AORC Technical meeting 2014 http : //www.cigre.org C4-1012 Alarm System Improvement in the Northern Region Dispatching Center of Thailand Mr. Manu PONGKAEW, Mr. Phathom TIPSUWAN Electricity Generating Authority of Thailand (EGAT) Thailand SUMMARY This paper presented the project of improvement on new alarm system for data providing from power substations while emergency case happening, especially for the event which occurred during nonbusiness hours. When the trouble occurs on equipment of power system, the dispatching center operators of EGAT have to diagnose the problem by information from the alarm system of EGAT SCADA (the SCADA system that was developed by EGAT team) along with the details from substation to restore the equipment. However, if the trouble occurs during non-business hours, the dispatching center needs to call the substation staffs to go to station-office and provide the details of the problem. This process will take a long time to identify the problem and the equipment may get damage. Therefore, EGAT needs to improve the process of substations data providing to reduce the analyzing time. EGAT SCADA System that implemented in the Northern Region dispatching center consists of 2 sets to control the power; they are called Main SCADA System and Backup SCADA System. The Main SCADA has higher speed but provides less data than the Backup one because it reduced the amount of scanned data by grouping and sending them to RTUs (Remote Terminal unit) which had been installed in substations. While the Backup SCADA scans and cascades all data. The data that provided by Backup SCADA is similar to the one from 42 substations, therefore dispatching center can get data from Backup SCADA instead of receiving from substation staffs. However, when the trouble occurs the details are hard to identify because the data of such event will show in many pages, moreover the normal data from other substations might be lost from focusing by operators. This will cause of long time taking to restore the system. To solve this problem, the team of Northern Region dispatching center had improved the alarm process of Backup SCADA System by creating the data-collecting page of each substation and had prepared its format by grouping information of transformers, breakers, transmission line, shunt capacitor and shunt reactor. All such data will be shown in one page for each substation. The display of warning will be flashed in red color which can be seen easily and will take short time to diagnose and to do the restoration. When there is unusual event on substation equipment, each step was taken and selected by the station and the dispatching center staffs who can see all those data at once. It s not necessary to waste the time for searching all data, like the restoration procedure in the former alarm system. The dispatching center staff will be able to decide promptly whether the event caused by which device. As a result, the system can be restored back to normal faster and will not be affected or taken a lowest amount of the power outage. For the comparison, it is evident that with the previous alarm system the dispatching center staff needs to see all data in several pages. But by the new one, the operators can focus on only one page, to complete and correct data. Therefore, we can restore the system back to normal, more quickly. However, the display file must be updated whenever the power system equipments had been changed, to retain database accuracy. KEYWORDS Alarm System, EGAT SCADA, Dispatching Center manu.p@egat.co.th
1. Introduction Northern Area Control Center (NAC) is one of dispatching center of EGAT, which has the main purpose of power system operation and restoration in the Northern Region of Thailand. NAC consists of 42 substations in17 provinces. NAC staffs use EGAT SCADA as the tool of power system monitoring and control. When an abnormal status occurs in the power system equipments, NAC staffs have to diagnose the problem precisely and action swiftly to retain equipment before any damage or led to the power system outage. If the trouble occurs during non business hours (16.00-08.00 next day), the NAC staffs need to call the substation staffs to go back to the office and provide the details of the problem. This process will take a long time to identify the problem that will let the equipment be damage. The approximate time of business time and non-business time work flow are shown in table 1 and 2 respectively. Procedure Time (Sec) Trouble start Preliminary inspection in abnormal substation 5 Search the abnormal point in Alarm Summary page 3 Gather all information (from substation staff) 180 Event Analysis 15 Restore the abnormal equipment Depend on each situation Total 203 Table 1 Approximate trouble diagnostic time during business hours Procedure Time (Sec) Trouble start Preliminary inspection in abnormal substation 5 Search the abnormal point in Alarm Summary page 3 Call substation staff to go to substation 1800 Gather all information (from substation staff) 180 Event Analysis 15 Restore the abnormal equipment Depend on each situation Total 1913 Table 2 Approximate trouble diagnostic time during non-business hours Therefore, this project was set up with the objective to improve a new alarm system for installing at the Backup SCADA in order that NAC operators can reduce the diagnostic time of a fault occurrence without a phone call to substation or no need to wait for more details from there 2. NAC SCADA System The Main SCADA System which is the primary equipment that implement in NAC has high speed monitoring and rapid control because of direct scan from NAC to Remote Terminal Unit (RTU) in each substation as shown in figure 1. 2
Figure 1. The Main SCADA System Diagram Disadvantage of Main SCADA System is being unable to provide complete information due to its key mission is to reduce amount of scanning data by combining them into groups in order to increase the efficiency of the control function in normal situation and also to operate the power system equipments as fast as possible. The list of groups is shown in table 3. Group 1 Group 2 Group 3 Group 4 Group 5 Group 6 Group 7 Group 8 Transformer major troubles Power circuit breaker major troubles Protection System Transformer minor troubles Power circuit breaker minor troubles Miscellaneous trouble Power circuit breaker failure or pole disagreements operate. Spare Table 3. List of data groupings in Main SCADA System Backup SCADA System which is the secondary equipment that implemented in NAC has the main objective to be used when Main SCADA System failed. It scans data from 4 Group Control Center substations (GCC). The Backup SCADA System has low speed monitoring and low speed control because of the process on cascade scan from NAC to GCC substation, from GCC to Computerized Control System (CCS) substation, and from CCS to RTU in each substation, as shown in figure 2. 3
Figure 2. The Backup SCADA System Diagram The advantage of Backup SCADA System is providing complete information which similar to the information from substation. In any abnormal case, Main SCADA System will display only data group1-7. If the trouble occurred during business period NAC operators have to request the details from substation. On the other hand, if the trouble occurs in non-business hours, NAC has to call the operator of the substation to go to the station office for sending back more info or NAC needs to search the details from alarm summary page in Backup SCADA System as shown in figure 3. Figure 3 Alarm Summary Display in the Backup SCADA System 4
The problem is that process will take a long time for problem diagnosis if there are a lot of data in many pages including normal messages from the other substations. 3. Alarm system improvement Users can view all digital alarm points in the database of the Backup SCADA System in digital point display pages as shown in figure 4. Figure 4. All data which received from the substations Information of digital points in display pages includes around 40000 points from 43 substations. The better way to diagnostic quickly is to categorize data into groups for each substation. There are 4 groups of data as shown in table 4 and the details of each group shown in table 5. The improvement concepts or strategies of the project are easier finding out of the data and such details from every substation must be displayed on only 1 page. Order Type 1 Information of Transformer 2 Information of Power Circuit Breaker 3 Information of Transmission Line 4 Information of Shunt Capacitor and Shunt Reactor Table 4. List of data groups 5
Transformer Transmission Line Power Circuit Breaker 125VDC SUPPLY FOR TAP DIFF FAIL 86DTT CUTOFF SWITCH ANTI PUMPING 86K4 DC SUPPLY FAIL DEF CARRIER SIGNAL FAIL BREAKER FAIL RELAY CUTOFF SWITCH 87K4 DC CONVERTER FAIL DEF CARRIER SIGNAL RECEIVED BREAKER FAIL RELAY DC SUPPLY FAIL 87K4 DC SUPPLY FAIL DEF CARRIER SIGNAL SEND BREAKER FAIL RELAY OPERATED 87K4-A RELAY OPERATED DIFF AT PEA#1 CUTOFF SW DC SUPPLY FAIL (LOCAL) 87K4-B RELAY OPERATED DIFF COMMUNICATION FAIL DC SUPPLY FAIL (REMOTE) 87K4-C RELAY OPERATED DIFF RLY AUX TRIP OP LOW GAS ALARM AC CONTROL FAIL DIFF RLY DC SUPPLY FAIL LOW GAS LOCKOUT AC REGULATING FAIL DIFF RLY DIFF BLOCK SPRING CHARGE MOTOR DC FAIL AC SUPPLY FAIL DIFFERENTIAL CUTOFF SW BUCHOLZ TRIP DIFFERENTIAL RELAY FAIL Main Bus DC CONTROL FAIL DTT CARRIER SIGNAL FAIL BUS DIFF RELAY PHASE A OP (87B) DC SUPPLY FAIL DTT CARRIER SIGNAL RECEIVED BUS DIFF RELAY PHASE B OP (87B) DIV.SWITCH OIL LEVEL DTT CARRIER SIGNAL SEND BUS DIFF RELAY PHASE C OP (87B) DIVERT SW.PRESSURE RELIEF DEVICE O/C RELAY AUX TRIP OPERATED BUS DIFF RELAY SUPERVISION OP FAN BKR.GROUP 1 O/C RELAY DC SUPPLY FAIL BUS DIFF RELAY DC SUPPLY FAIL FAN BKR.GROUP 2 OVERCURRENT RELAY FAIL BUS DIFF RELAY DC CONV FAIL FAN THERMAL RELAY GROUP 1 PRI 85CO SWITCH (PTT1 DEF1) BUS DIFF CUT OFF SW (87BCO) FAN THERMAL RELAY GROUP 2 PTT CARRIER SIGNAL FAIL FAULT PRESSURE RELAY TRIP PTT CARRIER SIGNAL RECEIVED Shunt Capacitor LTC OVERCURRENT DURING TAP CHANGE PTT CARRIER SIGNAL SEND DC SUPPLY FAIL LTC.DRIVE MOTOR BREAKER RECLOSER RELAY DC FAIL UNBALANCE RELAY TRIP LTC.PRESSURE RELAY TRIP RECLOSER RELAY FAIL OVERVOLTAGE RELAY OP OIL TEMP INDICATOR RECLOSER RELAY LOCKOUT OP RUBBER BAG RUPTURE TAP CHANGE DELAY TAP DIFFERENTIAL OPERATED TX.DIFF CUTOFF SW.(87CO) POSITION TX.OIL LEVEL GAUGE TX.PRESSURE RELIEF DEVICE Table 5. Alarm Categorize 6
NAC operators normally use Online Picture Generator program (OPG) to create and modify display in MMI of the Main SCADA System and the Backup SCADA System. This program was also utilized to improve the new alarm system according to the design objectives in this project. Whereas, the accurate database must be linked directly to the display monitor as shown in fig. 5. Figure 5. Display database After linking process was complete, the display must be uploaded to online mode as depicted in figure 6. Figure 6. Online Display 7
4. Improvement Result Whenever any fault outage occurred, the trouble point box will change into red color. It will also blink until acknowledgement from the NAC operator. The staff will find the problem much easier without wasting time for searching, unlike we had to do with the previous alarm system. NAC staff can then get the complete information immediately like the initial details from the substation provided by the staff, there. The approximate time of business period and non-business period workflow with the new alarm system are shown in table 6 and table 7 respectively. Using the new time. Time (sec.) Trouble start Preliminary inspection in abnormal substation 5 Search the abnormal point in Alarm Summary page 3 Gather all information (from substation staff) 5 Event Analysis 15 Restore the abnormal equipment Depend on each situation Total 28 Table 6. Approximate trouble diagnostic time with the new alarm system during business period Using the new time. Time (sec.) Trouble start Preliminary inspection in abnormal substation 5 Search the abnormal point in Alarm Summary page 3 Gather all information (from substation staff) 5 Event Analysis 15 Restore the abnormal equipment Depend on each situation Total 28 Table 7. Approximate trouble diagnostic time with the new alarm system during non-business period For other advantages of the new alarm system, it can hold the remaining trouble in red color until maintenance team had solved the equipment problem already. NAC staff can also find and summarize the remaining trouble easily. While the previous alarm system, the display can show only last 200 pages which often caused of losing on important data. The additional procedure of this new alarm system is to update its database immediately after the change on equipment of power system, in order to retain accuracy of such warning scheme. 8
5. Continuous Working The new alarm system can then be further implemented to other substations include 4 GCC and 39 CCS ones without the new display creating because the database of each place are similar to NAC s. Therefore, the staff can copy the display file from NAC to be used in other stations and also can upload database easily. 6. Conclusion When any trouble occurs on an equipment of power system. The new alarm system can help the operator of dispatching center to reduce the diagnostic time. The dispatching center staff can get the information immediately without necessary to call for more details from substation operator which took much time during non-working hours. This lets the operator can be able to analyze the problem faster than have been done with the previous alarm system. As a result, the system will be brought back to normal much more rapidly. And the power system will not be affected or will experience a lowest duration of the power outage. By comparison, it is evident that for the prior alarm system, the dispatching center staffs need to investigate all data in several pages. But in the new alarm system. They can focus on only one page, to analyze data and make decision. Thus, the restoration becomes more efficiency. However, the display file must be updated, whenever the power system equipment was changed, in order to retain accuracy of the database. REFERENCES [1] Atthawut Kundee, Thanakrit Jamjumrus, Manu Pongkaew, Sunthorn Phramphithak, "Lock-Out Logic Diagram New Technique To Reduce Power Outage Analyzing Time", CIGRE International Symposium, Auckland, New Zealand, September 2013 9