Test device for a photovoltaic system having solar cell string
A bypass diode with a disconnection fault is identified. A test device includes: a signal introduction circuit that applies a disconnection position identification signal to between a positive electrode and a negative electrode of a solar battery string; and a fault calculating part that identifies the bypass diode with a disconnection fault on the basis of an AC component of a voltage between a frame ground and the positive electrode or an AC component of a voltage between the frame ground and the negative electrode when the disconnection position identification signal is applied.
1. A test device that tests a solar cell string in which a plurality of solar cell modules in which a bypass diode is connected in parallel to one or more solar cells are connected in series when the solar cell string does not generate electric power, the test device comprising:
an application part configured to apply a disconnection position identification signal which is an electrical signal including an AC component to between a positive electrode and a negative electrode of the solar cell string; and
a disconnection position identifying part configured to identify a bypass diode with a disconnection fault on a basis of at least one of an AC component of a voltage generated between a frame ground and the positive electrode of the solar cell string and an AC component of a voltage generated between the frame ground and the negative electrode by application of the disconnection position identification signal.
2. The test device according to claim 1 , further comprising a power generation state determining part configured to determine whether the solar cell string is in a power non-generating state,
wherein, when the power generation state determining part determines that the solar cell string is in the power non-generating state, the application part applies the disconnection position identification signal and the disconnection position identifying part identifies a bypass diode with a disconnection fault.
3. The test device according to claim 1 , wherein the disconnection position identifying part identifies the bypass diode with a disconnection fault on a basis of a ratio of the AC component of the voltage generated between the frame ground and the positive electrode of the solar cell string or the AC component of the voltage generated between the frame ground and the negative electrode to an AC component of a voltage between the positive electrode and the negative electrode of the solar cell string.
4. The test device according to claim 1 , wherein the disconnection position identifying part identifies the bypass diode with a disconnection fault on a basis of a ratio of the AC component of the voltage generated between the frame ground and the positive electrode of the solar cell string and the AC component of the voltage generated between the frame ground and the negative electrode.
5. The test device according to claim 4 , further comprising a disconnection fault determining part configured to determine whether one of the bypass diodes has a disconnection fault,
wherein the disconnection position identifying part determines that the bypass diode located at a center has a disconnection fault when the disconnection fault determining part determines that one of the bypass diodes has a disconnection fault and the ratio is 1:1.
6. The test device according to claim 1 , wherein the disconnection position identification signal includes a forward DC component of the bypass diode.
7. The test device according to claim 2 , wherein the disconnection position identifying part identifies the bypass diode with a disconnection fault on a basis of a ratio of the AC component of the voltage generated between the frame ground and the positive electrode of the solar cell string or the AC component of the voltage generated between the frame ground and the negative electrode to an AC component of a voltage between the positive electrode and the negative electrode of the solar cell string.
8. The test device according to claim 2 , wherein the disconnection position identifying part identifies the bypass diode with a disconnection fault on a basis of a ratio of the AC component of the voltage generated between the frame ground and the positive electrode of the solar cell string and the AC component of the voltage generated between the frame ground and the negative electrode.
9. The test device according to claim 8 , further comprising a disconnection fault determining part configured to determine whether one of the bypass diodes has a disconnection fault,
wherein the disconnection position identifying part determines that the bypass diode located at a center has a disconnection fault when the disconnection fault determining part determines that one of the bypass diodes has a disconnection fault and the ratio is 1:1.
10. The test device according to claim 2 , wherein the disconnection position identification signal includes a forward DC component of the bypass diode.
11. The test device according to claim 3 , wherein the disconnection position identification signal includes a forward DC component of the bypass diode.
12. The test device according to claim 4 , wherein the disconnection position identification signal includes a forward DC component of the bypass diode.
13. The test device according to claim 5 , wherein the disconnection position identification signal includes a forward DC component of the bypass diode.
14. The test device according to claim 6 , wherein the disconnection position identification signal includes a forward DC component of the bypass diode.
15. The test device according to claim 7 , wherein the disconnection position identification signal includes a forward DC component of the bypass diode.
16. The test device according to claim 8 , wherein the disconnection position identification signal includes a forward DC component of the bypass diode.
17. The test device according to claim 9 , wherein the disconnection position identification signal includes a forward DC component of the bypass diode.