converter 50 has tripped, and adjust the AC output frequency F of the power conversion system 100 according to the status, thereby determining whether the solar photovoltaic converter 50 can be restarted. Connect to the grid for power supply. If the solar photovoltaic converter 50 detects that the voltage and frequency of the mains terminal are within the normal operating range, it will determine that the conditions for reconnection to the grid are met, and the solar photovoltaic converter 50 will count a specific number of seconds (for example: connected to the grid). The output will be fed into the network after 300 seconds as specified by regulations).

在本發明中，當頻率F介於F_Start和F_Stop之間時，對外輸出功率比值與頻率F呈現線性的反向關係，如第2圖所示。故相較於一般兩段式（即：太陽光電變流器以全輸出(100％)或無輸出(0％)的方式輸出）之控制方式，微控制單元40可以以更多段式的方式來調整太陽光電變流器50的輸出功率，而避免因太陽光電變流器瞬間地全輸出(100％)或無輸出(0％)而造成供電系統的不穩定。In the present invention, when the frequency F is between F_Start and F_Stop, the external output power ratio has a linear inverse relationship with the frequency F, as shown in Figure 2. Therefore, compared with the general two-stage control method (that is, the solar photovoltaic inverter outputs at full output (100%) or no output (0%)), the micro control unit 40 can operate in more stages. To adjust the output power of the solar photovoltaic converter 50, and avoid the instability of the power supply system caused by the instantaneous full output (100%) or no output (0%) of the solar photovoltaic converter.

此外，根據第2圖以及上述的步驟S203至S208可知，當微控制單元40偵測到發生市電離網（off-grid）時，微控制單元40會限制交流電電源埠10所輸出的交流電的頻率F在介於F_Start和F_Stop之間的預設範圍內，而在此預設範圍內，太陽光電變流器50的輸出功率與交流電的頻率F呈負相關。In addition, according to Figure 2 and the above steps S203 to S208, when the micro control unit 40 detects that the mains power is off-grid, the micro control unit 40 will limit the frequency of the alternating current output by the alternating current power port 10 F is within a preset range between F_Start and F_Stop, and within this preset range, the output power of the solar photovoltaic converter 50 is negatively correlated with the frequency F of the alternating current.

本發明的微控制單元40偵測到發生市電離網時則會讓功率轉換系統100輸出交流電頻率F，進而誘導太陽光電變流器50不進入孤島(Islanding)保護而能發電饋網，其能量可供給負載60與功率轉換系統100，微控制單元40會根據充電電池70的目前已充電比例，及對外輸出功率P_Inv的正負大小來動態調整功率轉換系統100所輸出的交流電的頻率，因此，功率轉換系統100之整體的電力潮流可得到有效率的調控。 以上所述僅為本發明之較佳實施例，凡依本發明申請專利範圍所做之均等變化與修飾，皆應屬本發明之涵蓋範圍。 When the micro-control unit 40 of the present invention detects that the mains power is off-grid, it will cause the power conversion system 100 to output the alternating current frequency F, thereby inducing the solar photovoltaic converter 50 to generate electricity and feed the grid without entering the islanding (Islanding) protection. The load 60 and the power conversion system 100 can be supplied. The micro control unit 40 will dynamically adjust the frequency of the alternating current output by the power conversion system 100 according to the current charging ratio of the rechargeable battery 70 and the positive and negative magnitude of the external output power P_Inv. Therefore, the power The overall power flow of the conversion system 100 can be efficiently controlled. The above are only preferred embodiments of the present invention, and all equivalent changes and modifications made in accordance with the patentable scope of the present invention shall fall within the scope of the present invention.

10:市電 12:市電連接埠 14:交流電電源埠 16:直流電電源埠 20:直流轉換器 22:電源逆變器 30:電壓電流計 40:微控制單元 50:太陽光電變流器 60:負載 70:充電電池 80:太陽能板 100:功率轉換系統 F:頻率 F_min:最小頻率 F_normal:一般頻率 F_Start:啟始頻率 F_Stop:停止頻率 F_Trip:截止頻率 Ia:電流 P_Inv:功率 Va:電壓 Vb,Vd:直流電壓 SOC:荷電狀態信號 S200至S212:步驟 10: Mains power 12: Mains power connection port 14:AC power port 16: DC power port 20:DC converter 22:Power inverter 30: Voltage ammeter 40:Micro control unit 50: Solar photoelectric converter 60:Load 70: Rechargeable battery 80:Solar panel 100:Power conversion system F: frequency F_min: minimum frequency F_normal: normal frequency F_Start: Start frequency F_Stop: stop frequency F_Trip: cutoff frequency Ia: current P_Inv: power Va: voltage Vb, Vd: DC voltage SOC: state of charge signal S200 to S212: steps

第1圖是本發明一實施例之功率轉換系統與所耦接的市電、負載、充電電池、太陽光電變流器及太陽能板之功能方塊圖。 第2圖是第1圖之太陽光電變流器的對外輸出功率比值與功率轉換系統所輸出的交流電的頻率之間的關係圖。 第3A圖和第3B圖是第1圖之微控制單元控制功率轉換系統的流程圖。 Figure 1 is a functional block diagram of a power conversion system and the coupled mains, load, rechargeable battery, solar photovoltaic converter and solar panel according to an embodiment of the present invention. Figure 2 is a relationship diagram between the external output power ratio of the solar photovoltaic converter in Figure 1 and the frequency of the alternating current output by the power conversion system. Figures 3A and 3B are flow charts of the power conversion system controlled by the micro control unit in Figure 1.

F_min:最小頻率 F_min: minimum frequency

F_normal:一般頻率 F_normal: normal frequency

F_Start:啟始頻率 F_Start: Start frequency

F_Stop:停止頻率 F_Stop: stop frequency

F_Trip:截止頻率 F_Trip: cutoff frequency

Claims (6)

一種功率轉換系統（Power conversion system；PCS），包含： 一交流電電源埠； 一直流電電源埠，耦接於一充電電池； 一電壓電流計，耦接於該交流電電源埠，用以偵測該功率轉換系統(PCS)從該交流電電源埠所輸出的電壓及電流； 一微控制單元（microcontroller unit；MCU），用以控制該功率轉換系統(PCS)的操作，並從該充電電池接收一荷電狀態（state of charge；SOC）信號； 其中該微控制單元根據該荷電狀態信號得到該充電電池的目前已充電比例，並依據該電壓電流計所偵測到的該電壓及該電流，得到該功率轉換系統的對外輸出功率；以及 其中當該微控制單元偵測到發生市電離網（off-grid）時，該微控制單元執行下述步驟： 當判斷出該充電電池的目前已充電比例大於一第一預設比例時，將該功率轉換系統從該交流電電源埠所輸出的一交流電的頻率調整至一第一頻率，以使耦接於該交流電電源埠的一太陽光電變流器停止輸出電能； 當判斷出該充電電池的目前已充電比例小於該第一預設比例且大於一第二預設比例，且該對外輸出功率的負值大於一第一預設功率時，將該交流電電源埠所輸出的該交流電的頻率調升一第一預設值；以及 當判斷出該充電電池的目前已充電比例小於一第三預設比例時，將該交流電電源埠所輸出的該交流電的頻率調降一第二預設值。 A power conversion system (PCS), including: an AC power port; a DC power port coupled to a rechargeable battery; a voltage ammeter, coupled to the AC power port, for detecting the voltage and current output by the power conversion system (PCS) from the AC power port; a microcontroller unit (MCU) to control the operation of the power conversion system (PCS) and receive a state of charge (SOC) signal from the rechargeable battery; The micro control unit obtains the current charging ratio of the rechargeable battery based on the state of charge signal, and obtains the external output power of the power conversion system based on the voltage and current detected by the voltage and ammeter; and When the micro control unit detects that the mains power is off-grid, the micro control unit performs the following steps: When it is determined that the current charged proportion of the rechargeable battery is greater than a first preset proportion, the frequency of an alternating current output by the power conversion system from the alternating current power port is adjusted to a first frequency, so that the frequency coupled to the A solar photovoltaic converter at the AC power port stops outputting electric energy; When it is determined that the currently charged proportion of the rechargeable battery is less than the first preset proportion and greater than a second preset proportion, and the negative value of the external output power is greater than a first preset power, the AC power supply port is The frequency of the output alternating current is increased by a first preset value; and When it is determined that the current charged ratio of the rechargeable battery is less than a third preset ratio, the frequency of the AC power output by the AC power port is reduced by a second preset value. 如請求項1所述的功率轉換系統，其中當判斷出該充電電池的目前已充電比例小於該第一預設比例且大於該第二預設比例，該對外輸出功率的負值未大於該第一預設功率，且該對外輸出功率小於該第二預設功率時，將該交流電電源埠所輸出的該交流電的頻率調升一第三預設值。The power conversion system of claim 1, wherein when it is determined that the currently charged proportion of the rechargeable battery is less than the first preset proportion and greater than the second preset proportion, the negative value of the external output power is not greater than the third preset proportion. A preset power, and when the external output power is less than the second preset power, the frequency of the AC power output by the AC power port is increased by a third preset value. 如請求項2所述的功率轉換系統，其中當該第二預設值等於該第三預設值。The power conversion system of claim 2, wherein when the second preset value is equal to the third preset value. 如請求項1所述的功率轉換系統，其中當該微控制單元偵測到發生市電離網時，若判斷出該對外輸出功率的負值未大於該第一預設功率，則該微控制單元限制該交流電電源埠所輸出的該交流電的頻率在一預設範圍內。The power conversion system as described in claim 1, wherein when the micro control unit detects that the mains power is off-grid, if it is determined that the negative value of the external output power is not greater than the first preset power, the micro control unit The frequency of the AC power output by the AC power port is limited to a preset range. 如請求項4所述的功率轉換系統，其中當該交流電電源埠所輸出的該交流電的頻率在該預設範圍內時，該太陽光電變流器的輸出功率與該交流電的頻率呈負相關。The power conversion system of claim 4, wherein when the frequency of the alternating current output by the alternating current power port is within the preset range, the output power of the solar photovoltaic converter is negatively correlated with the frequency of the alternating current. 如請求項1所述的功率轉換系統，其中該第一預設比例大於該第二預設比例，而該第二預設比例大於該第三預設比例。The power conversion system of claim 1, wherein the first preset ratio is greater than the second preset ratio, and the second preset ratio is greater than the third preset ratio.
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