CN103545835B - Direct-current power system commutation failure judgment method - Google Patents

Abstract

The invention discloses a direct-current power system commutation failure judgment method including the steps of (1) measuring values of the commutation voltage ULL, the direct current Id, the inverter-side extinction angle gamma and the gating advance angle beta of a direct-current power system, (2) calculating the per unit value U'L of the critical commutation voltage value when the minimum value of the extinction angle is equal to gamma', (3) if an alternating-current power system is in three-phase symmetry failure, measuring the commutation voltage value after failure, and making the judgment that the direct-current power system is going to be in commutation failure if the measured commutation voltage value is lower than the critical commutation voltage value U'LL. In the direct-current power system commutation failure judgment method, the variation amplitude of the direct current after the three-phase symmetry failure of the alternating-current power system is taken into consideration, the calculation precision of the critical commutation voltage can be improved, and prediction accuracy and prevention effect of the measures for preventing the direct-current power system commutation failure can also be improved.

Description

Direct-current power system commutation failure judgment method

Technical field

The invention belongs to electrical engineering technical field, relate to the prevention of AC and DC power system operation troubles, be specifically related to a kind of direct-current power system commutation failure judgment method.

Background technology

Along with the iterative method of " transferring electricity from the west to the east, north and south supply mutually and on national network " strategy, North China-Central China-East China will form synchronised grids by extra-high-voltage alternating current, and will that direct current mode be adopted to realize is asynchronous interconnected with northeast, northwest and 3, south electrical networks.If but certain current conversion station generation single commutation failure or continuous commutation failure in these direct current channels, will directly threaten the safe and stable operation of electric power system.Reactive power compensation can be adopted at present, increase the setting value of more front Trigger Angle and send the modes such as trigger impulse in advance to prevent the generation of commutation failure.Wherein, whether the preventive effect sending trigger impulse measure in advance depends on and can promptly judge whether commutation failure to occur, the need of sending trigger impulse in advance from the change of voltage.But, at present in the process calculating commutation voltage critical value when there is commutation failure, the direct relation of commutation voltage decline maximum and extinguish angle cannot be obtained.If ignore the impact of direct current, then error calculated can be made comparatively large, thus cause judgement disappearance or the erroneous judgement of direct current power system commutation failure.

Summary of the invention

The technical problem to be solved in the present invention is: for the defect of prior art, provides a kind of direct-current power system commutation failure judgment method.Use the method can make phase conversion failure judgment in advance, be beneficial to the generation preventing commutation failure.

Technical scheme of the present invention is, described direct-current power system commutation failure judgment method, it is the relational expression by commutation voltage and extinguish angle, obtain critical commutation voltage value during inverter side generation commutation failure, with this according to the commutation voltage value after AC electric power systems three-phase symmetrical fault, according to the size of commutation voltage value after described critical commutation voltage value and fault, make the judgement whether electric power system commutation failure can occur.The method comprises the following steps:

(1), when on commission AC and DC power system is normally run, the commutation voltage U of the direct current power system of this AC and DC power system is measured _lL, direct current I _d, inverter side extinguish angle γ and gating advance angle β value;

(2), be calculated as follows out extinguish angle minimum value be γ ' time critical commutation voltage value perunit value U ' _l:

${\cos \mathrm{\γ}}^{\′}=\sqrt{\frac{{\cos }^2\mathrm{\γ}-{\cos }^2\mathrm{\β}}{U_L^{\′2}}+{\cos }^2\mathrm{\β}}$

In formula, U ' _l=U ' _lL/ U _lL, U ' wherein _lLfor the famous value of critical commutation voltage, γ, β and U _lLrespectively be inverter side extinguish angle, gating advance angle and the commutation voltage measured by step (1);

(3) if the AC electric power systems generation three-phase symmetrical fault of described AC and DC power system, be considered as the judgement demand of the direct current power system generation commutation failure proposing whether to cause described AC and DC power system, immediately measure the commutation voltage value after this AC electric power systems generation three-phase symmetrical fault, if measured commutation voltage value is down to the critical commutation voltage value U ' that step (2) calculates _lLbelow, make direct current power system and the judgement of commutation failure will occur.If commutation failure precautionary measures need be coordinated, then send the trigger impulse of converter valve in advance; If the critical commutation voltage value U ' that measured commutation voltage value calculates higher than step (2) _lL, make the judgement that commutation failure can not occur direct current power system.

The invention has the beneficial effects as follows, the direct-current power system commutation failure judgment method proposed, consider the change amplitude of direct current after AC system three-phase symmetrical fault, the computational accuracy of critical commutation voltage can be improved, also can improve prediction accuracy and the preventive effect of direct current power system commutation failure precautionary measures.

Embodiment

Embodiment 1:

(1), when on commission AC and DC power system is normally run, the commutation voltage U of the direct current power system of this AC and DC power system is measured _lL, direct current I _d, inverter side extinguish angle γ and gating advance angle β value;

(2), be calculated as follows out extinguish angle minimum value be γ ' time critical commutation voltage value perunit value U ' _l:

${\cos \mathrm{\γ}}^{\′}=\sqrt{\frac{{\cos }^2\mathrm{\γ}-{\cos }^2\mathrm{\β}}{U_L^{\′2}}+{\cos }^2\mathrm{\β}}$

In formula, U ' _l=U ' _lL/ U _lL, U ' wherein _lLfor the famous value of critical commutation voltage, γ, β and U _lLrespectively be inverter side extinguish angle, gating advance angle and the commutation voltage measured by step (1);

(3), the AC electric power systems generation three-phase symmetrical fault of above-mentioned AC and DC power system, be considered as the judgement demand of the direct current power system generation commutation failure proposing whether to cause described AC and DC power system, immediately measure the commutation voltage value after this AC electric power systems generation three-phase symmetrical fault, record commutation voltage value and be down to the critical commutation voltage value U ' that step (2) calculates _lLbelow, make direct current power system and the judgement of commutation failure will occur.If commutation failure precautionary measures need be coordinated, then send the trigger impulse of converter valve in advance;

Embodiment 2:

Step (1) ~ (2) are with embodiment 1;

(3), the AC electric power systems generation three-phase symmetrical fault of above-mentioned AC and DC power system, be considered as the judgement demand of the direct current power system generation commutation failure proposing whether to cause described AC and DC power system, immediately measure the commutation voltage value after this AC electric power systems generation three-phase symmetrical fault, record the critical commutation voltage value U ' that commutation voltage value calculates higher than step (2) _lL, make the judgement that commutation failure can not occur direct current power system.

Claims (1)

1. a direct-current power system commutation failure judgment method, the method comprises the following steps:

(1), when on commission AC and DC power system is normally run, the commutation voltage U of the direct current power system of this AC and DC power system is measured _lL, direct current I _d, inverter side extinguish angle γ and gating advance angle β value;

(2), be calculated as follows out extinguish angle minimum value be γ ' time critical commutation voltage value perunit value U ' _l:

$\cos {\mathrm{\γ}}^{\′}=\sqrt{\frac{{\cos }^2\mathrm{\γ}-{\cos }^2\mathrm{\β}}{{U^{\′}}_L^2}+{\cos }^2\mathrm{\β}}$

In formula, U ' _l=U ' _lL/ U _lL, U ' wherein _lLfor critical commutation voltage value, γ, β and U _lLrespectively be inverter side extinguish angle, gating advance angle and the commutation voltage measured by step (1);

(3) if the AC electric power systems generation three-phase symmetrical fault of described AC and DC power system, be considered as the judgement demand of the direct current power system generation commutation failure proposing whether to cause described AC and DC power system, immediately measure the commutation voltage value after this AC electric power systems generation three-phase symmetrical fault, if measured commutation voltage value is down to the critical commutation voltage value U ' that step (2) calculates _lLbelow, making direct current power system by there is the judgement of commutation failure, if commutation failure precautionary measures need be coordinated, then sending the trigger impulse of converter valve in advance; If the critical commutation voltage value U ' that measured commutation voltage value calculates higher than step (2) _lL, make the judgement that commutation failure can not occur direct current power system.