Yes, if your power system has more than one frequency (e.g. you have installed a hvdc between two grids. Then you need two slack bus).

Best Regards,

Michał Połecki

yes, multiple slack bus models are available. But in a system there will only be one main slack or also called as mother slack. If you are implementing a controller you cant control main slack where as other slack bus are available to user for controlling. I believe you are working with PSAT and there you can find multiple slack bus model in its examples.

Regards

Chittesh VC

yes, you an select one slack bus for each area.

Yes. You can fix voltage amplitude and angle for more than one bus in power flow equations, thus having several slack buses. Power flow problem can be solved in the asme way as before, but you should exclude power flow equations for P and Q of additional slack bus.

Typically when there are different areas connected using DC connections, each area is defined with a slack-bus. 

The need of a slack bus is mathematics requirement to serve physical concept of a power flow problem. There is a bus which its scheduled power cannot be defined without knowing loss of a system. A distributed slack  bus concept can be formulated for some purposes e.g. for sharing of an incremental changed power of pv-buses from an original case or etc.

hi

Hi

But in my opinion

The power grid is only one bus must have the reference. Select more than one bus as the bus reference to choosing more than two reference sense circuit that such a thing is not possible

Hi

But in my opinion

The power grid is only one bus must have the reference. Select more than one bus as the bus reference to choosing more than two reference sense circuit that such a thing is not possible

hi

A distributed slack bus is entirely possible.

In essence what you are doing is distributing the losses over multiple generators. The PSAT toolbox, by Federico Milano can facilitate this functionality. For a good review paper look at "Application of distributed slack bus power flow to competitive environments", Chayakulkheeree, K. 2007

Yes, you can have more than one slack bus in a power system if there is an objective to partition the power system into many different zones. If your power system has 5 zones, you can theoretically have 5 slack buses. But, you have to come up with an objective why you want to have more than one slack bus because slack bus is a mathematical convenience in dealing with mismatches (P & Q) in a power system, when you are solving for a load flow solution.

Please, look up Federico Milano's "Power systems modelling and scripting", subsection 4.4.9, page 95 "Single and distributed slack bus models".

The answer to your question is an absolute, definitive YES. In fact, the distributed slack bus model is a more faithful representation of the real world dynamics. However, you have to define a participation factor for each generator, resulting in a new equation. This is how you may bypass the distributed reference problem that some of these answers focus on.

All discussions are brilliant. In a power flow problem, slack bus and reference bus are normally the same bus. However, the definition of a slack bus is a bus for compensating mismatch power of a system. This requires to serve mathematics purpose of an unknown loss before calculation. A reference bus is used for reference voltage angle at zero. Definitely, the term slack and reference have serve difference purpose. In a real power system, reference bus may be defined for each zone, which are interconnected. In contrast, a slack bus cannot be defined because a real system is not be operated such a way as simply stated as a power flow problem even in a quasi steady state. If it has to define slack buses for any purposes, in my opinion, they are all load following units at mention period.

A slack and a reference bus can be different. You can have distributed slack buses also.