CN113224764B - Device for dynamically adjusting power flow of power grid based on multistage fast switch and reactor - Google Patents
Device for dynamically adjusting power flow of power grid based on multistage fast switch and reactor Download PDFInfo
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- CN113224764B CN113224764B CN202110628152.6A CN202110628152A CN113224764B CN 113224764 B CN113224764 B CN 113224764B CN 202110628152 A CN202110628152 A CN 202110628152A CN 113224764 B CN113224764 B CN 113224764B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/04—Circuit arrangements for ac mains or ac distribution networks for connecting networks of the same frequency but supplied from different sources
- H02J3/06—Controlling transfer of power between connected networks; Controlling sharing of load between connected networks
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/001—Methods to deal with contingencies, e.g. abnormalities, faults or failures
Abstract
The invention relates to the technical field of power transmission, in particular to a device for dynamically adjusting the power flow of a power grid based on a multistage fast switch and a reactor, which is used for accessing a power transmission section with limited power transmission capacity caused by uneven power flow distribution, mainly comprises an electrically connected multistage series reactor, a fast switch and a control system, and is mainly installed on a power flow heavy-load circuit which does not meet the N-1 checking requirement; the dynamic power flow regulating device based on the multi-stage fast switch and the reactor can dynamically regulate the power flow of the power grid, does not increase the system loss in normal operation, is more economic in investment cost compared with a flexible power flow control device, and is relatively simple and flexible; the invention realizes the rapid adjustment of the tidal current after the fault by serially connecting the multistage rapid switch and the reactor on the line, has better overall economy, does not increase the system loss during normal operation, and can flexibly adjust the series and the size of the serially connected reactor according to the overload condition of the line after the fault so as to accurately control the tidal current.
Description
Technical Field
The invention relates to the technical field of power transmission, in particular to a device for dynamically adjusting power flow of a power grid based on a multistage fast switch and a reactor.
Background
Along with the continuous strengthening of the power grid structure, the structure of the power grid tends to be stable gradually, especially for some large-scale urban power grids, because of dense urban buildings, various pipe networks are complicated and complicated, the difficulty of newly-built power transmission lines is very high, the urban power load is continuously increased, and the demand for power consumption is also continuously increased, but in the urban development process, the distribution of the load is closely related to the industrial structure, so that the problem of serious uneven power flow distribution exists on the local section of the power transmission line, the overall power transmission capacity is limited, so that how to improve the section with uneven power flow distribution and the power transmission capacity of the power grid become one of the main concerns in recent years. However, in such periods, a large number of fully-controlled power electronic devices are required, the equipment manufacturing cost is high, and areas with weak power grid investment capacity cannot bear large investment; therefore, a relatively low technical scheme for solving the problem of uneven section tidal current is found and can be more suitable for the requirement of a large range of a power grid.
In principle, the problem of uneven power flow distribution is solved, one is to change the phase angle difference of the head end and the tail end of a line to change the power flow of a power grid, such as the unified power flow controller technology, the other is to change the impedance of the line, such as the series reactance on a heavy-load line, and force the power flow to be transferred to other lines, but the series impedance has the problem of larger loss in normal operation, namely if the series impedance is always through-current, the impedance loss of a system is always existed, and the overload problem of the power grid is that the line is overloaded only after N-1, namely the line is not overloaded in normal operation, and the line is overloaded and needs to be adjusted in real time after N-1. Therefore, the adjustment of the power flow needs to consider the economy of the device, consider that the equipment loss is reduced as much as possible during operation, improve the operation economy, and simultaneously realize the rapid adjustment of the power flow after the fault.
Disclosure of Invention
In order to solve the above problems, the present invention aims to disclose a power transmission technology field, and particularly to a device for dynamically adjusting a power grid tide based on a multistage fast switch and a reactor, which is connected to a heavy load circuit to achieve balance and improve the power transmission capacity of the power grid, so as to achieve the balance of the tide.
In order to achieve the purpose, the invention adopts the technical scheme that: a device for dynamically adjusting power flow of a power grid based on a multi-stage fast switch and a reactor is characterized in that the device is used for accessing a power transmission section with limited power transmission capacity caused by uneven power flow distribution, mainly comprises the multi-stage series reactor, the fast switch and a control system which are electrically connected, and is mainly installed on a power flow heavy-load circuit which does not meet the N-1 checking requirement.
Preferably, the fast switch is provided with a vacuum circuit breaker and is set to perform switching control within 20 ms.
Preferably, the working method of the device comprises the following steps:
s1, calculating a maximum impedance value through simulation analysis: calculating the maximum impedance required to be connected in series to meet the N-1 checking requirement of the system in different operation modes;
s2, distributing the series impedance reactors 1,2 and 3 according to the proportion of 1;
s3, connecting each impedance reactor with the fast switch in parallel respectively, and setting the withstand voltage and the reactance value of the fast switch to be in a direct proportion relation;
s4, in a normal operation state, when the line is not overloaded, the quick switch is closed and is connected in series in the impedance reactor bypass; and when the overload of the installed line is detected, sequentially opening the fast switches according to a set strategy and putting the impedance reactors into the fast switches until the line is limited below the rated current.
Preferably, the calculation of the impedance value in step S1 is performed according to a power grid operation mode, and the selected power grid operation mode can use a maximum reactance value that is not overloaded after the line is limited to N-1 as a total reactance value of the series.
Preferably, in step S2, when two stages of impedances are connected in series, the size of the series impedance reactor is distributed with a total impedance value according to a ratio of 1; when four-stage impedance is connected in series, the size of the series impedance reactor is divided into a total impedance value according to the proportion of 1.
Preferably, in the step S2, each reactance value in the series is assigned according to the series number, and when 2 stages are in the series, each reactance value is determined according to 1/3,2/3 of the total impedance; when 3 stages are connected in series, the reactance value of each stage is determined according to 1/7,2/7,4/7 of the total impedance; when 4 stages are connected in series, the reactance value of each stage is determined according to 1/11,2/11,4/11,7/11 of the total impedance; the number of series reactance stages is less than or equal to 3.
Preferably, in step S4, the predetermined policy is: and the control system of the multistage fast switch and the impedance reactor sets the input sequence and logic of the impedance reactor according to the overload degree.
The invention has the beneficial effects that: the dynamic power flow regulating device based on the multi-stage fast switch and the reactor can dynamically regulate the power flow of the power grid, does not increase the system loss in normal operation, is more economic in investment and cost compared with a flexible power flow control device, and is relatively simple and flexible. The invention realizes the rapid adjustment of the tidal current after the fault by serially connecting the multistage rapid switch and the reactor on the line, the device has better overall economy, the system loss is not increased during the normal operation, the series number and the size of the serially connected reactor can be flexibly adjusted according to the overload condition of the line after the fault, and the precise control of the tidal current is realized.
Drawings
Fig. 1 is an overall basic configuration diagram of the present invention.
Fig. 2 is a schematic diagram of a power flow of a power grid to which the present invention is applied.
FIG. 3 is a flow chart of the main parameter selection calculation of the apparatus of the present invention.
Detailed Description
The following detailed description of embodiments of the invention refers to the accompanying drawings:
a device for dynamically adjusting power flow of a power grid based on a multistage fast switch and an electric reactor is used for accessing a power transmission section with limited power transmission capacity caused by uneven power flow distribution and mainly comprises the multistage series electric reactor, the fast switch and a control system which are electrically connected, the device is mainly installed on a power flow heavy-load circuit which does not meet N-1 checking requirements, and the fast switch is provided with a vacuum circuit breaker and is set to realize on-off control within 20 ms.
Further, the working method of the device comprises the following steps:
s1, calculating a maximum impedance value through simulation analysis: calculating the maximum impedance required to be connected in series to meet the N-1 checking requirement of the system in different operation modes; calculating the magnitude of the impedance value according to the operation mode of the power grid, wherein the selected operation mode of the power grid can take the maximum reactance value which is not overloaded after the line is limited to N-1 as the total reactance value of the series connection;
s2, distributing the series impedance reactors 1,2 and 3 according to the proportion of 1; when two-stage impedance is connected in series, the total impedance value is distributed according to the proportion of 1; when four-stage impedance is connected in series, the size of the series impedance reactor is distributed according to the proportion of 1; the reactance value of each cascaded stage is determined according to the cascaded stage number, and when 2 stages are cascaded, the reactance value of each stage is determined according to 1/3,2/3 of the total impedance; when 3 stages are connected in series, the reactance value of each stage is determined according to 1/7,2/7,4/7 of the total impedance; when 4 stages are connected in series, the reactance value of each stage is determined according to 1/11,2/11,4/11,7/11 of the total impedance; the number of series reactance stages is less than or equal to 3;
s3, connecting each impedance reactor with the fast switch in parallel respectively, and setting the withstand voltage and the reactance value of the fast switch to be in a direct proportion relation;
s4, in a normal running state, when the line is not overloaded, the quick switch is closed and is connected in series in a bypass of the impedance reactor; when the overload of the installed line is detected, sequentially opening the fast switches and putting the impedance reactors according to a set strategy until the line is limited below the rated current; wherein the given policy is: and the control system of the multistage fast switch and the impedance reactor sets the input sequence and logic of the impedance reactor according to the overload degree.
As shown in fig. 1, the basic structure of the device for dynamically adjusting the power flow of the power grid based on the multi-stage fast switch and the reactor is that the fast switch and the reactor can be sequentially installed on a line; as shown in fig. 2, a device for dynamically adjusting power flow of a power grid based on a multi-stage fast switch and a reactor is illustrated by taking a certain power grid as an example, a power grid in a certain area is connected with a main grid through a 220kV line a channel and a channel B, each channel is a double-circuit line and receives the influence of natural distribution of power flow, the power flow of the channel B is heavy, and the line rated current of the channel B is 1.4kA; during the peak load period of a regional power grid B, a large amount of power needs to be received from a main grid, the load flow of the channel A is light and is 300MW; channel B is overloaded, the maximum power flow is 600MW, the other circuit behind the channel B circuit N-1 is 530MW, and the other circuit is overloaded (the overload is 10.4%); in order to prevent the overload behind the line N-1 of the channel B, the maximum transmission capacity of the section formed by the channel A and the channel B is limited to 810MW; a B channel double loop wire 540MW (the other wire just loads after N-1), and an A channel double loop wire 270MW; the existing channel power transmission capacity is difficult to meet the demand of load increase, so that the device for dynamically adjusting the power flow of the power grid based on the multistage fast switch and the reactor is considered to be adopted; referring to fig. 3, a basic step of selecting parameters of each stage of reactor and main equipment in this embodiment is to install the device on the heavy-duty B channel; the maximum reactance needing to be connected in series is 14 ohms after calculation in various modes; because the load change of the regional transformer is frequent, the requirement on the adjustment of the power flow needs to be relatively fine, and a 3-level reactor is considered; the reactance values of the three-level reactors are respectively set to be 2 ohms, 4 ohms and 8 ohms; by adopting the scheme of the grading reactor, reactance values of 7 levels, such as 2 ohms, 4 ohms, 6 ohms, 8 ohms, 10 ohms, 12 ohms and 14 ohms, can be put into the system, and the control on the power flow of the power grid can be more precise. The voltage withstand level of the fast switch in parallel with the three-stage reactor may be selected in direct proportion to the selected reactance value.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the technical scope of the present invention, and those skilled in the art may make modifications and variations within the spirit of the present invention, and all modifications, equivalents and modifications of the above embodiments according to the technical spirit of the present invention are within the scope of the present invention.
Claims (5)
1. A device for dynamically adjusting power flow of a power grid based on a multi-stage fast switch and a reactor is characterized in that the device is used for accessing a power transmission section with limited power transmission capacity caused by uneven power flow distribution, mainly comprises the multi-stage series reactor, the fast switch and a control system which are electrically connected, and is mainly installed on a power flow heavy-load circuit which does not meet the N-1 check requirement;
the working method of the device comprises the following steps:
s1, calculating a maximum impedance value through simulation analysis: calculating the maximum impedance required to be connected in series to meet the N-1 checking requirement of the system in different operation modes;
s2, distributing the series impedance reactors 1,2 and 3 according to the proportion of 1; when two-stage impedance is connected in series, the total impedance value is distributed according to the proportion of 1; when the four-stage impedance is connected in series, the size of the series impedance reactor is distributed according to the proportion of 1;
s3, connecting each impedance reactor with the fast switch in parallel respectively, and setting the withstand voltage and the reactance value of the fast switch to be in a direct proportion relation;
s4, in a normal operation state, when the line is not overloaded, the quick switch is closed and is connected in series in the impedance reactor bypass; and when the overload of the installed line is detected, sequentially opening the fast switches according to a set strategy and putting the impedance reactors into the fast switches until the line is limited below the rated current.
2. An arrangement for dynamically regulating power flow in a power network based on multi-stage fast switches and reactors as claimed in claim 1, characterized in that said fast switches are provided with a vacuum interrupter and are set to perform switching control within 20 ms.
3. The device for dynamically adjusting power flow of a power grid based on multi-stage fast switches and reactors as claimed in claim 2, wherein the calculation of the magnitude of the impedance value in step S1 is calculated according to the power grid operation mode, and the selected power grid operation mode can use the maximum reactance value of the line which is not overloaded after being limited to N-1 as the total reactance value of the series connection.
4. The device for dynamically adjusting power flow of a power grid based on the multistage fast switches and the reactors as claimed in claim 3, wherein in the step S2, the reactance value of each stage in series is assigned according to the number of the series-connected stages, and when 2 stages are in series, the reactance value of each stage is determined according to 1/3,2/3 of the total impedance; when 3 stages are connected in series, the reactance value of each stage is determined according to 1/7,2/7,4/7 of the total impedance; when 4 stages are connected in series, the reactance value of each stage is determined according to 1/11,2/11,4/11,7/11 of the total impedance; the number of the series reactance stages is less than or equal to 3.
5. The device for dynamically adjusting the power flow of the power grid based on the multi-stage fast switches and the reactors as claimed in claim 4, wherein in the step S4, the predetermined policy is: and the control system of the multistage fast switch and the impedance reactor sets the input sequence and logic of the impedance reactor according to the overload degree.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN105703376A (en) * | 2016-03-08 | 2016-06-22 | 全球能源互联网研究院 | Mixed type unified power flow controller |
| CN106159937A (en) * | 2015-04-01 | 2016-11-23 | 国家电网公司 | A kind of method improving multichannel section ability to transmit electricity |
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| CN205544326U (en) * | 2016-03-08 | 2016-08-31 | 全球能源互联网研究院 | Combined unified power flow controller |
| CN106159976A (en) * | 2016-08-16 | 2016-11-23 | 南京南瑞继保电气有限公司 | A kind of series compensation device |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN106159937A (en) * | 2015-04-01 | 2016-11-23 | 国家电网公司 | A kind of method improving multichannel section ability to transmit electricity |
| CN105703376A (en) * | 2016-03-08 | 2016-06-22 | 全球能源互联网研究院 | Mixed type unified power flow controller |
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