SHORTENING THE CHECKING TIME ON POWER CONSUMPTION
LOCAL SERVICE TERMINAL
Metrology QC team,metering center,Xiaoshan power supply bureau
PREFACE
2006 is a historically significant year for Xiaoshan Power Supply Bureau: its comprehensive strength ranked the first in the whole province, sales energy exceeded 10 billion kwh, power supply load reached 1.73 million kw, it also made new advances in safe production, grid construction, quality service, etc. and became a top 50 power supply enterprise in our country, passed the acceptance check of “National New Rural Electrization County”, was recognized as “National Consumers Satisfaction Enterprise”, received a Zhejiang Provincial-level energy metering authorization. Electric power in Xiaoshan develops healthily, swiftly and stably.
Accompanied by a rapid development in grid construction, to implement a better power demand side management and optimize the gird operation, power supply departments start to utilize a power consumption locale service terminal (hereafter referred as “terminal”) to real-time monitor and manage consumers’ power consumption, as a result, it is extremely necessary to validate the function and quality of terminals.
1 SURVEY
1.1 Brief introduction of team
Name / Metrology QC team, metering center, Xiaoshan power supply bureauPurpose / Guarantee metering precision, improve work efficiency
Founding time / Jun. 2002 / Registration time / Jan. 2006 / Registration No. / 2006118
Type of subject / Locale type / Number of team member / 7 / Times of activity / 18
Time of activity / Jan. 2006 – Jul. 2006 / Attendance rate / 100％
Team member
Situation
Name / Gender / Education / Position / Position in QC team / Enducation condition
Yaoliwen / female / bachelor / Watt-hour meter checking / team-leader / 30h
Chenyan / female / secondary school graduate / vice-monitor / vice-team-leader / 30h
Caiyong / male / junior college
graduate / director of institute / team member / 30h
Fangjianfen / female / junior college graduate / Watt-hour meter checking / team member / 30h
Shanweiying / female / secondary school graduate / Watt-hour meter checking / team member / 30h
Hanxiongfeng / female / junior college graduate / Watt-hour meter checking / team member / 30h
Shouliling / female / bachelor / Watt-hour meter checking / team member / 30h
Honor / National excellent quality control team in 2006 and 2007
1.2 Activity scheme
Table 1 Activity scheme（Gunter）
Time of activity : Jan.2006－Jul.2006Jan. / Feb. / Mar. / Apr. / May / Jun. / Jul.
P / Subject
selection /
Situation investigation /
Subject target / /
Cause analysis /
Cause confirmation /
Countermeasures establishment / /
D / Countermeasures implement /
C / Examination /
A / Strengthening measures /
Conclusion and plan /
Note / Intend scheme Actual progress
2 REASONS FOR SUBJECT SELECTION
In Aug. 2005, metering center of Xiaoshan Power Supply Bureau began to check the terminals formally.
According to statistics, 2880 terminals are in need in the whole region during Jan. 2006 to Dec. 2006.
Based on the current production technology, condition and capability in the checking room, it requires 550 minutes to check a batch of (16) terminals (including 194-min terminal test and 356-min invariable time); suppose that weekly working time is 1850 minutes (excluding everyday warm-up time), 3 batches of terminals (1850/550=3) could be checked every week, amounting to 48 terminals, thus, 2304 terminals could be checked in 2006, which could not meet the actual demand for 2880 terminals. (48 weeks a year)
To guarantee the metering precision, and complete the task smoothly, we chose this subject—to shorten the checking time on power consumption locale service terminal.
3 INVESTIGATION ON CURRENT SITUATION
Investigation Ⅰ Power consumption terminal
3.1.1 Terminal test
According to 《Regulation on Power Consumption Locale Service and Management System Communication in Zhejiang Province》, terminal test includes 20 items. An qualified test will be recognized only after finishing the 20 items entirely; otherwise, it will be determined as an unqualified one.
3.1.2 Test items
According to Regulation on Power Consumption Locale Service and Management System Communication in Zhejiang Province, test time in each item has been specified by checking software, namely the allowable longest time in the item. An qualified item will be recognized only if relevant data is transferred to the software within the specified period; otherwise, it will be determined as an unqualified one. Details of each item refer to the following table:
Table 2 The time specified by checking software
No. / Test item / Specified time (mins) / No. / Test item / Specified time (mins)1 / power source performance / 15 / 11 / terminal electrification / 8
2 / metering error / 10 / 12 / current imbalance / 8
3 / voltage
phase loss / 8 / 13 / CT secondary
open circuit / 8
4 / voltage
phase open / 8 / 14 / CT secondary short circuit / 8
5 / anti-polarizing current / 8 / 15 / energy decline / 70
6 / reactive power under compensation / 8 / 16 / fast-moving meter / 70
7 / reactive power over compensation / 8 / 17 / time-interval charge variation / 35
8 / current over load / 8 / 18 / demand reset / 35
9 / voltage reverse phase consequence / 8 / 19 / pausing meter / 70
10 / gate point / 8 / 20 / pulse constant variation / 35
3.1.3 Data reception
Check the 16 terminals at the same time, and then receive the 16 data according to DL/T645-1997 《Multi-function Watt-hour meter Communication Regulation》:
In each round, software spends 7 seconds receiving data from the terminals, which have not received data. If the data is received within 7 seconds successfully, the software will not receive data from that terminal over again in next round; otherwise, it will automatically forward to the next terminal that has not received data, until it finishes receiving data from all the other terminals that has not received data. Then begins the next round. After receiving the entire data successfully or unsuccessfully within the specified time, check the 16 terminals at the same time to distinguish between qualified and unqualified.
Therefore, in case of a poor performance, times of test rounds will be increased and checking time will be prolonged.
Conclusion I :
Checking time on power consumption terminals is affected by qualification rates of test items.
Investigation Ⅱ Qualification rates of test items
We complied statistics on qualification rates of each test items for Wansheng Power Consumption Terminal:
Table 3 Qualification rate for test items
No. / Test item / Qualification rate（％） / No. / Test item / Qualification rate（％）1 / power source performance / 95 / 11 / terminal electrification / 95
2 / metering error / 95 / 12 / current imbalance / 93
3 / voltage phase loss / 94 / 13 / CT secondary
open circuit / 90
4 / Voltage
phase open / 95 / 14 / CT secondary
short circuit / 90
5 / anti-polarizing current / 96 / 15 / energy decline / 40
6 / reactive power under compensation / 93 / 16 / fast-moving meter / 42
7 / reactive power over compensation / 95 / 17 / time-interval
charge variation / 44
8 / current over load / 94 / 18 / demand reset / 41
9 / voltage reverse phase consequence / 93 / 19 / pausing meter / 40
10 / gate point / 95 / 20 / pulse constant variation / 40
1. In the diagrams, qualification rates from No.1 to No.14 are relatively much higher, ones from No. 15 to No. 20 are relatively lower;
2. Six items should be checked through RS485 communication method, including energy decline, fast-moving meter, time-interval charge variation, demand reset, pausing meter, and pulse constant variation. In that case, we named these six items as RS485 communication items.
Conclusion II :
Qualification rates of RS485 communication items are low.
Investigation Ⅲ Time comparison between qualified and unqualified
We compared qualified ones with unqualified ones in the aspect of checking time in all of the 20 test items. Differences are following:
Table 4 Time comparison between qualified ones and unqualified ones
No. / Test item / Qualified / Unqualified / Time comparisonActual time (mean) (mins) / Actual time (mean) (mins)
1 / power source performance / 3 / 15 / 12
2 / metering error / 3 / 10 / 7
3 / voltage phase loss / 2 / 8 / 6
4 / voltage phase open / 2 / 8 / 6
5 / anti-polarizing current / 3 / 8 / 5
6 / reactive power under compensation / 5 / 8 / 3
7 / reactive power over compensation / 5 / 8 / 3
8 / current over load / 5 / 8 / 3
9 / voltage reverse phase consequence / 2 / 8 / 6
10 / gate point / 1 / 8 / 7
11 / terminal electrification / 1 / 8 / 7
12 / current imbalance / 5 / 8 / 3
13 / CT secondary open circuit / 3 / 8 / 5
14 / CT secondary short circuit / 2 / 8 / 6
15 / energy decline / 2 / 70 / 68
16 / fast-moving meter / 5 / 70 / 65
17 / time-interval charge variation / 2 / 35 / 33
18 / demand reset / 1 / 35 / 34
19 / pausing meter / 6 / 70 / 64
20 / pulse constant variation / 1 / 35 / 34
total / 59 / 436 / 377
1. Combined with investigation 1 and 2, according to formula (1), we conclude that checking time in 20 test items requires 194 minutes (average value), details refer to appendix 1;
t=specified time by software * unqualification rate + average time of qualified ones * qualification rate （1）
2. From table 4, in case of unqualification checked by RS485 communication items, the checking time is longer.
3. Combined with investigation II, qualification rates of RS485 communication items are low. The lower the qualification rate is, the
longer the checking time costs. As a result, the checking time of power consumption terminals is prolonged.
Conclusion III :
RS485 communication items are the key to solve the problem that checking time of terminals is long.
4 SUBJECT TARGET
Basis:
1. After discussion, we found it practical to shorten the checking time of RS485 communication items;
2. Among the 32 batches of Wansheng Power Consumption Terminals, 8 batches out of 32 were qualified after test. We chose one of
them whose checking time requires 66 minutes, which is longest of all.
5 ANALYSIS ON CAUSES
6 CONFIRMATION OF PRIMARY
Table 5 Confirmation of primary causes scheme
No. / End cause / Content / Method / Standard / Principal / Finish time1 / inexperience / whether operators pass the training / investigate the implementation of training system in teams / training by ourselves once a month technical Q&A once a week / Chen
yan / 13th.Feb
2 / low-level checking devices / whether level of checking devices meet the standard / refer to relevant regulation / GB11150-1989《Watt-hour meter checking equipment》National standard / Shou
liling / 13th.Feb
3 / time for RS485 communication
items checking supplied by
factories is counted too much / whether time-set in software scheme is rational / refer to relevanrt standard of making checking software / DL/T743-2001《Remote terminal unit of electric energy》 / Yao
liwen / 13th.Feb
4 / copper lead / whether lead materials meet the standard / check the coopper lead used during the operation / DL/T448-2000《Technical management regulation on electric energy devices》（5.4 configuration principle g on electric energy devices） / Han
xiongfen / 14th.Feb
5 / silver plated
copper clamp / whether clamp materials meet the standard / check the silver plated copper clamp used during the operation / DL/T448-2000《Technical management regulation on electric energy devices》（5.4 configuration principle g on electric energy devices） / Fang
jianfeng / 13th.Feb
6 / temperature and humidity control unperfected system / whether temperature and humidity control meet the standard / measure the temperature and humidity in the checking room / JJG596－1999《Regulation on electronic watt-hour meter checking》 / Cai
yong / 14th.Feb
7 COUNTERMEASURES ESTABLISHMENT
Table 6 Countermeasures
Item(primary cause) / countermeasure / target / measures / location / principal / due date
time in RS485 communication items verificat-
ion supplied by factories is cou-
nted too much / reinstall the spe-
cified time in
RS485 items,
and remain the
time in other
items / shorten the
specified time in RS485
items from
152 minutes
to 24 minutes (66-42=24), to improve
the efficiency / 1. confirm the time-set for RS485 items on the basis of normal distribution theory / library / Yaoliwen
Chenyan
Shoulilin / Feb.
2006
2. acquire data / checking room
3.aconfirm the time in RS485
items on the basis of normal
distribution theory and statistic-
al characteristic values / checking room
4.areinstall time scheme and oper-
ation process / checking room
5. check by using the new scheme / checking room
6.avary the scheme across differe-
nt factories / checking room