ﯾﮏ ﺳﺎﺧﺘﺎر ﮐﻨﺘﺮل ﻏﯿﺮﻣﺘﻤﺮﮐﺰ ﻣﺒﺘﻨﯽ ﺑﺮ ﻗﺎب ﻣﺠﺎزي ﻓﺮﮐﺎﻧﺲ-وﻟﺘﺎژ ﺑﺮاي ﻓﺮاﻫﻢﮐﺮدن ﺗﻘﺴﯿﻢ ﺻﺤﯿﺢ ﺗﻮانﻫﺎي اﮐﺘﯿﻮ و راﮐﺘﯿﻮ در رﯾﺰﺷﺒﮑﻪﻫﺎ

A Decentralized Control Method Based on Virtual Frequency-Voltage Frame for Accurate Active and Reactive Powers Sharing in Microgrids

درﺣﺎﻟﺖ ﻋﻤﻠﮑﺮد ﺟﺰﯾﺮهاي رﯾﺰﺷﺒﮑﻪﻫﺎ ﺗﻘﺴﯿﻢ ﺗﻮانﻫﺎي اﮐﺘﯿﻮ و راﮐﺘﯿﻮ ﺑﺎر ﺑﯿﻦ ﻣﻨﺎﺑﻊ ﻧﯿﺎز اﺳﺖ. ﺑﺮاي ﻓﺮاﻫﻢ ﮐﺮدن آن و ﺑﺮ اﺳﺎس روﯾﮑﺮد ﻏﯿﺮﻣﺘﻤﺮﮐﺰ از ﻣﺸﺨﺼﻪﻫﺎي اﻓﺘﯽ اﺳﺘﻔﺎده ﻣﯽﺷﻮد. ﻣﺸﺨﺼﻪﻫﺎي اﻓﺘﯽ ﻣﺮﺳﻮم ﺗﻮان اﮐﺘﯿﻮ-ﻓﺮﮐﺎﻧﺲ )P-ω( و ﺗﻮان راﮐﺘﯿﻮ-وﻟﺘﺎژ )Q-V( ﺑﺮ ﻓﺮض ﺧﺎﺻﯿﺖ ﺳﻠﻔﯽ اﻣﭙﺪاﻧﺲ ﺧﺮوﺟﯽ ﻣﻨﺎﺑﻊ ﺑﻨﺎ ﻧﻬﺎده ﺷﺪهاﻧﺪ. از آﻧﺠﺎ ﮐﻪ اﻣﭙﺪاﻧﺲ ﺧﺮوﺟﯽ ﺳﻠﻔﯽ ﻏﺎﻟﺐ ﻣﺨﺼﻮﺻﺎ در رﯾﺰﺷﺒﮑﻪﻫﺎي وﻟﺘﺎژ ﭘﺎﯾﯿﻦ ﻓﺮاﻫﻢ ﻧﻤﯽﺷﻮﻧﺪ، ﻣﺸﺨﺼﻪﻫﺎي اﻓﺘﯽ ﻗﺎب ﻣﺠﺎزي ﻓﺮﮐﺎﻧﺲ-وﻟﺘﺎژ ﮐﻪ ﺷﺎﻣﻞ ﻣﺸﺨﺼﻪ اﻓﺘﯽ ﺗﻮان اﮐﺘﯿﻮ-ﻓﺮﮐﺎﻧﺲ ﻣﺠﺎزي )ʹP-ω( و ﻣﺸﺨﺼﻪ اﻓﺘﯽ ﺗﻮان راﮐﺘﯿﻮ-وﻟﺘﺎژ ﻣﺠﺎزي )ʹQ-V( ﻫﺴﺘﻨﺪ ﻣﻮرد ﺗﻮﺟﻪ ﻣﺤﻘﻘﺎن ﻗﺮار ﮔﺮﻓﺘﻪ-اﻧﺪ. ﺧﺎﺻﯿﺖ ﻣﺤﻠﯽ ﻫﺮ دو ﮐﻤﯿﺖ ﻓﺮﮐﺎﻧﺲ ﻣﺠﺎزي و وﻟﺘﺎژ ﻣﺠﺎزي ﻣﻨﺠﺮ ﺑﻪ ﺑﺮوز ﺧﻄﺎﻫﺎي ﺗﻘﺴﯿﻢ ﺗﻮان اﮐﺘﯿﻮ و راﮐﺘﯿﻮ ﺑﺎ ﺑﻪﮐﺎر ﺑﺮدن اﯾﻦ ﻣﺸﺨﺼﻪﻫﺎ ﻣﯽﺷﻮد. ﻫﻤﭽﻨﯿﻦ ﻧﯿﺎز ﺑﻪ ﻣﺤﺪوده ﮐﻮﭼﮏ ﺗﻐﯿﯿﺮات ﻓﺮﮐﺎﻧﺲ ﻣﺠﺎزي و وﻟﺘﺎژ ﻣﺠﺎزي، ﻣﻨﺠﺮ ﺑﻪ ﺑﺮوز ﺧﻄﺎﻫﺎي ﺑﺰرگ ﺗﻘﺴﯿﻢ ﺗﻮان ﻣﯽﺷﻮد. ﺑﺮاي ﺑﺮﻃﺮف ﮐﺮدن ﺧﻄﺎﻫﺎي ﺗﻘﺴﯿﻢ ﺗﻮان اﮐﺘﯿﻮ و راﮐﺘﯿﻮ، در اﯾﻦ ﻣﻘﺎﻟﻪ ﯾﮏ روش ﮐﻨﺘﺮل ﻏﯿﺮ ﻣﺘﻤﺮﮐﺰ ﭘﯿﺸﻨﻬﺎد ﻣﯽﺷﻮد. در روش ﭘﯿﺸﻨﻬﺎدي ﻣﻨﺎﺑﻊ ﺑﻪﺟﺎي ﻓﺮﮐﺎﻧﺲ ﻣﺠﺎزي و وﻟﺘﺎژ ﻣﺠﺎزي ﺗﺮﻣﯿﻨﺎل ﺧﻮد، ﻓﺮﮐﺎﻧﺲ و وﻟﺘﺎژ ﻣﺠﺎزي ﻧﻘﻄﻪ اﺗﺼﺎل ﻣﺸﺘﺮك )PCC( را اﻓﺖ ﻣﯽدﻫﻨﺪ ﺗﺎ ﭘﺎراﻣﺘﺮي ﻣﺸﺘﺮك ﻣﺴﺌﻮل ﺗﻮﻟﯿﺪ ﺗﻮان اﮐﺘﯿﻮ و ﻫﻤﭽﻨﯿﻦ ﭘﺎراﻣﺘﺮي ﻣﺸﺘﺮك ﻣﺴﺌﻮل ﺗﻮﻟﯿﺪ ﺗﻮان راﮐﺘﯿﻮ ﻣﻨﺎﺑﻊ ﺷﺪه و ﺧﻄﺎي ﺗﻘﺴﯿﻢ ﺗﻮان ﺑﺮﻃﺮف ﺷﻮد. ﻧﺤﻮه ﺗﺤﻘﻖ اﯾﻦ ﻣﺸﺨﺼﻪﻫﺎي اﻓﺘﯽ ﺑﺎ ﺟﺰﺋﯿﺎت ﺗﻮﺿﯿﺢ داده ﺧﻮاﻫﺪ ﺷﺪ. ﺑﺮاي ﺗﺎﯾﯿﺪ ﻋﻤﻠﮑﺮد ﺳﺎﺧﺘﺎر ﮐﻨﺘﺮل ﭘﯿﺸﻨﻬﺎدي، ﺷﺒﯿﻪﺳﺎزي زﻣﺎﻧﯽ ﯾﮏ رﯾﺰﺷﺒﮑﻪ ﻧﻤﻮﻧﻪ در ﻧﺮم اﻓﺰار PSIM اراﺋﻪ ﺷﺪه اﺳﺖ.

In the islanded operation mode of microgrids, active and reactive powers sharing among sources is required. In order to provide this and based on decentralized approach, droop characteristics are used. The conventional droop characteristics of active power-frequency (P-ω) and reactive power-voltage (Q-V) are based on the assumption of inductive output impedance of sources. Since the dominant inductive output impedances are not provided, especially in low voltage microgrids, the virtual frequency-voltage frame droop characteristics, which include active power-virtual frequency (P-ωʹ) and reactive power-virtual voltage (Q-Vʹ) droop characteristics have been considered by researchers. By employing these droops, local property of both the virtual frequency and the virtual voltage leads to active power sharing error as well as reactive power sharing error. In addition, required small intended variation range of both virtual frequency and virtual voltage, results in big power sharing errors. In order to eliminate active and reactive power sharing errors, a decentralized control method is proposed in this paper. In the proposed method, instead of virtual frequency and virtual voltage of their terminal, sources droop virtual frequency and virtual voltage of point of common coupling (PCC) in order to a common parameter becomes in charge of active power generation as well as a common parameter becomes responsible for reactive power generation. Accordingly, the power sharing errors are resolved. Realization method of these droop characteristics will be explained in details. In order to confirm the performance of the proposed control method, simulation results of a test microgrid in PSIM software are presented.