CN103490384B - Multi-generator ship intermediate voltage electric power system protection method and device - Google Patents

Abstract

The invention relates to a multi-generator ship intermediate voltage electric power system protection method and device. The method comprises the steps that a busbar of a ship intermediate voltage electric power system is connected with a grounding transformer which is connected with a resonance grounding device, each generator neutral point in the ship intermediate voltage electric power system is connected with a high-resistance grounding device, and the resistance value of the high-resistance grounding device is determined according to a multi-tapping mode. The high-resistance grounding device and the resonance grounding device are connected in parallel, so that protection is effectively provided for an intermediate voltage generator and the electric power system, and meanwhile the mixed grounding mode can be effectively used in the complex working conditions such as multi-generator parallel separation.

Description

Multi-generator ship intermediate voltage electric power system protection method and device

Technical field

The present invention relates to ship intermediate voltage power system resist technology field, be specifically related to a kind of Multi-generator ship intermediate voltage electric power system protection method and device.

Background technology

In network of ship, the ratio of single phase ground fault is all greater than 50%, and wherein the single phase ground fault of more than 90% can produce electric arc.The electric arc overvoltage that single-phase earthing produces, can affect the insulation against ground of healthy phases cable, single phase ground fault is easy to worsen into phase-to phase fault, thus influential system power supply reliability and continuity.

The earthing mode of the single phase ground fault extent of injury and processing mode and neutral point of electric network is closely related.High Resistance Grounding Mode requires that high resistance grounding device can operate with failure 2 hours (high resistance refers to that resistance is 100-400 ohm), and can by Overvoltage suppressing below 2.6 times.This just requires that high resistance grounding current in the fault point is less than 10A, and the resistance of earth resistance must be less than system capacitive reactance value.By analytical calculation, obtain high resistance grounding and be only applicable to electric capacity and be less than 5.9uF system, inapplicable during bulky capacitor.Low resistance earthing can effective over-voltage suppression, but current in the fault point excessive (reaching 400A), easy infringement equipment, and in low resistance grounding mode, the infringement of generator is calculated, even if switch trips immediately after generator generation earth fault, fault energy is 67.2kJ, is greater than the standard of the 30kJ that Conrad determines, low resistance grounding mode exists the problem that stator core forever burns in other words.For resonance neutral grounding; in order to protect generator, every platform generator all needs to connect resonance grounding device, when generator generation single phase ground fault needs to hightail electrical network at neutral point; resonance grounding device has been adjusted delay, now cannot meet generator protection requirement.Simultaneously when several parallel running of generators, need to intercom mutually between earthing device, and will have a set of complex parameters setting method, costly, reliability is low for this earthing device.

Existing most of boats and ships are by separate unit or two middle Hair Fixer feeding electric motors, but for needing the application scenario of Hair Fixer feeding electric motors in multiple stage, electric power system operating mode is complicated, the situation that off-the-line in parallel is run can be frequently there is in multiple stage generator according to the change of operating mode, and cable and hull plate distance are closely, load is many, system direct-to-ground capacitance is large, when excessive distributed capacitance can make generation earth fault, zero-sequence current rises, adopt existing High Resistance Grounding Mode, when earth fault occurs, zero-sequence current does not allow more than 10A, therefore high resistance grounding device can not be applied under Iarge-scale system distributed capacitance condition.Simultaneously; high resistance grounding device must be connected to generator neutral point, and when multiple stage parallel operation of generator, equivalent grounding resistance declines; also can rise by causing trouble point electric current, therefore the high resistance grounding device of existing fixed resistance value can not form good protection to multiple stage generator.In sum, a kind of method and apparatus solving ship intermediate voltage power system earth fault protection problem is needed badly.

Summary of the invention

The object of the invention is to overcome above-mentioned defect and deficiency, a kind of Multi-generator ship intermediate voltage electric power system protection method that can protect generator and system when stator winding generation single phase ground fault, boats and ships generation earth fault and device are provided.

For achieving the above object; the Multi-generator ship intermediate voltage electric power system protection method of the present invention's design is: on the busbar of ship intermediate voltage power system, connect grounding transformer; grounding transformer connects resonance grounding device; every platform generator neutral point in ship intermediate voltage power system connects high resistance grounding device; the resistance value of high resistance grounding device is adjusted by many taps mode, the resistance value R of described high resistance grounding device _gsetting method is:

The generator quantity of setting access is m, and the single-phase direct-to-ground capacitance of generator that high resistance grounding device is protected is C _g, the single-phase distributed capacitance of electric power system is C ₀, rated voltage is U, and resonance grounding device off resonance degree is υ,

When ship intermediate voltage power system multiple stage parallel running of generators, the resistance value Rg setting method of high resistance grounding device is:

Make to flow through high resistance grounding device electric current and meet following formula:

$I_{\mathrm{Rg}}=\frac{v}{m}\frac{3\mathrm{\ω}{C}_{0}U}{\sqrt{3}}$

Resistance value Rg value is:

wherein, ω=2 π f, f=50Hz;

When there being alternator failure to need off-the-line in ship intermediate voltage power system, the resistance value R of high resistance grounding device _gvalue is:

$R_g=\frac{1}{3\mathrm{\ω}{C}_g}.$

In technique scheme, the off resonance degree υ of described resonance grounding device coordinates high resistance grounding device to adjust, and resonance grounding device adopts overcompensation mode, and off resonance degree is just, is adjusted by following formula:

$\mathrm{\υ}\≤\frac{10}{\sqrt{2}}\frac{1}{3\mathrm{\ω}{C}_{0}U}.$

The present invention additionally provides a kind of multiple generator ship intermediate voltage power system protective device simultaneously; comprise the grounding transformer be connected on the busbar of ship intermediate voltage power system; and be connected to the resonance grounding device between grounding transformer with the earth, every platform generator neutral point and the high resistance grounding device be connected between the earth; described high resistance grounding device is tapped variable resistor, the resistance value R of described high resistance grounding device _gsetting method is:

The generator quantity of setting access is m, and the single-phase direct-to-ground capacitance of generator that high resistance grounding device is protected is C _g, the single-phase distributed capacitance of electric power system is C ₀, rated voltage is U, and resonance grounding device off resonance degree is υ,

When ship intermediate voltage power system multiple stage parallel running of generators, when ship intermediate voltage power system multiple stage parallel running of generators, the resistance value Rg setting method of high resistance grounding device is:

Make to flow through high resistance grounding device electric current and meet following formula:

$I_{\mathrm{Rg}}=\frac{v}{m}\frac{3\mathrm{\ω}{C}_{0}U}{\sqrt{3}}$

Resistance value Rg value is:

wherein, ω=2 π f, f=50Hz;

When there being alternator failure to need off-the-line in ship intermediate voltage power system, the resistance value R of high resistance grounding device _gvalue is:

$R_g=\frac{1}{3\mathrm{\ω}{C}_g}.$

The off resonance degree υ of the resonance grounding device of technique scheme need coordinate high resistance grounding device to adjust, and resonance grounding device adopts overcompensation mode, and off resonance degree is just, is adjusted by following formula:

$\mathrm{\υ}\≤\frac{10}{\sqrt{2}}\frac{1}{3\mathrm{\ω}{C}_{0}U}.$

Distributed capacitance in this specification refers to: by the morphogenetic a kind of distributed constant of noncapacitive.Online and line or line electric capacity between the earth is generally referred in electric power system.The capacity of this electric capacity is usually very little, but more than 100uF, may have impact on system performance greatly in actual multiple generator Ship Electrical Power System; Grounding transformer refers to: a kind of system received without neutral point, to provide the three-phase transformer of an artificial neutral point to this system, and also can by way of parenthesis to the auxiliary mains supply of local; Resonance grounding device refers to: the one or more neutral point of neutral point resonant earthed system is by having the system of the equipment ground of induction reactance.These equipment can the capacitive effect of compensated line substantially when one-phase short-circuit current.The effect that neutral point connects high resistance grounding device is, when the earth-free operation of neutral point of electric network, even if the capacitance current of system is little, also can because of producing intermittent arc overvoltage when single-phase earthing, make the current potential perfecting phase may be elevated to the degree being enough to destroy its insulation level, even form phase fault.The electromagnetic energy in intermittent arc overvoltage if released after the neutral point (or using grounding transformer extraction neutral point) of transformer is connected in series a resistor; then neutral point potential reduces; the fault phase recovery voltage rate of climb also slows down; thus reduce the possibility of arc reignition; inhibit the amplitude of power network overvoltage, and selectively ground protection is achieved.

Earthing device in parallel with high resistance for arc suppression coil splits by the present invention, and high resistance grounding device is connected to generator neutral point.When stator winding generation single phase ground fault, after generator outlet end circuit breaker disconnects, high resistance grounding device can over-voltage suppression, simultaneously fault restriction point electric current.And due to system direct-to-ground capacitance excessive, adopt resonance neutral grounding protection system, building-out capacitor electric current.The high resistance of generator neutral point connection simultaneously is also adjusted by many taps mode, voluntarily to adapt to the changeable operating mode of boats and ships.Grounding scheme provided by the invention not only has higher power supply continuity when there is earth fault, and can be applied to excessive direct-to-ground capacitance situation.

Advantage of the present invention is:

(1) the present invention by by mode in parallel with resonance grounding device for high resistance grounding device effectively centering Hair Fixer motor and electric power system protection is provided, this mixing ground connection effectively can be applied at complex working conditions such as multiple generator off-the-lines in parallel simultaneously.

(2) the present invention is by the high resistance grounding device of resistance of can adjusting, and can provide according to the change of parallel generator quantity the grounding resistance adapted, making can by good protection in the frequent off-the-line situation in parallel of generator.

(3) the present invention suppresses the excessive earth fault current that causes of distributed capacitance, for high resistance grounding device can provide protection to provide condition to generator by the resonance grounding device accessing electrical network.

(4) hinge structure scheme of the present invention, cost is low, adjusts simple, is easy to realize.

Accompanying drawing explanation

Fig. 1 is circuit structure diagram of the present invention;

In Fig. 1, A, B, C are Hair Fixer motors in A, B, C three-phase alternating current, and R is high resistance grounding device, C ₀be system branch electric capacity, L is resonance grounding device, and T is grounding transformer;

Fig. 2 is the schematic diagram of apparatus of the present invention structure;

Fig. 3 is the intermittent defect phase voltage waveform not adopting the inventive method;

Fig. 4 is the intermittent defect phase voltage waveform figure adopting the inventive method.

Embodiment

Below in conjunction with the drawings and specific embodiments, the present invention is described in further detail:

As shown in FIG.; Multi-generator ship intermediate voltage electric power system protection method connects grounding transformer on the busbar of ship intermediate voltage power system; grounding transformer connects resonance grounding device; every platform generator neutral point in ship intermediate voltage power system connects high resistance grounding device; resistance in high resistance grounding device is adjusted by many taps mode, to adapt to the changeable operating mode of boats and ships.

Resistance in high resistance grounding device is adjusted and the single-phase direct-to-ground capacitance C of generator accessing generator quantity m and earth resistance and protect _git is relevant,

The resistance value R when multiple stage parallel operation of generator normally runs _gsetting method is as follows

Make to flow through high resistance grounding device electric current and meet following formula:

$I_{\mathrm{Rg}}=\frac{v}{m}\frac{3\mathrm{\ω}{C}_{0}U}{\sqrt{3}}$

Resistance value Rg value is:

$R_g=\frac{\frac{U}{\sqrt{3}}}{I_{\mathrm{Rg}}}=\frac{m}{3\mathrm{\ω}{C}_{0}v},---\left(1\right)$

Wherein, C ₀for the single-phase distributed capacitance of electric power system, U is rated voltage, and υ is resonance grounding device off resonance degree, ω=2 π f, f=50Hz.

When alternator failure needs off-the-line, high resistance grounding device resistance value should be adjusted rapidly, and setting method is such as formula shown in (2)

$R_g=\frac{1}{3\mathrm{\ω}{C}_g}---\left(2\right)$

The off resonance degree υ of resonance grounding device need coordinate high resistance grounding device to adjust.Resonance grounding device adopts overcompensation mode under normal circumstances, and off resonance degree is just.Because current in the fault point during high resistance grounding matching requirements fault is less than 10A, therefore off resonance degree υ can be determined by formula (3)

$\mathrm{\υ}\≤\frac{10}{\sqrt{2}}\frac{1}{3\mathrm{\ω}{C}_{0}U}---\left(3\right)$

Apply separately different from resonance grounding device, when resonance grounding device is applied separately, υ is generally 10%.And because the existence of High Resistance Grounding Mode can reduce neutral point displacement voltage in mixing earthing mode, therefore υ can control within 5%, reduce fault current.

Multiple generator ship intermediate voltage power system protective device comprises the grounding transformer be connected on the busbar of ship intermediate voltage power system; and being connected to the resonance grounding device between grounding transformer with the earth, every platform generator neutral point and the high resistance grounding device be connected between the earth, high resistance grounding device is tapped variable resistor.

High resistance grounding device is connected to generator neutral point, and when generator unit stator winding generation single phase ground fault, after generator outlet end circuit breaker disconnects, high resistance grounding device can over-voltage suppression, simultaneously fault restriction point electric current after adjusting.Adopt resonance neutral grounding protection system, by resonance grounding device by grounding transformer connecting system, can building-out capacitor electric current.Make high resistance grounding device can apply under large distributed capacitance condition simultaneously.

The Ship Electrical Power System being 6.6kV for generator outlet end line voltage is by hybrid earthing mode programming simulation in PSCAD-EMTDC environment, mixing earthing mode schematic diagram as shown in Figure 1, in Fig. 1, R is earth resistance, and L is arc suppression coil, and T is grounding transformer.Carry out earth fault emulation, simulation intermittent arc-earth fault.During isolated neutral system generation intermittent arc-earth fault, system phase voltage waveform as shown in Figure 3, and during mixing earthing mode generation intermittent arc-earth fault, system phase voltage waveform as shown in Figure 4.Isolated neutral system overvoltage is obvious as can be seen from Figure 2, and its ceiling voltage reaches 16kV, and exceed rated voltage peak value 3.5 times, this overvoltage enough causes system insulation fault.And the earthing device of mixing shown in Fig. 4 by Overvoltage suppressing within 2.5 times of rated voltage peak values, can protect system insulation effectively.Can be proved by emulation, mix earthing mode in shipboard power system under, effectively can suppress overvoltage protection shipboard power system trouble free service during intermittent arc-earth fault.

Specific works principle of the present invention is as follows:

When electrical network normally works, control device measures neutral point displacement voltage and system distributed capacitance in real time, when timing or measurement change, regulates arc suppression coil to compensate electric network capacitance and current, general employing overcompensation mode.Single phase ground fault and electrical network residual voltage occur when exceeding setting value, control device regulates arc suppression coil to compensating coefficient according to pre-set off resonance degree.

The existence of high resistance grounding device can eliminate the Xuhanting oral solution phenomenon that the arc suppression coil inductance that may exist and power-to-ground capacitance series resonance cause.And when there is single phase ground fault, high resistance can provide current path, is conducive to failure line selection.

Because the situation of parallel operation of generator and off-the-line often occurs Ship Electrical Power System; larger change can be there is along with the difference of operating mode in electric network composition; need to ensure that in each electric isolated island, drop into a resonance grounding device carrys out protection system from superpotential infringement, avoid multiple stage earthing device measure in system capacitance and conflict appears in parameter tuning simultaneously.

Every platform generator neutrality all requires connection high resistance grounding device; the overall performance of the resonance grounding that this earth resistance can improve; if generator generation single phase ground fault; before generator contactor disconnects rear rotor demagnetization during this period of time; the rapid set resistor value of high resistance grounding device, and generator is protected.

Claims (2)

1. a Multi-generator ship intermediate voltage electric power system protection method; it is characterized in that: on the busbar of ship intermediate voltage power system, connect grounding transformer; grounding transformer connects resonance grounding device; every platform generator neutral point in ship intermediate voltage power system connects high resistance grounding device; the resistance value of high resistance grounding device is adjusted by many taps mode, the resistance value R of described high resistance grounding device _gsetting method is:

The generator quantity of setting access is m, and the single-phase direct-to-ground capacitance of generator that high resistance grounding device is protected is C _g, the single-phase distributed capacitance of electric power system is C ₀, rated voltage is U, and resonance grounding device off resonance degree is υ,

When ship intermediate voltage power system multiple stage parallel running of generators, the resistance value Rg setting method of high resistance grounding device is:

Make to flow through high resistance grounding device electric current and meet following formula:

$I_{\mathrm{Rg}}=\frac{v}{m}\frac{3\mathrm{\ω}{C}_{0}U}{\sqrt{3}}$

Resistance value Rg value is:

$R_g=\frac{\frac{U}{\sqrt{3}}}{I_{\mathrm{Rg}}}=\frac{m}{3\mathrm{\ω}{C}_{0}v},$ Wherein, ω=2 π f, f=50Hz;

When there being alternator failure to need off-the-line in ship intermediate voltage power system, the resistance value R of high resistance grounding device _gvalue is:

$R_g=\frac{1}{3\mathrm{\ω}{C}_g},$

The off resonance degree υ of described resonance grounding device coordinates high resistance grounding device to adjust, and resonance grounding device adopts overcompensation mode, and off resonance degree is just, is adjusted by following formula:

$\mathrm{\υ}\≤\frac{10}{\sqrt{2}}\frac{1}{3\mathrm{\ω}{C}_{0}U}.$

2. a multiple generator ship intermediate voltage power system protective device; it is characterized in that: comprise the grounding transformer be connected on the busbar of ship intermediate voltage power system; and be connected to the resonance grounding device between grounding transformer with the earth, every platform generator neutral point and the high resistance grounding device be connected between the earth; described high resistance grounding device is tapped variable resistor, the resistance value R of described high resistance grounding device _gsetting method is:

The generator quantity of setting access is m, and the single-phase direct-to-ground capacitance of generator that high resistance grounding device is protected is C _g, the single-phase distributed capacitance of electric power system is C ₀, rated voltage is U, and resonance grounding device off resonance degree is υ,

When ship intermediate voltage power system multiple stage parallel running of generators, when ship intermediate voltage power system multiple stage parallel running of generators, the resistance value Rg setting method of high resistance grounding device is:

Make to flow through high resistance grounding device electric current and meet following formula:

$I_{\mathrm{Rg}}=\frac{v}{m}\frac{3\mathrm{\ω}{C}_{0}U}{\sqrt{3}}$

Resistance value Rg value is:

$R_g=\frac{\frac{U}{\sqrt{3}}}{I_{\mathrm{Rg}}}=\frac{m}{3\mathrm{\ω}{C}_{0}v},$ Wherein, ω=2 π f, f=50Hz;

When there being alternator failure to need off-the-line in ship intermediate voltage power system, the resistance value R of high resistance grounding device _gvalue is:

$R_g=\frac{1}{3\mathrm{\ω}{C}_g},$

The off resonance degree υ of described resonance grounding device coordinates high resistance grounding device to adjust, and resonance grounding device adopts overcompensation mode, and off resonance degree is just, is adjusted by following formula:

$\mathrm{\υ}\≤\frac{10}{\sqrt{2}}\frac{1}{3\mathrm{\ω}{C}_{0}U}.$