Summary of the invention
The technical problem that the present invention solved provides a kind of circuit of having simplified, and can detect the inverter and the detection method of solar panel and grid side insulation resistance simultaneously.
For solving above-mentioned technical problem, the technical scheme that the present invention takes:
A kind of inverter that detects solar panel and grid side insulation resistance; Its special character is: comprise boosting unit, inversion unit; Boosting unit is connected with inversion unit; Being provided with two-step relay between inversion unit end and the electrical network is that relay K 1, the relay K 3 of connecting is set on the L line, and relay K 2, the relay K 4 of series connection is set on the N line, and the centre of the centre of relay K 1, relay K 3 and relay K 2, relay K 4 is connected with relay K 5; The common point of relay K 5 connects a resistance R 1, and the other end of resistance R 1 is directly connected to casing.
A kind of detection method that detects the inverter of solar panel and grid side insulation resistance; Its special character is: through the switch of combination boosting unit and inversion unit; The first step makes an end of relay K 1 be connected with PV+; Connect relay K 1 and relay K 5 simultaneously, make resistance R 1 be connected to PV+, finally can constitute first equivalent electric circuit: PV+ and be connected with resistance R 1; Resistance R 1 and the equivalent resistance Rx1 parallel connection of PV+ to casing are again with the equivalent resistance Rx2 series connection formation electric resistance partial pressure of PV-to casing; Second step made relay K 2 be connected with PV-, connected relay K 2 simultaneously, made resistance R 1 be connected to PV-; Finally can constitute second equivalent electric circuit: PV-is connected with resistance R 1; Resistance R 1 and the equivalent resistance Rx2 parallel connection of PV-to casing with the equivalent resistance Rx1 series connection formation electric resistance partial pressure of PV+ to casing, detect sampling resistor R1 with digital processing unit simultaneously and go up voltage again; The voltage that collects constantly according to difference calculates, and obtains real-time solar panel and grid side grounding resistance.
A kind of detection method that detects solar panel and grid side insulation resistance, its special character is: concrete steps are following:
When switch S 1, switch S 2, switch S 3, switch S 4, switch S 5, relay K 1, relay K 2, relay K 3, relay K 4, relay K 5 all are in off-state; Vpv, Vg are in the real-time monitoring; Suppose that Rx1, Rx2 equivalence are solar panel both positive and negative polarity insulating resistance value over the ground, Rx3, Rx4 equivalence are grid side L, N utmost point insulating resistance value over the ground;
(1), close switch S5, relay K 2, relay K 5 does not have triggering signal, other switch is in off-state; Sampling resistor R1 goes up voltage, is recorded as Ue1, and constitute second equivalent electric circuit: PV-and directly be connected with resistance R 1 this moment; Resistance R 1 elder generation and PV-are to the equivalent resistance Rx2 parallel connection of casing, again with the equivalent resistance Rx1 series connection formation electric resistance partial pressure of PV+ to casing, because PV+ is known to the voltage of PV-; The last voltage of R1 also can detect, and can obtain equation according to the electric resistance partial pressure formula:
(2), close switch S2, relay K 2, relay K 5 have triggering signal, other switch is in off-state, this moment, sampling resistor R1 went up voltage; Be recorded as Ue2, constitute first equivalent electric circuit: PV+ and directly be connected with resistance R 1 this moment, and resistance R 1 elder generation and PV+ are to the equivalent resistance Rx1 parallel connection of casing; Again with the equivalent resistance Rx2 series connection formation electric resistance partial pressure of PV-to casing; Because PV+ is known to the voltage of PV-, the last voltage of R1 also can detect, and can obtain equation according to the electric resistance partial pressure formula:
(3), closing relay K4, relay K 5 does not have triggering signal, other switch is in off-state; Sampling resistor R1 goes up voltage; Write down mean value and called after Ue3 in the line voltage cycle, constitute second equivalent electric circuit this moment: grid side N line directly is connected with resistance R 1, and resistance R 1 elder generation and N line are to the equivalent resistance Rx4 parallel connection of casing; Again with the equivalent resistance Rx3 series connection formation electric resistance partial pressure of L line to casing; Because electrical network L line can detect at the mean value of an electrical network in the cycle the voltage of N line, the last voltage of R1 also can detect, and can obtain equation according to the electric resistance partial pressure formula:
In the formula Ug1 be with Ue3 with the line voltage sample mean in the period;
(4), closing relay K3, relay K 5 have triggering signal; Other switch is in off-state, and sampling resistor R1 goes up voltage, writes down mean value and called after Ue4 in the line voltage cycle; Constitute first equivalent electric circuit this moment: grid side L line directly is connected with resistance R 1; Resistance R 1 elder generation and L line are to the equivalent resistance Rx3 parallel connection of casing, again with the equivalent resistance Rx4 series connection formation electric resistance partial pressure of N line to casing, owing to the voltage of electrical network L line to the N line can detect at the mean value of an electrical network in the cycle; The last voltage of R1 also can detect, and can obtain equation according to the electric resistance partial pressure formula:
In the formula Ug be with Ue4 with the line voltage sample mean in the period;
(5), with equation (1) (2) simultaneous; The anode PV+ of solar panel can be tried to achieve to the negative terminal PV-of the insulating resistance value Rx1 of casing, the solar panel insulating resistance value Rx2 value to casing in solve an equation (1), (2); Wherein sampling resistor R1 is the resistance of the auxiliary detection that adds, and its resistance is much smaller than resistance R x1, resistance R x2, and its value size can be chosen according to the insulation resistance critical value of standard code; Influence degree according to resistance R 1 and 2 pairs of certainties of measurement of resistance R; Select its value to be 1/1000 of the critical value of standard code, like this at resistance R 1 or resistance R 2 and tested resistance R x1 with after resistance R x2 is parallelly connected, its parallelly connected value equals perhaps resistance R 2 of resistance R 1 basically; Thereby make formula (1) (2) set up; In like manner grid side L line can be tried to achieve to the insulating resistance value Rx3 of casing, the grid side N line insulating resistance value Rx4 to casing in simultaneous equations (3), (4), and grid side N line is direct-connected with the earth usually, so the Rx3 value should be very little.
Compared with prior art, beneficial effect of the present invention:
(1), the present invention simplified testing circuit, will detect solar panel and net side insulation resistance usually simultaneously, minimum needs two cover similar circuit.
(2), the detection method used among the present invention can be under the situation of not using more complicated additional circuit, both positive and negative polarity and electrical network L, the N line that can detect solar panel simultaneously are to the insulating resistance value between the earth.
(3), grid side N line is common and the earth is direct-connected, so the present invention also can be used as the inverter Earth Fault Detection.
Embodiment
Below in conjunction with accompanying drawing and embodiment the present invention is elaborated.
The present invention includes boosting unit, inversion unit; Boosting unit is connected with inversion unit; Being provided with two-step relay between inversion unit end and the electrical network is that relay K 1, the relay K 3 of connecting is set on the L line, and relay K 2, the relay K 4 of series connection is set on the N line, and the centre of the centre of relay K 1, relay K 3 and relay K 2, relay K 4 is connected with relay K 5; The common point of relay K 5 connects a resistance R 1, and the other end of resistance R 1 is directly connected to casing.It is forever to be connected with the centre of relay K 2, K4 that resistance R 1 is not given under the state of triggering signal in relay K 5, when triggering signal is arranged is to be connected with the middle of K1, K3.
Embodiment 1: referring to Fig. 1, the present invention includes boosting unit, inversion unit, boosting unit is connected with inversion unit, and boosting unit comprises L1, S1 and D1; PV+ is connected to inductance L 1 one ends earlier, and the L1 other end connects D1 one end, connects capacitor C 1 behind the D1 as the energy snubber unit, in the middle of L1 and D1, is connected with switch S 1; The S1 other end is connected to PV-, when S1 opens, through inductance L 1 storage power; When S1 turn-offed, inductance L 1 energy shifted to C1 through D1, reaches the power transfer purpose.Inversion unit comprises C1, S2, S3, S4, S5, L2 and L3; Switch S 2, switch S 4 and switch S 3, switch S 5 series connections are at the electric capacity two ends; Inductance L 2 and L3 connect the mid point of S2, S4 and S3, S5 respectively; HF switch through S2, S3, S4, S5 is gone up C1 to such an extent that direct voltage converts alternating voltage into, realizes energy output.
Being provided with two-step relay between inversion unit end and the electrical network is that relay K 1, the relay K 3 of connecting is set on the L line; Relay K 2, the relay K 4 of series connection are set on the N line; The centre of the centre of relay K 1, relay K 3 and relay K 2, relay K 4 is connected with relay K 5; The common point of relay K 5 connects a resistance R 1, and the other end of resistance R 1 is directly connected to casing.It is forever to be connected with the centre of relay K 1, K3 that resistance R 1 is not given under the state of triggering signal in relay K 5, when triggering signal is arranged is to be connected with the middle of K2, K4.
Embodiment 2, referring to Fig. 2, and boosting unit; Inversion unit can also have other form, and boosting unit is made up of S1, D1, L1, the direct and switch S 1 of PV+; The other end series inductance L1 that connects S1; S1 and L1 indirect diode D1, the D1 other end directly connects the negative terminal of PV-and C1, and inductance L 1 connects the anode of capacitor C 1.Inversion unit is made up of S2, S3, S4, S5, S6; S6 is serially connected between the brachium pontis that C1 and S2, S3, S4, S5 form; Switch S 2, switch S 4 and switch S 3, switch S 5 series connection backs and capacitor C 1 also are connected in two ends; Inductance L 2 and L3 connect the mid point of S2, S4 and S3, S5 respectively, go up C1 to such an extent that direct voltage converts alternating voltage into through the HF switch of S2, S3, S4, S5, realize energy output.When S1, S2, S6, K1, connection; When K5 has triggering signal; Circuit can equivalence be first equivalent electric circuit, and as S5, when K2 connects, circuit can equivalence be second equivalent electric circuit; Though contrasting two kinds of circuit boosts not quite alike with the inversion unit combining form; But crucial detecting element combining form is consistent, can both through unit switch to turn on and off circuit equivalent be first equivalent electric circuit and second equivalent electric circuit, the method for using through the present invention again reaches the purpose that detects solar panel and grid side insulation resistance.
Adopt the circuit of embodiment 1 or embodiment 2 arbitrarily; Detection method of the present invention is through the switch of combination boosting unit and inversion unit, and the first step makes an end of relay K 1 be connected with PV+, connects relay K 1 and relay K 5 simultaneously; Make resistance R 1 be connected to PV+; Finally can be connected with resistance R 1 by first equivalent electric circuit (referring to Fig. 3): PV+, resistance R 1 and the equivalent resistance Rx1 parallel connection of PV+ to casing are again with the equivalent resistance Rx2 series connection formation electric resistance partial pressure of PV-to casing; Second step made relay K 2 be connected with PV-; Connect relay K 2 simultaneously; Make resistance R 1 be connected to PV-, finally can be connected with resistance R 1 by second equivalent electric circuit (referring to Fig. 4): PV-, resistance R 1 and the equivalent resistance Rx2 parallel connection of PV-casing; Again with the equivalent resistance Rx1 series connection formation electric resistance partial pressure of PV+ to casing; Detect sampling resistor R1 with digital processing unit simultaneously and go up voltage, the voltage that collects constantly according to difference calculates, and obtains real-time solar panel and grid side grounding resistance.
Adopt the circuit of embodiment 1 or embodiment 2 arbitrarily, detection method of the present invention, concrete steps are following:
When switch S 1, switch S 2, switch S 3, switch S 4, switch S 5, relay K 1, relay K 2, relay K 3, relay K 4, relay K 5 all are in off-state; Vpv, Vg are in the real-time monitoring; Suppose that Rx1, Rx2 equivalence are solar panel both positive and negative polarity insulating resistance value over the ground, Rx3, Rx4 equivalence are grid side L, N utmost point insulating resistance value over the ground;
(1), close switch S5, relay K 2, relay K 5 does not have triggering signal, other switch is in off-state; Sampling resistor R1 goes up voltage, is recorded as Ue1, referring to Fig. 4; Constitute second equivalent electric circuit: PV-and directly be connected with resistance R 1 this moment, and resistance R 1 elder generation and PV-are to the equivalent resistance Rx2 parallel connection of casing, again with the equivalent resistance Rx1 series connection formation electric resistance partial pressure of PV+ to casing; Because PV+ is known to the voltage of PV-, the last voltage of R1 also can detect, and can obtain equation according to the electric resistance partial pressure formula:
(2), close switch S2, relay K 2, relay K 5 have triggering signal, other switch is in off-state, this moment, sampling resistor R1 went up voltage; Be recorded as Ue2; Referring to Fig. 3, constitute first equivalent electric circuit: PV+ and directly be connected with resistance R 1 this moment, and resistance R 1 elder generation and PV+ are to the equivalent resistance Rx1 parallel connection of casing; Again with the equivalent resistance Rx2 series connection formation electric resistance partial pressure of PV-to casing; Because PV+ is known to the voltage of PV-, the last voltage of R1 also can detect, and can obtain equation according to the electric resistance partial pressure formula:
(3), closing relay K4, relay K 5 does not have triggering signal, other switch is in off-state; Sampling resistor R1 goes up voltage, writes down mean value and called after Ue3 in the line voltage cycle, referring to Fig. 4; Constitute second equivalent electric circuit this moment: grid side N line directly is connected with resistance R 1; Resistance R 1 elder generation and N line are to the equivalent resistance Rx4 parallel connection of casing, again with the equivalent resistance Rx3 series connection formation electric resistance partial pressure of L line to casing, owing to the voltage of electrical network L line to the N line can detect at the mean value of an electrical network in the cycle; The last voltage of R1 also can detect, and can obtain equation according to the electric resistance partial pressure formula:
In the formula Ug1 be with Ue3 with the line voltage sample mean in the period;
(4), closing relay K3, relay K 5 have triggering signal, other switch is in off-state, sampling resistor R1 goes up voltage; Write down mean value and called after Ue4 in the line voltage cycle; Referring to Fig. 3, constitute first equivalent electric circuit this moment: grid side L line directly is connected with resistance R 1, and resistance R 1 elder generation and L line are to the equivalent resistance Rx3 parallel connection of casing; Again with the equivalent resistance Rx4 series connection formation electric resistance partial pressure of N line to casing; Because electrical network L line can detect at the mean value of an electrical network in the cycle the voltage of N line, the last voltage of R1 also can detect, and can obtain equation according to the electric resistance partial pressure formula:
In the formula Ug be with Ue4 with the line voltage sample mean in the period;
(5), with equation (1) (2) simultaneous; The anode PV+ of solar panel can be tried to achieve to the negative terminal PV-of the insulating resistance value Rx1 of casing, the solar panel insulating resistance value Rx2 value to casing in solve an equation (1), (2); Wherein sampling resistor R1 is the resistance of the auxiliary detection that adds, and its resistance is much smaller than resistance R x1, resistance R x2, and its value size can be chosen according to the insulation resistance critical value of standard code; Influence degree according to resistance R 1 and 2 pairs of certainties of measurement of resistance R; Select its value to be 1/1000 of the critical value of standard code, like this at resistance R 1 or resistance R 2 and tested resistance R x1 with after resistance R x2 is parallelly connected, its parallelly connected value equals perhaps resistance R 2 of resistance R 1 basically; Thereby make formula (1) (2) set up; In like manner grid side L line can be tried to achieve to the insulating resistance value Rx3 of casing, the grid side N line insulating resistance value Rx4 to casing in simultaneous equations (3), (4), and grid side N line is direct-connected with the earth usually, so the Rx3 value should be very little.