When we use two or more sources buses in a radial distribution system, the power flows become bidirectional in some of the branches. In this case, can we use forward-backward sweep method for load flow study?
In Load Flow Studies You can always treat a Bus to which a Generator is connected
with (Pg - Pl) + j (Qg-Ql) as Complex Power injection at that Bus. You may also treat it as Source Current Injection at that Bus which you say rightly as causing curret flow getting Split up.
So, the Methods used for Distribution Netwok with Distributed Generation can be used.
The following references will be useful.
1. Power Flow in Distribution System with Consideration of Distributed Generation
Ahmad Memaripour
Abstract
Power flow in distribution system is systematically different with transmission systems.
Because in distribution system the ration of R/X is high and the conventional power flow
methods such as Newton-Raphson cannot always be used. In this regard, Backward/
Forward (BW/FW) sweep algorithm has been developed for power flow in distribution system. In this paper, the proposed method is evaluated with consideration of distributed generation (DG).
Link: http://ijaras.isair.org/papers/2012/%2811%29November/IJARAS103%20%2810%29.pdf
2. Forward/backward sweep method based on map structure for power flow calculation of distribution system
Xu Jingzhou.Chen Xiao
ABSTRACT Power flow calculation is very important to distribution system management, and more and more attention are paid to calculation speed and accuracy due to the booming smart grids which allow interconnection of distributed generation of different kinds. A new forward/backward sweep method based on map structure is presented, which can calculate power flow of all complex radial distribution systems. Special coding of nodes, such as hierarchical coding, is not necessary, and results can be obtained directly through a global search of line map. Test shows that the method is time saving and insensitive to the system scale, which helps the popularity of smart grids.
Link: https://www.researchgate.net/publication/224225688_Forwardbackward_sweep_method_based_on_map_structure_for_
power_flow_calculation_of_distribution_system
3. Efficient load flow method for distribution systems with radial or mesh configuration
M.H. Haque
ABSTRACT The paper proposes a new and efficient method of solving the load
flow problem of a distribution system. The method can be applied to both
radial and mesh networks. A mesh network is converted to a radial
network by breaking the loops through adding some dummy buses. The power
injections at the loop break points (LBP) in the equivalent radial
network are computed through a reduced order node impedance matrix.
Unlike other methods, the shunt admittances are considered in the
proposed load flow algorithm and the effect of load admittance is also
incorporated in the calculation of power injections at the LBPs. Because
of the inclusion of shunt admittances, the method can also be used to
solve the load flow problem of some special transmission networks. Two
different networks with various configurations were used to demonstrate
the efficiency and convergence pattern of the method. The results
obtained by the proposed method were also compared with some other
methods
Link: https://www.researchgate.net/publication/3354175_Efficient_load_flow_method_for_distribution_systems_with_
radial_ormesh_configuration
P.S.
Conference Paper Forward/backward sweep method based on map structure for pow...
Article Efficient load flow method for distribution systems with rad...
In Load Flow Studies You can always treat a Bus to which a Generator is connected
with (Pg - Pl) + j (Qg-Ql) as Complex Power injection at that Bus. You may also treat it as Source Current Injection at that Bus which you say rightly as causing curret flow getting Split up.
So, the Methods used for Distribution Netwok with Distributed Generation can be used.
The following references will be useful.
1. Power Flow in Distribution System with Consideration of Distributed Generation
Ahmad Memaripour
Abstract
Power flow in distribution system is systematically different with transmission systems.
Because in distribution system the ration of R/X is high and the conventional power flow
methods such as Newton-Raphson cannot always be used. In this regard, Backward/
Forward (BW/FW) sweep algorithm has been developed for power flow in distribution system. In this paper, the proposed method is evaluated with consideration of distributed generation (DG).
Link: http://ijaras.isair.org/papers/2012/%2811%29November/IJARAS103%20%2810%29.pdf
2. Forward/backward sweep method based on map structure for power flow calculation of distribution system
Xu Jingzhou.Chen Xiao
ABSTRACT Power flow calculation is very important to distribution system management, and more and more attention are paid to calculation speed and accuracy due to the booming smart grids which allow interconnection of distributed generation of different kinds. A new forward/backward sweep method based on map structure is presented, which can calculate power flow of all complex radial distribution systems. Special coding of nodes, such as hierarchical coding, is not necessary, and results can be obtained directly through a global search of line map. Test shows that the method is time saving and insensitive to the system scale, which helps the popularity of smart grids.
Link: https://www.researchgate.net/publication/224225688_Forwardbackward_sweep_method_based_on_map_structure_for_
power_flow_calculation_of_distribution_system
3. Efficient load flow method for distribution systems with radial or mesh configuration
M.H. Haque
ABSTRACT The paper proposes a new and efficient method of solving the load
flow problem of a distribution system. The method can be applied to both
radial and mesh networks. A mesh network is converted to a radial
network by breaking the loops through adding some dummy buses. The power
injections at the loop break points (LBP) in the equivalent radial
network are computed through a reduced order node impedance matrix.
Unlike other methods, the shunt admittances are considered in the
proposed load flow algorithm and the effect of load admittance is also
incorporated in the calculation of power injections at the LBPs. Because
of the inclusion of shunt admittances, the method can also be used to
solve the load flow problem of some special transmission networks. Two
different networks with various configurations were used to demonstrate
the efficiency and convergence pattern of the method. The results
obtained by the proposed method were also compared with some other
methods
Link: https://www.researchgate.net/publication/3354175_Efficient_load_flow_method_for_distribution_systems_with_
radial_ormesh_configuration
P.S.
Conference Paper Forward/backward sweep method based on map structure for pow...
Article Efficient load flow method for distribution systems with rad...
Dear Prakash Kumar,
If you are satisfied with the Answer you may upvote my Answer.
Best Wishes.
P.S.
For generations having volage control can be modelled as PV buses. These PV buses can be handled along with the backward forward sweep algorithm using a sensitivity matrix method.
One of the paper which adresses this problem can be found in this link below:
Radial Load Flow for Systems Having Distributed Generation and Controlled Q Sources
Abstract
A load flow method that can be used for radial systems having all the common types of voltage control devices in addition to distributed generation sources is proposed. The method automatically adjusts the reactive power outputs of synchronous generators, switched capacitors, static var compensators and induction generators together with regulating transformer tap positions in an unified manner so as to satisfy the control characteristics of the respective devices by using a sensitivity based approach. In this context, a model for the induction generators that can be easily integrated with the proposed radial load flow method and a new approach to pre–calculate the sensitivity of node voltages, to regulator tap changes, are presented. Test results are provided to demonstrate the effectiveness of the algorithm.
http://www.tandfonline.com/doi/abs/10.1080/15325000590885397?journalCode=uemp20
Yes, but the second source should be modeled as negative load on that bus. Also, the voltage should be specified on that bus.
A BFS method for active distribution systems with renewable resources has recently been proposed here.
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