IEEE Power & Energy Magazine - September/October 2015 - 70

3.5
3
2.5
2
1.5
1
0.5
0
-0.5
-1
-1.5

Power Angle
Between (YN + GZ) and GD (º)

Power Angle
Between GZ and YN (º)

Much of the disturbance data recorded by PMUs
showed significant differences between the simulation results
and real system responses.

With GGI HVDC WADC
With GGI and GGII HVDC WADCs
No WADC
5

8
9
Time (s)
(a)

32
31
30
29
28
27
26
25
24
23

With GGI HVDC WADC
With GGI and GGII HVDC WADCs
No WADC
5

9
10
Time (s)
(b)

figure 13. The field test results for the CSG's HVdc WADC system.

Research on the implementation of the WADC has been
extensive, with power system stabilizers (PSSs) being used
as controllers. In 2013, this kind of wide-area PSS was
installed in both the Silin power plant in Guizhou province
and the Ertan power plant in Sichuan province.

and accelerate fault clearance. Field disturbance recordings
show that the fault clearance time for a circuit breaker failure
can be decreased from 1.0-2.0 s to 0.2 s with the aid of the
WAP system. Based on this WAP platform, a fast auto-switching of wide-area backup power supply can be fulfilled.

Wide-Area Protection Application

Outlook for PMU/WAMS
Applications in China

Existing protection systems are distributed control systems
that mainly use local information to detect power system
faults and abnormal states. To solve the problem of coordinating among different backup protection systems, wide-area
current differential backup protection is utilized. In this way,
faults can be correctly identified and cleared, and the time
for fault clearance shortened. In the case of power loss after
fault clearance in a bus or substation, fast recovery can be
achieved under this wide-area protection (WAP) platform.
Since it went into operation in December 2011, the Duyun
WAP project has been implemented on seven 110-kV substations in the Duyun district of Guizhou. The communication
structure of the system is designed in a ring-like form; its
architecture is shown in Figure 14. The system consists of
two (one for redundancy) master stations and seven subsidiary control stations. A master station can analyze the mode
and status of a power grid, determine fault locations, and
send corresponding commands to control stations. A subsidiary control station is responsible for acquiring electrical and
state quantities and issuing protection and control functions
that only require local substation information.
The coordination among backup protection systems can be
realized by using the WAP system to isolate faulty components
70

ieee power & energy magazine

In the past decade, an increasing number of PMUs and WAMSs
have been put into service, and the development of synchrophasor technology has allowed its advanced application in
power grid management, stability enhancement, and efficiency
improvement. Current application trends include switching
from offline to online and from monitoring to control. Some
demonstration projects have been commissioned in China and
have shown excellent performance and strong potential. However, the huge amount of data measured by the PMU/WAMS
system remains far from being fully exploited to meet all smart
grid requirements. Combining China's PMU/WAMS with big
data technology offers an important opportunity to extend their
combined applications further. Other research directions include
developing high-precision PMUs and exploring the applications
of PMU data in power distribution systems and in some industrial power systems.

Acknowledgments
This work was supported by the National Key Basic Research
Program of China (2012CB215206, 2013CB228203), the
Program of the National Natural Science Foundation of
China (51107061), and the Innovative Research Groups
september/october 2015

Table of Contents for the Digital Edition of IEEE Power & Energy Magazine - September/October 2015