CN202522678U - Three-phase photovoltaic inverter relay fault detection device - Google Patents

Abstract

The utility model discloses a three-phase photovoltaic inverter relay fault detection device, which is characterized by comprising the first, second and third voltage acquisition modules (7, 8 and 9) which are spanned between each live wire and null line between a relay unit (2) and an inversion output end (1) of a photovoltaic inverter, and the fourth, fifth and sixth voltage acquisition modules (10, 11 and 12) which are spanned between each live wire and null line between the relay unit (2) and a power grid (3), wherein all the voltage acquisition modules are connected with a processing unit (6). The voltage is detected by wiring on the live wires and null lines outside the relay unit only, so that the relay fault can be detected, the detection is convenient, and the fault judgment is accurate.

Description

A kind of three-phase photovoltaic DC-to-AC converter relay failure detector

Technical field

The utility model relates to a kind of relay failure detector, particularly three-phase photovoltaic DC-to-AC converter relay failure detector.

Background technology

Relay is a very important part in the photovoltaic combining inverter, and it places between inversion output and the electrical network, and purpose is when fault takes place, and effectively breaks off being connected of inverter system and electrical network, improves the security and the reliability of system.Relay has adopted the mode of 2 one group series redundancy, even that is: a relay has been broken, the another one relay also can make inverter effectively cut off electrical network.

Reliability (effectively closed and disconnected) in order to guarantee relay can effectively cut off electrical network to guarantee inverter, and the detection of relay is particularly important.

The utility model content

The purpose of the utility model is, a kind of three-phase photovoltaic DC-to-AC converter relay failure detector is provided.It can adopt the means of external detection to realize the purpose of photovoltaic DC-to-AC converter relay fault detect under broken situation of changing inverter structure, and detects more conveniently, and the result is more accurate.

The technical scheme of the utility model:

A kind of three-phase photovoltaic DC-to-AC converter relay failure detector; Be included in first, second and tertiary voltage acquisition module of cross-over connection between every live wire and the zero line between relay group and the photovoltaic DC-to-AC converter inverting output terminal; And the 4th, the 5th and the 6th voltage acquisition module of cross-over connection between every live wire between relay group and the electrical network and zero line, all voltage acquisition modules all link to each other with processing unit.

Compared with prior art, the utility model only needs on the outside live wire of relay group and zero line, to carry out wiring detection voltage can realize the detection to the relay fault, detects more conveniently, and can make fault judgement more accurate in the method for the utility model.

Description of drawings

Fig. 1 is the structural representation of the utility model;

Fig. 2 is the relay status synoptic diagram of the utility model embodiment.

Embodiment

Below in conjunction with accompanying drawing and embodiment the utility model is further described, but not as the foundation to the utility model restriction.

Embodiment.

A kind of three-phase photovoltaic DC-to-AC converter relay failure detector; As shown in Figure 1: first, second and tertiary voltage acquisition module 7,8 and 9 that are included in cross-over connection between every live wire and the zero line between relay group 2 and the photovoltaic DC-to-AC converter inverting output terminal 1; And the 4th, the 5th and the 6th voltage acquisition module 10,11 and 12 of cross-over connection between every live wire between relay group 2 and the electrical network 3 and zero line, all voltage acquisition modules all link to each other with processing unit 6.

Principle of work:

When each relay continuously changes open and-shut mode in the relay group between photovoltaic DC-to-AC converter inverting output terminal and electrical network; Voltage between live wire between the relay group of sampling respectively and the photovoltaic DC-to-AC converter inverting output terminal and zero line; And voltage between live wire between relay group and the electrical network (L1, L2 and L3) and zero line (N), judged whether that through the voltage that relatively collects relay breaks down.The relay group comprises two one group relay S1 and S2, relay S3 and S4 and relay S5 and S6 that is serially connected on each bar live wire respectively; The relay S7 and the S8 that are connected in series on the zero line; Voltage U 4, U5 and U6 between each bar live wire between detection relay group and the photovoltaic DC-to-AC converter inverting output terminal and zero line; And voltage U 1, U2 and U3 between each bar live wire between relay group and the electrical network and zero line, wherein U1 and U4 detect voltage on the same live wire that is separated by relay S1 and S2, and U2 and U5 detection voltage are on the same live wire that is separated by relay S3 and S4; U4 and U6 detect voltage on the same live wire that is separated by relay S5 and S6; Voltage U 1 and U4 under each state of comparator relay group again, U2 and U5, and whether U4 and U6 draw and have relay to break down.Said each state of relay group is divided into a, b, c, d, e, f, g, h and nine continuous variable condition of i, and the state of S1, S3 and S5 is identical all the time, and the state of S2, S4 and S6 is also identical all the time; 8 relays are divided into relay " S1, S3 and S5 ", " S2, S4 and S6 ", " S7 "; And " S8 " these four groups; State a is four groups and all breaks off that state b is for wherein 3 making up, and state c, d, e, f, g and h are and on the basis of preceding state, only change wherein one group state; State i is four groups and all closes, and is as shown in Figure 2.

Under state b, d, f and h:

$V_{\mathrm{\Δ}2}\left(\mathrm{RMS}\right)=\sqrt{\frac{\underset{k=1}{\overset{n}{\mathrm{\Σ}}}{(U_5-U_2)}^2}{n}}$ With $V_{\mathrm{\Δ}3}\left(\mathrm{RMS}\right)=\sqrt{\frac{\underset{k=1}{\overset{n}{\mathrm{\Σ}}}{(U_4-U_1)}^2}{n}}$ Simultaneously greater than threshold value, and under state i V _{Δ 1}(RMS), V _{Δ 2}And V (RMS), _{Δ 3}(RMS) during simultaneously little threshold value, the relay group is the non-fault relay; N is the voltage sample quantity in every 20ms.

Claims (1)

1. three-phase photovoltaic DC-to-AC converter relay failure detector; It is characterized in that: first, second and tertiary voltage acquisition module (7,8 and 9) that are included in cross-over connection between every live wire and the zero line between relay group (2) and the photovoltaic DC-to-AC converter inverting output terminal (1); And the 4th, the 5th and the 6th voltage acquisition module (10,11 and 12) of cross-over connection between every live wire between relay group (2) and the electrical network (3) and zero line, all voltage acquisition modules all link to each other with processing unit (6).

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