PV-BESS Power Station and Dynamic Control Method Thereof
Publication Date: 2016-Sep-06
The IP.com Prior Art Database
HaiLian Xie: AUTHOR [+5]
This disclosure proposes a Photovoltaic – Battery Energy Storage System (PV-BESS) power station, in which a novel dynamic control method is used. This ID could be used for · New developed PV-BESS power station that need to provide dynamic frequency support and meet the requirements given in standards/grid codes · PV power station with limited cost and footprint for energy storage system.
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PV-BESS Power Station and Its Dynamic Control Method
This disclosure proposes a Photovoltaic - Battery Energy Storage System (PV-BESS) power station, in which a novel dynamic control method is used. This ID could be used for
· New developed PV-BESS power station that need to provide dynamic frequency support and meet the requirements given in standards/grid codes
· PV power station with limited cost and footprint for energy storage system
Problem Overcome by the Disclosure
Due to the environmental issue, more and more new energy are used in the power system, e.g. solar power. However, PV power resources are integrated to the power system through power electronic devices, making the power control response too fast to provide support for the dynamic frequency response of synchronous generators, which might threaten the transient stability of the power grid after disturbances with the increase of PV generation installed capacity. To increase the accommodation level of solar power, PV-BESS is proposed by many researchers and different control strategies aiming to improve the dynamic frequency support, e.g. virtual inertia control, virtual synchronous generator control.
Nowadays, two groups of control methods for PV-BESS are basically used to provide dynamic frequency supports, i.e. Virtual Inertia (VI) control and Virtual Synchronous Generator (VSG) control.
For these existing control methods, the problems are:
1) The performance of VI control is not so stable because it strongly depend on the measurement accuracy of the system frequency.
2) The current VSG control cannot be used for the control of whole PV-BESS power station. This is due to the fact that its design is only suitable to be implemented in single inverter.
3) Large BESS capacity is needed to fulfill active power response requirement.
In existing control methods, the PV power adjustment (e.g. necessary power curtailment or reduce power generation reference) is not considered and the compensation for the active power is purely rely on the BESS. Therefore, the capacity of BESS has to be large.
4) In existing control methods, the requirement for the Reactive Current Injection (RCI) given in the Grid Codes might not be met.
As the inverter capacity is not reserved for RCI when the active current/power references are assigned, the RCI requirement might not be met due to the limitation of the inverter capacity.
Solution with the Disclosure
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To solve the above mentioned problems, a novel active power and reactive current allocation strategy is proposed in this ID to adapt the VSG control for power station level application. By using this proposed strategy, the active power and reactive current references are properly distributed among multiple inverters of BESS, PV and STATCOM connected to the power station. The RCI requirements given in the Grid Codes could be met by considering the priority between active power and reactive current ou...