CN102682358B - A kind of assessment wind-electricity integration scale and Net Frame of Electric Network adaptive planning simulation method - Google Patents

Abstract

The present invention provides a planning simulation method for evaluating wind power grid-connected scale and grid grid adaptability, comprising the following steps: (1). Performing a steady-state analysis on the planning scheme, and performing a steady-state analysis on the grid planning scheme according to the steady-state analysis results Adjustment; (2). Dynamically analyze the planning scheme, and adjust the power grid planning scheme according to the dynamic analysis results; (3). Analyze the interaction between the wind power scale and the grid-connected grid structure in the near area, and according to the interaction analysis results Adjusting the grid planning scheme; (4). Correcting and verifying the grid planning scheme to obtain a revised planning scheme for wind power and grid coordination. The planning and simulation method for assessing the grid-connected scale of wind power and the adaptability of the grid grid provided by the present invention can fully take into account the influence of large-scale wind power grid-connected on the dynamic characteristics of the power system due to the differences in the types of wind power and response characteristics and the characteristics of wind resources. It is beneficial to promote the coordinated development of grid-connected wind power and grid planning.

Description

A planning simulation method for evaluating wind power grid-connected scale and grid grid adaptability

technical field

The invention belongs to the field of grid-connected planning for renewable energy power generation, in particular to a planning simulation method for evaluating the grid-connected scale of wind power and the adaptability of grid grids.

Background technique

After the large-scale integration of intermittent wind power and renewable energy into the grid, due to its randomness and volatility, the operation mode of the power system will change greatly. Such as spinning reserve ratio, system peak shaving, frequency modulation service arrangement, etc. On the other hand, due to the power production characteristics of renewable energy itself, large-scale access will also affect system characteristics. Therefore, it is necessary to deeply analyze the changes in dynamic characteristics of the system such as active power, reactive power, frequency, and voltage after large-scale access to renewable energy.

In the wind power industry of all countries in the world, the development of wind power in countries with a vast population presents the following characteristics: fast development speed, large-scale wind farms, long transmission distances and high voltage levels. The above-mentioned characteristics of wind power development, combined with the "wind characteristics" problems such as frequent changes in wind, uncontrollable wind power, and uneven distribution of wind energy resources, have brought major challenges to wind power grid integration planning.

(1) As far as wind resource characteristics are concerned, wind power has random and intermittent characteristics, making it difficult for wind power to formulate and implement accurate power generation plans in advance like conventional power sources. (2) In terms of fan characteristics, the impact of wind turbines on the safety and stability of the power grid is different from that of conventional synchronous generators. Wind turbines using asynchronous machines emit active power while absorbing reactive power, and voltage control is more difficult. (3) In countries with vast populations, the geographic location of wind farms is generally relatively remote, the grid structure at the grid connection point is generally not strong enough, the power supply structure is relatively simple, the system is relatively weak, and the large-scale access of wind power affects these areas. There is a big problem with the planning of the grid.

With the expansion of the scale of wind farms, the proportion of wind power installed capacity in the power grid is getting higher and higher, and the access voltage level is increasing, the scope of its influence on the power grid is also gradually expanding from the local area. Looking at my country's wind power development plan, such a large-scale wind power generation centralized connection to the power grid poses new challenges to the planning, development and stable operation of the power grid, and there is no ready-made experience in the world to learn from. Corresponding research needs to be carried out urgently on the coordination of wind turbines and power grid under the connection.

Since the development and utilization of renewable energy takes a long time, and renewable energy is mostly connected to the power grid in a decentralized manner, its research mainly focuses on the impact on the distribution network, and it is of little reference to the situation of large-scale centralized connection. . With the rapid development of renewable energy power generation, scholars are paying more and more attention to the impact of its large-scale access to the power grid. The content involves multiple aspects such as power supply, main network and distribution network, as well as planning, design and operation. However, relatively complete and clear ideas, strategies and frameworks have not yet been formed.

Contents of the invention

In order to overcome the above-mentioned defects, the present invention provides a planning simulation method for evaluating the scale of wind power grid-connected and the adaptability of the grid grid, which can fully take into account the large-scale wind power grid-connected due to its multi-wind turbine types and differences in response characteristics and wind resources. The impact of characteristics on the dynamic characteristics of the power system, and the accurate assessment of the impact of wind power grid connection on the grid connection and the security bottleneck are conducive to promoting the coordinated development of grid-connected wind power and grid planning.

In order to achieve the above object, the present invention provides a planning simulation method for evaluating the grid-connected scale of wind power and the adaptability of the grid grid, and adjusts the planning scheme for wind power and grid coordination. The improvement is that the method includes the following steps :

(1). Carry out a steady-state analysis on the planning scheme, and adjust the grid planning scheme according to the steady-state analysis results;

(2). Dynamically analyze the planning scheme, and adjust the grid planning scheme according to the dynamic analysis results;

(3). Analyze the interaction between the scale of wind power and grid-connected near-area grid, and adjust the grid planning scheme according to the results of the interaction analysis;

(4). Revise and verify the grid planning scheme, and obtain the revised planning scheme for wind power and grid coordination.

In the optimal technical solution provided by the present invention, the steady-state analysis, dynamic analysis, and analysis of the interaction between the scale of wind power and grid-connected near-area grid structures respectively call the wind power simulation method adapted to the network source coordination planning analysis.

In the second optimal technical solution provided by the present invention, the wind power simulation method adapted to network resource coordination planning and analysis includes: reasonable equivalent processing of static characteristics of wind power, accurate simulation of dynamic characteristics of wind power, and differences in actual characteristics of wind power deal with.

In the third preferred technical solution provided by the present invention, the reasonable equivalence treatment of the static characteristics of the wind power supply includes: in the wind farm, the wind turbines are connected with one unit and one transformer, and the transformers have the same type; several wind turbines are connected to the high voltage side of the transformer Collected and connected to the low-voltage side of the main substation of the wind farm through a collector line; the active and reactive losses of the current on the transformer are:

${\mathrm{<span\; class="notranslate">\; \&Delta;P</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Q</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; it</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; ,</span>$ ${\mathrm{<span\; class="notranslate">\; \&Delta;Q</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Q</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; it</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}$

Among them, P _i , Q _i are the injected active power and reactive power of the transformer connected to the _i -th wind turbine; U _it , R _i , Xi are the voltage, equivalent resistance and equivalent reactance of the transformer respectively; ΔP _i , ΔQ _i are the active power loss and reactive power loss of the current on the transformer respectively; therefore, the power injected into the collector line by the i-th wind turbine is:

${\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; jQ</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&Delta;P</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; Q</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&Delta;Q</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; )</span>$

in, are respectively the active power and reactive power injected into the collector line by the i-th wind turbine;

At the same time, according to the voltage drop phasor diagram: in, respectively and U _it and and The angle between the phasors; AB represents the line length of the AB segment; from this formula, the active power at the outlet of the high-voltage side of the transformer of each wind turbine can be obtained reactive power and power factor

When multiple wind turbines are connected in parallel to the same collector line, their power factors are set to be Then the total power output at the outlet of the high-voltage side of the wind turbine transformer is:

Among them, P _i and Q _i are the total active power and total reactive power output at the outlet of the high-voltage side of the wind turbine transformer, are the active power of the nth wind turbine and the angle between the voltage and current phasor of the wind turbine. In the wind farm, each row of wind turbines can be equivalent to one wind turbine by the above formula, and the capacity of the equivalent wind turbine It is equal to the sum of the capacity of each wind turbine; for the whole wind farm, the wind farm can be equivalent to one or more wind turbines according to factors such as wind turbines and generator transformer parameters, and each wind turbine is equal to The check-in unit is used as the PQ node, then the capacity S of the equivalent wind turbine is:

${\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; \&Sigma;\&Sigma;</span>}}<span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; m</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; m</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; +</span>\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; m</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; Q</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}}^{<span\; class="notranslate">\; \&prime;</span>}$

In the formula, i and j represent the position of the wind turbine in the wind farm, and n and m respectively represent the number of wind turbines on each collector line in the wind farm and the number of collector lines in the wind farm;

When calculating the power flow, the collector lines inside the wind farm should be equivalent to an equivalent impedance according to the arrangement of the wind turbines. The collector lines inside the wind farm are divided into two types: direct buried cables and overhead lines; The parameters vary greatly, and the collector lines inside the wind farm should be equivalent according to the type of collector lines.

In the fourth optimal technical solution provided by the present invention, the accurate simulation of the dynamic characteristics of the wind power supply includes: wind power generators mostly use asynchronous generators, and when studying the equivalent value of the wind farm fleet, the physical quantities that need to be equivalent are studied through the mathematical model of the wind power generator stand-alone ; From the mathematical model of the asynchronous generator set and the motion model of the generator rotor, the key parameters equivalent to the wind farm can be deduced as follows:

T _J equivalent inertial time constant:

Similar to the asynchronous motor, the equivalent method of the rotor inertia time constant of the asynchronous generator is to weight the equivalent value according to the capacity, and get: $T_J=\frac{1}{S_m}\underset{j=1}{\overset{\mathrm{no}}{\mathrm{\&Sigma;}}}{T}_j{S}_j;$

Among them, S _j and T _j refer to the capacity and inertia time constant of the jth asynchronous motor respectively, S _M is the sum of the capacity of each asynchronous motor, T _J is the inertia time constant of the equivalent asynchronous machine, n is the total asynchronous motor Number of units;

S equivalent initial slip:

First connect the Γ-type equivalent circuit of the asynchronous machine in parallel, use the Thevenin equivalent method to obtain the equivalent resistance R _M of the two machines, and obtain the slip s _M of the equivalent generator in the initial state;

${\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}{<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}{{\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; +</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; l</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; l</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}{{\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; l</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; +</span><span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; l</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}{{\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; ]</span>}$

Among them, R ₁ and R ₂ represent the sum of the stator and rotor resistances of the two motors respectively, X _l1 and X _l2 represent the sum of the stator and rotor leakage reactances of the motors respectively, s ₁ and s ₂ represent the initial operating slip of the two motors respectively, the formula The units of each physical quantity in are per unit value;

X is the equivalent synchronous reactance, X' is the equivalent transient reactance and is the equivalent rotor winding time constant;

The above three parameters can be calculated as follows:

$\left\{\begin{array}{c}\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}\\ {\mathrm{<span\; class="notranslate">\; x</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; /</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; )</span>\\ {\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; /</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; )</span>\end{array}\right.$

In the formula, R _s is the stator resistance; R _r is the rotor resistance; X _s is the stator reactance; X _r is the rotor reactance; X _m is the excitation reactance.

In the fifth preferred technical solution provided by the present invention, the processing of differences in actual characteristics of wind power sources includes: separately processing time differences and space differences.

In the sixth preferred technical solution provided by the present invention, the time difference processing includes: according to the randomness of the output of the wind farm, the dispersion of the distribution of the wind farm and the wind turbines, and based on the meteorological data w of the wind farm, determine the wind resource of the wind farm The cumulative effect of characteristic dependencies reduces the power output characteristics of the function P _WF =F(w), where PWF represents the output power of the wind farm.

In the seventh optimal technical solution provided by the present invention, the spatial difference processing includes: using an equivalent model in static and dynamic simulations, converting the fan in the wind farm into a single equivalent unit, and establishing a detailed wind farm model; in the process of modeling the detailed model of the wind farm, all parameters should use the actual parameters of various equipment in the wind farm obtained; if there are some unknown actual parameters, it should be considered according to the most conservative situation within a reasonable range;

The detailed model modeling of the wind farm includes: wind turbines, box-type transformers, collector lines, step-up transformers and access system lines.

In the eighth preferred technical solution provided by the present invention, in the step 1, the steady-state analysis calls for reasonable equivalent processing of the static characteristics of the wind power source, respectively for the impact of wind power on the power flow of the power grid, static security, and wind power grid integration The influence of the reactive power and voltage characteristics of the power grid is analyzed.

In the ninth preferred technical solution provided by the present invention, in the step 2, the dynamic analysis calls for accurate simulation of the dynamic characteristics of the wind power supply, respectively for the transient stability of the system after the wind power is connected, and the system voltage stability after the wind power is connected , System frequency stability after wind power connection and system small disturbance stability after wind power connection are analyzed.

In the tenth preferred technical solution provided by the present invention, in the step 3, the interaction analysis calls for accurate simulation of the dynamic characteristics of the wind power supply, and respectively analyzes the wind power delivery capability, the isolated grid operation capability, and the relationship between the wind power supply and the conventional power supply in the near area. Analyze the interaction.

In the preferred technical solution provided by the present invention, in the step 4, the difference processing of the actual characteristics of the wind power source is invoked to correct and verify the grid planning scheme.

In the second more preferred technical solution provided by the present invention, the impact of wind power on the power flow of the power grid and the static safety analysis include: analyzing the influence of wind power grid connection on the power flow of the planned power grid and the load rate of power transmission and transformation equipment, and the analysis has no faults Whether the thermal stability limit constraint of power transmission and transformation equipment is satisfied under the breaking condition.

In the third preferred technical solution provided by the present invention, the analysis of the influence of the wind power grid connection on the reactive power voltage characteristics of the power grid includes: under the condition that the wind farm is not equipped with a reactive power compensation device, through calculation, the change in the active power output caused by According to the voltage fluctuation of the busbars of the access points and nearby areas of each substation, a reactive power compensation scheme including inductive compensation under light power flow and capacitive compensation under heavy power flow is proposed.

In the fourth preferred technical solution provided by the present invention, the transient stability analysis of the system after the wind farm is connected includes: after the wind farm is connected, N-1 fault checking is performed on the near area of the connected system, and serious For fault checking, the two conditions of constant power factor operation mode and constant voltage operation mode of the fan, and whether there is low voltage ride-through capability are studied separately.

In the fifth preferred technical solution provided by the present invention, the analysis of the system voltage stability after the wind farm is connected includes calculating the bus voltage drop and Recovery status; voltage stability of the system under severe fault conditions; analysis of the impact of wind farm access on the system's mid- and long-term voltage stability, and calculation of system reactive power reserve changes before and after wind farm access.

In the sixth more preferred technical solution provided by the present invention, the analysis of the system frequency stability after the wind farm is connected includes: calculating the wind farm connected to the system to form an isolated grid operation in the near area, and the isolated grid system in the case of a certain power imbalance frequency changes, and frequency stabilization measures.

In the seventh preferred technical solution provided by the present invention, the small-disturbance stability analysis of the system after the wind farm is connected includes: calculating the main low-frequency oscillation mode of the system, comparing the damping ratio of each main oscillation mode before and after the wind farm is connected Changes.

Compared with the prior art, the present invention provides a planning simulation method for assessing the grid-connected scale of wind power and the adaptability of the grid grid, which fully considers the characteristics of large-scale wind power bases, and realizes accurate modeling of wind turbines and large-scale wind farms. Reasonable equivalence, suitable for effective evaluation of wind turbine differences in engineering applications; for the first time, a wind power planning simulation method that can comprehensively consider the wind resource characteristics of wind power generation, wind turbine static and dynamic response characteristics, and the actual characteristics of wind power sources. Based on this method, the overall analysis technical framework for the coordinated planning of wind power sources and power grids under large-scale wind power access is proposed. Coordinated planning provides a technical means of simulation analysis; the above innovative research results have expanded the depth and breadth of wind power grid-connected planning simulation calculation work; moreover, this method is the first to comprehensively and objectively consider the impact of large-scale wind power base grid-connected The impact of the power system planning scheme, accurately assessing the impact of wind power access on the planned grid structure and the security bottleneck. This is conducive to the coordinated planning of wind power sources and power grids, and is of great significance for guiding the formulation of reasonable wind power source and grid planning schemes and ensuring the normal operation of the system after wind power access.

Description of drawings

Figure 1 is a schematic diagram of a typical wind farm wiring.

Figure 2 is a schematic diagram of the wiring of a single wind turbine.

Figure 3 is a voltage drop vector diagram.

Figure 4 is a detailed wiring diagram of a typical wind farm.

Figure 5 shows the overall analysis technical framework of the coordinated planning of wind power source and power grid under large-scale wind power access.

Figure 6 shows the analysis algorithm flow of wind power source and grid coordination planning.

detailed description

The goal of a planning simulation method for evaluating the scale of wind power grid-connected and the adaptability of grid grid is to effectively take into account the impact of static characteristics and dynamic characteristics of large-scale wind power bases on grid-connected The impact of the grid structure, accurately grasp the constraints of the target planning grid structure on the grid-connected wind power, give the corresponding network source coordination planning plan, and reasonably evaluate the layout of the wind farm, wind turbine type, and fan characteristics when wind power is connected to the grid. The degree of revision of the planning scheme due to the actual difference. To this end, the following problems need to be solved: static characteristic simulation and dynamic characteristic simulation of wind turbines in planning simulation analysis, establishment of a complete network source coordination planning process scheme, and correction analysis of planning schemes due to differences in actual characteristics of wind turbines, etc. In response to the above problems, this patent proposes for the first time the principle of simulation analysis of wind power power supply that takes into account the differences in static characteristics, dynamic characteristics and actual characteristics of large-scale wind power bases in the analysis of network source coordination planning. Based on this principle, the wind power power supply and power grid The overall analysis process and framework of coordinated planning provides a relatively complete and clear analysis thinking, technical framework and technical methods for grid planning under large-scale wind power grid integration.

The technical content of this patent will be introduced in detail below.

Wind Power Simulation Principles Adapted to Coordinated Planning and Analysis of Network Sources

Reasonable Equivalence of Static Characteristics of Wind Power

Taking a typical wind farm as an example to illustrate the principle of reasonable equivalence of static characteristics of wind power sources.

In the wind farm shown in Figure 1, the wind turbines are wired with one unit and one transformer, and the transformers are of the same type. Collect several wind turbines at the high-voltage side of the transformer, and connect them to the low-voltage side of the main substation of the wind farm through a collector line. The wiring of a single wind turbine is shown in Figure 2. The voltage drop phasor diagram of the i-th wind turbine transformer is shown in Figure 3. The active and reactive losses of the current on the transformer are:

${\mathrm{<span\; class="notranslate">\; \&Delta;P</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Q</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; it</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; ,</span>$ ${\mathrm{<span\; class="notranslate">\; \&Delta;Q</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Q</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; it</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}$

Among them, P _i , Q _i are the injected active power and reactive power of the transformer connected to the i-th wind turbine; U _it , R _i , Xi are the voltage, equivalent resistance and equivalent reactance of the transformer _, respectively. ΔP _i , ΔQ _i are the active power loss and reactive power loss of the current on the transformer, respectively. Therefore, the power injected into the collector line by the i-th wind turbine is:

${\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; jQ</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&Delta;P</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; Q</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&Delta;Q</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; )</span>$

in, are the active power and reactive power injected into the collector line of the i-th wind turbine, respectively. At the same time, according to the voltage drop phasor diagram: in, are respectively in the accompanying drawing 3 and U _it and and The angle between the phasors. The meaning of AB is shown in the line length of AB section in the accompanying drawing 3. From this formula, the active power at the outlet of the high-voltage side of the transformer of each wind turbine can be obtained reactive power and power factor

When multiple wind turbines are connected in parallel to the same collector line, their power factors are set to be Then the total power output at the outlet of the high-voltage side of the wind turbine transformer is:

Among them, P _i and Q _i are the total active power and total reactive power output at the outlet of the high-voltage side of the wind turbine transformer, are the active power of the nth wind turbine and the angle between the voltage and current phasor of the wind turbine. In the wind farm, each row of wind turbines can be equivalent to one wind turbine by the above formula, and the capacity of the equivalent wind turbine Equal to the sum of the capacity of each wind turbine. For the whole wind farm, the wind farm can be equivalent to one or more wind turbines according to factors such as wind turbines and transformer parameters, and each equivalent wind turbine can be used as a PQ node in the power flow calculation, then the equivalent The capacity of the wind turbine is:

${\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; \&Sigma;\&Sigma;</span>}}<span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; m</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; m</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; +</span>\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; m</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; Q</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}}^{<span\; class="notranslate">\; \&prime;</span>}$

In the formula, i and j represent the position of the wind turbine in the wind farm, and n and m respectively represent the number of wind turbines on each collector line in the wind farm and the number of collector lines in the wind farm.

When calculating the power flow, the collector lines inside the wind farm should be equivalent to an equivalent impedance according to the arrangement of the wind turbines. The collector lines inside the wind farm are divided into two types: direct buried cables and overhead lines. Due to the large difference in parameters between cable lines and overhead lines, the collector lines inside the wind farm should be equivalent according to the type of collector lines.

(2) Accurate simulation of wind power dynamic characteristics

When studying the model of a large-scale grid-connected wind farm, since the wind farm is composed of a large number of wind turbines, the mathematical model of the wind farm is established based on the mathematical model of the wind turbine, but the stand-alone model cannot be simply applied, and the wind farm itself should be considered According to different research problems, wind farm models with different levels of detail are equivalently produced.

When studying the stability of power systems with wind farms, although the full transient model of asynchronous generators can be used to represent each generator in the wind farm, due to the large number of generators in the wind farm, the application of this model will lead to simulation calculations The traditional full transient model is not suitable for wind farm simulation calculation. Therefore, it is necessary to design a complete algorithm to make an appropriate mathematical description of the dynamic equivalent link of the wind farm.

Wind turbines mostly use asynchronous generators. When studying the equivalent value of wind farm fleets, the physical quantities that need to be equivalent are first studied through the mathematical model of a single wind turbine. The key parameters that can be derived from the mathematical model of the asynchronous generator set and the rotor motion model of the generator are as follows:

T _J equivalent inertial time constant

Similar to the asynchronous motor, the equivalent method of the rotor inertia time constant of the asynchronous generator is to weight the equivalent value according to the capacity, and get: $T_J=\frac{1}{S_m}\underset{j=1}{\overset{\mathrm{no}}{\mathrm{\&Sigma;}}}{T}_j{S}_j;$

Among them, S _j and T _j refer to the capacity and inertia time constant of the jth asynchronous motor respectively, S _M is the sum of the capacity of each asynchronous motor, T _J is the inertia time constant of the equivalent asynchronous machine, n is the total asynchronous motor Number of units.

S equivalent initial slip

Firstly, the Γ-type equivalent circuit of the asynchronous machine is connected in parallel, and the equivalent resistance RM of the two machines is obtained by using the Thevenin equivalent method, and the slip sM of the equivalent generator in the initial state can be obtained.

${\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}{<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}{{\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; +</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; l</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; l</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}{{\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; l</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; +</span><span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; l</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}{{\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; ]</span>}$

Among them, R ₁ and R ₂ represent the sum of the stator and rotor resistances of the two motors respectively, X _l1 and X _l2 represent the sum of the stator and rotor leakage reactances of the motors respectively, s ₁ and s ₂ represent the initial operating slip of the two motors respectively, the formula The units of all physical quantities are standard unit values.

X equivalent synchronous reactance

X' equivalent transient reactance

Equivalent rotor winding time constant

The above three parameters can be calculated as follows:

$\left\{\begin{array}{c}\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}\\ {\mathrm{<span\; class="notranslate">\; x</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; /</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; )</span>\\ {\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; /</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; )</span>\end{array}\right.$

In the formula, R _s - stator resistance; R _r - rotor resistance; X _s - stator reactance; X _r - rotor reactance; X _m - excitation reactance.

(3) Handling of differences in the actual characteristics of wind power sources in the revision and verification of planning schemes

When analyzing the impact of wind power grid-connected on the grid, large-scale wind power bases have adopted static and dynamic equivalent models. When the analysis conclusion shows that the planned power grid is not suitable for wind power access, and the original power grid planning scheme needs to be revised, in the correction verification analysis, the difference between the equivalent model and the actual situation needs to be considered to ensure that the proposed planning correction scheme is correct sex. The principle of dealing with differences in the actual characteristics of wind power includes time differences and spatial differences. The following specific analysis

(a) Time difference

Wind farms are very different from conventional power plants. Firstly, the output of a wind farm is affected by its driving force wind and fluctuates randomly. In most cases, its output is lower than its rated capacity; secondly, an area may There are multiple wind farms, that is, the distribution of wind farms in a region is scattered; third, a wind farm is often composed of dozens, hundreds or even hundreds of wind turbines, that is, the distribution of wind turbines in a wind farm is scattered. of. Due to the randomness of wind farm output and the dispersed distribution of wind farms and wind turbines, it is necessary to study the correlation of wind farms based on the meteorological data w of wind farms and determine the cumulative effect reduction function of the correlation of wind resource characteristics of wind farms The power output characteristics of F(w) provide a basis for power system calculations.

(b) Spatial difference

Due to the use of the equivalent model in the static and dynamic simulation of wind turbines, the equivalent value of multiple wind turbines becomes a single equivalent unit, which may lead to certain deviations in the analysis results. Therefore, in the verification analysis, the detailed model needs to be considered as needed.

During the detailed modeling process of the wind farm, all parameters should use the actual parameters of various equipment in the wind farm obtained from funding. If some actual parameters are unknown, consider the most conservative case within a reasonable range.

The detailed modeling of the wind farm should include: wind turbines (modeled separately for each wind turbine), box-type transformer (the cable between the wind turbine and the box transformer is ignored), collector lines, step-up transformers, and access system lines. The details are shown in Figure 4.

Overall analysis technical framework for coordinated planning of wind power source and power grid under large-scale wind power access

The overall analysis technical framework of wind power source and power grid coordination planning must include the analysis of the impact of wind power grid connection on various aspects of the power grid and the impact of grid failure and other factors on wind power source. The specific analysis technology content includes the following parts, which can be appropriately chosen in practical applications.

(1) Analysis of the influence of wind power grid integration on the steady-state characteristics of the planned grid

(a) The impact of wind power grid connection on the power flow of the grid and static security analysis

Analyze the impact of wind power grid connection on the planned power flow of the grid and the load rate of power transmission and transformation equipment (lines, transformers); analyze whether the thermal stability limit constraints of power transmission and transformation equipment are satisfied under the condition of no fault interruption.

(b) Analysis of the influence of wind power grid connection on the reactive power and voltage characteristics of the grid

This part of the analysis is mainly through calculation and analysis to show the voltage fluctuation of the access point and the busbar of each substation in the nearby area caused by the change of its own active power output in the wind farm under the condition of no reactive power compensation device; and then Through calculation, suggestions for reactive power compensation schemes under various possible conditions are put forward.

Analysis of the influence of wind power grid connection on the dynamic characteristics of the planned grid

(a) Transient stability analysis of the system after the wind farm is connected

After the wind farm is connected, N-1 fault checks and serious fault checks are performed in the vicinity of the access system, and various conditions such as various operating modes of the wind turbines and whether they have low-voltage ride-through capabilities are studied.

(b) Analysis of system voltage stability after the wind farm is connected

Calculate the drop and recovery of the bus voltage of each substation after a short-circuit fault occurs in the vicinity of the access system after the wind farm is connected; the voltage stability of the system in the event of a serious fault; the impact of the wind farm connection on the medium and long-term voltage stability of the system Analyze and calculate the changes of the reactive power reserve of the system before and after the wind farm is connected.

(c) Analysis of system frequency stability after wind farm connection

Calculate the frequency change of the isolated grid system when the wind farm is connected to the system in the near area to form an isolated grid operation, and there is a certain power imbalance, and the frequency stabilization measures.

(d) Small disturbance stability analysis of the system after the wind farm is connected

Calculate the main low-frequency oscillation modes of the system, and compare the changes in the damping ratio of each main oscillation mode before and after the wind farm is connected.

(3) Analysis of the interaction between the scale of wind power development and grid structure in the grid-connected area

This part needs to be carried out in combination with the characteristics of access to the nearby power grid, including: analysis of wind power transmission capacity, analysis of isolated grid operation capacity, and analysis of the mutual influence between wind power and conventional power in the near area.

2. The overall analysis technical framework of coordinated planning of wind power source and power grid under large-scale wind power access is shown in Figure 5.

Analysis algorithm flow of wind power source and grid coordination planning

Based on the wind power source simulation principle adapted to grid source coordination planning analysis in content 1 and the overall analysis technical framework of wind power source and grid coordination planning under large-scale wind power access in content 2, the algorithm flow of wind power source and grid coordination planning analysis algorithm is designed and proposed. The details are shown in Figure 6.

It should be declared that the contents and specific implementation methods of the present invention are intended to prove the practical application of the technical solutions provided by the present invention, and should not be construed as limiting the protection scope of the present invention. Those skilled in the art may make various modifications, equivalent replacements, or improvements under the inspiration of the spirit and principles of the present invention. But these changes or modifications are all within the protection scope of the pending application.

Claims (15)

1. A planning simulation method for evaluating the adaptability of a wind power grid-connected scale and a power grid network frame adjusts a planning scheme for coordinating a wind power supply and a power grid, and is characterized by comprising the following steps:

(1) carrying out steady state analysis on the planning scheme, and adjusting the power grid planning scheme according to a steady state analysis result;

(2) dynamically analyzing the planning scheme, and adjusting the power grid planning scheme according to the dynamic analysis result;

(3) analyzing the mutual influence between the wind power scale and the grid-connected near-zone grid structure, and adjusting the power grid planning scheme according to the mutual influence analysis result;

(4) correcting and checking the power grid planning scheme to obtain a corrected wind power supply and power grid coordination planning scheme;

the steady state analysis, the dynamic analysis and the mutual influence analysis of the wind power scale and the grid-connected near-zone grid structure respectively call a wind power supply simulation method suitable for grid source coordination planning analysis;

the wind power supply simulation method suitable for network source coordination planning analysis comprises the following steps: reasonable equivalence processing of static characteristics of the wind power supply, accurate simulation of dynamic characteristics of the wind power supply and difference processing of actual characteristics of the wind power supply;

the accurate simulation of the dynamic characteristics of the wind power supply comprises the following steps: the wind generating set mostly adopts an asynchronous generator, and physical quantities needing equivalence are researched through a wind generator single machine mathematical model when equivalence of a wind power plant cluster is researched; equivalent key parameters of the wind power plant can be obtained by an asynchronous generator set mathematical model and a generator rotor motion model as follows:

T_Jequivalent inertia time constant:

similar to an asynchronous motor, the inertia time constant equivalence method of the rotor of the asynchronous generator weights according to the capacity to obtain:

wherein S is_jAnd T_jRespectively refer to the capacity and inertia time constant, S, of the jth asynchronous motor_MIs the sum of the capacities of the asynchronous motors, T_JThe inertia time constant of the equivalent asynchronous machine is obtained, and n is the total number of the asynchronous machines;

s equivalent initial slip:

firstly, connecting the equivalent circuits of the asynchronous machines in parallel, and obtaining the equivalent resistance R of the two machines by using a Thevenin equivalent method_MThe slip s of the equivalent generator in the initial state can be obtained_M；

$s_M=\frac{R_M{(\frac{R_1}{s_1}+\frac{R_2}{s_2})}^2+R_M{(X_{l1}+X_{l2})}^2}{\left(\frac{R_1}{s_1}\right)\&lsqb;X_{l2}^2+{\left(\frac{R_2}{s_2}\right)}^2\&rsqb;+\left(\frac{R_2}{s_2}\right)\&lsqb;X_{l1}^2+{\left(\frac{R_1}{s_1}\right)}^2\&rsqb;}$

Wherein R is₁And R₂Respectively representing the sum of the resistances of the stator and the rotor of two motors, X_l1And X_l2Respectively representing the sum of leakage reactance of stator and rotor of motor, s₁、s₂Respectively representing the initial running slip of the two motors, wherein each physical quantity unit is a per unit value;

x is equivalent synchronous reactance, X 'is equivalent transient reactance and T'₀Is the equivalent rotor winding time constant;

the three parameters can be calculated according to the following formula:

$\left\{\begin{array}{c}X=X_s+X_m\\ X^{\&prime;}=X_s+X_r{X}_m/(X_r+X_m)\\ T_0^{\&prime;}=(X_r+X_m)/\left(2{\mathrm{\&pi;R}}_r\right)\end{array}\right.$

in the formula, R_sIs a stator resistor; r_rIs the rotor resistance; x_sIs a stator reactance; x_rIs the rotor reactance; x_mIs an excitation reactance.

2. The planning simulation method of claim 1, wherein the reasonable equivalence processing of the static characteristics of the wind power supply comprises: in a wind power plant, a wind turbine generator adopts unit wiring of 1 machine and 1 transformer, and the models of the transformers are the same; collecting the wind turbine generator connected to 1 collecting line at the high-voltage side of the transformer, and connecting the wind turbine generator to the low-voltage side of a main transformer station of a wind power plant through 1 collecting line; the active loss and the reactive loss of the current on the transformer are respectively as follows:

${\mathrm{\&Delta;P}}_i=\frac{P_i^2+Q_i^2}{U_{it}^2}{R}_i,{\mathrm{\&Delta;Q}}_i=\frac{P_i^2+Q_i^2}{U_{it}^2}{X}_i$

wherein, P_i、Q_iInjecting active power and reactive power into a transformer connected with the ith wind turbine generator set; u shape_it、R_i、X_iThe voltage, the equivalent resistance and the equivalent reactance of the transformer are respectively; delta P_i、ΔQ_iThe active loss and the reactive loss of the current on the transformer are respectively; therefore, the power injected into the current collecting circuit by the ith wind turbine generator set is as follows:

P'_i+jQ'_i＝(P_i-ΔP_i)+j(Q_i-ΔQ_i)

wherein, P'_i、Q'_iRespectively injecting active power and reactive power of a current collection circuit into the ith wind turbine generator set;

meanwhile, according to the voltage drop phasor diagram, the following can be obtained:wherein (a),Are respectively asAnd U_itAndandthe included angle between the phasors; AB represents the length of the AB segment; active power P 'at the outlet of the high-voltage side of the transformer of each wind turbine generator can be obtained according to the formula'_iAnd reactive power Q'_iAnd power factor

When a plurality of wind turbine generators are connected in parallel to the same current collecting line, the power factors are respectively set asThe total power output at the high-voltage side outlet of the transformer of the wind turbine generator is as follows:

wherein P is_i、Q_iThe total active power and the total reactive power P output from the high-voltage side outlet of the transformer of the wind turbine generator_n'、The active power of the nth wind turbine generator set and the included angle of the voltage and current phasor of the nth wind turbine generator set are respectively included, in the wind power plant, each wind turbine generator set can be equivalent to 1 wind turbine generator set by the above formula, and the capacity of the equivalent wind turbine generator set is equal to the sum of the capacities of each wind turbine generator; for the whole wind power plant, the wind power plant equivalent can be 1 wind power plant according to factors such as parameters of a wind power plant and a generator transformer, and the equivalent generator is taken as a PQ node during load flow calculation, so that the capacity S of the equivalent wind power plant is as follows:

$S_{\mathrm{\&Sigma;}\mathrm{\&Sigma;}}=\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}\underset{j=1}{\overset{m}{\mathrm{\&Sigma;}}}{S}_{i,j}=\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}\underset{j=1}{\overset{m}{\mathrm{\&Sigma;}}}{P}_{i,j}^{\&prime;}+\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}\underset{j=1}{\overset{m}{\mathrm{\&Sigma;}}}{Q}_{i,j}^{\&prime;}$

in the formula, i and j represent the positions of the wind turbines in the wind power plant, and n and m respectively represent the number of fans on each current collecting line in the wind power plant and the number of the current collecting lines in the wind power plant;

during load flow calculation, current collecting lines inside a wind power plant are equivalent to 1 equivalent impedance according to the arrangement of wind turbine generators, wherein the current collecting lines inside the wind power plant are divided into two types, namely direct-buried cables and overhead lines; due to the fact that parameter difference between a cable line and an overhead line is large, equivalent values of the current collecting lines in the wind power plant are required to be carried out according to the types of the current collecting lines.

3. The planning simulation method according to claim 1, wherein the difference of the actual characteristics of the wind power supply is processed, and the time difference and the space difference are processed respectively.

4. The planning simulation method according to claim 3, wherein the temporal diversity processing comprises: determining an accumulative effect reduction function P of wind power plant wind resource characteristic correlation based on meteorological data w of the wind power plant according to the randomness of the output of the wind power plant, the dispersity of the distribution of the wind power plant and wind generating sets_WFPower output characteristic of f (w), where PWF represents the output power of the wind farm.

5. The planning simulation method according to claim 3, wherein the spatial diversity processing comprises: an equivalent model is used in static and dynamic simulation, all fans in a wind power plant are equivalent to a single equivalent unit, and a detailed model of the wind power plant is established; in the modeling process of the wind power plant detailed model, all parameters use actual parameters of various devices of the wind power plant; if the situation that part of actual parameters are unknown exists, the most conservative situation in a reasonable range is considered;

the modeling of the wind power plant detailed model comprises the following steps: the wind power generation set comprises a wind power generation set, a box type transformer, a current collection circuit, a boosting transformer and an access system circuit.

6. The planning simulation method according to any one of claims 1 to 5, wherein in the step (1), the steady-state analysis invokes a wind power supply static characteristic reasonable equivalence process to analyze the influence of wind power on the power flow of the power grid and the static safety, and the influence of wind power integration on the reactive voltage characteristic of the power grid, respectively.

7. The planning simulation method according to any one of claims 1 to 5, wherein in the step (2), the dynamic analysis calls an accurate simulation of the dynamic characteristics of the wind power supply, and analyzes the transient stability of the system after the wind power access, the voltage stability of the system after the wind power access, the frequency stability of the system after the wind power access, and the small interference stability of the system after the wind power access.

8. The planning simulation method according to any one of claims 1 to 5, wherein in the step (3), the mutual influence analysis calls a wind power supply dynamic characteristic accurate simulation to analyze the wind power sending capacity, the isolated network operation capacity and the mutual influence of the wind power supply and a near-region conventional power supply respectively.

9. The planning simulation method according to any one of claims 1 to 5, wherein in the step (4), the difference processing of the actual characteristics of the wind power supply is invoked to correct and verify the power grid planning scheme.

10. The planning simulation method of claim 6, wherein the influence of the wind power on the grid power flow and the static safety analysis comprise: the influence of wind power integration on the planning power flow of a power grid and the load rate of power transmission and transformation equipment is analyzed, and whether the thermal stability limit constraint of the power transmission and transformation equipment is met under the condition of no fault disconnection is analyzed.

11. The planning simulation method according to claim 6, wherein the analysis of the influence of the wind power integration on the reactive voltage characteristics of the power grid comprises: under the condition that a reactive power compensation device is not configured in the wind power plant, reactive power compensation scheme suggestions including inductive compensation under light load flow and capacitive compensation under heavy load flow are provided for voltage fluctuation of the access point and each substation in the nearby area caused by active power output change through calculation.

12. The planning simulation method of claim 7, wherein the post-wind farm access system transient stability analysis comprises: after the wind power plant is accessed, N-1 fault checking and serious fault checking are carried out on the access system near area, and a constant power factor operation mode, a constant voltage operation mode and the condition of the existence of low voltage ride through capability of a fan are respectively researched.

13. The planning simulation method according to claim 7, wherein the analysis of the system voltage stability after the wind farm is connected comprises calculating the dropping and recovery conditions of the bus voltage of each transformer substation after the wind farm is connected and the short-circuit fault occurs in the near area of the connected system; voltage stability of the system in case of severe failure; analyzing the influence of wind power plant access on the medium-term and long-term voltage stability of the system, and calculating the change condition of reactive power reserve of the system before and after the wind power plant access.

14. The planning simulation method according to claim 7, wherein the analyzing of the frequency stability of the system after the wind farm is accessed comprises: and calculating the frequency change condition of the isolated network system under the condition that the wind power plant access system is in isolated network operation in the near region and certain power is unbalanced, and frequency stabilizing measures.

15. The planning simulation method according to claim 7, wherein the analyzing of the stability of the system small interference after the wind farm is accessed comprises: and calculating the main low-frequency oscillation mode of the system, and comparing the damping ratio change conditions of the main oscillation modes before and after the wind power plant is accessed.