Electrical power distribution monitoring system and method

• US 5,963,457 A
• Filed: 03/14/1995
• Issued: 10/05/1999
• Est. Priority Date: 03/18/1994
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Inoue, Hiroshi, Kudo, Hiroyuki, Kawakami, Junzo, Nishijima, Kazuo, Kanoi, Minoru, Takei, Toru, Yasukawa, Saburou, Imamura, Yuzuru, Iwashita, Kiyoji
• Primary Examiner(s): Trammell, James P.
• Assistant Examiner(s): Nguyen, Cuong H.
• Application Number:
  US08/403,434
• Time in Patent Office: 1,666 Days
• Field of Search: 307/31-41, 307/59-63, 307/115, 307/126, 307/130, 307/131, 364/139, 364/132, 364/528.21, 364/528.28, 364/528.26, 702/62, 702/58, 702/63, 702/66
• US Class Current: 700/291
• CPC Class Codes: H02J 13/00002 characterised by monitoring
• CPC Class Codes: H02J 3/00 Circuit arrangements for ac mains or ac distribution networks
• CPC Class Codes: H02J 3/04 for connecting networks of the same frequency but supplied from different sources
• CPC Class Codes: Y02E 60/00 Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
• CPC Class Codes: Y04S 10/30 State monitoring, e.g. fault, temperature monitoring, insulator monitoring, corona discharge

Abstract

An electrical power distribution monitoring system is provided for a power distribution line having a plurality of sections with a plurality of electrical loads connected to the power distribution line to form a power distribution network. The monitoring system has at least one sensor for at least one present electrical value at at least one point of the network, and estimates electrical values for at least one section of the line in dependence on both of present electrical values measured by the sensor and data relating to past power consumption by loads connected to the line. Improved prediction of actual conditions in the distribution line can be obtained.

Claims

1. An electrical power distribution monitoring system, for a power distribution line having a plurality of sections with a plurality of electrical loads connected to the power distribution line to form a power distribution network, said monitoring system comprising:

(a) at least one first power sensor arranged to measure power being supplied to said power distribution line at a power input end of said power distribution line;

(b) at least one second power sensor arranged to measure power passing between said power distribution line and at least one specific one of said electrical loads;

(c) a data store containing data set in advance relating to power consumption of said plurality of sections; and

(d) calculating means arranged to estimate electrical values for at least one of said sections of said power distribution line in dependence on present electrical power data measured by said first power sensor and said second power sensor, and in dependence on said data in said data store.

2. An electrical power distribution monitoring system according to claim 1, wherein said at least one first power sensor measures total power being supplied to said power distribution line.

3. An electrical power distribution monitoring system according to claim 1, wherein said at least one second power sensor comprises a power sensor device arranged to measure power passing in a branch of said power distribution network connecting said at least one specific electrical load to said power distribution line.

4. An electrical power distribution monitoring system according to claim 1, wherein said at least one second power sensor comprises two power sensor devices arranged to measure power passing in said power distribution line at respective points in said power distribution line, between which said at least one specific electrical load is connected to said power distribution line, thereby to provide a measurement of power passing between said power distribution line and said at least one specific electrical load.

5. An electrical power distribution monitoring system according to claim 1, wherein said at least one specific load, on average, consumes at least 5% of the total consumption by all of the electrical loads connected to said power distribution line.

6. An electrical power distribution monitoring system according to claim 1, wherein said calculating means is arranged to use data from said data store for predicting consumption by all of the electrical loads connected to said power distribution line except said at least one specific electrical load.

7. An electrical power distribution monitoring system according to claim 1, wherein said electrical loads comprise a plurality of electricity-consuming buildings.

8. An electrical power distribution monitoring system according to claim 1, wherein said calculating means calculates the difference of said at least one first power sensor and said at least one second power sensor, and calculates power consumption of every one of said sections by distributing calculated electrical power data.

9. An electrical power distribution monitoring system according to claim 1, wherein said at least one second power sensor includes a power sensor arranged to measure power passing in a branch of said network connecting said specific load to said power distribution line.

10. An electrical power distribution monitoring system according to claim 1, wherein said calculating means is arranged to calculate estimated power values in each of a plurality of said sections of said line.

11. An electrical power distribution monitoring system according to claim 1, wherein said data in said data store comprises, as said data relating to past power consumption, data relating to past power consumption of each of said sections of said power distribution line.

12. An electrical power distribution monitoring system according to claim 1, wherein said calculating means is arranged further to calculate, from sections, the degree of deviation of said estimated electrical values from a predetermined standard value or values.

13. An electrical power distribution monitoring system, for a power distribution line having a plurality of sections and having a power input at an input end, there being a plurality of electrical loads connected to the power distribution line, said monitoring system comprising:

(a) measurement means for measuring an electrical value at at least one of (i) a point on said power distribution line, (ii) a selected one of said electrical loads, and (iii) a selected group of said electrical loads,

(b) a data store containing data relating to past power consumption by electrical loads connected to said power distribution line, and

(c) calculating means connected to said measurement means and to said data store and arranged to calculate estimated electrical values in at least one of said sections of said power distribution line from both of at least one currently measured electrical value obtained by said measurement means and said data in said data store;

wherein said measurement means comprises at least a first measurement device for measuring said at least one currently measured electrical value in a portion of said power distribution line closer to said input end thereof than all of said electrical loads.

14. An electrical power distribution monitoring system according to claim 13, wherein said measurement means further comprises a second measurement device arranged to measure, as said at least one currently measured electrical value, at least the current passing between said power distribution line and said selected one of said electrical loads.

15. An electrical power distribution monitoring system according to claim 14, wherein said selected one of said electrical loads, on average, consumes at least 5% of total power consumption by all of the electrical loads connected to said power distribution line.

16. An electrical power distribution monitoring system according to claim 13, wherein said measurement means further comprises a plurality of second measurement devices arranged in said power distribution line to measure, as said at least one currently measured electrical value, at least the current passing between said power distribution line and said selected one or selected group of said electrical loads.

17. An electrical power distribution monitoring system according to claim 13, wherein said calculating means is arranged to calculate estimated power values in each of plural ones of said plurality of sections of said power distribution line.

18. An electrical power distribution monitoring system according to claim 13, wherein said data store contains, as said data relating to past power consumption, data relating to past power consumption of each said section of said power distribution line.

19. An electrical power distribution monitoring system according to claim 13, wherein said calculating means is arranged further to calculate, from estimated electrical values in plural ones of said plurality of sections, the degree of deviation of said estimated electrical values from respective predetermined standard values.

20. An electrical power distribution monitoring system, for a power distribution network having at least one bus connected to a higher level power network through a transformer and at least one bank comprising a plurality of distribution lines each composed of a plurality of sections and connected to one of said at least one bus;

said monitoring system comprising;

for each said distribution line, a first sensor device for measuring the electricity transmission amount at an input end of the distribution line from one of said at least one bus;

for each said distribution line, at least one second sensor device for measuring the electricity amount passing between the distribution line and at least one specific electrical load connected thereto;

administrative information calculating means for calculating load distribution coefficients of each said section of each said distribution line from data of past power consumption of each said section;

section predicting means for calculating a predicted electrical value of each said section of each said distribution line from outputs of said first and second sensor devices and said load distribution coefficients; and

network supervising means for calculating deviations of said predicted electrical valves from a predetermined value or values.

21. An electrical power distribution monitoring means according to claim 20, wherein said predicted electrical values calculated by said section predicting means are values of electrical power in the respective sections, and wherein said network supervising means comprises:

means for calculating a section voltage value from the predicted electrical power values of each said section;

section-wise supervising means for calculating a voltage deviation from a predetermined value for each respective section voltage value;

distribution line supervising means for calculating a distribution line performance index of each distribution line from the voltage deviation of each section of the respective distribution line;

bank supervising means for calculating a bank normal index of the bank from said distribution line performance index of each distribution line belonging to the same bank; and

bank analysis means for sampling one or more portions of said network suffering voltage deviation, by reference to said voltage deviations, said distribution line performance index, and said bank normal index.

22. An electrical power distribution monitoring means according to claim 21, wherein said distribution line performance index is composed of a first mean value which is a mean value of said voltage deviations of said sections of the distribution lines and a maximum value of said voltage deviations;

and

said bank normal index is composed of a second mean value which is a mean value of said first mean values of the respective distribution lines belonging to the bank, a maximum value of said first mean values, a maximum value of said voltage deviations, and voltages of the input points of the distribution lines from said bus.

23. A method of monitoring an electrical power distribution network which has a power distribution line having a plurality of sections and a power input at an input end, there being a plurality of electrical loads connected to said power distribution line, said method comprising the steps of:

(a) measuring power being supplied to said input end of said power distribution line;

(b) measuring power passing between said power distribution line and at least one specific one of said electrical loads; and

(c) calculating, from measurements of said step (a) and step (b) and from data set in advance relating to power consumption by electrical loads connected to said power distribution line, estimated electrical power data of at least one of said sections of said power distribution line.

24. A method according to claim 23, wherein step (c) calculates said estimated electrical power data of a plurality of said sections of said power distribution line, and the method further comprises the step of comparing said estimated electrical power data of each section with a predetermined standard value.

25. An electrical power distribution monitoring system, for a power distribution network having at least one bus connected to a higher level power network through a transformer and at least one bank comprising a plurality of distribution lines each composed of a plurality of sections and connected to said at least one bus, the system comprising:

means for obtaining electricity amounts of said sections;

means for calculating an electricity amount with respect to at least one said distribution line on the basis of the obtained electricity amounts;

means for calculating an electricity amount with respect to said bank;

means for comparing said electricity amounts calculated with respect to said at least one distribution line and said bank with preset reference electricity amounts for a distribution line and a bank; and

means for supervising a state in which the electricity amounts calculated with respect to said at least one distribution line and said bank deviate from the reference electricity amounts.

26. An electrical power distribution monitoring system according to claim 25, wherein said means for calculating an electricity amount with respect to said at least one distribution line calculates voltage penalty values from voltage values for each of a plurality of sections of the at least one distribution line and calculates said electricity amount for the at least one distribution line from said voltage penalty values.

27. An electrical power distribution monitoring system according to claim 26, wherein said means for calculating an electricity amount with respect to said at least one distribution line further stores a worst value of the voltage penalty functions of the respective sections thereof.

28. An electrical power distribution monitoring system according to claim 26, wherein said means for calculating an electricity amount with respect to said bank obtains a plurality of said electricity amounts with respect to respective distribution lines of said bank, and calculates said electricity amount for said bank therefrom.

29. An electrical power distribution monitoring system according to claim 28, wherein said means for calculating an electricity amount with respect to said bank further stores a worst value of said electricity amounts of the respective distribution lines.

30. An electrical power distribution monitoring system according to claim 25, wherein said means for calculating an electricity amount with respect to said bank obtains a plurality of said electricity amounts with respect to respective distribution lines of said bank, and calculates said electricity amount for said bank therefrom.

31. An electrical power distribution monitoring system according to claim 30, wherein said means for calculating an electricity amount with respect to said bank further stores a worst value of said electricity amounts of the respective distribution lines.