Page 63 - Mathematical Models and Algorithms for Power System Optimization

Optimization of Annual Generator Maintenance Scheduling 53

A GMS problem should have the following characteristics: the maintenance time for full or
partial maintenance can be different. Each unit’s maintenance can be performed multiple
times within a given interval. When developing a GMS, the proposed ES can determine the
priority.

The objective function should consider both the maximizing reserve margin and minimizing
production cost. The constraints should consider the maximum area maintenance capability, the
reserve margin of generators, the maintenance window cycle, continuous maintenance
conditions, and available manpower.
The GMS problem mentioned earlier requires a lengthy solution time and large computing
memory. The existing programming techniques cannot be directly applied. However, a dispatch
engineer with GMS experience may potentially be able to solve the GMS problem. Using their
experience, an ES can be constructed. But the prototype ES can only be used to solve the GMS
problem of a particular system. The generalized ES proposed in this chapter can be applied to
GMS problems of different power systems.

In view of the large differences in the number of generators and the capacity of each
power plant in each region, maintenance periods vary in length; some are shorter
(more than 7 days), whereas some are much longer (more than 35 days). Some
generators must be maintained within a given time, whereas others can be handled
in a flexible way. There are many necessary conditions and constraints to be
considered in the GMS problem. The following briefly introduces the modeling
ideas of GMS.

3.2.1 Way of Handling Unit Maintenance Intervals

A GMS problem can divide the units in need of maintenance into two categories based on
maintenance time: fixed maintenance and flexible maintenance.

(1) Fixed maintenance refers to the unit being maintained or the unit that needs to be
maintained at the specified time. Its maintenance capacity must be reserved in the
GMS. For those units that have shut down due to a fault, the maintenance should
obviously be classified as a fixed maintenance. Therefore, the fixed maintenance
arrangement can also be used to simplify the GMS in some cases.
(2) Flexible maintenance refers to the units that are not included in the fixed maintenance,
that is, the units whose maintenance start time can be flexibly arranged and
optimized to some extent. In the case of the current general lack of electricity in the power
grid, the objective function of GMS in the flexible maintenance can be set to
maximize the reserve margin of the system for the general system, and to minimize
the production and maintenance costs of the system with adequate reserve margin.