Hardware and Functional Development of Protection Devices and Systems - Digital Signal Processing in Power System Protection and Control - page 15

Table 3.1 Enhancements in processing power of digital systems

Year Memory RAM/EPROM Data bus width (bits) Calculation speed (MIPS)

1986 64k/128k 16 0.5

1992 256k/512k 16 1.0

1999 512k/4 MB

+4 MB D-RAM

32 35

2004 16 MB Flash

+12 MB D-RAM

32 80

Protection
equipment

Adaptable filters
and algorithms
Iterative and intelligent
algorithms

Modern
relays & future
ideas

Distance,
differential
relays

Fourier filters
(multiplication)

Walsh filters
(addition, subtraction)

OC relays
(1st versions)

Advancements
in technology

8 bit
processors

16 bit
processors

32 bit
processors

64 bit
processors
Signal processors

Fig. 3.2 Development of protection equipment vs. advancements in technology

• facility of communication,
• self-testing capabilities.

Realization of more and more complex measurements and other protection
functions have become possible thanks to advancements in digital technology.
Better and more powerful processors (Table 3.1 ) enable implementation of more
sophisticated methods and algorithms (Fig. 3.2 ), including also self-testing and
communication with the environment. The integration of more and more protec-
tion functions in one cubicle has become a common practice. Examples of feeder
protection relays (Z\, I[ directional) of three generations can be seen in Fig. 3.3 .
More and more efficient digital processing of relaying signals as well as con-
tinuous progress in telecommunication enabled coming of the era of 4th generation
of protective devices. It is the era of Wide-Area Measurement and Protection
Systems (WAMPS), which combine sophisticated digital processing with the fast
and reliable exchange of information via telecommunication links [ 1 , 3 , 14 ].
The 4th generation has the following properties:

• wide area measuring of signals and transfer of the results to the decision-making
points,