Hi;
morteza rahimian wrote:
I executed the AC OPF on a real power system. There are 52 power units
in this network considered as P-V buses. when the OPF is run, the active
outputs of some of them are zero, because they have higher cost of
production. In other words, they are shot down.
Not exactly. The standard OPF problem does not include as variables
the decision to shut a generator off or commit it. If it reaches
an active dispatch of zero that just reflects the fact that Pmin
has been defined so.
The problem that does include the decision to commit or shut off
the units is called the "unit commitment" (UC) problem and it usually
considers a finite time horizon. not a particular instant in time
like the OPF. By itself, classical unit commitment employs limited
criteria for flow optimality, but many algorithms exist that enhance
it with different degrees of power flow "optimality".
In practice, UC is usually combined with other forms of security
assessment that affect the choice of committed units.
But I face with a
wonderful problem. The generators with zero active production still
produce reactive power, however in realistic when a generator is shot
down it can not also produce reactive power in addition of active power.
Why this happen in matpower and how I can solve this?
The answer to this question is that matpower solves the standard OPF
problem and under that framework this is a perfectly valid solution for
the given data.
If you are interested in solving not an OPF but a combined
unit commitment and optimal power flow, matpower does include
a heuristic method for a single temporal slice UC that shuts down
candidate generators to see if the total cost goes down when doing so;
it is implemented in uopf.m .
carlos.
Morteza Rahimiyan
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