CN115954956A - Method and system for evaluating access capacity of distributed power supply of power distribution network - Google Patents
Method and system for evaluating access capacity of distributed power supply of power distribution network Download PDFInfo
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Abstract
The invention relates to a method and a system for evaluating the access capacity of a distributed power supply of a power distribution network, wherein the method comprises the following steps: layering according to a topological graph of the power distribution network from high to low according to voltage grades, checking the current state values of short-circuit current and voltage deviation of each bus, harmonic waves of each node and voltage unbalance monitoring data under the current voltage grade in a range to be evaluated, and judging whether the current voltage grade has a condition of accessing a distributed power supply according to a checking result; when the current voltage class has the condition of accessing the distributed power supply, calculating the reverse load rate of a transformer or a line in the power distribution network to be evaluated, and judging whether the transformer or the line has the condition of accessing the distributed power supply or not according to the reverse load rate; when the transformer or the line has the condition of accessing the distributed power supply, calculating the capacity of the transformer or the line capable of newly increasing the distributed power supply; and repeating the steps to evaluate the next voltage level until all the voltage levels are evaluated.
Description
Technical Field
The invention relates to the technical field of distribution networks, in particular to a method and a system for evaluating the access capacity of a distributed power supply of a power distribution network.
Background
The rapid development of distributed power supplies is a common choice for dealing with energy crisis and environmental problems in all countries in the world, and the market demand and the industry potential are huge. A large number of distributed power supplies with intermittent and random characteristics are connected into the power distribution network, complexity and management and control difficulty of the power distribution network are greatly increased, and great influence is generated on safe, reliable and economic operation of the power distribution network, so that the distributed power supplies are a common challenge facing all countries in the world. In order to promote the healthy and orderly development of the distributed power supply and the safe and stable operation of the power distribution network, the evaluation of the maximum access capacity of the power distribution network to the distributed power supply needs to be carried out urgently.
Disclosure of Invention
The invention aims to provide a method and a system for evaluating the access capacity of a distributed power supply of a power distribution network, which can accurately evaluate the maximum access capacity of the distributed power supply of the power distribution network.
The technical scheme adopted by the invention for solving the technical problems is as follows: the method for evaluating the access capacity of the distributed power supply of the power distribution network comprises the following steps:
determining the range of the power distribution network of the area to be evaluated, and determining a topological graph of the power distribution network of the area to be evaluated;
layering according to the topological graph from high to low according to the voltage grade, checking the current state values of short-circuit current and voltage deviation of each bus, harmonic waves of each node and voltage unbalance monitoring data under the current voltage grade in a range to be evaluated, and judging whether the current voltage grade has the condition of accessing a distributed power supply according to the checking result;
when the current voltage class has the condition of accessing the distributed power supply, calculating the reverse load rate of a transformer or a line in the power distribution network to be evaluated, and judging whether the transformer or the line has the condition of accessing the distributed power supply according to the reverse load rate;
when the transformer or the line has the condition of accessing the distributed power supply, calculating the capacity of the newly added distributed power supply of the transformer or the line;
and repeating the steps to evaluate the next voltage level until all the voltage levels are evaluated.
The method for checking the current state values of short-circuit current and voltage deviation of each bus, harmonic waves of each node and voltage unbalance monitoring data in the current voltage class within the range to be evaluated specifically comprises the following steps:
calculating the current state values of short-circuit current and voltage deviation of each bus under the current voltage level in the range to be evaluated, and collecting harmonic wave and voltage unbalance monitoring data of each node;
judging whether the bus short-circuit current is smaller than the minimum value of the cut-off current limit values of corresponding circuit breakers on all equipment connected with the bus and a feed-out line, and if so, checking the bus short-circuit current to pass;
judging whether the maximum positive voltage deviation is smaller than the maximum positive voltage deviation allowable value or not and whether the maximum negative voltage deviation is larger than the maximum negative voltage deviation allowable value or not, and if so, checking the current voltage deviation value;
judging whether the h-th harmonic current value is smaller than the h-th harmonic current limit value or not and whether the content rate of each inter-harmonic voltage of the node does not exceed a specified limit value or not, and if so, checking the harmonic of each node;
judging whether the negative sequence voltage unbalance degree is smaller than an allowable value of the negative sequence voltage unbalance degree or not, and if so, checking the voltage unbalance monitoring data;
and only when the current state values of the bus short-circuit current and the voltage deviation, and the harmonic waves and the voltage unbalance monitoring data of each node pass the checking, the current voltage grade has the condition of accessing the distributed power supply.
The method comprises the steps of calculating the reverse load rate of a transformer or a line in the power distribution network to be evaluated, and judging whether the transformer or the line has a condition of accessing a distributed power supply according to the reverse load rate, and specifically comprises the following steps:
by passing
Calculating the reverse load rate of the transformer or the line in the power distribution network to be evaluated, wherein lambda (t) is the reverse load rate of the transformer or the line at the time t, P D (t) distributed Power output at time t, P L (t) is the load at time t, S e (t) is the actual operation limit value of the transformer or the line at the moment t;
and judging whether the reverse load rate of the transformer or the line exceeds the allowable value of the directional load rate of the distribution network equipment, if not, indicating that the transformer or the line has the condition of accessing the distributed power supply.
When the capacity of the distributed power supply can be newly increased by the transformer or the line is calculated, the P is passed m ＝(k r -λ max )×S e Calculating the capacity of the transformer or line to add new distributed power supply, wherein P m Capacity, k, of the distributed power supply can be increased for transformers or lines r Is the allowable value of the directional load rate, lambda, of the distribution network equipment max To evaluate the maximum reverse load rate in the period, S e Indicating that the transformer or line has a maximum value of λ in the reverse load factor max An operational limit for the time of day.
After the calculating the capacity of the transformer or the line capable of newly increasing the distributed power supply, the method further comprises the following steps:
calculating the updated reverse load rate according to the capacity of the newly-added distributed power supply, and determining a rechecking project according to the updated reverse load rate;
and checking the rechecking project, if the rechecking project does not pass, reducing the capacity of the newly added distributed power supply, returning to the previous step until the rechecking passes, and if the rechecking passes, taking the capacity of the newly added distributed power supply as an evaluation result of the current voltage level.
The method comprises the following steps of calculating an updated reverse load rate according to the capacity of the newly-added distributed power supply, and determining a rechecking project according to the updated reverse load rate, wherein the method specifically comprises the following steps:
by passing
Calculating an updated reverse load rate, wherein new For updated reverse load rate, P m The capacity, lambda, of the distributed power supply can be increased for transformers or lines max To evaluate the maximum reverse load rate in the period, S e Indicating that the transformer or line has a maximum value of λ in the reverse load factor max An operational limit of time;
when the reverse load rate λ is updated new ∈(-100％，α]When the data is needed, the data is not checked again; when the updated reverse load rate lambda new ∈(α，0]In the process, the current state values of bus short-circuit current and voltage deviation, harmonic waves of each node and voltage unbalance monitoring data need to be checked again; when the reverse load rate λ is updated new ∈(0，k r ]In the process, the current state values of bus short-circuit current and voltage deviation, harmonic waves of each node, voltage unbalance monitoring data and power distribution network protection configuration need to be checked again.
After the step of taking the capacity of the newly added distributed power source as a final result, the method further comprises the following steps:
and checking the evaluation result of the current voltage level and the evaluation result of the previous voltage level, wherein the checking principle is that the capacity of the newly-added distributed power supply of the low voltage level is not greater than the capacity of the newly-added distributed power supply of the previous voltage level which is directly electrically connected with the newly-added distributed power supply of the low voltage level.
The technical scheme adopted by the invention for solving the technical problem is as follows: the utility model provides a distribution network distributed power source inserts capacity evaluation system, includes:
the determining module is used for determining the range of the power distribution network in the area to be evaluated and determining a topological graph of the power distribution network in the area to be evaluated;
the checking module is used for layering according to the topological graph from high to low according to the voltage grade, checking the current values of short-circuit current and voltage deviation of each bus, harmonic waves of each node and voltage unbalance monitoring data under the current voltage grade in a range to be evaluated, and judging whether the current voltage grade has the condition of accessing the distributed power supply or not according to the checking result;
the judging module is used for calculating the reverse load rate of a transformer or a line in the power distribution network to be evaluated when the current voltage level has the condition of accessing the distributed power supply, and judging whether the transformer or the line has the condition of accessing the distributed power supply or not according to the reverse load rate;
the calculation module is used for calculating the capacity of the newly added distributed power supply of the transformer or the line under the condition that the transformer or the line has access to the distributed power supply;
and the evaluation module is used for repeating the operation of the modules to evaluate the next voltage level until the evaluation of all the voltage levels is finished.
The technical scheme adopted by the invention for solving the technical problem is as follows: an electronic device is provided, which includes a memory, a processor, and a computer program stored in the memory and executable on the processor, and when the processor executes the computer program, the processor implements the steps of the above method for evaluating the access capacity of the distributed power source of the power distribution network.
The technical scheme adopted by the invention for solving the technical problems is as follows: there is provided a computer readable storage medium having stored thereon a computer program which, when being executed by a processor, carries out the steps of the above-mentioned power distribution network distributed power access capacity evaluation method.
Advantageous effects
Due to the adoption of the technical scheme, compared with the prior art, the invention has the following advantages and positive effects: on the premise of ensuring safe and stable operation of a power grid, the invention considers the limitation of multiple factors such as grid structure, load level, overall operation characteristic, voltage, short-circuit current, electric energy quality and the like on the access of the distributed power supply, provides an evaluation method for the maximum access capacity of the distributed power supply of the power distribution network, and provides decision basis for making a grid-connected scheme, an operation strategy, a regional distributed power supply development plan and the like for grid-connected distributed power supply interest relevant parties such as a distributed power supply investor, a power grid operation management department, a national energy management department and the like.
Drawings
Fig. 1 is a flowchart of a method for evaluating the access capacity of a distributed power source of a power distribution network according to a first embodiment of the present invention.
Detailed Description
The invention will be further illustrated with reference to the following specific examples. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Further, it should be understood that various changes or modifications of the present invention can be made by those skilled in the art after reading the teaching of the present invention, and these equivalents also fall within the scope of the claims appended to the present application.
The first embodiment of the invention relates to a method for evaluating the access capacity of a distributed power supply of a power distribution network, which can provide decision basis for making a grid-connected scheme, an operation strategy, a regional distributed power supply development plan and the like for grid-connected distributed power supply interest relevant parties such as a distributed power supply investor, a power grid operation management department, a national energy management department and the like. As shown in fig. 1, the method specifically comprises the following steps:
step 1, determining the range of the power distribution network in the area to be evaluated, and drawing a topological graph of the power distribution network in the area to be evaluated.
And step 2, carrying out hierarchical evaluation according to the topological graph from high to low according to the voltage grade, checking the current state values of short-circuit current and voltage deviation of each bus, harmonic waves of each node and voltage unbalance monitoring data under the current voltage grade in the range to be evaluated during evaluation, and judging whether the current voltage grade has the condition of accessing the distributed power supply according to the checking result. The method specifically comprises the following substeps:
calculating the current state values of short-circuit current and voltage deviation of each bus under the current voltage level in the range to be evaluated, and collecting harmonic wave and voltage unbalance monitoring data of each node; when the short-circuit current of each bus is calculated, the voltage deviation is based on IEC 60909-0.
And the short-circuit current check is carried out on the principle that the short-circuit current of each bus node of the system does not exceed the cut-off current limit value of the corresponding circuit breaker after the distributed power supply is connected. And checking the short-circuit current according to the current short-circuit current situation of the system in a normal/typical operation mode in an evaluation range and the capacity of the to-be-checked distributed power supply of the built and batched complex power supply. In this embodiment, the short-circuit current is checked according to the following formula:
I xz ＜I m
wherein, I xz Short-circuit current is the system bus; i is m For the limit of the breaking current, the minimum of the limit of the breaking current of the corresponding circuit breaker on all the devices connected with the bus and the feed-out line should be selected. That is to say, when the short-circuit current is checked, whether the bus short-circuit current is smaller than the minimum value of the open-circuit current limit values of the corresponding circuit breakers on all the devices connected with the bus and the feed-out line is judged, and if the bus short-circuit current passes the check.
The voltage deviation checking should take the principle of reactive power in-situ balance and the principle that the voltage of the power grid is not out of limit after the distributed power supply is connected. The checking object comprises each voltage grade bus in the evaluation range, and the maximum positive voltage deviation delta U of the region caused by the access of the newly added distributed power supply is calculated according to the capacity of the distributed power supply to be checked H And maximum negative voltage deviation delta U L And checking the voltage deviation according to the following formula:
ΔU H ＞δU H &ΔU L ＞δU L
wherein, delta U H And Δ U L Respectively representing the maximum positive voltage deviation allowance value and the maximum negative voltage deviation allowance value. That is, when the present voltage deviation value is checked, it is determined whether the maximum positive voltage deviation is smaller than the maximum positive voltage deviation allowable value and whether the maximum negative voltage deviation is larger than the maximum negative voltage deviation allowable value, and if so, the present voltage deviation value is checked to pass.
The harmonic wave checking is based on the principle that the harmonic wave current value and the inter-harmonic wave voltage content rate of a distributed power supply access power grid node in the system are not out of limit. The harmonic currents should meet the relevant specifications for IEC 61000-3-2 and IEC 61000-3-6, and the inter-harmonic voltages should meet the relevant specifications for IEC 62749. The checking object comprises all nodes which are possibly influenced by harmonic current and inter-harmonic voltage provided by the distributed power supply, and the harmonic current is checked according to the following formula:
I xz,h ＜I h
wherein, I xz,h Denotes the h-th harmonic current value, I h Representing the h-th harmonic current limit. When checking the inter-harmonic voltage content, the comparison with a specified limit value is only needed. That is, when performing the harmonic check, it is determined whether or not the h-th harmonic current value is smaller than the h-th harmonic current limit value and whether or not the inter-harmonic voltage content of each node does not exceed a predetermined limit value, and if so, the harmonic check of each node is passed.
For a power distribution network with distributed power supply single-phase access, the principle that the voltage unbalance degree of the power distribution network is not out-of-limit is taken as a principle. The voltage imbalance should meet the relevant regulations of IEC 62749. The checking object is the bus voltage of the analyzed power distribution network, and checking is carried out through the following formula:
wherein the content of the first and second substances,
represents a negative sequence voltage unbalance>
Indicating the allowable value of the negative sequence voltage unbalance. That is, when the voltage unbalance monitoring data is checked, it is determined whether the negative sequence voltage unbalance degree is smaller than an allowable value of the negative sequence voltage unbalance degree, and if so, the voltage unbalance monitoring data is checked to pass.
And only when the current state values of the bus short-circuit current and the voltage deviation, and the harmonic waves and voltage unbalance monitoring data of each node pass the verification, the current voltage level has the condition of accessing the distributed power supply. If any one of the monitoring data of short-circuit current, voltage deviation, harmonic waves and voltage unbalance does not pass through, the condition that the voltage class and the regional power grid below the voltage class do not have access to the distributed power supply is avoided.
And step 3, carrying out thermal stability calculation analysis in a normal operation mode of the power distribution network, and determining the reverse load rate of the transformer or line to be evaluated.
The evaluation object of the thermal stability evaluation in the step should comprise the transformer and the line in the evaluation rangeAnd the reverse load rate is used as an evaluation index. The reverse load rate is calculated according to factors such as the operation mode of the power distribution network, the limit values of the transformer and the line, the load condition, the power generation condition, the output characteristics of the distributed power supply and the like, and the reverse load rate of the transformer or the line can be calculated
Calculated, where λ (t) is the reverse load rate of the transformer or line at time t, P D (t) distributed Power output at time t, P L (t) is the load at time t, S e And (t) is the actual operation limit value of the transformer or the line at the moment t.
Step 4, if the reverse load rate calculated according to the step 3 exceeds the allowable value of the directional load rate of the distribution network equipment, the transformer or the line does not have the condition of accessing the distributed power supply; otherwise, according to P m ＝(k r -λ max )×S e Calculating a newly-added distributed power capacity, wherein P m Capacity, k, of the distributed power supply can be increased for transformers or lines r For the directional load rate allowable value, lambda, of the distribution network equipment max To evaluate the maximum reverse load rate in the period, S e Indicating that the transformer or line has a maximum value of λ in the reverse load factor max The operational limit of the time of day.
And 5, calculating the updated reverse load rate according to the capacity of the newly-added distributed power supply, and determining a rechecking project according to the updated reverse load rate.
In this step, by
Calculating an updated reverse load rate, wherein new Is the updated reverse load rate. As shown in Table 1, the reverse load factor λ after updating new ∈(-100％，α]When the data is needed, the data is not checked again; when the updated reverse load rate lambda new ∈(α，0]In the process, the current state values of bus short-circuit current and voltage deviation, harmonic waves of each node and voltage unbalance monitoring data need to be checked again; when the reverse load rate λ is updated new ∈(0，k r ]When the method is used, the current state values of bus short-circuit current and voltage deviation, harmonic waves of all nodes, voltage unbalance monitoring data and power distribution network protection configuration need to be checked again.
TABLE 1 Re-check item Table
And 6, checking the rechecking items determined in the step 5, reducing the capacity of the newly-added distributed power supply if the rechecking items do not pass the checking, returning to the step 5 to re-determine the rechecking items and check until the checking passes, and finally obtaining a value which is the capacity result of the newly-added distributed power supply.
And 7, carrying out evaluation on the next voltage grade step by step according to the steps 3-5, and checking the calculation results of the voltage grades mutually, wherein the checking principle is that the capacity of the low-voltage-grade newly-increased distributed power supply is not more than the capacity of the newly-increased distributed power supply of the last voltage grade directly electrically connected with the low-voltage-grade newly-increased distributed power supply, so as to ensure that the calculation results are matched mutually.
It is easy to find that, on the premise of ensuring safe and stable operation of a power grid, the embodiment considers the limitation of multiple factors such as the grid structure, the load level, the overall operation characteristic, the voltage, the short-circuit current, the electric energy quality and the like on the access of the distributed power supply, and provides a method for evaluating the maximum access capacity of the distributed power supply of the power distribution network, thereby providing decision basis for making a grid-connected scheme, an operation strategy, a regional distributed power supply development plan and the like for distributed power supply investors, power grid operation management departments, national energy management departments and other related parties of distributed power supply benefits.
A second embodiment of the present invention relates to a power distribution network distributed power supply access capacity evaluation system, including:
the determining module is used for determining the range of the power distribution network of the area to be evaluated and determining a topological graph of the power distribution network of the area to be evaluated;
the checking module is used for layering according to the topological graph from high to low according to the voltage grade, checking the current values of short-circuit current and voltage deviation of each bus, harmonic waves of each node and voltage unbalance monitoring data under the current voltage grade in a range to be evaluated, and judging whether the current voltage grade has the condition of accessing the distributed power supply or not according to the checking result;
the judging module is used for calculating the reverse load rate of a transformer or a line in the power distribution network to be evaluated when the current voltage level has the condition of accessing the distributed power supply, and judging whether the transformer or the line has the condition of accessing the distributed power supply according to the reverse load rate;
the calculation module is used for calculating the capacity of the newly added distributed power supply of the transformer or the line under the condition that the transformer or the line has access to the distributed power supply;
and the evaluation module is used for repeating the operation of the modules to evaluate the next voltage level until the evaluation of all the voltage levels is finished.
The checking module comprises:
the calculation and collection unit is used for calculating the current state values of short-circuit current and voltage deviation of each bus under the current voltage level in the range to be evaluated and collecting harmonic wave and voltage unbalance monitoring data of each node;
the first judgment unit is used for judging whether the bus short-circuit current is smaller than the minimum value of the cut-off current limit values of corresponding breakers on all equipment connected with the bus and a feed-out line, and if so, the bus short-circuit current passes the check;
the second judgment unit is used for judging whether the maximum positive voltage deviation is smaller than the maximum positive voltage deviation allowable value or not and whether the maximum negative voltage deviation is larger than the maximum negative voltage deviation allowable value or not, and if so, the current voltage deviation value is checked to pass;
the third judging unit is used for judging whether the h-th harmonic current value is smaller than the h-th harmonic current limit value or not and whether the content rate of each inter-harmonic voltage of the node does not exceed a specified limit value or not, and if yes, the harmonic check of each node is passed;
the fourth judgment unit is used for judging whether the negative sequence voltage unbalance degree is smaller than the allowable value of the negative sequence voltage unbalance degree or not, and if so, the voltage unbalance monitoring data passes the verification;
and when the judgment results of the first judgment unit, the second judgment unit, the third judgment unit and the fourth judgment unit are all yes, the current voltage class has the condition of accessing the distributed power supply.
The judging module comprises:
a computing unit for passing
Calculating the reverse load rate of the transformer or the line in the power distribution network to be evaluated, wherein lambda (t) is the reverse load rate of the transformer or the line at the moment t, P D (t) distributed Power output at time t, P L (t) is the load at time t, S e (t) is the actual operation limit value of the transformer or the line at the moment t;
and the fifth judging unit is used for judging whether the reverse load rate of the transformer or the line exceeds the allowable value of the directional load rate of the distribution network equipment, and if not, the transformer or the line is in a condition of accessing the distributed power supply.
The calculation module passes P m ＝(k r -λ max )×S e Calculating the capacity of the transformer or line to add a new distributed power supply, wherein P m The capacity, k, of the distributed power supply can be increased for transformers or lines r For the directional load rate allowable value, lambda, of the distribution network equipment max To evaluate the maximum reverse load rate in the period, S e Indicating that the transformer or line has a maximum value of λ in the reverse load factor max The operational limit of the time of day.
The system for evaluating the access capacity of the distributed power supply of the power distribution network further comprises:
the calculation determining module is used for calculating the updated reverse load rate according to the capacity of the newly-added distributed power supply and determining a rechecking project according to the updated reverse load rate;
and the rechecking module is used for checking the rechecking items, reducing the capacity of the newly added distributed power supply if the rechecking items do not pass the checking, returning to the previous step until the checking passes, and taking the capacity of the newly added distributed power supply as an evaluation result of the current voltage level if the checking passes the checking.
The calculation determination module includes:
a reverse load rate calculation unit for passing
Calculating an updated reverse load rate, wherein new For updated reverse load rate, P m The capacity, lambda, of the distributed power supply can be increased for transformers or lines max To evaluate the maximum reverse load rate in the period, S e Indicating that the transformer or line has a maximum value of λ in the reverse load factor max An operational limit of time;
a rechecking item determining unit for determining the updated reverse load rate lambda new ∈(-100％，α]When the data is needed, the data is not checked again; reverse load ratio lambda after update new ∈(α，0]When the bus is in short circuit, the current state values of the bus short circuit current and voltage deviation, and the harmonic wave and voltage unbalance monitoring data of each node are rechecked; reverse load ratio lambda after update new ∈(0，k r ]And in the process, the current state values of the bus short-circuit current and voltage deviation, harmonic waves of each node, voltage unbalance monitoring data and the power distribution network protection configuration are rechecked.
The system for evaluating the access capacity of the distributed power supply of the power distribution network further comprises:
and the mutual checking module is used for checking the evaluation result of the current voltage level and the evaluation result of the previous voltage level, and the checking principle is that the capacity of the newly-added distributed power supply with the low voltage level is not greater than the capacity of the newly-added distributed power supply with the previous voltage level which is directly electrically connected with the newly-added distributed power supply.
A third embodiment of the present invention relates to an electronic device, which includes a memory, a processor, and a computer program stored in the memory and executable on the processor, where the processor implements the steps of the power distribution network distributed power access capacity evaluation method according to the first embodiment when executing the computer program.
A fourth embodiment of the present invention relates to a computer-readable storage medium, on which a computer program is stored, which, when being executed by a processor, implements the steps of the method for assessing the access capacity of a distributed power supply of a power distribution network of the first embodiment.
As will be appreciated by one skilled in the art, embodiments of the present invention may be provided as a method, system, or computer program product. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein. The scheme in the embodiment of the invention can be realized by adopting various computer languages, such as object-oriented programming language Java and transliterated scripting language JavaScript.
The present invention is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including the preferred embodiment and all changes and modifications that fall within the scope of the invention.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.
Claims (10)
1. A method for evaluating the access capacity of a distributed power supply of a power distribution network is characterized by comprising the following steps:
determining the range of the power distribution network in the area to be evaluated, and determining a topological graph of the power distribution network in the area to be evaluated;
layering according to the topological graph from high to low according to the voltage grade, checking the current state values of short-circuit current and voltage deviation of each bus, harmonic waves of each node and voltage unbalance monitoring data under the current voltage grade in a range to be evaluated, and judging whether the current voltage grade has the condition of accessing a distributed power supply according to the checking result;
when the current voltage class has the condition of accessing the distributed power supply, calculating the reverse load rate of a transformer or a line in the power distribution network to be evaluated, and judging whether the transformer or the line has the condition of accessing the distributed power supply according to the reverse load rate;
when the transformer or the line has the condition of accessing the distributed power supply, calculating the capacity of the newly added distributed power supply of the transformer or the line;
and repeating the steps to evaluate the next voltage level until all the voltage levels are evaluated.
2. The method for evaluating the access capacity of the distributed power supply of the power distribution network according to claim 1, wherein the current state values of short-circuit current and voltage deviation of each bus, harmonic waves of each node and voltage unbalance monitoring data of each bus at the current voltage level in the range to be evaluated are checked, and the method specifically comprises the following steps:
calculating the current state values of short-circuit current and voltage deviation of each bus under the current voltage level in the range to be evaluated, and collecting harmonic wave and voltage unbalance monitoring data of each node;
judging whether the bus short-circuit current is smaller than the minimum value of the cut-off current limit values of all equipment connected with the bus and corresponding breakers on a feed-out line, and if so, checking the bus short-circuit current to pass;
judging whether the maximum positive voltage deviation is smaller than the maximum positive voltage deviation allowable value or not and whether the maximum negative voltage deviation is larger than the maximum negative voltage deviation allowable value or not, and if so, checking the current voltage deviation value;
judging whether the h-th harmonic current value is smaller than the h-th harmonic current limit value or not and whether the content rate of each inter-harmonic voltage of the node does not exceed a specified limit value or not, and if so, checking the harmonic of each node;
judging whether the negative sequence voltage unbalance degree is smaller than an allowable value of the negative sequence voltage unbalance degree or not, and if so, checking the voltage unbalance monitoring data;
and only when the current state values of the bus short-circuit current and the voltage deviation, and the harmonic waves and voltage unbalance monitoring data of each node pass the verification, the current voltage level has the condition of accessing the distributed power supply.
3. The method for evaluating the access capacity of the distributed power sources of the power distribution network according to claim 1, wherein the method comprises the steps of calculating the reverse load rate of a transformer or a line in the power distribution network to be evaluated, and judging whether the transformer or the line has a condition of accessing the distributed power sources according to the reverse load rate, and specifically comprises the following steps:
by passing
Calculating the reverse load rate of the transformer or the line in the power distribution network to be evaluated, wherein lambda (t) is the reverse load rate of the transformer or the line at the moment t, P D (t) is the distributed power output at time t,
P L (t) is the load at time t, S e (t) is the actual operation limit value of the transformer or the line at the moment t;
and judging whether the reverse load rate of the transformer or the line exceeds the allowable value of the directional load rate of the distribution network equipment, and if not, indicating that the transformer or the line has the condition of accessing the distributed power supply.
4. The method for evaluating the access capacity of the distributed power sources of the power distribution network according to claim 1, wherein when the capacity of the distributed power sources can be newly increased by the transformer or the line, the P is calculated m ＝(k r -λ max )×S e Calculating the capacity of the transformer or line to add new distributed power supply, wherein P m The capacity, k, of the distributed power supply can be increased for transformers or lines r Is the allowable value of the directional load rate, lambda, of the distribution network equipment max To evaluate the maximum reverse load rate in the period, S e Indicating that the transformer or line has a maximum value of λ in the reverse load factor max The operational limit of the time of day.
5. The method for evaluating the access capacity of the distributed power sources of the power distribution network according to claim 1, wherein after calculating the capacity of the transformer or the line capable of newly increasing the distributed power sources, the method further comprises:
calculating the updated reverse load rate according to the capacity of the newly-added distributed power supply, and determining a rechecking project according to the updated reverse load rate;
and checking the rechecking project, if the rechecking project does not pass, reducing the capacity of the newly added distributed power supply, returning to the previous step until the rechecking passes, and if the rechecking passes, taking the capacity of the newly added distributed power supply as an evaluation result of the current voltage level.
6. The method for evaluating the access capacity of the distributed power sources of the power distribution network according to claim 4, wherein the step of calculating the updated reverse load rate according to the capacity of the newly-added distributed power sources and determining the rechecking project according to the updated reverse load rate specifically comprises the steps of:
by passing
Calculating an updated reverse load ratio, wherein new For updated reverse load rate, P m The capacity, lambda, of the distributed power supply can be increased for transformers or lines max To evaluate the maximum reverse load rate in the cycle, S e Indicating that the transformer or line has a maximum value of λ in the reverse load factor max An operational limit of time;
when the updated reverse load rate lambda new ∈(-100％，α]When the data is needed, the data is not checked again; when the updated reverse load rate lambda new ∈(α，0]In the process, the current state values of bus short-circuit current and voltage deviation, harmonic waves of each node and voltage unbalance monitoring data need to be checked again; when the updated reverse load rate lambda new ∈(0，k r ]In the process, the current state values of bus short-circuit current and voltage deviation, harmonic waves of each node, voltage unbalance monitoring data and power distribution network protection configuration need to be checked again.
7. The method for evaluating the access capacity of the distributed power sources of the power distribution network according to claim 1, wherein after taking the capacity of the newly added distributed power source as a final result, the method further comprises:
and checking the evaluation result of the current voltage level and the evaluation result of the previous voltage level, wherein the checking principle is that the capacity of the newly-added distributed power supply of the low voltage level is not greater than the capacity of the newly-added distributed power supply of the previous voltage level which is directly electrically connected with the newly-added distributed power supply of the low voltage level.
8. A power distribution network distributed power access capacity evaluation system is characterized by comprising:
the determining module is used for determining the range of the power distribution network of the area to be evaluated and determining a topological graph of the power distribution network of the area to be evaluated;
the checking module is used for layering according to the topological graph from high to low according to the voltage grade, checking the current state values of short-circuit current and voltage deviation of each bus, harmonic waves of each node and voltage unbalance monitoring data under the current voltage grade in the range to be evaluated, and judging whether the current voltage grade has the condition of accessing the distributed power supply according to the checking result;
the judging module is used for calculating the reverse load rate of a transformer or a line in the power distribution network to be evaluated when the current voltage level has the condition of accessing the distributed power supply, and judging whether the transformer or the line has the condition of accessing the distributed power supply according to the reverse load rate;
the calculation module is used for calculating the capacity of the newly added distributed power supply of the transformer or the line under the condition that the transformer or the line has access to the distributed power supply;
and the evaluation module is used for repeating the operation of the modules to evaluate the next voltage level until the evaluation of all the voltage levels is finished.
9. An electronic device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, wherein the processor when executing the computer program performs the steps of the method for assessing the access capacity of a distributed power supply of a power distribution network according to any one of claims 1 to 7.
10. A computer-readable storage medium, on which a computer program is stored, which, when being executed by a processor, carries out the steps of the method for assessing the access capacity of a distributed power supply of a power distribution network according to any one of claims 1 to 7.
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| CN116799780A (en) * | 2023-05-17 | 2023-09-22 | 国网信息通信产业集团有限公司 | Distributed photovoltaic bearing capacity assessment method, system and terminal for power distribution network |
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