CN202997511U - Alternating current and direct current injection type rotor one-point-grounding protecting device - Google Patents

Abstract

The utility model discloses an alternating current and direct current injection type rotor one-point-grounding protecting device. The protection configuration is formed by injection alternating current rotor one-point-grounding protection and injection direct current rotor one-point-grounding protection. As for the injection alternating current one-point-grounding protection, an external alternating current power source injects an alternating current voltage signal of a certain altitude into a rotor return circuit, the voltage signal is injected into the positive end and the negative end of a rotor winding LE symmetrically, the alternating current voltage UA and the return circuit current IA with respect to the ground represented in a graph are taken, impedance to the ground of the rotor winding is calculated, and the resistance to the ground of the rotor is further calculated through certain compensation. As for the injection direct current rotor one-point-grounding protection, a direct current voltage is injected between the negative end of the rotor winding LE and the ground or between the positive end of the rotor winding LE and the ground through resistors R4 and R5, leakage current under the two states is obtained through switching of an electric switch, and the grounding resistance of the rotor is calculated. One of the two sets of protection can be automatically run, and also the two sets of protection can be run in parallel at the same time, and therefore doubling configuration of one-point-grounding protection of the rotor is achieved.

Description

The pouring-in rotor one-point grounding protection device of a kind of AC and DC

Technical field

The utility model relates to the rotor one-point grounding protection apparatus and method in the transformer unit protection, belongs to the power automation technical field.

Background technology

Rotor earth fault protection is the important component part of transformer unit protection system, and turbo generator and hydraulic generator all should be installed rotor one-point grounding protection.The rotor one-point grounding protection principle can be divided into pouring-in and non-pouring-in two large classes.Non-pouring-in principle relies on the electric parameters of rotor winding itself to consist of the protection criterion, as switch sampling formula (ping-pong type) principle; Pouring-in principle needs to add accessory power supply, gives rotor winding injecting voltage over the ground, gathers associated electrical tolerance and consists of the protection criterion, as injecting the direct voltage principle, inject the alternating voltage principle and injecting the square-wave voltage principle.The protection scheme of present large-scale transformer unit requires to adopt the dual configuration, and rotor earth fault protection can only the single cover operation of dual configuration due to the reason of protection philosophy, namely adopts cover operation one a cover standby mode, when needing by artificial charged switching.The two cover operations that realize rotor one-point grounding protection in transformer unit protection both at home and abroad are insurmountable difficult problems always.

The utility model content

But the purpose of this utility model is to provide a kind of pouring-in rotor one-point grounding protection method of AC and DC of dual paired running; the protection configuration consists of by injecting the direct current rotor one-point grounding protection and injecting the AC rotor one point earth fault protection; two cover protections are paired running simultaneously, also can independently use.

To achieve these goals, technical solution adopted in the utility model is:

The pouring-in rotor one-point grounding protection device of a kind of AC and DC; it is characterized in that: comprise alternating current unit, direct current unit and rotor winding L E; described rotor winding L E one end is connected with the alternating current unit; the other end is connected with the direct current unit, and described alternating current unit, direct current unit and rotor winding L E be ground connection respectively.The pouring-in rotor one-point grounding protection device of aforesaid a kind of AC and DC; it is characterized in that: described alternating current unit comprises AC power, transformer, resistance R 1, resistance R 2, resistance R 3, capacitor C 1 and capacitor C 2; AC power is connected with the rotor winding by transformer positive output end, resistance R 1, resistance R 2, resistance R 3, capacitor C 1, capacitor C 2, and described AC power is connected to the ground by the transformer negative output terminal.

The pouring-in rotor one-point grounding protection device of aforesaid a kind of AC and DC; it is characterized in that: described direct current unit comprises DC power supply, resistance R 4 and resistance R 5; described dc power anode is connected with rotor winding element direct-flow input end by resistance R 4, and described dc power cathode is connected to the ground by resistance R 5.

The pouring-in rotor one-point grounding protection device of aforesaid a kind of AC and DC is characterized in that: be connected in parallel to an electronic switch at the two ends of resistance R 5.

The beneficial effects of the utility model are:

1, between the protective device of two kinds of principles, wiring is simple.

2, can realize rotor winding 100% ground protection, any one point earth on the rotor winding, protection sensitivity is close.

3, pouring-in principle is all adopted in two cover protections, realize rotor one-point grounding protection shut down or open state under paired running, and all can monitor the insulation of rotor winding.

4, two cover protections both can put into operation simultaneously, also can isolated operation.One cover protection is when out of service, and another set of can automatically identification do not affect the operation of self.

Description of drawings

Fig. 1 is that rotor one-point grounding protection dual direct current injects the configuration principle schematic from negative terminal.

Fig. 2 is that rotor one-point grounding protection dual configuring direct current is from anode injecting principle schematic diagram.

Fig. 3 is leakage current I when injecting the isolated operation of direct current rotor one-point grounding protection _DAnalogous diagram.

Fig. 4 is two cover protections dc leakage-current I when moving simultaneously _DAnalogous diagram.

Fig. 5 is ac circuit electric current I when injecting the isolated operation of AC rotor one point earth fault protection _AAnalogous diagram.

Fig. 6 is ac circuit voltage U when injecting the isolated operation of AC rotor one point earth fault protection _AAnalogous diagram.

Fig. 7 is two cover protections ac circuit electric current I when moving simultaneously _AAnalogous diagram.

Fig. 8 is two cover protections ac circuit voltage U when moving simultaneously _AAnalogous diagram.

Fig. 9 is equivalent circuit diagram when injecting direct current rotor one-point grounding protection electronic switch and opening.

Figure 10 is equivalent circuit diagram when injecting direct current rotor one-point grounding protection electronic switch closes.

Figure 11 is equivalent circuit diagram when injecting AC rotor one point earth fault protection electronic switch and opening.

Figure 12 is equivalent circuit diagram when injecting AC rotor one point earth fault protection electronic switch closes.

Figure 13 is two cover protection coordination schematic diagram of mechanism.

Embodiment

The utility model to study in have:

1, rotor one-point grounding protection dual paired running principle design

In order to realize rotor one-point grounding protection dual configuration truly; but the pouring-in rotor one-point grounding protection method of the AC and DC that the utility model proposes a kind of dual paired running, the protection configuration is made of stack direct current rotor one-point grounding protection and stack AC rotor one point earth fault protection.This two covers protection can be used in conjunction with simultaneously, also can independently use.

2, the design of AC and DC infusion circuit

The design that exchanges infusion circuit need to consider that the rotor high voltage to injecting the infringement of power supply, will consider that also rotor winding medium-high frequency component is to the infringement of infusion circuit.

3, protection module filtering measures

Stack direct current rotor earth fault protection calculates earth resistance by detection rotor ground connection folding leakage current, and leakage current is subject to the impact of rotor direct-to-ground capacitance, and the impact that the research leakage current is avoided the rotor direct-to-ground capacitance is one of research contents of the present utility model.

Stack AC rotor ground protection rotor winding alternating voltage and alternating current over the ground calculates earth resistance; when earth resistance is larger; rotor winding alternating voltage over the ground is larger; reach tens volts; be milliampere level to earth-current, how reasonably gathering voltage and current is earth resistance meter no accurate key at last.In the unit operation situation, may contain high order harmonic component in the rotor winding system, as 6 subharmonic, need to adopt corresponding measure filtering.

4, interactional braking measure between two principles

Because two kinds of principles are injected simultaneously direct current and exchange the rotor winding, impact each other is unavoidable, and it is necessary adopting corresponding inhibitory effect measure, as adds electric capacity every directly, and earth resistance is carried out suitable compensation etc.

Below in conjunction with accompanying drawing, the utility model is further described.

The configuration of rotor one-point grounding protection dual as illustrated in fig. 1 and 2; comprise alternating current unit, direct current unit and rotor winding L E; described rotor winding L E one end is connected with the alternating current unit; the other end is connected with the direct current unit, and described alternating current unit, direct current unit and rotor winding L E be ground connection respectively.

The alternating current unit comprises AC power, transformer, resistance R 1, resistance R 2, resistance R 3, capacitor C 1 and capacitor C 2, AC power is connected with the rotor winding by transformer positive output end, resistance R 1, resistance R 2, resistance R 3, capacitor C 1, capacitor C 2, and described AC power is connected to the ground by the transformer negative output terminal.

The direct current unit comprises DC power supply, resistance R 4 and resistance R 5, described dc power anode is connected with rotor winding element direct-flow input end by resistance R 4, described dc power cathode is connected to the ground by resistance R 5, is connected in parallel to an electronic switch at the two ends of resistance R 5.

1), principle analysis

By protection dual configuration principle, two cover protections are come into operation simultaneously, for injecting the direct current rotor one-point grounding protection, due to C1, C2 every straight effect, make DC component can not enter the interchange infusion circuit, but alternating current component can flow into the direct current infusion circuit.Fig. 3 is for injecting direct current rotor one-point grounding protection isolated operation hourglass electric current I _DAnalogous diagram is along with the folding of electronic switch, I _DThe amplitude size can change.Due to the existence of rotor winding-to-earth capacity, at the moment that electronic switch switches, I _DThe transient process that a decay is arranged when sampling is calculated, need be avoided this transient process.

Fig. 4 is two cover protections I when moving simultaneously _DAnalogous diagram is owing to there being of ac to inject DC loop, at I _DIn be injected with alternating current component; Again because the switching of electronic switch causes circuit structure to change, thereby makes the alternating current component amplitude also different under two states.Therefore detect open electric current and close electric current in contain and exchange, this alternating current component of filtering need to take appropriate measures.

The emulation schematic diagram of sample rate current and sampled voltage during as shown in Figure 3 for the isolated operation of injection AC rotor one point earth fault protection.The alternating current that the calculating earth resistance is sampled and alternating voltage present steady-state sine to be changed.When two cover protections moved simultaneously, along with the switching of electronic switch, alternating current and voltage presented cyclic variation, and switch moment at electronic switch, and AC current-voltage also has a transient process, and alternating voltage is particularly evident, as shown in Figure 3.By can find out in Fig. 3, when two cover protections moved simultaneously, the alternating current amplitude increased during than isolated operation to some extent, illustrate that the AC power load becomes greatly, and reason is that DC loop causes.Thus, can obtain following some conclusion:

(1), because causing alternating current and voltage, the electronic switch folding presents cyclic variation, the folding condition of need tracking electronic switch.

(2), when sample rate current voltage calculates, the transient process in the time of need to escaping electronic switch and switch.Alternating current component can flow into the direct current infusion circuit, therefore, injects the earth resistance that the AC rotor one point earth fault protection calculates, and need to the convert resistance of direct current infusion circuit be compensated.

2, protection algorithm design

1), inject the direct current rotor one-point grounding protection

As shown in Figure 1, inject a direct voltage U for rotor winding negative terminal _D(U _D=50V), when establishing normal operation, rotor winding earth impedance is infinity, and thinks that exciting voltage E remains unchanged in the electronic switch moving process.If at the rotor winding a bit through R _gGround connection, the fault point is α E apart from the electromotive force of rotor winding negative terminal.When two cover protections move simultaneously, as shown in Figure 1, due to C1, C2 every straight effect, make DC component can not enter the interchange infusion circuit, inject direct current rotor one-point grounding protection equivalent electric circuit as shown in Figure 9.

In Fig. 9, R ₄=R ₅=R writes the loop equation by Fig. 9 row:

$\left\{\begin{array}{c}{U}_D+\mathrm{\αE}=I_o(R_g+2R)\\ U_D+\mathrm{\αE}=I_c(R_g+R)\end{array}\right.---\left(1\right)$

Got by (1) formula:

$R_g=\frac{2I_o-I_c}{I_c-I_o}R---\left(2\right)$

$\mathrm{\α}=\frac{I_o{I}_{c}R}{(I_c-I_o)E}-\frac{U_D}{E}---\left(3\right)$

In formula: R _gBe earth resistance; I _o/ I _cBe respectively the loop that corresponding electronic switch opens/close under state and measure leakage current; R is DC loop access resistance.

Can obtain earth resistance R by formula (2), (3) _gAnd corresponding position of failure point.

2), inject the AC rotor one point earth fault protection

The 50Hz alternating voltage is injected between rotor winding and ground through R1, R2, R3, C1 and C2, when two cover protections move simultaneously, if in rotor winding somewhere through R _gGround connection, the alternating current earth resistance R that not only flows through _gWith direct-to-ground capacitance C _g, also flowing through the direct current infusion circuit simultaneously, its equivalent electric circuit is as shown in figure 10.

In Figure 10, R _e, C _eEquivalent resistance and equivalent capacity for R1, R2, R3, C1, C2; R ₄=R ₅=R is for DC loop is injected resistance.

When electronic switch is opened, by Figure 10 (a):

${\stackrel{\·}{U}}_{\mathrm{go}}=\stackrel{\·}{U_A}-\stackrel{\·}{I_{\mathrm{Ao}}}*(R_e+j{X}_e)---\left(4\right)$

$R_{\mathrm{go}}=\frac{1}{\mathrm{Re}({\stackrel{\·}{I}}_{\mathrm{Ao}}/{\stackrel{\·}{U}}_{\mathrm{go}})}---\left(5\right)$

In formula:

Ac circuit electric current under this state; jX _e=-j/ ω C _e

Consider the compensation of DC loop:

$R_g=\frac{2R{R}_{\mathrm{go}}}{2R-R_{\mathrm{go}}}---\left(6\right)$

When electronic switch closes, by Fig. 5 (b):

${\stackrel{\·}{U}}_{\mathrm{gc}}=\stackrel{\·}{U_A}-\stackrel{\·}{I_{\mathrm{Ac}}}*(R_e+j{X}_e)---\left(7\right)$

$R_{\mathrm{gc}}=\frac{1}{\mathrm{Re}({\stackrel{\·}{I}}_{\mathrm{Ac}}/{\stackrel{\·}{U}}_{\mathrm{gc}})}---\left(8\right)$

In formula:

Ac circuit electric current under this state.

Consider the compensation of DC loop:

$R_g=\frac{R{R}_{\mathrm{gc}}}{R-R_{\mathrm{gc}}}---\left(9\right)$

Got by formula (6) and (9):

$R_g=\frac{R_{\mathrm{go}}{R}_{\mathrm{gc}}}{{2R}_{\mathrm{gc}}-R_{\mathrm{go}}}---\left(10\right)$

Known by formula (10): earth resistance R _gThe not compensating resistance that calculates when the not compensating resistance that calculates when opening with electronic switch and electronic switch closes is relevant, and is not subjected to the impact of loop resistance R.

3), two cover protection coordination mechanism

In Figure 11, T is electronic switch switching time, and I1 is the alternating current component that ac circuit flows into DC loop,

By Figure 11, can obtain:

1), due to the existence of capacitor C in ac circuit 1, C2, DC component can not enter ac circuit, inject the direct current rotor earth fault protection and can not be subject to the impact of ac circuit structure, only need to enter the alternating current component filtering of DC loop, will consider that simultaneously capacitor C 1, C2 switch the impact of transient process on the DC loop electronic switch;

2), alternating current component enters DC loop, need to compensate earth resistance.Inject the AC rotor one point earth fault protection and introduced the electronic switch state, switch when normal when electronic switch being detected, employing formula (10) is calculated; Inject direct current rotor one-point grounding protection power down or out of service when the electronic switch state being detected when undesired (the switching interval time is greater than 2s), thinking.

3), the electronic switch state is undesired is divided into two kinds of situations: inject the out of service but DC loop of direct current protecting and do not remove; Inject the out of service and DC loop of direct current protecting and remove, by I ₁Differentiate:

A, I ₁During 〉=α, inject the out of service but DC loop of direct current protecting and do not remove, earth resistance is calculated in employing formula (4), (5), (6).

B, I ₁During＜α, inject the out of service and DC loop of direct current protecting and remove, need not to compensate, therefore employing formula (4), formula (5) are calculated earth resistance.

Calculate earth resistance, protect operation, the protection operation equation is:

(1) R _g＜R _g1, as the earth resistance R that calculates _gLess than R _g1The time, alarm signal is sent out in protection,

(2) R _g＜R _g2, as the earth resistance R that calculates _gLess than R _g2The time, trip signal and outlet tripping operation are sent out in protection,

In formula: R _g1, R _g2Be the protection setting value.

Above demonstration and described basic principle of the present utility model, principal character and advantage.The technical staff of the industry should understand; the utility model is not restricted to the described embodiments; that describes in above-described embodiment and specification just illustrates principle of the present utility model; under the prerequisite that does not break away from the utility model spirit and scope; the utility model also has various changes and modifications, and these changes and improvements all fall in claimed the utility model scope.The claimed scope of the utility model is defined by appending claims and equivalent thereof.

Claims (4)

1. pouring-in rotor one-point grounding protection device of AC and DC; it is characterized in that: comprise alternating current unit, direct current unit and rotor winding L E; described rotor winding L E one end is connected with the alternating current unit; the other end is connected with the direct current unit, and described alternating current unit, direct current unit and rotor winding L E be ground connection respectively.

2. the pouring-in rotor one-point grounding protection device of a kind of AC and DC according to claim 1; it is characterized in that: described alternating current unit comprises AC power, transformer, resistance R 1, resistance R 2, resistance R 3, capacitor C 1 and capacitor C 2; AC power is connected with the rotor winding by transformer positive output end, resistance R 1, resistance R 2, resistance R 3, capacitor C 1, capacitor C 2, and described AC power is connected to the ground by the transformer negative output terminal.

3. the pouring-in rotor one-point grounding protection device of a kind of AC and DC according to claim 2; it is characterized in that: described direct current unit comprises DC power supply, resistance R 4 and resistance R 5; described dc power anode is connected with rotor winding element direct-flow input end by resistance R 4, and described dc power cathode is connected to the ground by resistance R 5.

4. the pouring-in rotor one-point grounding protection device of a kind of AC and DC according to claim 3, is characterized in that: be connected in parallel to an electronic switch at the two ends of resistance R 5.

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