CN103346541B - Convertor station direct current filter differential protection method and device - Google Patents

Abstract

The present invention relates to convertor station direct current filter differential protection method and device, first protective device gathers DC filter high and low pressure side electric current, calculates both differences, then carries out Logic judgment and process according to the logic of protection.Method proposed by the invention can failure judgement fast and accurately, and when avoiding fault, CT saturation occurs to measure the risk that distortion causes false protection or tripping.

Description

Convertor station direct current filter differential protection method and device

Technical field

The present invention relates to method and the fixed value adjusting of a kind of DC filter differential protection in a kind of high voltage direct current transmission project, be applicable to high voltage direct current transmission DC filter protection system.

Background technology

DC filter is the visual plant in HVDC (High Voltage Direct Current) transmission system, and in current conversion station, between the bus being in DC side, as shown in Figure 1, DC filter two ends are connected to high voltage bus and neutral bus every cutter and low-pressure side every cutter respectively by high-pressure side.

DC filter differential protection is the main protection in DC filter protection, realizes defencive function during DC filter internal ground fault.DC filter differential protection gathers the current signal of the on high-tension side current signal of DC filter and low-pressure side, and protect the region between two measuring points, two measuring points are respectively current transformer T1 and T4 in Fig. 1.When there is earth fault in its protection zone, the electric current of both sides has very large difference, when this difference is greater than action definite value, through certain time delay output protection actuating signal, pulls open DC filter high-pressure side every cutter or stoppage in transit HVDC (High Voltage Direct Current) transmission system.

Existing DC filter differential protecting method, employing: current differential is greater than a fixing definite value, output protection actuating signal after longer time delay; But when breaking down, a large amount of direct currents is often flow through in fault point, and magnetic saturation phenomenon can occur current transformer, causes measurement distortion, and DC filter differential protection exists the risk of false protection and tripping.

Summary of the invention

The object of this invention is to provide a kind of DC filter differential protecting method, there is the problem of mistake action and rejecting action hidden danger in order to solve existing guard method.

For achieving the above object, the solution of the present invention comprises:

Convertor station direct current filter differential protection method, is characterized in that, step is as follows:

1) DC filter high voltage side current signal IT1 and low-pressure side current signal IT4 is gathered, and according to the current signal calculating current difference DIF gathered;

2) carry out differential protection judgement, criterion is DIF> Δ+K*IT1 _rms, Δ is constant definite value, and K is ratio brake coefficient, IT1 _rmsfor the effective value of high voltage side current;

3) when meeting described criterion, protection act.

DC filter differential protection is divided into three sections, and every section has respective protection definite value, time delay and action policy, and three sections of corresponding criterions, time delay and action policies are respectively:

(1) DIF> Δ 1+K1*IT1 _rmsaMP.AMp.Amp IT1 _rms< Δ 0; Time delay T1; Action policy: pull open DC filter high-pressure side every cutter; Δ 0 is that high-pressure side is every cutter arcing ability set point; Δ 1 is that first paragraph and second segment protect definite value, and K1 is first paragraph and second segment ratio brake coefficient, and T1 is first paragraph and second segment action delay;

(2) DIF> Δ 1+K1*IT1 _rmsaMP.AMp.Amp IT1 _rms> Δ 0; Time delay T1; Action policy: send out phase shift locking order to pole control system, stoppage in transit HVDC (High Voltage Direct Current) transmission system, the AC circuit breaker of tripping simultaneously, startup breaker fail protection;

(3) DIF> Δ 2+K2*IT1 _rms; Time delay T2; Action policy: send out phase shift locking order to pole control system, stoppage in transit HVDC (High Voltage Direct Current) transmission system, the AC circuit breaker of tripping simultaneously, startup breaker fail protection; Δ 2 is three section protection definite value, and K2 is the 3rd section of ratio brake coefficient, and T2 is the 3rd period of operate time.

High-pressure side is determined by the arcing ability of primary equipment DC filter high-pressure side every cutter every cutter arcing ability set point Δ 0; Three section protection definite value Δ the 2, the 3rd section of ratio brake coefficient K2 and the 3rd section action delay T2 according to DC filter and high-pressure side the short circuit trouble point between cutter (F1) determine; First paragraph and second segment protect definite value Δ 1, first paragraph and second segment ratio brake coefficient K1 and first paragraph and second segment action delay T1 according to DC filter internal short circuit fault point and and the short circuit trouble point of low-pressure side between cutter (F2, F3, F4) determine.

Step 1) in, wherein N is the sampling number in a power frequency period, and K is ratio brake coefficient, be the mean value of IT1 and IT4 difference in a power frequency period.

${\mathrm{IT}1}_{\mathrm{rms}}=\frac{\sqrt{\underset{1}{\overset{N}{\mathrm{\&Sigma;}}}{\mathrm{IT}1}^2}}{N}.$

Convertor station direct current filter differential protection, is characterized in that, comprising:

1) acquisition elements: gather DC filter high voltage side current signal IT1 and low-pressure side current signal IT4, and according to the current signal calculating current difference DIF gathered;

2) judgment component: carry out differential protection judgement, criterion is DIF> Δ+K*IT1 _rms, Δ is constant definite value, and K is ratio brake coefficient, IT1 _rmsfor the effective value of high voltage side current;

3) executive component: when meeting described criterion, protection act.

DC filter differential protection is divided into three sections, and every section has respective protection definite value, time delay and action policy, and three sections of corresponding criterions, time delay and action policies are respectively:

(1) DIF> Δ 1+K1*IT1 _rmsaMP.AMp.Amp IT1 _rms< Δ 0; Time delay T1; Action policy: pull open DC filter high-pressure side every cutter; Δ 0 is that high-pressure side is every cutter arcing ability set point; Δ 1 is that first paragraph and second segment protect definite value, and K1 is first paragraph and second segment ratio brake coefficient, and T1 is first paragraph and second segment action delay;

(2) DIF> Δ 1+K1*IT1 _rmsaMP.AMp.Amp IT1 _rms> Δ 0; Time delay T1; Action policy: send out phase shift locking order to pole control system, stoppage in transit HVDC (High Voltage Direct Current) transmission system, the AC circuit breaker of tripping simultaneously, startup breaker fail protection;

(3) DIF> Δ 2+K2*IT1 _rms; Time delay T2; Action policy: send out phase shift locking order to pole control system, stoppage in transit HVDC (High Voltage Direct Current) transmission system, the AC circuit breaker of tripping simultaneously, startup breaker fail protection; Δ 2 is three section protection definite value, and K2 is the 3rd section of ratio brake coefficient, and T2 is the 3rd period of operate time.

High-pressure side is determined by the arcing ability of primary equipment DC filter high-pressure side every cutter every cutter arcing ability set point Δ 0; Three section protection definite value Δ the 2, the 3rd section of ratio brake coefficient K2 and the 3rd section action delay T2 according to DC filter and high-pressure side the short circuit trouble point between cutter (F1) determine; First paragraph and second segment protect definite value Δ 1, first paragraph and second segment ratio brake coefficient K1 and first paragraph and second segment action delay T1 according to DC filter internal short circuit fault point and and the short circuit trouble point of low-pressure side between cutter (F2, F3, F4) determine.

Step 1) in, wherein N is the sampling number in a power frequency period, and K is ratio brake coefficient, be the mean value of IT1 and IT4 difference in a power frequency period.

${\mathrm{IT}1}_{\mathrm{rms}}=\frac{\sqrt{\underset{1}{\overset{N}{\mathrm{\&Sigma;}}}{\mathrm{IT}1}^2}}{N}.$

DC filter differential protecting method of the present invention; the operating current of differential protection is no longer definite value; but adopt constant to add the novel criterion of ratio brake; and ratio brake is relevant to high voltage side current; reduce the measurement impact that magnetic saturation causes, thus reduce the risk of differential protection malfunction and tripping.

Further, method of the present invention additionally uses the strategy of protection segmentation, and DC filter differential protection is divided into three sections, and every section has different protection definite values and corresponding time delay, action measures, and makes protection more accurately reliable.

Finally, method of the present invention gives the measure of adjusting of definite value.Apply method of the present invention, can failure judgement quickly and accurately, when avoiding fault CT saturation cause and measure the risk that distortion makes false protection or tripping.

Accompanying drawing explanation

Fig. 1 is DC filter winding diagram;

Fig. 2 is the differential protecting method logic diagram of embodiment 2;

Fig. 3 is the critical failure point schematic diagram of DC filter differential protection fixed value adjusting.

Embodiment

Below in conjunction with accompanying drawing, the present invention will be further described in detail.

The present invention's convertor station direct current filter required for protection differential protection is interpreted as the function module member based on differential protecting method of the present invention, is not entity apparatus, so hereafter eliminate device embodiment.The present invention can realize with built-in industrial parametric controller or PC device, and these two kinds of devices are devices that high-voltage dc transmission electrical domain is conventional.

The exemplary block diagram of DC filter and differential protection electric current measuring point, as shown in Figure 1.It is arranged in the middle of high direct voltage bus and DC bus, and its structure is made up of high-side capacitance device and the element such as low-side resistor, inductance; Measuring point is mainly high pressure and surveys electric current I T1, low pressure survey electric current I T4.

Embodiment 1

According to method of the present invention, first gather DC filter high voltage side current signal IT1 and low-pressure side current signal IT4, and according to the current signal calculating current difference DIF gathered; Then carry out differential protection judgement, criterion is DIF> Δ+K*IT1 _rms, Δ is constant definite value, and K is ratio brake coefficient, IT1 _rmsfor the effective value of high voltage side current; When meeting described criterion, protection act.

As a kind of DIF and IT1 _rmsaccount form, wherein N is the sampling number in a power frequency period, and K is ratio brake coefficient, be the mean value of IT1 and IT4 difference in a power frequency period, ${\mathrm{IT}1}_{\mathrm{rms}}=\frac{\sqrt{\underset{1}{\overset{N}{\mathrm{\&Sigma;}}}{\mathrm{IT}1}^2}}{N}.$

Embodiment 2

In order to implement protection better, carry out protection segmentation: DC filter differential protection is divided into three sections, every section has different protection definite values and accordingly time delay, action policy.Corresponding criterion, time delay and action policy are respectively:

(1) DIF> Δ 1+K1*IT1 _rmsaMP.AMp.Amp IT1 _rms< Δ 0; Time delay T1; Action policy: pull open DC filter high-pressure side every cutter; Δ 0 is that high-pressure side is every cutter arcing ability set point; Δ 1 is that first paragraph and second segment protect definite value, and K1 is first paragraph and second segment ratio brake coefficient, and T1 is first paragraph and second segment action delay; & is logical AND.

(2) DIF> Δ 1+K1*IT1 _rmsaMP.AMp.Amp IT1 _rms> Δ 0; Time delay T1; Action policy: send out phase shift locking order to pole control system, stoppage in transit HVDC (High Voltage Direct Current) transmission system, the AC circuit breaker of tripping simultaneously, startup breaker fail protection;

(3) DIF> Δ 2+K2*IT1 _rms; Time delay T2; Action policy: send out phase shift locking order to pole control system, stoppage in transit HVDC (High Voltage Direct Current) transmission system, the AC circuit breaker of tripping simultaneously, startup breaker fail protection; Δ 2 is three section protection definite value, and K2 is the 3rd section of ratio brake coefficient, and T2 is the 3rd period of operate time.

The result of the foundation dynamic performance testing of adjusting of protection definite value; when when will consider fault during test especially, DC component increases; now Measurement Result of Current Transformer will distortion; so (under failure condition) should be being put before this carry out the DCO of each fault point, ensureing that defencive function can correct operation under various operating condition further.Critical failure point F1, F2, F3, F4 of DC filter differential protection fixed value adjusting, as shown in Figure 3.In the present invention, the definite value of each segment protect and the coefficient of ratio are determined by dynamic performance testing result; setting principle is that during earth fault, protection can action message according in district; prevent during external area error, passing through formula electric current and cause false protection, to determine protection act definite value, ratio brake coefficient and action delay.

Claims (8)

1. convertor station direct current filter differential protection method, is characterized in that, step is as follows:

1) DC filter high voltage side current signal IT1 and low-pressure side current signal IT4 is gathered, and according to the current signal calculating current difference DIF gathered;

2) carry out differential protection judgement, criterion is DIF> Δ+K*IT1 _rms, Δ is constant definite value, and K is ratio brake coefficient, IT1 _rmsfor the effective value of high voltage side current;

3) when meeting described criterion, protection act;

DC filter differential protection is divided into three sections, and every section has respective protection definite value, time delay and action policy, and three sections of corresponding criterions, time delay and action policies are respectively:

(1) DIF> Δ 1+K1*IT1 _rmsaMP.AMp.Amp IT1 _rms< Δ 0; Time delay T1; Action policy: pull open DC filter high-pressure side every cutter; Δ 0 is that high-pressure side is every cutter arcing ability set point; Δ 1 is that first paragraph and second segment protect definite value, and K1 is first paragraph and second segment ratio brake coefficient, and T1 is first paragraph and second segment action delay;

(2) DIF> Δ 1+K1*IT1 _rmsaMP.AMp.Amp IT1 _rms> Δ 0; Time delay T1; Action policy: send out phase shift locking order to pole control system, stoppage in transit HVDC (High Voltage Direct Current) transmission system, the AC circuit breaker of tripping simultaneously, startup breaker fail protection;

(3) DIF> Δ 2+K2*IT1 _rms; Time delay T2; Action policy: send out phase shift locking order to pole control system, stoppage in transit HVDC (High Voltage Direct Current) transmission system, the AC circuit breaker of tripping simultaneously, startup breaker fail protection; Δ 2 is three section protection definite value, and K2 is the 3rd section of ratio brake coefficient, and T2 is the 3rd period of operate time.

2. according to convertor station direct current filter differential protection method according to claim 1, it is characterized in that, high-pressure side is determined by the arcing ability of primary equipment DC filter high-pressure side every cutter every cutter arcing ability set point Δ 0; Three section protection definite value Δ the 2, the 3rd section of ratio brake coefficient K2 and the 3rd section action delay T2 according to DC filter and high-pressure side the short circuit trouble point between cutter (F1) determine; First paragraph and second segment protect definite value Δ 1, first paragraph and second segment ratio brake coefficient K1 and first paragraph and second segment action delay T1 according to DC filter internal short circuit fault point and and the short circuit trouble point of low-pressure side between cutter (F2, F3, F4) determine.

3. convertor station direct current filter differential protection method according to claim 1, is characterized in that, step 1) in, wherein N is the sampling number in a power frequency period, and K is ratio brake coefficient, be the mean value of IT1 and IT4 difference in a power frequency period.

4. convertor station direct current filter differential protection method according to claim 3, is characterized in that, ${\mathrm{IT}1}_{\mathrm{rms}}=\frac{\sqrt{\underset{1}{\overset{N}{\mathrm{\&Sigma;}}}{\mathrm{IT}1}^2}}{N}.$

5. convertor station direct current filter differential protection, is characterized in that, comprising:

1) acquisition elements: gather DC filter high voltage side current signal IT1 and low-pressure side current signal IT4, and according to the current signal calculating current difference DIF gathered;

2) judgment component: carry out differential protection judgement, criterion is DIF> Δ+K*IT1 _rms, Δ is constant definite value, and K is ratio brake coefficient, IT1 _rmsfor the effective value of high voltage side current;

3) executive component: when meeting described criterion, protection act;

DC filter differential protection is divided into three sections, and every section has respective protection definite value, time delay and action policy, and three sections of corresponding criterions, time delay and action policies are respectively:

(1) DIF> Δ 1+K1*IT1 _rmsaMP.AMp.Amp IT1 _rms< Δ 0; Time delay T1; Action policy: pull open DC filter high-pressure side every cutter; Δ 0 is that high-pressure side is every cutter arcing ability set point; Δ 1 is that first paragraph and second segment protect definite value, and K1 is first paragraph and second segment ratio brake coefficient, and T1 is first paragraph and second segment action delay;

(2) DIF> Δ 1+K1*IT1 _rmsaMP.AMp.Amp IT1 _rms> Δ 0; Time delay T1; Action policy: send out phase shift locking order to pole control system, stoppage in transit HVDC (High Voltage Direct Current) transmission system, the AC circuit breaker of tripping simultaneously, startup breaker fail protection;

(3) DIF> Δ 2+K2*IT1 _rms; Time delay T2; Action policy: send out phase shift locking order to pole control system, stoppage in transit HVDC (High Voltage Direct Current) transmission system, the AC circuit breaker of tripping simultaneously, startup breaker fail protection; Δ 2 is three section protection definite value, and K2 is the 3rd section of ratio brake coefficient, and T2 is the 3rd period of operate time.

6. convertor station direct current filter differential protection according to claim 5, is characterized in that, high-pressure side is determined by the arcing ability of primary equipment DC filter high-pressure side every cutter every cutter arcing ability set point Δ 0; Three section protection definite value Δ the 2, the 3rd section of ratio brake coefficient K2 and the 3rd section action delay T2 according to DC filter and high-pressure side the short circuit trouble point between cutter (F1) determine; First paragraph and second segment protect definite value Δ 1, first paragraph and second segment ratio brake coefficient K1 and first paragraph and second segment action delay T1 according to DC filter internal short circuit fault point and and the short circuit trouble point of low-pressure side between cutter (F2, F3, F4) determine.

7. convertor station direct current filter differential protection according to claim 5, is characterized in that, step 1) in, wherein N is the sampling number in a power frequency period, and K is ratio brake coefficient, be the mean value of IT1 and IT4 difference in a power frequency period.

8. convertor station direct current filter differential protection according to claim 7, is characterized in that, ${\mathrm{IT}1}_{\mathrm{rms}}=\frac{\sqrt{\underset{1}{\overset{N}{\mathrm{\&Sigma;}}}{\mathrm{IT}1}^2}}{N}.$