Distribution automation systems solutions

What are the difficulties in overhead line operation and maintenance?

Difficulty one:
Overhead lines of distribution network have wide coverage,complicatedterrain,many radiation branches and distributed power supply,resultingin "many line faults and difficulty in fault troubleshooting".
Difficulty Two:
Manual troubleshooting is time-consuming and laborious.Meanwhile,therunning current,voltage and switching state of the line cannot be graspedin real time,because of the lack of intelligent technical means.
Difficulty Three:
The fixed value of line protection cannot be adjusted remotely,and thefield maintenance work is heavy.
Difficulty Four:
Fault message is not pushed in time which lengthening the fault outagetime and impacting on power supply quality and company's reputation.
Difficulty Five:
The line power supply load curve can not be controlled timely and effectively,which leads to the irrationality of the protection setting.

Five core functions of Distribution automation systems

①Fault Isolation
Fast isolation of fault section,reduce the scope of power cuts,avoid overridetrip and expand the outage scope.
②Fault location
Locate fault section accurately,shorten the time of troubleshooting.
③Alarm Push
Push the fault type,fault time and switch position to the responsible person'smobile phone and monitoring center in time.
④Monitoring Analysis
Real-time monitoring of load current,voltage,switch state,three-phaseunbalance,overload abnormal alarm,viewing the historical data statistics,analyzing historical load and setting reasonable value.
⑤Setting Value Remotely
Adjusting protection values remotely for saving times and efforts.

What is the effect of  system implementation?

Before installing the system,a power supply bureau indicated thatwhen the line has a fault,it have to take about half an hour to one hour forthe fault information to be fed back to the operation and maintenancedepartment.

At the same time,troubleshooting is also a big pain point.You have to take much efforts to find the fault point and it even takes youabout one day to troubleshoot sometimes(especially search afteroverride trip).During the period,you will also get lots of complaints frompeople.

Since the implementation of system,it can push faultinformation (location,fault type and time)in time and reduce the time fortroubleshooting greatly.Besides,the reasonable protection setting alsoreduced override trip and outage range.

In brief,system improves the reliability of power supply,the quality of power grid and the satisfaction of users.Meanwhile,therewill be a complete load record for forecasting load accurately and makingthe expansion plan of distribution network more targeted.

Common faults of 10-35 kV overhead lines

①Single-phase grounding is the most common fault of power distribution system,which mostly occurs in wet and rainy weather.It is caused by manyfactors,such as tree barrier,single-phase breakdown of insulator on distributionline,over-load burning or oxidative corrosion shedding at wire junction,single-phase broken line and so on.

②Interphase short circuit fault refers to the fault that two points of differentpotential in the line are short-connected by the conductor,or the insulationbetween them is broken,causing the line to fail to work normally.According todifferent situations,short circuit fault can be divided into metallic short circuit andnon-metallic short circuit;single phase short circuit and polyphase short circuit.

Fault handling

There are two modes for feeder terminal to deal with single-phasegrounding fault which is warning or tripping.

When the feeder terminal samples the single-phase grounding faultcurrent,the terminal will carry warning or trip circuit breaker according to thepre-selected mode.At the same time,pushing the fault information(location,fault type and time)to the relevant personnel of operation and maintenancedepartment,so that the responsible personnel can grasp the fault information atthe first time and take actions.

When the feeder terminal samples the interphase short circuit current,theterminal will let the circuit breaker act quickly to isolate the fault,so as to avoidoverride tripping to expand the power cut range.Meanwhile,pushing the faultinformation (location,fault type and time)to the relevant personnel of operationand maintenance department,so that the responsible personnel can grasp thefault information at the first time and take actions.