Three-phase AC phase sequence detecting method and apparatus
View Patent ↗The disclosure provides a three-phase AC phase sequence detecting method, including the steps of: 1 ) sampling instant values of three-phase AC electrical signal in real-time; 2 ) converting said instant values into electrical signal components in a two-phase still coordinate system in manner of coordinate conversion; 3 ) performing an arc tangent calculation on the electrical signal components to obtain a output signal value; 4 ) executing step 1 ) to step 3 ) one or more times, to obtain one or more output signal values; 5 ) the output signal values obtained from step 3 ) and the one or more output signal values obtained from step 4 ) composing a periodic function, if the periodic function is an increasing function within one minimum positive period, the three-phase AC phase sequence is determined to be positive sequence; otherwise, negative sequence. Three-phase AC phase detecting a detecting apparatus using the above detecting method is also provided.
1. A three-phase AC phase sequence detecting method, including the steps of:
1 ) sampling instant values of a three-phase AC electrical signal in real-time to obtain a set of instant values;
2 ) converting, using coordinate conversion, said set of instant values into electrical signal components in a two-phase still coordinate system;
3 ) performing an arc tangent calculation on the electrical signal components to obtain an output signal value corresponding to a sampling timing;
4 ) executing step 1 ) to step 3 ) one or more times, to obtain one or more output signal values corresponding to one or more sampling timings adjacent with said sampling timing at step 3 );
5 ) combining the output signal values obtained from step 3 ) and the one or more output signal values obtained from step 4 ) to form one periodic function, which is a linear function within one minimum positive period, and the period of the periodic function is the same as that of the three-phase AC electrical signal, determining the three-phase AC phase sequence to be positive or negative based on whether the periodic function is an increasing or a decreasing function within one minimum positive period: if the periodic function is an increasing function within one minimum positive period, the three-phase AC phase sequence is determined to be positive sequence; if the periodic function is a decreasing function within one minimum positive period, the three-phase AC phase sequence is determined to be negative sequence,
wherein the waveform between two adjacent peaks in the waveform of any phase in three-phase AC electrical signal corresponds to one minimum positive period.
2. The detecting method according to claim 1 , wherein the three-phase AC electrical signal is a three-phase AC phase voltage signal or a three-phase AC phase current signal.
3. The detecting method according to claim 1 , in the step 2 ), said conversion is Clarke coordinate conversion; and the following equation of the Clarke coordinate conversion is used:
{
[
D
α
D
β
]
=
2
3
[
1
-
1
2
-
1
2
0
3
2
-
3
2
]
[
D
a
D
b
D
c
]
D
a
+
D
b
+
D
c
=
0
(
1
)
wherein: D a , D b and D c are the instant values of three-phase AC electrical signal, D α and D β are the electrical signal components in the two-phase still coordinate system obtained after the Clarke coordinate conversion is performed on instant values D a , D b and D c .
4. The detecting method according to claim 3 , in the step 3 ), the equation used to perform the arc tangent calculation on the electrical signal components is:
y
=
{
arctan
(
u
β
/
u
α
)
0
<
arctan
(
u
β
/
u
α
)
<
π
arctan
(
u
β
/
u
α
)
+
2
π
-
π
<
arctan
(
u
β
/
u
α
)
<
0
(
2
)
wherein, y is said output signal value, D α and D β are the electrical signal components in the two-phase still coordinate system, which are obtained after the Clarke coordinate conversion is performed on instant values D a , D b and D c .
5. The detecting method according to claim 1 , in the step 5 ), the way to determine whether the periodic function is an increasing or a decreasing function within one minimum positive period is:
Δy=y(n)−y(n−1), wherein, y(n) and y(n−1) are the output signal values corresponding to the instant values of three-phase AC electrical signals obtained by sampling a electrical signal of the three-phase AC electrical signal at two adjacent sampling timings within one minimum positive period, respectively,
if 0<Δy<2π, the periodic function is an increasing function within one minimum positive period; if −2π<Δy<0, the periodic function is a decreasing function within one minimum positive period.
6. The detecting method according to claim 1 , said step 1 ) also including per-unit processing said set of instant values, and the following equation of the per-unit processing is used:
d x =D x /d max (3)
wherein, x is a, b and c, D a , D b and D c are the instant values of the three-phase AC electrical signals, d max is the maximum value of three-phase AC electrical signal, d a , d b and d c are the per-unit values of the instant values of the three-phase AC electrical signals.
7. The detecting method according to claim 1 , the step 3 ) also including per-unit processing the output signal value, and the following equation of the per-unit processing is used:
y*=y/ 2π (4)
wherein, y is the output signal value, y* is the per-unit value of the output signal value.
8. A three-phase AC phase sequence detecting apparatus, including a three-phase AC sampling module, a coordinate system conversion module, an arc tangent function calculation module and a phase sequence direction deciding determining module;
the three-phase AC sampling module performs real-time sampling on the instant values of three-phase AC electrical signals;
the coordinate system conversion module converts the instant values of at least two sets of three-phase AC electrical signals in a three-phase still coordinate system obtained by real-time sampling via the three-phase AC sampling module into electrical signal components in a two-phase still coordinate system respectively, and transfer them to the arc tangent function calculation module in real-time;
the arc tangent function calculation module performs an arc tangent calculation on the electrical signal components, respectively, to obtain at least two output signal values, and transfer them to the phase sequence direction determining module;
the phase sequence direction determining module combines at least two output signal values to form one periodic function, and determines whether the three-phase AC phase sequence is positive or negative based on whether the periodic function is an increasing function or a decreasing function within one minimum positive period,
wherein the waveform between two adjacent peaks in the waveform of any phase in three-phase AC electrical signal corresponds to one minimum positive period.
9. The detecting apparatus according to claim 8 , said detecting apparatus also including a first per-unit processing module and/or a second per-unit processing module,
said first per-unit processing module per-unit processes the instant values of the at least two sets of three-phase AC electrical signals obtained by real-time sampling via said three-phase AC sampling module, and output the per-unit values to the coordinate system conversion module in real-time;
said second per-unit processing module per-unit processes at least two output signals obtained by said arc tangent function calculation module, and output the per-unit values to the phase sequence direction determining module in real-time.