The continuous penetration of DGs in distribution system
leads to the needs effective control and operate the system. To
achieve this status, distribution network needs to use
information and communication technologies to collect realtime
data in order to make a decision for best operation
condition. Therefore, utilities are expected to implement
efficient monitoring devices to obtain an accurate state of the
system. In order to develop distribution networks, many other
automated meters, distribution SCADA and Distribution
Management System (DMS) need to install in distribution
level. Although, these technologies will be expected to setup
in distribution level, the numbers of real-time measurement
devices are very few due to high cost of these devices. On the
other hand, the state estimation function of the transmission
level cannot be directly implemented to the distribution level
due to differing operation and structure philosophy. The major
state estimation function differences between the transmission
and distribution levels are summarized as follows: