CN116073392A - Island power distribution network optimized operation method based on reactive compensation - Google Patents

Island power distribution network optimized operation method based on reactive compensation Download PDF

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CN116073392A
CN116073392A CN202211617121.1A CN202211617121A CN116073392A CN 116073392 A CN116073392 A CN 116073392A CN 202211617121 A CN202211617121 A CN 202211617121A CN 116073392 A CN116073392 A CN 116073392A
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power
reactive
node
distribution network
island
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Inventor
赵一园
潘耘峰
汤瀚博
曾晓
薛福霞
汤义勤
华文
周升彧
陈�峰
尤明升
黄宇
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Taizhou Power Supply Co of State Grid Zhejiang Electric Power Co Ltd
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Taizhou Power Supply Co of State Grid Zhejiang Electric Power Co Ltd
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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
    • H02J3/18—Arrangements for adjusting, eliminating or compensating reactive power in networks
    • H02J3/1821—Arrangements for adjusting, eliminating or compensating reactive power in networks using shunt compensators
    • H02J3/1835—Arrangements for adjusting, eliminating or compensating reactive power in networks using shunt compensators with stepless control
    • H02J3/1842—Arrangements for adjusting, eliminating or compensating reactive power in networks using shunt compensators with stepless control wherein at least one reactive element is actively controlled by a bridge converter, e.g. active filters
    • 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
    • H02J3/12—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load
    • H02J3/16—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load by adjustment of reactive power
    • 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
    • H02J2203/00—Indexing scheme relating to details of circuit arrangements for AC mains or AC distribution networks
    • H02J2203/10—Power transmission or distribution systems management focussing at grid-level, e.g. load flow analysis, node profile computation, meshed network optimisation, active network management or spinning reserve management
    • 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
    • H02J2203/00—Indexing scheme relating to details of circuit arrangements for AC mains or AC distribution networks
    • H02J2203/20—Simulating, e g planning, reliability check, modelling or computer assisted design [CAD]
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
    • Y02E40/30—Reactive power compensation

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Abstract

The invention improves the prior art scheme, and provides a reactive compensation-based island power distribution network optimizing operation method, which at least comprises the steps of acquiring a radiation network model; analyzing the loss and line voltage change of sea cable laying on the island power distribution network through a radiation network model; presetting standby site selection of a plurality of island distribution network static var compensators; establishing an objective function with the aim of reducing active power loss, and establishing constraint conditions according to the network operation state; and carrying out power flow calculation according to the structure and connection condition of the regional distribution network to obtain the output condition of the regional static var compensator and the traditional reactive power compensation device, and selecting the preset standby site of the static var compensator of the island distribution network. By adopting the technical scheme, the invention fully utilizes the scheme of optimally controlling the static reactive power compensator and the traditional reactive power compensation device which are arranged in the power grid, thereby realizing on-site balancing. And the economy and reliability of power supply in the island environment are improved.

Description

Island power distribution network optimized operation method based on reactive compensation
Technical Field
The invention relates to the technical field of loss reduction of power distribution network technology, in particular to an island power distribution network optimization operation method based on reactive compensation.
Background
With the proposal of building a novel power system target, the proportion of wind power, photovoltaic and other distributed energy sources connected into a power grid is continuously increased, and the island region makes the island a development region with great attention by virtue of abundant wind power resources.
The actual utilization of the electric energy of the island is also continuously developed, and the earliest patent of the invention with the patent number of CN201310492376.4 is a multi-objective island distributed power supply optimizing method, and only an off-island type distributed power supply can be adopted. As renewable energy sources for sea are being developed deeply, the power grid connected between islands and between islands and land is also increasing, and the patent application number is: the grid-connected island power grid in the patent of the invention of CN201510271935.8, namely a micro-grid system of the grid-connected island power grid, is connected with an external large power grid through a submarine cable or an overhead line, renewable energy sources such as wind power, photovoltaics and the like which are rich in islands can be sent out to the large power grid through the submarine cable or the overhead line while meeting the power requirements of the islands, and the method is suitable for large-scale development and utilization of renewable energy sources such as offshore wind power plants and the like around the islands. However, the existence of the sea cable causes the island power distribution network to always have more or less reactive power unbalance, so the loss reduction work of the island power distribution network is also more and more important. At present, various compensating devices are installed in most areas, but with the increase of submarine cables and various distributed power supplies, part of compensating devices cannot adapt to the current situation, so that reactive power compensating devices are required to be additionally arranged, and reactive power output of each device is reasonably arranged to achieve the purpose of optimizing operation of a power distribution network.
Disclosure of Invention
The invention aims to solve the technical problems and provide the technical task of perfecting and improving the prior art scheme and provides the island power distribution network optimizing operation method based on reactive compensation so as to achieve the purpose of reducing the power distribution network loss in island environment.
Therefore, the island power distribution network optimization operation method based on reactive compensation at least comprises the following steps:
step 1: acquiring a radiation network model;
step 2: analyzing the loss and line voltage change of sea cable laying on the island power distribution network through a radiation network model;
step 3: presetting standby sites of a plurality of island distribution network static var compensators according to the analysis result in the step 2;
step 4: establishing an objective function with the aim of reducing active power loss, and establishing constraint conditions according to the network operation state;
step 5: and (3) carrying out power flow calculation according to the structure and connection condition of the regional distribution network to obtain the output condition of the regional static var compensator and the traditional reactive power compensation device, and selecting the standby site of the static var compensator of the island distribution network preset in the step (3).
Preferably, in step 2, under the condition that the voltage and power of the line head end are known, the voltage value of the end node can be calculated backward, and the total active power loss is calculated:
Figure BDA0004002000260000021
u in the above 1 R is the head end voltage L Is sea cable resistance, X L For sea cable reactance, P 2 For the end active power, Q 2 For terminal reactive power, Δq y1 Delta Q is the reactive power of the susceptance branch at the head-end node y2 Is the reactive power of the susceptance branch at the end node. When the load of the system is large, the charging power generated by the submarine cable can be absorbed by the load, so that a large amount of reactive power cannot flow in the line; when the load of the system is smaller and the charging power of the submarine cable is larger, a large amount of capacitive reactive power can be injected into the power grid, and even reactive power dumping occurs, so that the active power loss of the line is increased.
Preferably, in step 2, the node voltage at the end of the line is represented by the following formula:
Figure BDA0004002000260000031
u in 1 Is the head-end voltage, P 1 For head-end active power, Q 1 R is the reactive power of the head end L Is sea cable resistance, X L Is the sea cable reactance.
When the line terminal is in an idle or light load state, the reactive power of the first section of the line is a negative value when the capacitive reactive power brought by the line susceptance is large, and the reactance of the line is far greater than the resistance, so that the value of the longitudinal component of the voltage drop is a negative number, and the condition that the voltage of the line terminal is higher than the voltage of the first section of the line occurs. When the value of the voltage drop longitudinal component is large, the condition of voltage out-of-limit occurs at the tail end of the line, and the voltage value at the moment is not in a specified fluctuation range, so that whether the power grid can stably operate is unknown, and the power quality is greatly influenced.
Preferably, in step 3, the preset position is a regional power grid based on PL-SJW, and the line, the transformer and the connected load are subjected to equivalent processing, and node numbers are marked at each node.
Preferably, in step 4, the objective function is specifically:
Figure BDA0004002000260000032
wherein P is loss_m Active power loss on branch m of the distribution network; l is the total branch number of the power distribution network; i m Is the current on branch m; r is R m Is the resistance of branch m.
Preferably, the step 4 constraint includes an equality constraint, an inequality constraint, and a position constraint. Each constraint condition has advantages and disadvantages, and needs to be selected according to actual conditions.
Preferably, the equality constraint is a load flow balance constraint, namely when a reactive compensation device is connected to a certain node and performs corresponding compensation, the load flow at the node should satisfy the equality constraint as shown in the following formula:
Figure BDA0004002000260000041
Figure BDA0004002000260000042
/>
wherein P is Gi 、Q Gi Active and reactive power output for node i; p (P) Li 、Q Li Active and reactive loads at node i, respectively; q (Q) BCi The reactive capacity compensated by the reactive compensation device at the node i is positive when the compensation capacity is inductive reactive, and negative when the compensation capacity is negative; u (U) i Is the voltage at node i; y is Y ij Is the admittance between node i and node j.
Preferably, the inequality constraint is a node voltage constraint, and the node voltage constraint should satisfy the inequality as shown below:
U imin ≤U i ≤U imax
in U imin 、U imax The voltage at node i is the minimum and maximum, respectively. Reactive power of the system may cause voltage out-of-limit conditions at low peak loads,therefore, when balancing the reactive power of the system, the conditions that the voltage of each node fluctuates within an allowable range need to be satisfied, so that the stable operation of the system is ensured while the reactive power of the power grid is reduced.
Preferably, the location constraint is that an optimal node is selected in the alternatives generated in step 3, that is, the following formula needs to be satisfied:
i BC ∈S BC
wherein i is BC The node is the last node installed for the reactive power compensation device; s is S BC Is an alternative set of installation nodes for the reactive compensation device. Such a scheme is used in cases where the alternative selection is more accurate.
Preferably, the output conditions of the static var compensator and the traditional var compensator in the region are finally obtained after power flow calculation according to specific constraint conditions, and fine adjustment is performed after the preset standby site selection of the static var compensator of the island power distribution network.
By adopting the technical scheme, the invention provides a scheme for optimally controlling the static reactive power compensator and the traditional reactive power compensation device which are arranged in the power grid in the island environment in the load peak period, and compared with the traditional reactive power compensation method, the method can better control the flow of reactive power in the power grid and realize on-site balance. The power distribution network loss is reduced, the power supply quality is improved, and the economy and reliability of power supply in the island environment are improved.
Drawings
FIG. 1 is a flow chart of an optimization operation method of an island power distribution network based on reactive compensation;
FIG. 2 is a simple radial distribution line power flow calculation model of the island distribution network optimization operation method based on reactive power compensation;
FIG. 3 is a regional power grid connection diagram of the island power distribution network optimization operation method based on reactive compensation;
fig. 4 is a regional power grid equivalent diagram of the island power distribution network optimization operation method based on reactive compensation;
FIG. 5 is a schematic diagram of a scheme-installation of the method for optimizing operation of the island-in-sea power distribution network based on reactive compensation of the present invention;
FIG. 6 is a schematic diagram of a scheme II installation of the island distribution network optimization operation method based on reactive compensation;
fig. 7 is a schematic diagram of a scheme III installation of the island power distribution network optimizing operation method based on reactive compensation;
FIG. 8 shows the active power loss during peak load time of the island distribution network optimized operation method based on reactive compensation of the invention;
FIG. 9 is a diagram showing the total loss of the power grid of the island power distribution network optimizing operation method based on reactive compensation;
fig. 10 shows a peak load time grid voltage condition of the island power distribution network optimization operation method based on reactive compensation.
Detailed Description
The technical scheme of the invention is further described in detail below with reference to the attached drawings.
The invention is widely applied to SVG, i.e. reactive power compensation device. It is a device for improving the quality of electrical energy=, which can perform reactive compensation, suppress harmonics, reduce voltage fluctuations and flicker and solve three-phase imbalance. As shown in fig. 1, the island power distribution network optimization operation method based on reactive compensation of the invention comprises the following steps:
step 1: acquiring a radiation network model as shown in fig. 2;
step 2: analyzing the loss and line voltage change of sea cable laying on the island power distribution network through a radiation network model;
the equivalent sea cable centralized parameter model is shown in figure 2, R in the figure L 、X L 、B y The resistance, reactance and susceptance of the submarine cable are respectively; the apparent power at the line start is
Figure BDA0004002000260000061
The load at the line end is +.>
Figure BDA0004002000260000062
U 1 、U 2 At node 1 and node 2 respectivelyAnd the voltage of the first and the end of the line is represented. Let the line head voltage be the rated voltage U N The voltage phase angle is 0.
In order to illustrate that the active power loss of the power grid is affected by submarine cabling, an analysis and an explanation will be made below by taking a simple radiation type power distribution network as an example.
With the known distribution network line voltage class, the voltage at the head end, node 1, and the power at the tail end, node 2, the power at the head end node and the voltage at the tail end node are approximately calculated by using a power flow method to analyze the power flow of the power grid and quantify the power grid loss, wherein a forward push back method is adopted. The power of the susceptance branches connected in parallel at the end nodes is shown as follows:
Figure BDA0004002000260000063
in the method, in the process of the invention,
Figure BDA0004002000260000064
current for the line-to-ground branch; u (U) N Is the rated voltage of the power grid; b (B) y Is the opposite sodium of the submarine cable.
The loss of the submarine cable conductor can be calculated by the following formula:
Figure BDA0004002000260000071
the susceptance branch power calculation method of the parallel connection at the node 1 is the same as the susceptance branch power of the parallel connection at the node 2, and the following formula is adopted:
Figure BDA0004002000260000072
in the method, in the process of the invention,
Figure BDA0004002000260000073
current for the line-to-ground branch.
Therefore, the line head-end node power is:
Figure BDA0004002000260000074
the power flowing through the impedance branch of the line is
Figure BDA0004002000260000075
Marked as->
Figure BDA0004002000260000076
Then
Figure BDA0004002000260000077
Under the condition that the voltage and the power of the head end of the line are known, the voltage value of the end node can be calculated backwards, and the total active power loss is calculated: />
Figure BDA0004002000260000078
U in the above 1 R is the head end voltage L Is sea cable resistance, X L For sea cable reactance, P 2 For the end active power, Q 2 For terminal reactive power, Δq y1 Delta Q is the reactive power of the susceptance branch at the head-end node y2 Is the reactive power of the susceptance branch at the end node. When the load of the system is large, the charging power generated by the submarine cable can be absorbed by the load, so that a large amount of reactive power cannot flow in the line; when the load of the system is smaller and the charging power of the submarine cable is larger, a large amount of capacitive reactive power can be injected into the power grid, and even reactive power dumping occurs, so that the active power loss of the line is increased.
Still referring to the pi equivalent circuit of the submarine cable line shown in fig. 2 when considering the voltage relationship on the line, the following relationship is satisfied between the line node 1 and the node 2 under the condition of neglecting a large amount of capacitive reactive power generated by the submarine cable:
Figure BDA0004002000260000081
in the formula DeltaU 1 Is the longitudinal component of the line voltage drop; δU (delta U) 1 Is the corresponding transverse component. In general, δU 1 Is much smaller than DeltaU 1 Therefore, this value can be ignored when calculating the node voltage magnitude. Thus, the node voltage magnitude may be represented by:
Figure BDA0004002000260000082
u in the above 1 Is the head-end voltage, P 1 For head-end active power, Q 1 R is the reactive power of the head end L Is sea cable resistance, X L Is the sea cable reactance.
When the line terminal is in an idle or light load state, the reactive power of the first section of the line is a negative value when the capacitive reactive power brought by the line susceptance is large, and the reactance of the line is far greater than the resistance, so that the value of the longitudinal component of the voltage drop is a negative number, and the condition that the voltage of the line terminal is higher than the voltage of the first section of the line occurs. When the value of the voltage drop longitudinal component is large, the condition of voltage out-of-limit occurs at the tail end of the line, and the voltage value at the moment is not in a specified fluctuation range, so that whether the power grid can stably operate is unknown, and the power quality is greatly influenced.
Step 3: presetting standby sites of a plurality of island distribution network static var compensators according to the analysis result in the step 2; the process is as follows:
in order to study the influence of reactive compensation on the power grid loss caused by cabling, the invention selects a regional power grid which is more typical, has larger charging power and is older and incomplete in reactive compensation device and mainly takes PL change-SJW change as the main part for study. The regional grid connection is shown in fig. 3.
In order to facilitate the selection of the position of the subsequent reactive power compensation device and the calculation of the power flow, the line, the transformer and the connected load are subjected to equivalent processing, the node numbers are marked at the positions of all the nodes, a specific equivalent circuit diagram is shown in fig. 4, and specific parameter conditions are shown in the following table.
Table 1 transformer substation parameter conditions
Figure BDA0004002000260000091
The high-voltage side of the PL transformer, namely node 2, the low-voltage side of the PL transformer, namely node 3, and the high-voltage side of the SJW transformer, namely node 12, are all nodes for installing new reactive power compensation devices, and in order to avoid larger loss caused by the flowing of reactive power in a line, the reactive power compensation devices can be respectively installed at the three nodes.
Scheme one: the reactive power compensation device is installed at the high voltage side of the PL transformer, namely at node 2. The installation schematic is shown in fig. 5.
Scheme II: the reactive power compensation device is installed at node 11, which is the low-voltage side of PL transformer 3 #. The installation schematic is shown in fig. 6.
Scheme III: the reactive compensation device is installed at the high voltage side of the SJW transformer, i.e. at node 12. The installation schematic is shown in fig. 7.
(3) Establishing an objective function with the aim of reducing active power loss, and establishing load flow balance, node voltage and position constraint conditions according to the network operation state;
step 4: and establishing an objective function with the aim of reducing active power loss, and establishing constraint conditions according to the network operation state. Wherein the objective function: considering the charging power generated by laying the submarine cable, the main transformers in the substations at the two ends of the submarine cable are provided with reactive compensation devices with different capacities so as to meet reactive balance in a power grid, the different reactive compensation capacities are also one of the influencing factors of the power grid loss, and the power grid loss and the reactive compensation capacity show a nonlinear relation. The active power loss can reflect the power grid loss condition most directly, so that the sum of the active losses of the island region power grid is determined to be minimum as an objective function, and the specific function is shown as the following formula:
Figure BDA0004002000260000101
/>
wherein P is loss_m Active power loss on branch m of the distribution network; l is the total branch number of the power distribution network; i m Is the current on branch m; r is R m Is the resistance of branch m.
Wherein the constraints include the following:
1. equation constraint: the equality constraint here is a load flow balance constraint, namely when a reactive compensation device is connected to a certain node and performs corresponding compensation, the load flow at the node should meet the equality constraint shown in the following formula:
Figure BDA0004002000260000102
Figure BDA0004002000260000103
wherein P is Gi 、Q Gi Active and reactive power output for node i; p (P) Li 、Q Li Active and reactive loads at node i, respectively; q (Q) BCi The reactive capacity compensated by the reactive compensation device at the node i is positive when the compensation capacity is inductive reactive, and negative when the compensation capacity is negative; u (U) i Is the voltage at node i; y is Y ij Is the admittance between node i and node j.
2. Inequality constraint: the inequality constraint here is a node voltage constraint, and the reactive power of the system may cause a voltage out-of-limit condition in the low-valley load, so when balancing the reactive power of the system, the condition that each node voltage fluctuates within an allowable range needs to be satisfied, so that the stable operation of the system is ensured in the condition of reducing the reactive power of the power grid, and the node voltage constraint should satisfy the inequality as follows:
U imin ≤U i ≤U imax
in U imin 、U imax The voltage at node i is the minimum and maximum, respectively.
3. Position constraint: the installation location of the reactive compensation device has been discussed in step 2, resulting in an alternative, and therefore, an optimal node of the 3 alternative nodes is selected, i.e. the following formula is required:
i BC ∈S BC
wherein i is BC The node is the last node installed for the reactive power compensation device; s is S BC Is an alternative set of installation nodes for the reactive compensation device.
(4) And according to the structure and connection condition of the regional distribution network, MATIPOWER is used for carrying out load flow calculation to obtain the output conditions of the regional reactive power compensation device and the traditional reactive power compensation device, and a reactive power compensation scheme is selected to solve the problem of loss of the island distribution network.
Step 5: and (3) carrying out power flow calculation according to the structure and connection condition of the regional distribution network to obtain the output condition of the regional static var compensator and the traditional reactive power compensation device, and selecting the standby site of the static var compensator of the island distribution network preset in the step (3). When the system is in the electricity consumption peak period, the active power and the reactive power at each node are relatively large, and reactive power on-site balance compensation needs to be performed in time in order to avoid reactive power flowing in a line. In general, most of loads in a power grid are inductive, so a large amount of capacitive reactive power needs to be input, and therefore, a parallel capacitor at the low-voltage winding side of each main transformer and a newly added reactive power compensation device are all control objects. Considering the 3 positions of the reactive compensation device, the active power loss results are shown in fig. 8, and the total power loss is shown in fig. 9.
As can be seen from comparing the loss results of fig. 8 and fig. 9, after the compensation device is installed, the active power loss on each branch is smaller than that before the installation, which indicates that the reactive power compensation device is installed to perform reactive power compensation to effectively reduce the grid loss, and the total loss of the grid before the compensation is 1153kW. Comparing 3 schemes of SVG installation positions, it can be found that although any scheme has the effect of reducing the network loss, the network loss is 964kW when a scheme-based reactive power compensation device is installed at the node 2, the network loss can be reduced to 956.6kW when a scheme-based reactive power compensation device is installed at the node 11, and the network loss is 1.100.3 kW when a scheme-based reactive power compensation device is installed at the node 12. It can be seen that the loss reduction effect of the second scheme is better than that of the first scheme and the third scheme.
The peak time voltage conditions at each node are shown in fig. 10. As can be seen from fig. 10, the voltage of the node before installing the compensation device fluctuates greatly, and the voltage of some nodes is already lower than the lower limit value of the voltage, compared with the case before installing the compensation device. After the compensation device is installed, the fluctuation of the node voltage is obviously improved. Comparing the 3 SVG installation schemes, it can be found that when the scheme two reactive compensation device is adopted to install at the node 11, the voltage is within the deviation range, the fluctuation is minimum and most of the node voltages tend to be stable.
And by combining the voltage of each node and the active power loss of the power grid, the effect is optimal when the reactive power compensation device of the scheme II is arranged at the node 11, namely the PL transformer main transformer 3# low-voltage side. When the compensation device is not installed, the loss of the power grid is 1153kWh, the total loss of the power grid is 956.6kWh after the scheme II is adopted, the loss of the power grid is reduced by 196.4kWh, and the loss reduction rate reaches 17.03%. In this case, the force conditions of the respective compensation devices are shown in the following table.
Table 2 scheme two peak load stage output of each compensating device
Figure BDA0004002000260000121
The actual installation position of the reactive compensation device can be finally determined according to the method.
The island distribution network optimization operation method based on reactive compensation is a specific embodiment of the invention, has shown the substantial characteristics and the progress of the invention, and can be subjected to equivalent modification in the aspects of shape, structure and the like according to the actual use requirement under the teaching of the invention, and the equivalent modification is within the protection scope of the scheme.

Claims (10)

1. The island power distribution network optimizing operation method based on reactive compensation is characterized by comprising the following steps of: at least comprising the steps of:
step 1: acquiring a radiation network model;
step 2: analyzing the loss and line voltage change of sea cable laying on the island power distribution network through a radiation network model;
step 3: presetting standby sites of a plurality of island distribution network static var compensators according to the analysis result in the step 2;
step 4: establishing an objective function with the aim of reducing active power loss, and establishing constraint conditions according to the network operation state;
step 5: and (3) carrying out power flow calculation according to the structure and connection condition of the regional distribution network to obtain the output condition of the regional static var compensator and the traditional reactive power compensation device, and selecting the standby site of the static var compensator of the island distribution network preset in the step (3).
2. The island-in-sea power distribution network optimized operation method based on reactive power compensation according to claim 1, wherein: in step 2, under the condition of knowing the voltage and power of the line head end, the voltage value of the end node can be calculated backward, and the total active power loss is calculated:
Figure FDA0004002000250000011
u in the above 1 R is the head end voltage L Is sea cable resistance, X L For sea cable reactance, P 2 For the end active power, Q 2 For terminal reactive power, Δq y1 Delta Q is the reactive power of the susceptance branch at the head-end node y2 Is the reactive power of the susceptance branch at the end node.
3. The island-in-sea power distribution network optimized operation method based on reactive power compensation according to claim 1, wherein: in step 2, the node voltage at the end of the line is represented by the following formula:
Figure FDA0004002000250000021
u in 1 Is the head-end voltage, P 1 For head-end active power, Q 1 R is the reactive power of the head end L Is sea cable resistance, X L Is the sea cable reactance.
4. The island-in-sea power distribution network optimized operation method based on reactive power compensation according to claim 1, wherein: in the step (3) of the process,
the preset position is a regional power grid based on PL change-SJW change, and the line, the transformer and the connected load are subjected to equivalent processing, and node numbers are marked at each node.
5. The island-in-sea power distribution network optimized operation method based on reactive power compensation according to claim 1, wherein: in step 4, the objective function is specifically:
Figure FDA0004002000250000022
wherein P is loss_m Active power loss on branch m of the distribution network; l is the total branch number of the power distribution network; i m Is the current on branch m; r is R m Is the resistance of branch m.
6. The island-in-sea power distribution network optimized operation method based on reactive power compensation according to claim 1, wherein: step 4 constraints include equality constraints, inequality constraints, and position constraints.
7. The reactive compensation-based island-in-sea power distribution network optimal operation method according to claim 6, wherein: the equality constraint is a load flow balance constraint, namely when a reactive compensation device is connected to a certain node and performs corresponding compensation, the load flow at the node should meet the equality constraint shown in the following formula:
Figure FDA0004002000250000023
Figure FDA0004002000250000024
wherein P is Gi 、Q Gi Active and reactive power output for node i; p (P) Li 、Q Li Active and reactive loads at node i, respectively; q (Q) BCi The reactive capacity compensated by the reactive compensation device at the node i is positive when the compensation capacity is inductive reactive, and negative when the compensation capacity is negative; u (U) i Is the voltage at node i; y is Y ij Is the admittance between node i and node j.
8. The reactive compensation-based island-in-sea power distribution network optimal operation method according to claim 6, wherein: the inequality constraint is a node voltage constraint that should satisfy the inequality as shown below:
U imin ≤U i ≤U imax
in U imin 、U imax The voltage at node i is the minimum and maximum, respectively.
9. The reactive compensation-based island-in-sea power distribution network optimal operation method according to claim 6, wherein: the location constraint is that an optimal node is selected from the alternatives generated in step 3, that is, the following formula needs to be satisfied:
i BC ∈S BC
wherein i is BC The node is the last node installed for the reactive power compensation device; s is S BC Is an alternative set of installation nodes for the reactive compensation device.
10. The island in sea distribution network optimized operation method based on reactive power compensation according to any one of claims 7-9, wherein: and finally obtaining the output conditions of the static reactive compensator and the traditional reactive compensation device in the region after carrying out power flow calculation according to specific constraint conditions, and carrying out fine tuning after selecting the preset standby site of the static reactive compensator of the island power distribution network.
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* Cited by examiner, † Cited by third party
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CN117559460A (en) * 2023-11-17 2024-02-13 国网吉林省电力有限公司长春供电公司 Middle-low voltage cloud edge cooperative voltage control method based on fusion terminal

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