CN106329512A - According to the technical scheme provided by the present invention, the black-start speed and stability of the power grid are improved. - Google Patents

Abstract

The invention provides a converter valve design method for black start of a DC system, comprising: building a converter valve system simulation model: using the converter valve system simulation model to obtain the voltage in the converter valve when the DC system is used for the black start of the power grid , current stress and loss of damping circuit, thyristor and surge arrester; configure converter valve arrester parameters: use the simulation model of the converter valve system to integrate different damping circuit losses, thyristor turn-on and turn-off losses, and converter valve commutation process The peak value of the surge voltage is used to obtain the optimal solution for damping parameter configuration and waterway configuration; analyze the black-start operation capability of the converter valve, and judge whether the arrester operates when the converter valve is in a black-start of the power grid based on the leakage current waveform of the converter valve arrester obtained by simulation ; Judging by the loss of the arrester whether the converter valve can operate stably in the case of black start. The technical scheme provided by the invention improves the black start speed and stability of the power grid.

Description

A Design Method of Converter Valve for Black Start of DC System

technical field

The invention relates to a design method of a converter valve, in particular to a design method of a converter valve for black start of a direct current system.

Background technique

In the field of power grid black start technology, many years of theoretical research have been carried out at home and abroad from the selection of black start power supply, the rule strategy of the black start phase, and the optimization of power grid recovery paths, and a series of exchanges have been successfully carried out based on the research results. Grid black start test. Compared with the start-up of the AC system, the DC system has the characteristics of large transmission power, fast start-up and adjustment speed, and strong controllability. These characteristics can play a greater role in the early stage of black start, which can speed up networking and enhance power transmission. ability. However, it is still in its infancy to use the DC system to drive the black start of the power grid. It is also based on the ideal operating state of the converter equipment, and does not consider the capacity of the converter equipment to withstand voltage, current and loss during black start.

When the converter is black-started in the power grid, it will cause a series of problems such as increased commutation overshoot, increased loss of thyristors in the converter valve due to frequent switching off, and increased transfer energy of arresters. In view of the efficiency of the water-cooling system, the limitation on losses will be relatively strict, so the problem of black start capability of HVDC converter valves has become an engineering problem that needs to be solved urgently.

Contents of the invention

In order to solve the above-mentioned deficiencies in the prior art, the object of the present invention is to provide a method for designing a converter valve for black start of a direct current system, so as to improve the black start speed and stability of the power grid.

The object of the present invention is to adopt following technical scheme to realize:

A method for designing a converter valve for a black start of a DC system, the improvement of which is that the method includes:

Build the converter valve system simulation model: use the converter valve system simulation model to obtain the voltage and current stress in the converter valve and the loss of the damping circuit, thyristor and arrester when the DC system is used for black start of the power grid;

Configure converter valve arrester parameters: use the converter valve system simulation model to combine different damping circuit losses, thyristor turn-on and turn-off losses, and converter valve commutation overshoot voltage peak values to obtain the optimal damping parameter configuration and waterway configuration. Excellent solution;

Analyze the black start operation capability of the converter valve, and judge from the leakage current waveform of the arrester of the converter valve obtained by simulation, whether the arrester operates when the converter valve is in a black start of the power grid; judge whether the converter valve can be stable in the case of a black start based on the loss of the arrester run.

Wherein, said building the simulation model of the converter valve system includes:

Build a 6-pulse converter unit: including converter transformers, damping resistors, damping capacitors, DC equalizing resistors, thyristors, valve reactors, valve stray capacitors and valve arresters; the equivalent reactance of the converter transformer through the converter valve system The device is connected with the three-phase rectifier bridge; each phase of the three-phase rectifier bridge is composed of upper and lower bridge arms, and each bridge arm is composed of a converter valve; each converter valve is connected with a valve arrester in parallel; the converter The valve includes a damping circuit, a DC voltage equalizing circuit, a thyristor, a saturated reactor and stray capacitance in the valve; the damping circuit, the DC voltage equalizing circuit and the thyristor are connected in parallel to form a damping circuit-DC voltage equalizing circuit-thyristor parallel branch, and the damping Circuit-DC equalizing circuit-Thyristor parallel branch is connected in series with saturated reactor and parallel with stray capacitance in the valve;

Input parameters in the established converter valve system simulation model, including: thyristor on-state voltage drop U _T , thyristor slope resistance RT , thyristor off-state resistance _RD , thyristor holding current I _w , converter valve damping capacitance _{C S} , converter valve damping resistance R _S , DC voltage equalizing resistance R _dc , saturated reactor unsaturated inductance L _m and stray capacitance C _y .

Wherein, the configuration parameters of the converter valve arrester include:

According to the UI characteristic of the monolithic surge arrester valve plate and the overvoltage protection level SIPL of the converter valve operation, calculate the number N _arr of the converter valve arrester in series and parallel;

Calculate the U-I characteristics of the converter valve arrester after series and parallel connection;

Input the U-I parameters of the arrester in the simulation model of the converter valve system.

Wherein, the number N _arr of the series-parallel connection is calculated by the following formula:

${\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}\mathrm{<span\; class="notranslate">\; r</span>}\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; S</span>}\mathrm{<span\; class="notranslate">\; I</span>}\mathrm{<span\; class="notranslate">\; W</span>}\mathrm{<span\; class="notranslate">\; Z</span>}}}{{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; )</span>}}$

Among them, U _SIWZ is the operation shock protection level of the converter valve, and U _R(s) is the residual voltage value of the arrester valve plate under the rated operating current.

Wherein, the U-I characteristic of the arrester of the converter valve is obtained by multiplying the U-I characteristic of the valve plate of the single arrester provided by the arrester manufacturer by the number of valve plates connected in series.

Wherein, the analysis of the black start operation capability of the converter valve includes:

Simulate the commutation overshoot voltage when the converter valve is turned off;

Calculate the leakage current and loss of the arrester;

Calculate the damping loop loss;

Calculate the loss in the case of frequent switching of the thyristor;

Calculate the thyristor operating junction temperature.

Wherein, the leakage current _ia of the arrester is obtained from the UI characteristic of the arrester;

The arrester loss is expressed by the following expression:

${\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 50</span>}{<span\; class="notranslate">\; \&Integral;</span>}_{\mathrm{<span\; class="notranslate">\; 0</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}\mathrm{<span\; class="notranslate">\; d</span>}\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; ;</span>$

Among them, V _a is the voltage at both ends of the arrester, _ia is the leakage current of the arrester; T is the power frequency cycle, which is 0.02s.

Among them, the damping circuit loss is composed of the sum of the damping resistance loss P _RS and the damping capacitance loss P _CS :

${\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}\mathrm{<span\; class="notranslate">\; S</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; \&pi;f</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; V</span>}\mathrm{<span\; class="notranslate">\; 0</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}\mathrm{<span\; class="notranslate">\; C</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}\mathrm{<span\; class="notranslate">\; C</span>}}<span\; class="notranslate">\; \{</span>\frac{\mathrm{<span\; class="notranslate">\; 4</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}}{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; -</span>\frac{\sqrt{\mathrm{<span\; class="notranslate">\; 3</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; 7</span>}\mathrm{<span\; class="notranslate">\; \&mu;</span>}}{\mathrm{<span\; class="notranslate">\; 4</span>}}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 7</span>}}{\mathrm{<span\; class="notranslate">\; 8</span>}}\mathrm{<span\; class="notranslate">\; the\; s</span>}\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; no</span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 7</span>}}{\mathrm{<span\; class="notranslate">\; 8</span>}}\mathrm{<span\; class="notranslate">\; the\; s</span>}\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&mu;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \}</span>$

${\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}\mathrm{<span\; class="notranslate">\; S</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 7</span>}{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; V</span>}\mathrm{<span\; class="notranslate">\; 0</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; h</span>}\mathrm{<span\; class="notranslate">\; f</span>}}}{\mathrm{<span\; class="notranslate">\; 4</span>}}<span\; class="notranslate">\; \&lsqb;</span>{\mathrm{<span\; class="notranslate">\; sin</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; sin</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; \&mu;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&rsqb;</span>$

Among them: T is the power frequency cycle, take 0.02s; C _AC is the effective damping capacitance value at both ends of the converter valve; R _AC is the effective damping resistance value connected in series with C _AC ; C _AC is the design value of the damping capacitance of a valve divided by Take the number of thyristors of the valve; R _AC is the design value of the damping resistance of a valve multiplied by the number of thyristors of the valve; C _HF is the effective total capacitance of all capacitive voltage equalizing network branches at both ends of the valve; U _V0 is the valve side line voltage ; f is the system frequency; μ is the commutation angle; α is the firing angle.

Among them, the loss expression in the case of frequent switching of the thyristor is as follows:

$\mathrm{<span\; class="notranslate">\; P</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 50</span>}{<span\; class="notranslate">\; \&Integral;</span>}_{\mathrm{<span\; class="notranslate">\; 0</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; d</span>}\mathrm{<span\; class="notranslate">\; t</span>}$

Among them: V _T0 is the on-state threshold voltage of the thyristor; r _T is the on-state slope resistance of the thyristor; i is the instantaneous value of the fault current; T is the power frequency cycle, which is 0.02s.

Wherein, the expression of the operating junction temperature of the thyristor is as follows:

T _j1 =T _c +P _thy ×R _thjc

Among them: T _j1 is the thyristor junction temperature (°C); T _c is the highest coolant temperature at the radiator inlet of the most unfavorable thyristor; P _thy is the maximum continuous overload thyristor loss; R _thjc is the thyristor junction to the cooling liquid at this place thermal resistance.

The excellent effect that technical scheme provided by the invention has is:

1. Use the electromagnetic transient simulation method to obtain the valve arrester, damping circuit voltage, and current waveforms, and use the integral method within one cycle to calculate the arrester loss, damping circuit loss and thyristor switching loss during the black start of the DC system, which is intuitive and effective .

2. By setting up the parameters of the converter valve system model, the damping parameters can be changed multiple times in a short period of time, and the optimal value of the damping parameter configuration and waterway configuration can be found relatively quickly by combining different damping circuit losses and commutation overshoot voltage peak values. Excellent solution.

3. The leakage current waveform of the valve arrester obtained from the simulation can intuitively and quickly judge whether the arrester operates frequently during the black start of the converter valve; whether the converter valve can operate stably under the black start condition can be analyzed from the loss of the arrester.

Description of drawings

Fig. 1 is the flow chart of the converter valve design method for black start of DC system provided by the present invention;

Fig. 2 is a simulation model diagram of the converter valve system provided by the present invention.

detailed description

The specific implementation manners of the present invention will be further described in detail below in conjunction with the accompanying drawings.

The following description and drawings illustrate specific embodiments of the invention sufficiently to enable those skilled in the art to practice them. Other embodiments may incorporate structural, logical, electrical, process, and other changes. The examples merely represent possible variations. Individual components and functions are optional unless explicitly required, and the order of operations may vary. Portions and features of some embodiments may be included in or substituted for those of other embodiments. The scope of embodiments of the present invention includes the full scope of the claims, and all available equivalents of the claims. These embodiments of the present invention may be referred to herein, individually or collectively, by the term "invention", which is for convenience only and is not intended to automatically limit the application if in fact more than one invention is disclosed The scope is any individual invention or inventive concept.

The present invention provides a method for designing a converter valve suitable for black start of a DC system, the flow chart of which is shown in Figure 1, including:

Converter valve system model building steps: Use the method of building a converter valve system simulation model to obtain the voltage and current stress in the converter valve and the loss of the damping circuit, thyristor and arrester when the DC system is used for black start of the power grid.

Steps for parameter configuration of converter valve surge arrester: use the built simulation model to find the optimal solution for damping parameter configuration and waterway configuration by integrating different damping circuit losses, thyristor turn-on and turn-off losses, and peak value of commutation overshoot voltage of converter valve .

Analysis steps of converter valve black start operation capability: the leakage current waveform of the valve arrester obtained by simulation can intuitively determine whether the arrester operates when the converter valve is in a black start of the power grid; the loss of the arrester can be used to judge whether the converter valve can operate under black start conditions. run stably.

1) Construction of the simulation model of the converter valve system. The simulation model of the converter valve system is shown in Figure 2, including the following sub-steps:

① Build a 6-pulse converter unit: including converter transformers, damping resistors, damping capacitors, DC equalizing resistors, thyristors, valve reactors, stray capacitors in valves and valve arresters; the equivalent The reactor is connected to the three-phase rectifier bridge; each phase of the three-phase rectifier bridge is composed of upper and lower bridge arms, and each bridge arm is composed of a converter valve; each converter valve is connected in parallel with a valve arrester; The flow valve includes a damping circuit, a DC voltage equalizing circuit, a thyristor, a saturated reactor and stray capacitance in the valve; the damping circuit, the DC voltage equalizing circuit and the thyristor are connected in parallel to form a damping circuit-DC voltage equalizing circuit-thyristor parallel branch, Damping circuit-DC voltage equalizing circuit-thyristor parallel branch and saturated reactor in series and valve stray capacitance in parallel;

②Input parameters in the established converter valve system simulation model: thyristor on-state voltage drop U _T , thyristor slope resistance R _T , thyristor off-state resistance R _D , thyristor holding current I _w , converter valve damping capacitance C _S , Converter valve damping resistance R _S , DC voltage equalizing resistance R _dc , saturated reactor unsaturated inductance L _m , stray capacitance C _f .

2) Arrester parameter configuration steps, including the following sub-steps:

①According to the UI characteristics of the valve plate of the single-piece arrester and the overvoltage protection level SIPL of the converter valve operation, calculate the number N _arr of the series-parallel connection required by the valve arrester; the number N _arr of the series-parallel connection is expressed by the following expression:

${\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}\mathrm{<span\; class="notranslate">\; r</span>}\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; S</span>}\mathrm{<span\; class="notranslate">\; I</span>}\mathrm{<span\; class="notranslate">\; W</span>}\mathrm{<span\; class="notranslate">\; Z</span>}}}{{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; )</span>}}$

Among them, U _SIWZ is the operation shock protection level of the converter valve, and U _R(s) is the residual voltage value of the arrester valve plate under the rated operating current.

② Calculate the U-I characteristic of the valve arrester after series and parallel connection; the U-I characteristic of the converter valve arrester is obtained by multiplying the U-I characteristic of the single arrester valve plate provided by the arrester manufacturer by the number of valve plates in series.

③Input the U-I parameters of the arrester in the converter valve system model.

3) The black start operation capability analysis step of the converter valve includes the following sub-steps:

①Simulation and calculation of commutation overshoot voltage when the converter valve is turned off;

② Calculate the leakage current and loss of the arrester; the leakage current i _a of the arrester is obtained from the UI characteristic of the arrester;

The arrester loss is expressed by the following expression:

${\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 50</span>}{<span\; class="notranslate">\; \&Integral;</span>}_{\mathrm{<span\; class="notranslate">\; 0</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}\mathrm{<span\; class="notranslate">\; d</span>}\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; ;</span>$

Among them, V _a is the voltage at both ends of the arrester, _ia is the leakage current of the arrester; T is the power frequency cycle, which is 0.02s.

③ Calculate the damping circuit loss; the damping circuit loss is composed of the sum of the damping resistance loss P _RS and the damping capacitance loss P _CS :

${\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}\mathrm{<span\; class="notranslate">\; S</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; \&pi;f</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; V</span>}\mathrm{<span\; class="notranslate">\; 0</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}\mathrm{<span\; class="notranslate">\; C</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}\mathrm{<span\; class="notranslate">\; C</span>}}<span\; class="notranslate">\; \{</span>\frac{\mathrm{<span\; class="notranslate">\; 4</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}}{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; -</span>\frac{\sqrt{\mathrm{<span\; class="notranslate">\; 3</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; 7</span>}\mathrm{<span\; class="notranslate">\; \&mu;</span>}}{\mathrm{<span\; class="notranslate">\; 4</span>}}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 7</span>}}{\mathrm{<span\; class="notranslate">\; 8</span>}}\mathrm{<span\; class="notranslate">\; the\; s</span>}\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; no</span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 7</span>}}{\mathrm{<span\; class="notranslate">\; 8</span>}}\mathrm{<span\; class="notranslate">\; the\; s</span>}\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&mu;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \}</span>$

${\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}\mathrm{<span\; class="notranslate">\; S</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 7</span>}{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; V</span>}\mathrm{<span\; class="notranslate">\; 0</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; h</span>}\mathrm{<span\; class="notranslate">\; f</span>}}}{\mathrm{<span\; class="notranslate">\; 4</span>}}<span\; class="notranslate">\; \&lsqb;</span>{\mathrm{<span\; class="notranslate">\; sin</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; sin</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; \&mu;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&rsqb;</span>$

Among them: T is the power frequency cycle, take 0.02s; C _AC is the effective damping capacitance value at both ends of the converter valve; R _AC is the effective damping resistance value connected in series with C _AC ; C _AC is the design value of the damping capacitance of a valve divided by Take the number of thyristors of the valve; R _AC is the design value of the damping resistance of a valve multiplied by the number of thyristors of the valve; C _HF is the effective total capacitance of all capacitive voltage equalizing network branches at both ends of the valve; U _V0 is the valve side line voltage ; f is the system frequency; μ is the commutation angle; α is the firing angle.

④ Calculate the loss in the case of frequent switching of the thyristor; the expression of the loss in the case of frequent switching of the thyristor is as follows:

$\mathrm{<span\; class="notranslate">\; P</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 50</span>}{<span\; class="notranslate">\; \&Integral;</span>}_{\mathrm{<span\; class="notranslate">\; 0</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; d</span>}\mathrm{<span\; class="notranslate">\; t</span>}$

Among them: V _T0 is the on-state threshold voltage of the thyristor; r _T is the on-state slope resistance of the thyristor; i is the instantaneous value of the fault current; T is the power frequency cycle, which is 0.02s.

⑤ Calculate the operating junction temperature of the thyristor; the expression of the operating junction temperature of the thyristor is as follows:

T _j1 =T _c +P _thy ×R _thjc

Among them: T _j1 is the thyristor junction temperature (°C); T _c is the highest coolant temperature at the radiator inlet of the most unfavorable thyristor; P _thy is the maximum continuous overload thyristor loss; R _thjc is the thyristor junction to the cooling liquid at this place thermal resistance.

By using the method of building the simulation model of the converter valve system, the voltage and current stress in the valve and the loss of the damping circuit, thyristor and arrester are obtained when the DC system is used for the black start of the power grid. Combining different damping circuits, thyristor losses and commutation overshoot voltage peaks, the optimal scheme of damping parameter configuration can be found. Reasonably design the water-cooling system of the converter valve through the loss of the thyristor, and the leakage current waveform of the valve arrester obtained by simulation can intuitively determine whether the arrester operates frequently during the black start operation of the converter valve; the loss of the arrester can determine whether the converter valve can operate Stable operation under black boot condition.

The above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art can still modify or equivalently replace the specific embodiments of the present invention. , any modifications or equivalent replacements that do not deviate from the spirit and scope of the present invention are within the protection scope of the claims of the present invention pending application.

Claims (10)

1. the converter valve method for designing for straight-flow system black starting-up, it is characterised in that described method includes:

Build converter valve system simulation model: utilize converter valve system simulation model to be obtained by straight-flow system and carry out power grid"black-start" Time converter valve in the loss of voltage, current stress and damping circuit, IGCT and spark gap；

Configuration converter valve spark gap parameter: utilize described converter valve system simulation model, the most different damping circuit loss, brilliant Brake tube turns on and off loss, converter valve commutation overshoot voltage peak value, obtains damping parameter configuration and the optimal case of water route configuration；

Analyze converter valve black starting-up service ability, and the converter valve lightning arrester leakance waveform obtained by emulation judges that converter valve is at electricity During net black starting-up, spark gap whether action；Judged whether converter valve can stable operation in the case of black starting-up by spark gap loss.

2. converter valve method for designing as claimed in claim 1, it is characterised in that described in build converter valve system simulation model bag Include:

Build 6 pulse conversion units: converter power transformer is connected with three-phase commutation bridge by the equivalent reactance device of converter valve system；Three The each of commutating phase bridge is constituted by upper and lower two brachium pontis, and each brachium pontis is constituted by converter valve；Each converter valve two ends parallel valve Spark gap；Described converter valve includes that damping circuit, direct current all push back stray capacitance in road, IGCT, saturable reactor and valve； Described damping circuit, direct current form damping circuit-direct current after all pushing back road and IGCT parallel connection and all push back road-IGCT parallel branch, Damping circuit-direct current all pushes back road-IGCT parallel branch and connects with saturable reactor in parallel with stray capacitance in valve；

Parameter is inputted in the converter valve system simulation model established, including: IGCT on-state voltage drop U_T, IGCT slope electricity Resistance R_T, IGCT off-state resistance R_D, IGCT maintain electric current I_w, converter valve damping capacitor C_S, converter valve damping resistance R_S、 Direct current equalizing resistance R_dc, saturable reactor unsaturation inductance value L_mWith stray capacitance capacitance C_y。

3. converter valve method for designing as claimed in claim 1, it is characterised in that described configuration converter valve spark gap parameter includes:

U-I characteristic according to monolithic arrester valve piece and converter valve switching-surge protective level SIPL, calculate converter valve spark gap Required connection in series-parallel sheet number N_arr；

Calculate the converter valve spark gap U-I characteristic after connection in series-parallel；

Spark gap U-I parameter is inputted in converter valve system simulation model.

4. converter valve method for designing as claimed in claim 3, it is characterised in that described connection in series-parallel sheet number N_arrCalculate with following formula:

$N_{arr}=\frac{U_{SIWZ}}{U_{R\left(s\right)}}$

Wherein, U_SIWZFor converter valve switching impulse level of protection, U_R(s)For arrester valve piece residual voltage under specified running current Value.

5. converter valve method for designing as claimed in claim 3, it is characterised in that described converter valve spark gap U-I characteristic is by keeping away The U-I characteristic of the monolithic arrester valve piece that Lei Qi producer provides is multiplied by valve block serial number and obtains.

6. converter valve method for designing as claimed in claim 1, it is characterised in that described analysis converter valve black starting-up service ability Including:

Commutation overshoot voltage when emulation converter valve turns off；

Calculate leakage current of an arrester and loss；

Calculating damping circuit is lost；

Calculate the loss in the case of IGCT frequently cut-offs；

Calculating IGCT and run junction temperature, its expression formula is as follows:

T_j1=T_c+P_thy×R_thjc

Wherein: T_j1: IGCT junction temperature (DEG C)；T_c: the highest coolant temperature at the radiator inlet of least favorable IGCT；P_thy: Maximum overload IGCT loss continuously；R_thjc: IGCT ties the thermal resistance of coolant at this.

7. converter valve method for designing as claimed in claim 6, it is characterised in that described spark gap Leakage Current i_aBy spark gap U-I characteristic obtains；

Spark gap loss expressions below represents:

$P_a=50{\&Integral;}_0^T{V}_a{i}_{a}dt;$

Wherein, V_aFor spark gap both end voltage, i_aFor spark gap Leakage Current；T is power frequency period, takes 0.02s.

8. converter valve method for designing as claimed in claim 6, it is characterised in that damping circuit loss is lost by damping resistance P_RSP is lost with damping capacitor_CSTwo parts are added and constitute:

$\begin{array}{c}{P}_{RS}=2{\mathrm{\&pi;f}}^2{U}_{V0}^2{C}_{AC}^2{R}_{AC}\{\frac{4\mathrm{\&pi;}}{3}-\frac{\sqrt{3}}{2}-\frac{7\mathrm{\&mu;}}{4}+\frac{7}{8}sin2\mathrm{\&alpha;}+\frac{7}{8}sin(2\mathrm{\&alpha;}+2\mathrm{\&mu;})\}\\ P_{CS}=\frac{7U_{V0}^2\&times;f\&times;C_{HF}}{4}\&lsqb;{\sin }^2\left(\mathrm{\&alpha;}\right)+{\sin }^2(\mathrm{\&alpha;}+\mathrm{\&mu;})\&rsqb;\end{array}$

Wherein: T is power frequency period, takes 0.02s；C_ACFor converter valve two ends effective damping capacitance；R_ACFor with C_ACSeries connection Effective damping resistance value；C_ACIt is that the design load of damping capacitor of a valve is divided by the IGCT number of this valve；R_ACIt it is the resistance of a valve The design load of buffer resistance is multiplied by the IGCT number of this valve；C_HFAll capacitive equalizing lattice effective total capacitances of network branch road for valve two ends； U_V0For valve side line voltage；F is system frequency；μ is angle of overlap；α is Trigger Angle.

9. converter valve method for designing as claimed in claim 6, it is characterised in that IGCT frequently cut-off in the case of attrition table Reach formula as follows:

$P=50{\&Integral;}_0^T(V_{T0}+r_{T}i)idt$

Wherein: V_T0For IGCT on-state threshold voltage；r_TFor IGCT on-state slope resistance；I is fault current instantaneous value；T For power frequency period, take 0.02s.

10. converter valve method for designing as claimed in claim 6, it is characterised in that described IGCT runs the expression formula of junction temperature As follows:

T_j1=T_c+P_thy×R_thjc

Wherein: T_j1For IGCT junction temperature (DEG C)；T_cFor the highest coolant temperature at the radiator inlet of least favorable IGCT；P_thy It is lost for maximum continuous overload IGCT；R_thjcThe thermal resistance of coolant at this is tied for IGCT.