CN110569534B - New energy grid-connected scale determination method and system considering short-circuit current influence - Google Patents
New energy grid-connected scale determination method and system considering short-circuit current influence Download PDFInfo
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Abstract
The invention relates to a new energy grid-connected scale determining method and system considering short circuit current influence, comprising the following steps: establishing a basic unit-scale electromagnetic transient model of a new energy station to finely determine the influence value of the new energy station on the short-circuit current generated by the power grid; constructing a power grid simulation model by utilizing a new energy station of a basic unit scale; determining a short-circuit current safety margin corresponding to each transformer substation according to the interruption capacity of each transformer substation breaker; determining a second short-circuit current of each transformer substation of the power grid under the condition of full output of new energy stations of the current starting quantity of the power grid; and determining the grid-connected scale of the new energy according to the second short-circuit current. The invention provides a method for determining the grid-connected capacity of the new energy by taking the safety margin of the short-circuit current as the constraint condition for power system planning and operation technicians, avoids disordered development of the new energy, has strong operability and provides practical guiding suggestion for power system operation and planning personnel.
Description
Technical Field
The invention relates to the technical field of power systems, in particular to a new energy grid-connected scale determining method and system considering short-circuit current influence.
Background
With the economic development, the energy demand will continue to increase, and the traditional energy development mode established on fossil energy is difficult to succeed. Implementing "two alternatives" with clean energy alternatives and electrical energy alternatives as the main content is an important direction of sustainable development of energy in the world. The progressive exhaustion of traditional fossil energy has prompted various countries to begin to seek diverse energy supply sources, and large-scale clean energy access, represented by wind power and solar photovoltaic power, has become increasingly important. The utilization of new energy is highly emphasized in China. In 2006, the "renewable energy method" is formally implemented, which clearly indicates that the country encourages and supports renewable energy grid-connected power generation, and the grid enterprise is required to fully acquire the online electric quantity of the renewable energy grid-connected power generation project in the power grid coverage range. Various encouraging policies in the country have greatly facilitated the development of the renewable energy power generation industry.
In the early stage, because the wind power grid-connected scale is smaller and is mainly developed in a scattered form, it is widely believed that the short-circuit current provided by wind power to grid-connected points is far smaller than the short-circuit current of the grid-connected points, and the short-circuit current provided by a wind power plant to a system is negligible, so that the research work of wind power is mainly concentrated in the directions of stable voltage, frequency, small interference and the like after grid connection, and the short-circuit current problem of the system after grid connection of wind power is less concerned. In the aspect of researching the influence of photovoltaic power generation on the short-circuit current level of a power grid, the research at home and abroad is less, the research which is developed at present is mostly aimed at researching the influence of distributed photovoltaic access on the short-circuit current of the power distribution network and the protection configuration of the power distribution network, the photovoltaic grid-connected capacity is often smaller, and the influence of large-scale photovoltaic access on the short-circuit current level of the power grid is not achieved. According to the current planning scheme, areas such as Gansu spring, xinjiang, qinghai and the like in northwest and North China are built to form millions of kilowatt-level large new energy bases, and the capacity, the wind power or photovoltaic scale and the concentration of the new energy bases are further increased. With the increase of concentrated grid-connected wind power and photovoltaic scale, the influence of new energy on the short-circuit current of the system has become an important concern for the current power planning and operation departments.
At present, a method for relatively accurately evaluating the influence of new energy access on the short-circuit current level of a power grid is not available, and power grid related departments cannot determine the capacity of the new energy which is allowed to be connected in a grid mode according to the short-circuit current margin.
Disclosure of Invention
The invention provides a new energy grid-connected scale determining method and system considering short-circuit current influence, which are used for solving the problem of how to determine the new energy grid-connected scale.
In order to solve the above problems, according to an aspect of the present invention, there is provided a new energy grid-connected scale determining method considering an influence of a short-circuit current, the method including:
step 1, constructing a grid-connected system simulation model of a new energy station with a basic unit scale according to access information of the new energy station, and determining a short-circuit current influence value of the new energy station with the basic unit scale on a power grid;
step 2, determining an equivalent model of a new energy station of a basic unit scale capable of reflecting the influence of short-circuit current, planning installed capacity according to the new energy station, and constructing a power grid simulation model by using the equivalent model;
step 3, determining a first short-circuit current of each transformer substation of the power grid under the zero output condition of the new energy station, and determining a short-circuit current safety margin corresponding to each transformer substation according to the breaking capacity of a breaker of the transformer substation;
step 4, initializing the starting number of the new energy stations with the basic unit scale to be 1;
step 5, determining a second short-circuit current of each transformer substation of the power grid under the condition of full output of the new energy stations of the current starting quantity of the power grid;
step 6, judging whether the second short-circuit current of each transformer substation meets the safety margin of the short-circuit current corresponding to the transformer substation and does not exceed the interruption capacity corresponding to the transformer substation, if all the transformer substations meet, adding 1 to the number of basic unit scales, and returning to the step 5; otherwise, determining that the number of the new energy sources of the basic unit scale which allows the grid connection is the current number minus 1, and the grid connection scale of the new energy sources is the product of the number of the new energy sources of the basic unit scale which allows the grid connection and the basic unit scale.
Preferably, the access information of the new energy station includes: access scale information of new energy, site selection information of new energy stations, model selection information of new energy stations and in-site electrical design information of new energy stations.
Preferably, the building a grid-connected system simulation model including a new energy station with a basic unit scale according to the access information of the new energy station, and determining a short-circuit current influence value of the new energy station with the basic unit scale on the power grid, includes:
based on an electromagnetic transient simulation platform, constructing a grid-connected system simulation model of the new energy station with one basic unit scale according to access information of the new energy station and the set basic unit scale; wherein the simulation model comprises: the new energy power generation unit, each stage of step-up transformer, line or cable and the new energy integrated power grid simplified equivalent model;
and setting short-circuit faults at the side of the power system to determine the influence value of a new energy station with a basic unit scale on the short-circuit current generated by the power grid.
Preferably, the determining the first short-circuit current of each substation of the power grid under the zero output condition of the new energy station includes:
setting a new energy station to be in a zero starting state, and determining a short circuit current calculation condition according to the actual dispatching running state of the power grid;
and performing BPA short-circuit current simulation calculation, and determining a first short-circuit current of each transformer substation of the power grid under the zero-output condition of the new energy station.
Preferably, the determining the safety margin of the short-circuit current corresponding to each substation according to the interruption capacity of the circuit breaker of the substation includes:
M i ＝(I maxi -I i )/I maxi ，
wherein M is i The safety margin of the short circuit current corresponding to the ith transformer substation is set; i maxi The breaking capacity of the ith transformer substation breaker; i i Is the first short-circuit current of the ith substation.
Preferably, the determining the second short-circuit current of each transformer substation of the power grid under the condition of full output of the new energy field stations of the current startup quantity includes:
setting new energy stations with the current starting number to be in a full-starting state, and selecting the same short-circuit current calculation condition as that under the zero-output condition;
and performing BPA short-circuit current simulation calculation, and determining a second short-circuit current of each transformer substation of the power grid under the condition of full output of the new energy stations with the current starting number.
According to another aspect of the present invention, there is provided a new energy grid-connected scale determination system considering an influence of a short-circuit current, the system comprising:
the short-circuit current influence value determining unit is used for constructing a grid-connected system simulation model of the new energy station with a basic unit scale according to the access information of the new energy station, and determining the short-circuit current influence value of the new energy station with the basic unit scale on the power grid;
the power grid simulation model building unit is used for determining an equivalent model of a new energy station of a basic unit scale capable of reflecting the influence of short-circuit current, planning the installed capacity according to the new energy station, and building a power grid simulation model by using the equivalent model;
the short-circuit current safety margin determining unit is used for determining a first short-circuit current of each transformer substation of the power grid under the condition of zero output of the new energy station and determining a short-circuit current safety margin corresponding to each transformer substation according to the interruption capacity of each transformer substation breaker;
the starting-up quantity initialization setting unit is used for initializing and setting the starting-up quantity of the new energy stations of the basic unit scale to be 1;
the second short-circuit current determining unit is used for determining the second short-circuit current of each transformer substation of the power grid under the condition of full output of the new energy stations of the current starting quantity of the power grid;
the grid-connected scale determining unit is used for respectively judging whether the second short-circuit current of each transformer substation meets the short-circuit current safety margin corresponding to the transformer substation and does not exceed the interruption capacity corresponding to the transformer substation, and if all the transformer substations meet, adding 1 to the number of the basic unit scales and entering the second short-circuit current determining unit; otherwise, determining that the number of the new energy sources of the basic unit scale which allows the grid connection is the current number minus 1, and the grid connection scale of the new energy sources is the product of the number of the new energy sources of the basic unit scale which allows the grid connection and the basic unit scale.
Preferably, the access information of the new energy station includes: access scale information of new energy, site selection information of new energy stations, model selection information of new energy stations and in-site electrical design information of new energy stations.
Preferably, the determining unit of the short-circuit current influence value builds a grid-connected system simulation model including a new energy station with a basic unit scale according to access information of the new energy station, and determines the short-circuit current influence value of the new energy station with the basic unit scale on the power grid, including:
based on an electromagnetic transient simulation platform, constructing a grid-connected system simulation model of the new energy station with one basic unit scale according to access information of the new energy station and the set basic unit scale; wherein the simulation model comprises: the new energy power generation unit, each stage of step-up transformer, line or cable and the new energy integrated power grid simplified equivalent model;
and setting short-circuit faults at the side of the power system to determine the influence value of a new energy station with a basic unit scale on the short-circuit current generated by the power grid.
Preferably, the short-circuit current safety margin determining unit determines a first short-circuit current of each substation of the power grid under the zero output condition of the new energy station, including:
setting a new energy station to be in a zero starting state, and determining a short circuit current calculation condition according to the actual dispatching running state of the power grid;
and performing BPA short-circuit current simulation calculation, and determining a first short-circuit current of each transformer substation of the power grid under the zero-output condition of the new energy station.
Preferably, the short-circuit current safety margin determining unit determines, according to the interruption capacity of each substation breaker, a short-circuit current safety margin corresponding to the substation, including:
M i ＝(I maxi -I i )/I maxi ，
wherein M is i Is the ithShort-circuit current safety margin corresponding to the transformer substation; i maxi The breaking capacity of the ith transformer substation breaker; i i Is the first short-circuit current of the ith substation.
Preferably, the second short-circuit current determining unit determines a second short-circuit current of each transformer substation of the power grid under the condition of full output of the new energy field stations with the current startup quantity, and includes:
setting new energy stations with the current starting number to be in a full-starting state, and selecting the same short-circuit current calculation condition as that under the zero-output condition;
and performing BPA short-circuit current simulation calculation, and determining a second short-circuit current of each transformer substation of the power grid under the condition of full output of the new energy stations with the current starting number.
The invention provides a new energy grid-connected scale determining method and system considering short-circuit current influence, comprising the following steps: establishing a basic unit-scale electromagnetic transient model of a new energy station to finely determine the influence value of the new energy station on the short-circuit current generated by the power grid; constructing a power grid simulation model by utilizing a new energy station of a basic unit scale; determining a short-circuit current safety margin corresponding to each transformer substation according to the interruption capacity of each transformer substation breaker; determining a second short-circuit current of each transformer substation of the power grid under the condition of full output of new energy stations of the current starting quantity of the power grid; and determining the grid-connected scale of the new energy according to the second short-circuit current. According to the method, the influence of new energy grid connection on the short circuit level of the power grid is comprehensively evaluated, the short circuit current safety margin of key sites of the power grid is further determined, the new energy grid connection scale is determined according to the short circuit current safety stability margin index allowed by the power grid regulation, a method for determining the new energy grid connection capacity by taking the short circuit current safety margin as a constraint condition is provided for power system planning and operation technicians, the unordered development of new energy is avoided, the waste of natural resources, social resources and human resources is avoided, the clean energy substitution and sustainable development are better promoted, the strong operability is achieved, and practical guiding suggestions are provided for power system operation and planning personnel.
Drawings
Exemplary embodiments of the present invention may be more completely understood in consideration of the following drawings:
FIG. 1 is a flow chart of a new energy grid-tie scale determination method 100 that accounts for short-circuit current effects according to an embodiment of the present invention;
FIG. 2 is a diagram of a typical star configuration within a train energy station according to an embodiment of the present invention; and
fig. 3 is a schematic structural diagram of a new energy grid-connected scale determining system 300 considering the influence of short-circuit current according to an embodiment of the present invention.
Detailed Description
The exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, however, the present invention may be embodied in many different forms and is not limited to the examples described herein, which are provided to fully and completely disclose the present invention and fully convey the scope of the invention to those skilled in the art. The terminology used in the exemplary embodiments illustrated in the accompanying drawings is not intended to be limiting of the invention. In the drawings, like elements/components are referred to by like reference numerals.
Unless otherwise indicated, terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art. In addition, it will be understood that terms defined in commonly used dictionaries should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense.
Fig. 1 is a flowchart of a new energy grid-tie scale determination method 100 that considers the effects of short-circuit current according to an embodiment of the present invention. As shown in fig. 1, the new energy grid-connected scale determining method considering the influence of the short-circuit current provided by the embodiment of the invention determines the new energy grid-connected scale according to the short-circuit current safety stability margin index allowed by the regulation of the power grid by comprehensively evaluating the influence of the new energy grid-connected on the short-circuit level of the power grid and further determining the short-circuit current safety stability margin index of the key site of the power grid, provides a method for determining the new energy grid-connected capacity by taking the short-circuit current safety margin as a constraint condition for power system planning and operation technicians, avoids unordered development of the new energy, wastes natural resources, social resources and manpower resources, promotes clean energy substitution and sustainable development better, has strong operability, and provides practical guiding suggestions for power system operation and planning personnel. The method 100 for determining the grid-connected scale of the new energy source, which is provided by the embodiment of the invention and considers the influence of the short-circuit current, starts from the step 101, builds a grid-connected system simulation model of the new energy source station with a basic unit scale according to the access information of the new energy source station in the step 101, and determines the influence value of the short-circuit current generated by the new energy source station with the basic unit scale on the power grid.
Preferably, the access information of the new energy station includes: access scale information of new energy, site selection information of new energy stations, model selection information of new energy stations and in-site electrical design information of new energy stations.
Preferably, the building a grid-connected system simulation model including a new energy station with a basic unit scale according to the access information of the new energy station, and determining a short-circuit current influence value of the new energy station with the basic unit scale on the power grid, includes:
based on an electromagnetic transient simulation platform, constructing a grid-connected system simulation model of the new energy station with one basic unit scale according to access information of the new energy station and the set basic unit scale; wherein the simulation model comprises: the new energy power generation unit, each stage of step-up transformer, line or cable and the new energy integrated power grid simplified equivalent model;
and setting short-circuit faults at the side of the power system to determine the influence value of a new energy station with a basic unit scale on the short-circuit current generated by the power grid.
In an embodiment of the invention, the influence of the new energy station on the short-circuit current is finely determined by establishing an electromagnetic transient model of the new energy station comprising a basic unit scale. Firstly, carrying out investigation to determine new energy access information of a planned power grid, including: access scale, new energy station site selection, unit selection, electrical design and other data. Specifically, the method comprises the following steps: investigation and planning of resource evaluation conditions of new energy stations connected in grid; the method for researching and planning the meteorological conditions of the grid-connected new energy station comprises the following steps: weather station position, altitude, annual average air temperature, extreme highest air temperature, extreme lowest air temperature, average air pressure, annual average wind speed, maximum wind speed, minimum wind speed, new energy station ground roughness, terrain, annual average relative humidity, annual average precipitation, illumination intensity, illumination time and the like; planning machine type selection of a new energy station of grid connection, comprising: single machine capacity, model, operating characteristics, etc.; the electrical design in the field of planning new energy station of the grid-connected, mainly consider the current collecting line connection mode in the field, include: chain type structure, single side annular structure, double side annular structure, composite annular structure, star type structure, etc.
And then, building a basic unit-scale electromagnetic transient simulation model of the new energy station according to the electric wiring form of the new energy station, and researching the influence of the electromagnetic transient simulation model on the full-voltage-class short-circuit current of the power grid. Specifically, the method comprises the following steps: based on an electromagnetic transient simulation platform, building a grid-connected system simulation model of the new energy station with one basic unit scale according to access information of the new energy station and the set basic unit scale, wherein the model comprises a new energy power generation unit, various levels of step-up transformers, circuits or cables and a power grid simplified equivalent model of new energy integration; and setting a short-circuit fault on the side of the power system, researching short-circuit current provided by the new energy station to the power grid after the power grid has the short-circuit fault, and determining the influence value of the short-circuit current.
Wherein, the basic unit scale P of the new energy station 0 Setting according to actual needs. For example, it may be set to 10MW, 50MW, 100MW, or the like.
In step 102, an equivalent model of a new energy station of a basic unit scale capable of reflecting the influence of short-circuit current is determined, and a power grid simulation model is built by using the equivalent model according to the planned installed capacity of the new energy station.
For example, if the planning installed capacity of the new energy station is 300MW and the basic unit size of the new energy station is 100MW, the new energy station with 3 basic unit sizes can be selected by adopting the multiplication set model for equivalence, that is, the power grid simulation model is built by using 3 equivalence models.
In step 103, a first short-circuit current of each transformer substation of the power grid under the zero output condition of the new energy station is determined, and a short-circuit current safety margin corresponding to each transformer substation is determined according to the breaking capacity of each transformer substation breaker.
Preferably, the determining the first short-circuit current of each substation of the power grid under the zero output condition of the new energy station includes:
setting a new energy station to be in a zero starting state, and determining a short circuit current calculation condition according to the actual dispatching running state of the power grid;
and performing BPA short-circuit current simulation calculation, and determining a first short-circuit current of each transformer substation of the power grid under the zero-output condition of the new energy station.
Preferably, the determining the safety margin of the short-circuit current corresponding to each substation according to the interruption capacity of the circuit breaker of the substation includes:
M i ＝(I maxi -I i )/I maxi ，
wherein M is i The safety margin of the short circuit current corresponding to the ith transformer substation is set; i maxi The breaking capacity of the ith transformer substation breaker; i i Is the first short-circuit current of the ith substation.
In the embodiment of the invention, firstly, the interruption capacity of a bus breaker of each transformer substation of the power grid is obtained according to investigation data, and BPA power flow and stable calculation data of the power grid are built according to the investigation data. The investigation data includes: grid structure, generator parameters, load parameters, line parameters, transformer parameters, etc.
Then, setting the new energy stations to be in a zero starting state, and determining a short circuit current calculation condition according to actual scheduling operation experience of the power grid; and running a short-circuit current calculation program of the BPA to calculate the first short-circuit current of each transformer substation of the power grid under the zero output condition of the new energy station.
Then, determining a short-circuit current safety margin corresponding to each transformer substation by using the following formula, wherein the short-circuit current safety margin comprises:
M i ＝(I maxi -I i )/I maxi ，
wherein M is i The safety margin of the short circuit current corresponding to the ith transformer substation is set; i maxi The breaking capacity of the ith transformer substation breaker; i i Is the first short-circuit current of the ith substation.
In step 104, the number of start-up stations of the new energy station for which the basic unit scale is set is initialized to 1.
In step 105, a second short-circuit current of each substation of the power grid is determined under the condition that the power grid is fully powered on in the new energy stations of the current startup quantity.
Preferably, the determining the second short-circuit current of each transformer substation of the power grid under the condition of full output of the new energy field stations of the current startup quantity includes:
setting new energy stations with the current starting number to be in a full-starting state, and selecting the same short-circuit current calculation condition as that under the zero-output condition;
and performing BPA short-circuit current simulation calculation, and determining a second short-circuit current of each transformer substation of the power grid under the condition of full output of the new energy stations with the current starting number.
In the embodiment of the invention, the method for determining the second short-circuit current is the same as the method for determining the first short-circuit current, and the only difference is that when the second short-circuit current is determined, the new energy stations with the current startup quantity are in the startup state in the power grid.
In step 106, whether the second short-circuit current of each transformer substation meets the safety margin of the short-circuit current corresponding to the transformer substation and does not exceed the interruption capacity corresponding to the transformer substation is judged, if all the transformer substations meet, the number of the basic unit scales is increased by 1, and step 105 is returned; otherwise, determining that the number of the new energy sources of the basic unit scale which allows the grid connection is the current number minus 1, and the grid connection scale of the new energy sources is the product of the number of the new energy sources of the basic unit scale which allows the grid connection and the basic unit scale.
In the embodiment of the invention, for each transformer substation, whether the second short-circuit current after the new energy station with 1 basic unit scale is connected with the network meets the safety margin of the short-circuit current corresponding to the transformer substation and does not exceed the interruption capacity corresponding to the transformer substation is judged, if all the transformer substations meet, the number of the basic unit scales is increased by 1, the current startup number becomes 2, and the step 105 is returned to recalculate the second short-circuit current. Otherwise, determining that the number of the new energy sources of the basic unit scale which allows the grid connection is the current number minus 1, and the grid connection scale of the new energy sources is the product of the number of the new energy sources of the basic unit scale which allows the grid connection and the basic unit scale.
If the starting number is N-1, all substations meet the requirement, and if the starting number is N, the new energy source number of the basic unit scale allowed to be connected is N-1, and the new energy source grid-connected scale is (N-1) P 0 Wherein P is 0 Is the basic unit scale of new energy.
If N=1, all substations do not meet the requirements, the network is directly withdrawn, and the network frame optimization is carried out on the power grid, and then new energy grid connection is considered.
The following specifically exemplifies embodiments of the present invention
In the embodiment of the invention, a certain new energy station is planned to have a installed capacity of 300MW and is connected into a certain regional power grid at 110kV voltage level. The star scheme employed within the station is shown in fig. 2. The open current of a 110kV bus breaker of the regional power grid is known to be 31.5kA, and the safety margin index of the short circuit current is set to be 10%. Of course, the short-circuit current safety margin can also be calculated according to the calculation method of the invention, so that it is set.
Firstly, establishing a basic unit scale new energy station electromagnetic transient model, wherein the basic unit scale P 0 Set to 100MW. And simulation analysis shows that after the new energy station of the basic unit scale is connected to a 110kV power grid, the influence value of short-circuit current to the connected substation is 0.61kA.
And then, carrying out equivalence on the 300MW new energy station by adopting a multiplication aggregation model, and constructing power grid simulation analysis data by adopting the new energy station model with the equivalence.
Through calculation, under the condition of zero output of new energy, the short-circuit current (namely first short-circuit current) of the 110kV bus is 26.46kA. Therefore, considering that the safety margin of the short-circuit current is 10% according to the switching interruption capacity of 31.5kA, the allowable increment of the short-circuit current of the grid-connected point is 1.89kA after the new energy is grid-connected.
And sequentially iterating according to the starting-up quantity of the new energy sources, wherein the short-circuit current change after the new energy sources with different starting-up quantities are connected in a grid is shown in a table 1. When the starting-up number of the new energy sources in the basic unit scale is increased to 3, the total short-circuit current increase amount reaches 1.80kA, and the short-circuit current safety margin of the parallel network point is close. When the starting-up number of the new energy sources in the basic unit scale is increased to 4, the short-circuit current of the grid-connected point exceeds the interruption capacity of the switch, and after the actual grid-connected operation, the risk is brought to the safe and stable operation of the power grid.
TABLE 1 short-circuit current variation after grid-connected of different unit sizes
Therefore, the grid-connected scale of the new energy source can be determined, namely the grid-connected point allows the installed scale of the new energy source to be accessed to be 3*P 0 ＝3*100MW＝300MW。
Fig. 3 is a schematic structural diagram of a new energy grid-connected scale determining system 300 considering the influence of short-circuit current according to an embodiment of the present invention. As shown in fig. 3, the new energy grid-connected scale determining system 300 provided by the embodiment of the invention, which considers the influence of short-circuit current, includes: a short-circuit current influence value determining unit 301, a power grid simulation model building unit 302, a short-circuit current safety margin determining unit 303, a startup number initialization setting unit 304, a second short-circuit current determining unit 305 and a grid-connected scale determining unit 306.
Preferably, the short-circuit current impact value determining unit 301 is configured to build a grid-connected system simulation model including a new energy station with a basic unit scale according to access information of the new energy station, and determine a short-circuit current impact value of the new energy station with the basic unit scale on the power grid.
Preferably, the access information of the new energy station includes: access scale information of new energy, site selection information of new energy stations, model selection information of new energy stations and in-site electrical design information of new energy stations.
Preferably, the determining unit 301 of the short-circuit current impact value builds a simulation model of a grid-connected system including a new energy station with a basic unit scale according to access information of the new energy station, and determines the short-circuit current impact value of the new energy station with the basic unit scale on the power grid, including: based on an electromagnetic transient simulation platform, constructing a grid-connected system simulation model of the new energy station with one basic unit scale according to access information of the new energy station and the set basic unit scale; wherein the simulation model comprises: the new energy power generation unit, each stage of step-up transformer, line or cable and the new energy integrated power grid simplified equivalent model; and setting short-circuit faults at the side of the power system to determine the influence value of a new energy station with a basic unit scale on the short-circuit current generated by the power grid.
Preferably, the power grid simulation model building unit 302 is configured to determine an equivalent model of a new energy station capable of reflecting a basic unit scale of an influence of a short-circuit current, and build a power grid simulation model by using the equivalent model according to a planned installed capacity of the new energy station.
Preferably, the short-circuit current safety margin determining unit 303 is configured to determine a first short-circuit current of each substation of the power grid under the condition of zero output of the new energy station, and determine a short-circuit current safety margin corresponding to the substation according to the breaking capacity of each substation breaker.
Preferably, the short-circuit current safety margin determining unit 303 determines a first short-circuit current of each substation of the power grid under the zero output condition of the new energy station, including:
setting a new energy station to be in a zero starting state, and determining a short circuit current calculation condition according to the actual dispatching running state of the power grid;
and performing BPA short-circuit current simulation calculation, and determining a first short-circuit current of each transformer substation of the power grid under the zero-output condition of the new energy station.
Preferably, the short-circuit current safety margin determining unit 303 determines the short-circuit current safety margin corresponding to each substation according to the interruption capacity of the circuit breaker of the substation, including:
M i ＝(I maxi -I i )/I maxi ，
wherein M is i The safety margin of the short circuit current corresponding to the ith transformer substation is set; i maxi The breaking capacity of the ith transformer substation breaker; i i Is the first short-circuit current of the ith substation.
Preferably, the start-up number initialization setting unit 304 is configured to initialize the start-up number of the new energy stations with the basic unit size to 1.
Preferably, the second short-circuit current determining unit 305 is configured to determine a second short-circuit current of each substation of the power grid under the condition that the power grid is fully powered on by the new energy stations of the current startup number.
Preferably, the grid-connected scale determining unit 306 is configured to determine whether the second short-circuit current of each substation meets the short-circuit current safety margin corresponding to the substation and does not exceed the interruption capacity corresponding to the substation, and if all the substations meet the requirement, add 1 to the number of basic unit scales, and enter the second short-circuit current determining unit 305; otherwise, determining that the number of the new energy sources of the basic unit scale which allows the grid connection is the current number minus 1, and the grid connection scale of the new energy sources is the product of the number of the new energy sources of the basic unit scale which allows the grid connection and the basic unit scale.
Preferably, the second short-circuit current determining unit 305 determines a second short-circuit current of each substation of the power grid under the condition of full output of the new energy stations of the current startup number, including:
setting new energy stations with the current starting number to be in a full-starting state, and selecting the same short-circuit current calculation condition as that under the zero-output condition;
and performing BPA short-circuit current simulation calculation, and determining a second short-circuit current of each transformer substation of the power grid under the condition of full output of the new energy stations with the current starting number.
The new energy grid-connected scale determining system 300 with consideration of short-circuit current influence according to the embodiment of the present invention corresponds to the new energy grid-connected scale determining system 300 with consideration of short-circuit current influence according to another embodiment of the present invention, and is not described herein.
The invention has been described with reference to a few embodiments. However, as is well known to those skilled in the art, other embodiments than the above disclosed invention are equally possible within the scope of the invention, as defined by the appended patent claims.
Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise therein. All references to "a/an/the [ means, component, etc. ]" are to be interpreted openly as referring to at least one instance of said means, component, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.
Claims (6)
1. The new energy grid-connected scale determining method considering the influence of short-circuit current is characterized by comprising the following steps of:
step 1, constructing a grid-connected system simulation model of a new energy station with a basic unit scale according to access information of the new energy station, and determining a short-circuit current influence value of the new energy station with the basic unit scale on a power grid;
step 2, determining an equivalent model of a new energy station of a basic unit scale capable of reflecting the influence of short-circuit current, planning installed capacity according to the new energy station, and constructing a power grid simulation model by using the equivalent model;
step 3, determining a first short-circuit current of each transformer substation of the power grid under the zero output condition of the new energy station, and determining a short-circuit current safety margin corresponding to each transformer substation according to the breaking capacity of a breaker of the transformer substation;
step 4, initializing the starting number of the new energy stations with the basic unit scale to be 1;
step 5, determining a second short-circuit current of each transformer substation of the power grid under the condition of full output of the new energy stations of the current starting quantity of the power grid;
step 6, judging whether the second short-circuit current of each transformer substation meets the safety margin of the short-circuit current corresponding to the transformer substation and does not exceed the interruption capacity corresponding to the transformer substation, if all the transformer substations meet, adding 1 to the number of basic unit scales, and returning to the step 5; otherwise, determining that the number of the new energy sources of the basic unit scale which allows the grid connection is the current number minus 1, wherein the grid connection scale of the new energy sources is the product of the number of the new energy sources of the basic unit scale which allows the grid connection and the basic unit scale;
wherein the determining the first short-circuit current of each transformer substation of the power grid under the condition of zero output of the new energy station comprises:
setting a new energy station to be in a zero starting state, and determining a short circuit current calculation condition according to the actual dispatching running state of the power grid;
performing BPA short-circuit current simulation calculation, and determining a first short-circuit current of each transformer substation of the power grid under the condition of zero output of the new energy station;
the determining the safety margin of the short-circuit current corresponding to each transformer substation according to the breaking capacity of the breaker of the transformer substation comprises the following steps:
M i ＝(I maxi -I i )/I maxi ，
wherein M is i The safety margin of the short circuit current corresponding to the ith transformer substation is set; i maxi The breaking capacity of the ith transformer substation breaker; i i A first short-circuit current for the ith substation;
the determining the second short-circuit current of each transformer substation of the power grid under the condition of full output of the new energy stations of the current startup quantity comprises the following steps:
setting new energy stations with the current starting number to be in a full-starting state, and selecting the same short-circuit current calculation condition as that under the zero-output condition;
and performing BPA short-circuit current simulation calculation, and determining a second short-circuit current of each transformer substation of the power grid under the condition of full output of the new energy stations with the current starting number.
2. The method of claim 1, wherein the access information of the new energy station comprises: access scale information of new energy, site selection information of new energy stations, model selection information of new energy stations and in-site electrical design information of new energy stations.
3. The method according to claim 1, wherein constructing a grid-connected system simulation model including a new energy station of a basic unit scale according to the access information of the new energy station, and determining a short-circuit current influence value of the new energy station of the basic unit scale on the power grid, comprises:
based on an electromagnetic transient simulation platform, constructing a grid-connected system simulation model of the new energy station with one basic unit scale according to access information of the new energy station and the set basic unit scale; wherein the simulation model comprises: the new energy power generation unit, each stage of step-up transformer, line or cable and the new energy integrated power grid simplified equivalent model;
and setting short-circuit faults at the side of the power system to determine the influence value of a new energy station with a basic unit scale on the short-circuit current generated by the power grid.
4. A new energy grid-tie scale determination system considering short-circuit current influence, the system comprising:
the short-circuit current influence value determining unit is used for constructing a grid-connected system simulation model of the new energy station with a basic unit scale according to the access information of the new energy station, and determining the short-circuit current influence value of the new energy station with the basic unit scale on the power grid;
the power grid simulation model building unit is used for determining an equivalent model of a new energy station of a basic unit scale capable of reflecting the influence of short-circuit current, planning the installed capacity according to the new energy station, and building a power grid simulation model by using the equivalent model;
the short-circuit current safety margin determining unit is used for determining a first short-circuit current of each transformer substation of the power grid under the condition of zero output of the new energy station and determining a short-circuit current safety margin corresponding to each transformer substation according to the interruption capacity of each transformer substation breaker;
the starting-up quantity initialization setting unit is used for initializing and setting the starting-up quantity of the new energy stations of the basic unit scale to be 1;
the second short-circuit current determining unit is used for determining the second short-circuit current of each transformer substation of the power grid under the condition of full output of the new energy stations of the current starting quantity of the power grid;
the grid-connected scale determining unit is used for respectively judging whether the second short-circuit current of each transformer substation meets the short-circuit current safety margin corresponding to the transformer substation and does not exceed the interruption capacity corresponding to the transformer substation, and if all the transformer substations meet, adding 1 to the number of the basic unit scales and entering the second short-circuit current determining unit; otherwise, determining that the number of the new energy sources of the basic unit scale which allows the grid connection is the current number minus 1, wherein the grid connection scale of the new energy sources is the product of the number of the new energy sources of the basic unit scale which allows the grid connection and the basic unit scale;
the short-circuit current safety margin determining unit determines a first short-circuit current of each transformer substation of the power grid under the condition of zero output of the new energy station, and comprises the following steps:
setting a new energy station to be in a zero starting state, and determining a short circuit current calculation condition according to the actual dispatching running state of the power grid;
performing BPA short-circuit current simulation calculation, and determining a first short-circuit current of each transformer substation of the power grid under the condition of zero output of the new energy station;
the short-circuit current safety margin determining unit determines a short-circuit current safety margin corresponding to each transformer substation according to the interruption capacity of each transformer substation breaker, and includes:
M i ＝(I maxi -I i )/I maxi ，
wherein M is i The safety margin of the short circuit current corresponding to the ith transformer substation is set; i maxi The breaking capacity of the ith transformer substation breaker; i i A first short-circuit current for the ith substation;
the second short-circuit current determining unit determines a second short-circuit current of each transformer substation of the power grid under the condition that the power grid is fully powered on by the new energy stations in the current starting quantity, and the second short-circuit current determining unit comprises:
setting new energy stations with the current starting number to be in a full-starting state, and selecting the same short-circuit current calculation condition as that under the zero-output condition;
and performing BPA short-circuit current simulation calculation, and determining a second short-circuit current of each transformer substation of the power grid under the condition of full output of the new energy stations with the current starting number.
5. The system of claim 4, wherein the access information of the new energy station comprises: access scale information of new energy, site selection information of new energy stations, model selection information of new energy stations and in-site electrical design information of new energy stations.
6. The system according to claim 4, wherein the short-circuit current influence value determining unit builds a grid-connected system simulation model including a new energy station of a basic unit scale according to access information of the new energy station, and determines a short-circuit current influence value of the new energy station of the basic unit scale on the power grid, and includes:
based on an electromagnetic transient simulation platform, constructing a grid-connected system simulation model of the new energy station with one basic unit scale according to access information of the new energy station and the set basic unit scale; wherein the simulation model comprises: the new energy power generation unit, each stage of step-up transformer, line or cable and the new energy integrated power grid simplified equivalent model;
and setting short-circuit faults at the side of the power system to determine the influence value of a new energy station with a basic unit scale on the short-circuit current generated by the power grid.
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| CN109659934A (en) * | 2018-12-24 | 2019-04-19 | 中国电力科学研究院有限公司 | New-energy grid-connected based on short circuit current nargin plans preferred method |
| CN109787285A (en) * | 2019-02-14 | 2019-05-21 | 国网甘肃省电力公司嘉峪关供电公司 | Method and system for decision new energy group of planes connect-in strategy |
| CN109888820A (en) * | 2019-02-14 | 2019-06-14 | 国网甘肃省电力公司嘉峪关供电公司 | Method for calculating the short circuit current contribution value of new energy unit |
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| CN109659934A (en) * | 2018-12-24 | 2019-04-19 | 中国电力科学研究院有限公司 | New-energy grid-connected based on short circuit current nargin plans preferred method |
| CN109787285A (en) * | 2019-02-14 | 2019-05-21 | 国网甘肃省电力公司嘉峪关供电公司 | Method and system for decision new energy group of planes connect-in strategy |
| CN109888820A (en) * | 2019-02-14 | 2019-06-14 | 国网甘肃省电力公司嘉峪关供电公司 | Method for calculating the short circuit current contribution value of new energy unit |
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