CN110460095B - Household photovoltaic grid-connected inverter distributed control method based on voltage sensitivity matrix - Google Patents

Household photovoltaic grid-connected inverter distributed control method based on voltage sensitivity matrix Download PDF

Info

Publication number
CN110460095B
CN110460095B CN201910725267.XA CN201910725267A CN110460095B CN 110460095 B CN110460095 B CN 110460095B CN 201910725267 A CN201910725267 A CN 201910725267A CN 110460095 B CN110460095 B CN 110460095B
Authority
CN
China
Prior art keywords
voltage
node
control
power
nodes
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
CN201910725267.XA
Other languages
Chinese (zh)
Other versions
CN110460095A (en
Inventor
唐金锐
张明浩
熊斌宇
李旸
侯慧
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Wuhan University of Technology WUT
Original Assignee
Wuhan University of Technology WUT
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Wuhan University of Technology WUT filed Critical Wuhan University of Technology WUT
Priority to CN201910725267.XA priority Critical patent/CN110460095B/en
Publication of CN110460095A publication Critical patent/CN110460095A/en
Application granted granted Critical
Publication of CN110460095B publication Critical patent/CN110460095B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • 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
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B10/00—Integration of renewable energy sources in buildings
    • Y02B10/10—Photovoltaic [PV]
    • 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
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy
    • Y02E10/56—Power conversion systems, e.g. maximum power point trackers

Abstract

The invention relates to a low-voltage distribution network technology, in particular to a household photovoltaic grid-connected inverter distributed control method based on a voltage sensitivity matrix, which comprises the following steps: establishing a network structure model of the low-voltage distribution network; selecting a voltage priority control node in the power distribution network; selecting the roof photovoltaic control of all the voltage priority control nodes as a power factor-active output control mode, wherein the control mode starts to output reactive power when the active output of the photovoltaic system reaches a starting value; according to the descending order of the voltage priority control nodes in the nodes with large influence weight on the voltage, determining the power factor threshold constraint conditions of the voltage priority control nodes, and constructing a low-voltage distribution network voltage control model by taking the minimum sum of the output reactive power of the photovoltaic systems at all the voltage priority control nodes as a target, thereby determining the power factor control value of the roof photovoltaic inverter at each voltage priority control node. The method ensures the coordinated control of each node during distributed control and reduces the network loss during reactive compensation control.

Description

Household photovoltaic grid-connected inverter distributed control method based on voltage sensitivity matrix
Technical Field
The invention belongs to the technical field of low-voltage distribution networks, and particularly relates to a household photovoltaic grid-connected inverter distributed control method based on a voltage sensitivity matrix.
Background
Distributed photovoltaic power generation is one of main technical measures for further improving the permeability of new energy in China.
Since typical residential electrical loads do not match the rooftop photovoltaic power generation system output power, the voltage of a partial node in the low-voltage distribution network may exceed an allowable upper limit value during the day. Due to the high resistance-reactance ratio of the low-voltage distribution line, the voltage regulation method of the low-voltage distribution network can be divided into two categories: the control method based on active power reduction and the control method based on reactive power compensation. The control method based on reactive power compensation is the most economical low-voltage distribution network voltage regulation method at present. In the existing research, all roof photovoltaic grid-connected inverters adopt the same control parameters, and the difference of each node is not taken into account. In fact, the reactive power variation of any node has different weight on the voltage influence of the whole low-voltage distribution network, so that different control strategies should be adopted for the household photovoltaic inverter at the installation position according to the different node positions, so as to optimize the total output reactive power and reduce the system network loss.
Disclosure of Invention
The invention aims to provide a method for determining respective control parameters of photovoltaic inverters installed at different nodes, controlling the voltage of the nodes of a low-voltage distribution network within an allowable range, and reducing the total output reactive power of the photovoltaic inverters so as to reduce the network loss.
In order to realize the purpose, the invention adopts and adopts the technical scheme that: the voltage sensitivity matrix-based distributed control method for the household photovoltaic grid-connected inverter comprises the following steps:
step 1, establishing a network structure model of a low-voltage distribution network, and establishing a voltage-reactive sensitivity matrix according to impedance information of each line of the low-voltage distribution network;
step 2, according to the voltage-reactive sensitivity matrix and by combining load information of each node, calculating the influence weight W of reactive power change values of each node on the voltage of the whole low-voltage distribution network, and selecting a voltage priority control node in the distribution network;
step 3, selecting the roof photovoltaic control of all voltage priority control nodes as a power factor-active output control mode, wherein the control mode starts to output reactive power when the active output of the photovoltaic system reaches a starting value, and the starting value is determined on the condition that any node of the power distribution network has voltage out-of-limit;
and 4, determining a power factor threshold constraint condition according to the descending order of the voltage priority control nodes in the nodes with large voltage influence weight, and constructing a low-voltage distribution network voltage control model by taking the minimum sum of the reactive power output by the photovoltaic system at all the voltage priority control nodes as a target, so as to determine the power factor control value of the roof photovoltaic inverter at each voltage priority control node.
In the household photovoltaic grid-connected inverter distributed control method based on the voltage sensitivity matrix, the specific method for establishing the low-voltage distribution network structure model in the step 1 is as follows:
step 1.1, the number of nodes of the power distribution network is N and Z i For the branch impedance, P, from node i-1 to node i i +jQ i Is the load of node i, P i For the loaded active power of node i, Q i Load reactive power for node iRate, determining the upper limit allowable value of voltage as U max Determining the lower limit allowable value of the voltage as U min ；i∈[1,N]；
And determining that the voltage of each node of the power distribution network should meet the following requirements by using the load of each node and the branch impedance:
Figure BDA0002158700640000021
in the formula of U i Is the voltage at node i, [ theta ] CN0,i Is a collection of lines and nodes on the path from node 0 to node i, P l And Q l Respectively representing active power and reactive power transmitted from a node l-1 to a node l;
step 1.2, obtaining a power distribution network active and reactive sensitivity matrix according to the load data of each node as follows:
Figure BDA0002158700640000031
Figure BDA0002158700640000032
in the formula
Figure BDA0002158700640000033
Representing the voltage-active sensitivity, U, of node i to node j i Is the voltage of node i, P j And Q j Respectively represents the active power and the reactive power of the node j, theta CN0,i ∩Θ CN0,j Is the intersection of the line and node on the path from node 0 to node i and node 0 to node j, U l Is the voltage data of node l, R l And X l Representing resistance and reactance data, respectively, of the load at node l.
In the voltage sensitivity matrix-based household photovoltaic grid-connected inverter distributed control method, step 2, calculating the influence weight W of each node reactive power change value on the voltage of the whole low-voltage distribution network, and selecting a distribution network voltage priority control node specifically comprises the following steps:
step 2.1, calculating by the formula (3) to obtain the low-voltage distribution network reactive sensitivity matrix S with n nodes U-Q Comprises the following steps:
Figure BDA0002158700640000034
calculating the total voltage adjustment V according to the formula (4) adjust ：
Figure BDA0002158700640000035
Step 2.2, keeping the voltage within a reasonable range with the minimum output reactive power, and setting the voltage influence weight W i The method is used for reflecting the influence of the reactive power change of a single node on the global voltage, and specifically comprises the following steps:
Figure BDA0002158700640000036
in the formula
Figure BDA0002158700640000037
The voltage-reactive sensitivity of the node i +1 to the node j +1 is represented, and n represents the number of nodes of the power distribution network;
step 2.3, rearranging the nodes to form a set K according to the voltage influence weight from large to small, and controlling the voltage operation condition of each node in the power distribution network by controlling the nodes with higher voltage influence weight, wherein the number p of the voltage priority control nodes should meet the constraint condition:
Figure BDA0002158700640000041
in the formula, n represents the number of nodes of the power distribution network, K i Representing the magnitude of the ith voltage influencing weight in the new set K.
In the household photovoltaic grid-connected inverter distributed control method based on the voltage sensitivity matrix, the active output starting value in the step 3 is obtained by the following method: according to photovoltaic output and load conditions of each node, the power and voltage of each node are used as constraint conditions, and a preliminary power flow calculation model is constructed by using a forward-backward substitution algorithm:
Figure BDA0002158700640000042
in the formula P load,j And Q load,j Respectively represents the active and reactive load size of the node j, theta CNi,n Representing a set of nodes, P, between node i and end node n line,i And Q line,i Representing the active and reactive power, P, transmitted between node i-1 to node i start,j The active output starting value of the photovoltaic system at the node j is represented, and delta is a deviation value between the node voltage and the voltage limiting value; delta is 0.01p.u., and the active output starting value P of the photovoltaic system at all voltage priority control points is determined by using a forward-backward substitution algorithm through a formula (8) start 。
In the foregoing method for decentralized control of a photovoltaic grid-connected inverter for a user based on a voltage sensitivity matrix, the step 4 of determining a power factor control value of a rooftop photovoltaic inverter at each voltage priority control node includes the following steps:
step 4.1, calculating the number p of voltage-preferred control nodes according to the active and reactive sensitivity matrixes established by the formulas (2) and (3) and the formula (7), and calculating a control parameter threshold condition which should be met by voltage control in the voltage-preferred control node j by combining a power factor-active output control mode, wherein the power factor PF of the voltage-preferred control node j j The calculation formula of (2) is as follows:
Figure BDA0002158700640000051
(9) In the formula PF ct,j Maximum power angle, P, set for node j rated Rated output active power, P, for node photovoltaic start，j When starting voltage regulation control for node jWork power;
step 4.2, after the power factor control value of the voltage optimal control node j is obtained, the voltage of each node is calculated by using the voltage sensitivity, and the method specifically comprises the following steps:
Figure BDA0002158700640000052
in the formula of U i ' is the voltage magnitude of node i after iteration, U i Is the initial voltage magnitude of node i;
power factor PF of nodes ordered by j in high permeability rooftop photovoltaic systems j Determined by the voltage sensitivity and the amount of voltage adjustment required;
4.3, according to the reactive power change at the voltage priority control node, the voltage influence weights are arranged in a descending order, and the power factor control value of the voltage priority control node is analyzed according to the following formula:
Figure BDA0002158700640000061
wherein r represents the number of the sequence numbers of the nodes j forming the set K in the formula (7), P pv Representing the output active power, PF, of a photovoltaic power generation system set For a preset power factor parameter, PF, at the maximum voltage influence weight node ct,j Represents the power factor threshold, U, of the photovoltaic inverter at node j lim,i A defined voltage value for node i; delta is a deviation value between the node voltage and the voltage limit value; delta is 0.01p.u., the node voltage is calculated by using a forward-backward substitution algorithm to obtain a power factor parameter PF preset at the node with the maximum voltage influence weight set And thereby determine the power factor parameter values at all preferred control nodes.
The method has the advantages that (1) the voltage priority control node is determined according to the weight of the influence of the reactive power variation of each node on the voltage of the whole low-voltage distribution network, and compared with a low-voltage distribution network voltage regulation scheme in which all the nodes are control nodes, the control strategy is simplified;
(2) The voltage priority control node adopts a power factor-active output control mode, and the power factor control values of the priority control nodes are different, so that the coordination control of the nodes in distributed control is ensured. When the voltage of each node is controlled to be within the range of the allowed value, the total output reactive power is minimum, and the network loss during reactive compensation control is reduced.
Drawings
Fig. 1 is a flow chart of a distributed control strategy of a low-voltage distribution network according to an embodiment of the invention;
fig. 2 (a) is a schematic diagram of a typical low voltage distribution network according to an embodiment of the present invention;
FIG. 2 (b) is a graph of the load of the residents according to one embodiment of the present invention;
FIG. 2 (c) is a photovoltaic output curve according to one embodiment of the present invention;
fig. 3 is a voltage variation curve of each node of the low-voltage distribution network under different control parameters according to an embodiment of the present invention;
fig. 4 is a reactive output curve of each control node of the low-voltage distribution network under different control parameters according to an embodiment of the present invention;
fig. 5 is a reactive output curve of each control node of the low-voltage distribution network under the same control parameter according to an embodiment of the invention.
Detailed Description
Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.
The embodiment provides a household photovoltaic grid-connected inverter distributed control method based on a voltage sensitivity matrix, which adopts different control parameters for photovoltaic inverters installed at different nodes, can provide a control strategy for the operation condition of a roof photovoltaic inverter, ensures that the node voltage of a low-voltage distribution network operates within a reasonable range, and simultaneously reduces the total output reactive power of the roof photovoltaic inverter in the low-voltage distribution network.
Firstly, calculating a voltage-reactive power sensitivity matrix according to load data of a low-voltage distribution network; then, according to the voltage-reactive sensitivity matrix of each node of the low-voltage distribution network, calculating the weight of the voltage influence of any node reactive variable quantity on the whole low-voltage distribution network and arranging the voltage influence weight in a descending order; then, 20% of the number of the nodes of the low-voltage distribution network is selected and rounded to be used as the total number of voltage priority control nodes, and according to the total number, the nodes with large influence weight on the voltage are selected in a descending order to be determined as the priority control nodes; selecting the roof photovoltaic control at all priority control nodes as a power factor-active output control mode, wherein the whole control mode starts to output reactive power when the active output of the photovoltaic system reaches a starting value, the active output starting values of the photovoltaic system at all the priority control nodes are equal, and the starting value is determined on the condition that any node of the whole power distribution network has voltage out-of-limit; the power factor control values of the roof photovoltaic inverters at all priority control nodes are different, for a specific priority control node, the power factor threshold constraint condition is determined according to the sequence in descending order arrangement of nodes with large voltage influence weight of the control point, a low-voltage distribution network voltage control model is constructed by taking the minimum sum of the output reactive power of the photovoltaic systems at all the priority control nodes as a target, and the power factor control value of the roof photovoltaic inverter at each priority control node is determined according to the minimum sum; the active output starting value and the power factor control value of the rooftop photovoltaic inverter of each priority control node in the priority control node and the power factor-active output control mode jointly form a distributed control strategy of the household photovoltaic grid-connected inverter provided by the embodiment.
The embodiment is realized by the following technical scheme, as shown in fig. 1, a voltage sensitivity matrix-based distributed control method for a household photovoltaic grid-connected inverter comprises the following steps:
s1: establishing a network structure model of the low-voltage distribution network, and establishing a voltage-reactive power sensitivity matrix according to impedance information of each line of the low-voltage distribution network;
s2: according to the sensitivity matrix, combining the load information of each node, calculating the influence weight W of the reactive power change value of each node on the voltage of the whole low-voltage distribution network, and selecting a voltage priority control node in the distribution network;
s3: the roof photovoltaic control at all voltage priority control nodes is selected as a power factor-active output control mode, the whole control mode starts to output reactive power when the active output of the photovoltaic system reaches a starting value, the active output starting values of the photovoltaic system at all the voltage priority control nodes are equal, and the starting value is determined on the condition that any node of the whole power distribution network has voltage out-of-limit.
S4: the power factor control values of the roof photovoltaic inverters at each control point are different, for a specific control point, the power factor threshold constraint condition of the control point is determined according to the sequence of the control point in the descending order arrangement of the nodes with large influence weight on the voltage, a low-voltage distribution network voltage control model is constructed by taking the minimum sum of the output reactive power of the photovoltaic systems at all the control points as a target, and the power factor control value of the roof photovoltaic inverter at each control point is determined according to the minimum sum.
S1.1, the establishment of the power distribution network structure model in S1 comprises the following steps:
the number of the nodes of the power distribution network is N and Z i For the branch impedance, P, from node i-1 to node i i +jQ i Is the load of node i, P i For the loaded active power of node i, Q i Determining the upper limit allowable value of voltage as U for the load reactive power of the node i max Determining the lower limit allowable value of the voltage as U min ；i∈[1,N]；
According to the network structure model, the voltage of each node of the power distribution network can be determined to meet the following conditions by using the load of each node and the branch impedance:
Figure BDA0002158700640000091
in the formula of U i Is the voltage at node i, [ theta ] CN0,i Is a collection of lines and nodes on the path from node 0 to node i, P l And Q l Respectively representing the active and reactive power transmitted by the path from the node l-1 to the node l.
Therefore, the active and reactive sensitivity matrix of the power distribution network can be obtained according to the load data of each node, and the matrix is specifically as follows:
Figure BDA0002158700640000092
Figure BDA0002158700640000093
in the formula
Figure BDA0002158700640000094
Representing the voltage-active sensitivity, U, of node i to node j i Is the voltage of node i, P j And Q j Respectively represents the active power and the reactive power of the node j, theta CN0,i ∩Θ CN0,j Is the intersection of the line and node on the path from node 0 to node i and node 0 to node j, U l Is the voltage data of node l, R l And X l Representing resistance and reactance data, respectively, of the load at node l.
And S2.1, calculating the voltage influence weight W of each node in S2, and specifically selecting the key nodes for voltage control in the power distribution network as follows:
the reactive sensitivity matrix S of the low-voltage distribution network with n nodes can be obtained through calculation of the formula (3') S1.1 U-Q As follows:
Figure BDA0002158700640000101
then, as the reactive power change of each node will affect the voltages of all other nodes of the power distribution network, the total voltage adjustment V can be calculated adjust ：
Figure BDA0002158700640000102
Therefore, the relationship between the reactive power change of each node and the global voltage adjustment amount can be obtained, and the voltage influence weight W should be set in order to keep the voltage within a reasonable range with the minimum output reactive power i The method is used for reflecting the influence of the reactive power change of a single node on the global voltage, and specifically comprises the following steps:
Figure BDA0002158700640000103
in the formula
Figure BDA0002158700640000104
The voltage-reactive sensitivity of the node i +1 to the node j +1 is represented, and n represents the number of nodes of the power distribution network.
In the actual control, as all the nodes are controlled, the control strategy is quite complex, and the voltage of an output node is not stable enough in the control operation process, the concept of voltage priority control nodes is introduced, namely, the nodes are rearranged from large to small according to the voltage influence weight to form a set K, and the voltage operation condition of each node in the power distribution network is controlled to a large extent by controlling the nodes with higher voltage influence weight, wherein the number of the voltage priority control nodes should meet the constraint condition:
Figure BDA0002158700640000105
wherein p represents the number of selected key nodes, n represents the total number of nodes of the distribution network, and K i Representing the magnitude of the ith voltage influencing weight in the new set K.
And S3.1, in the voltage regulation process of the voltage priority control node determined in S3, a power factor-active output control mode is adopted. The active output starting value of the photovoltaic system of each voltage priority control node in the power factor-active output control mode is as follows:
according to the photovoltaic output and the load condition of each node (the coverage area of the low-voltage distribution network is limited, the photovoltaic output of each node can be approximately treated as equal), the power and the voltage of each node are used as constraint conditions, and a preliminary power flow calculation model is constructed by utilizing a forward-backward substitution algorithm:
Figure BDA0002158700640000111
in the formula P load,j And Q load,j Respectively represent the active and reactive load of the node j, theta CNi,n Representing a set of nodes, P, between node i and end node n line,i And Q line,i Representing the active and reactive power, P, transmitted between node i-1 and node i start,j Is the active output starting value of the photovoltaic system at the node j, and delta is the node voltage and the voltage limit value (here, the upper voltage limit allowable value U) max ) The deviation value therebetween.
Because the photovoltaic output of each node of the low-voltage distribution network is approximately equal, P of all the nodes j start,j Can be considered equal and is P start . At the moment, according to the given value of delta, 0.01p.u. is taken, and by utilizing a forward-backward substitution algorithm, the active output starting value P of the photovoltaic system at all voltage priority control points can be determined through the formula start 。
S4.1, in the voltage regulation process of the key node, determining the power factor control value of the roof photovoltaic inverter of each voltage priority control node in a power factor-active output control mode:
according to the active and reactive sensitivities established in S1.1 and the number p of the key nodes calculated in S2.1, a control parameter threshold value condition which should be met by voltage control in the voltage priority control node can be calculated by combining a power factor-active output control mode. Voltage priority control node j power factor PF j The calculation formula of (2) is as follows:
Figure BDA0002158700640000121
in the formula PF ct,j Maximum power angle, P, set for node j rated Rated output active power, P, for node photovoltaic start，j And starting voltage regulation control on the node j to obtain the active power.
Therefore, with the power factor control value of the voltage priority control node, the voltage magnitude of each node can be calculated by using the voltage sensitivity, specifically:
Figure BDA0002158700640000122
in the formula of U i ' is the voltage magnitude of node i after iteration, U i Is the initial voltage magnitude of node i.
Thus, in a high permeability rooftop photovoltaic system, the power factor PF of the nodes ordered by j j Will be determined by the voltage sensitivity and the amount of voltage adjustment required.
Considering that the nodes have difference in the operation process, the voltage influence weight is subjected to descending order according to the reactive power change at the voltage priority control node, and the power factor control value of the voltage priority control node is analyzed according to the following formula:
Figure BDA0002158700640000123
wherein r represents the number of the sequence number of the node j forming the set K in S2.1, P pv Representing the output active power, PF, of a photovoltaic power generation system set For a power factor parameter, PF, preset at the maximum voltage influence weight node ct,j Represents the power factor threshold, U, of the photovoltaic inverter at node j lim,i Is a defined voltage value of node i. Delta is the node voltage and the voltage limit (here, the upper voltage limit allowed value U) max ) The deviation value therebetween.
At the moment, according to the given value of delta, 0.01p.u. is taken, the node voltage is calculated by using a forward-backward substitution algorithm, and the power factor parameter PF preset at the node with the maximum voltage influence weight can be obtained set And then determining power factor parameter values at all control nodes.
In specific implementation, as shown in fig. 2 (a), a 220V low-voltage distribution network system is connected with residential loads and rooftop photovoltaics at all nodes except node 1.
Firstly, a network structure model of the low-voltage distribution network is established, and a voltage-reactive sensitivity matrix is established according to impedance information of each line of the low-voltage distribution network. Obtaining the number of nodes of the power distribution network as N and the branch impedance as Z i = (0.65+j0.412) omega/km, node iLoad of P i +jQ i ，P i For the loaded active power of node i, Q i Determining an upper voltage limit of U for the reactive power of the load at node i max Determining the lower limit of voltage as U min The photovoltaic output data is alpha, and the household load change data is beta;
Figure BDA0002158700640000131
then, according to the load information of each node, the active and reactive sensitivity matrix of the power distribution network can be established as follows:
Figure BDA0002158700640000132
Figure BDA0002158700640000133
in the formula
Figure BDA0002158700640000134
Representing the voltage-active sensitivity, U, of node i to node j i Is the voltage of node i, P j And Q j Respectively represents the active power and the reactive power of the node j, theta CN0,i ∩Θ CN0,j Is the intersection of node 0 to node i and the line and node on the path from node 0 to node j, U l Is the voltage data of node l, R l And X l Representing resistance and reactance data, respectively, of the load at node l.
From this it can be obtained that the reactive sensitivity matrix is:
Figure BDA0002158700640000141
and secondly, calculating the voltage influence weight W of each node, and accordingly selecting a key node for voltage control in the power distribution network.
Through the first calculation, n nodes can be obtainedLow voltage distribution network reactive sensitivity matrix S U-Q As follows:
Figure BDA0002158700640000142
then, since the reactive power change of each node will affect the voltages of all other nodes of the power distribution network, the total voltage adjustment V can be calculated adjust ：
Figure BDA0002158700640000143
Thus, the relationship between the reactive power variation of each node and the global voltage adjustment can be obtained, and the voltage can be kept within a reasonable range with the minimum output reactive power. The voltage influence weight W should be set i The method is used for reflecting the influence of the reactive power change of a single node on the global voltage, and specifically comprises the following steps:
Figure BDA0002158700640000144
in the formula
Figure BDA0002158700640000151
Representing the voltage-reactive sensitivity of node i to node j, and n representing the number of nodes of the distribution network.
The calculation method for obtaining the voltage influence weight of each node specifically comprises the following steps:
W i ＝[-6.6080 -12.2011 -16.9355 -18.7141 -19.5120 -19.5089 -21.0671 -21.8896]×10 -4
according to the second step of the determination method, the voltage sensitivity at the node 9 is the maximum value, followed by the sensitivity at the node 8.
In actual control, because control over all nodes causes a quite complex control strategy and the voltage of an output node is not stable enough in the control operation process, the voltage operation condition of each node in the power distribution network is controlled to a greater extent by controlling the node with higher voltage influence weight, and the node 9 and the node 8 are selected as voltage priority control nodes for regulating voltage according to a method for selecting the voltage priority control nodes.
Thirdly, determining the active output starting value of the roof photovoltaic inverter of the voltage priority control node in the power factor-active output control mode (the active output of the photovoltaic system starts to output reactive power when reaching the starting value):
according to the topological structure of the low-voltage distribution network given in the figure 2 (a), the residential load given in the figure 2 (b) and the photovoltaic output curve given in the figure 2 (c), the voltage of each node of the low-voltage distribution network in 24 hours is calculated, and the active output starting value control parameter P of the rooftop photovoltaic inverter of each voltage priority control node is obtained start，j The voltage at node 9 is initially close to the upper tolerance of 1.07p.u. and is uniform to 0.9425p.u.
And fourthly, determining a power factor control value of the rooftop photovoltaic inverter of the voltage priority control node in a power factor-active output control mode:
considering that the nodes have difference in the operation process, the voltage influence weight is subjected to descending order according to the reactive power change at the voltage priority control node, and the power factor control value of the voltage priority control node is analyzed according to the following formula:
Figure BDA0002158700640000161
where r represents the number of sequence numbers where the node j in the set K formed in the second step is located, P pv Representing the output active power, PF, of a photovoltaic power generation system set For a power factor parameter, PF, preset at the maximum voltage influence weight node ct,j Represents the power factor threshold, U, of the photovoltaic inverter at node j lim,i Is a defined voltage value for node i.
In practical calculation, the power factor control value PF of the node 9 can be obtained according to the formula by preferentially controlling the node 8 and the node 9 according to the selected voltage ct,9 Power factor control value PF of node 8 of 0.98p.u ct,8 0.99p.u. At this time, the voltage change curve of each node of the low-voltage distribution network is shown in fig. 3. The reactive output curves of nodes 8 and 9 are shown in fig. 4.
If the control parameters of the control nodes are consistent, the power factor control values are all 0.981 at the moment through analysis, and the low-voltage distribution network voltage can be guaranteed not to be out of limit. The reactive output curves at nodes 8 and 9 are shown in fig. 5. Comparing fig. 4 and fig. 5, the method of this embodiment can reduce the total reactive output by 11.6% compared with the conventional method using the same control parameter while ensuring that the voltage does not exceed the limit.
It should be understood that parts of the specification not set forth in detail are well within the prior art.
Although specific embodiments of the present invention have been described above with reference to the accompanying drawings, it will be appreciated by those skilled in the art that these are merely illustrative and that various changes or modifications may be made to these embodiments without departing from the principles and spirit of the invention. The scope of the invention is only limited by the appended claims.

Claims (5)

1. The voltage sensitivity matrix-based distributed control method for the household photovoltaic grid-connected inverter is characterized by comprising the following steps of:
step 1, establishing a network structure model of a low-voltage distribution network, and establishing a voltage-reactive sensitivity matrix according to impedance information of each line of the low-voltage distribution network;
step 2, according to the voltage-reactive sensitivity matrix and in combination with load information of each node, calculating the influence weight W of reactive power change values of each node on the voltage of the whole low-voltage distribution network, and selecting a voltage priority control node in the distribution network;
step 3, selecting the roof photovoltaic control of all voltage priority control nodes as a power factor-active output control mode, wherein the control mode starts to output reactive power when the active output of the photovoltaic system reaches a starting value, and the starting value is determined on the condition that any node of the power distribution network has voltage out-of-limit;
and 4, determining a power factor threshold constraint condition according to the descending order of the voltage priority control nodes in the nodes with large voltage influence weight, and constructing a low-voltage distribution network voltage control model by taking the minimum sum of the reactive power output by the photovoltaic system at all the voltage priority control nodes as a target, so as to determine the power factor control value of the roof photovoltaic inverter at each voltage priority control node.
2. The voltage sensitivity matrix-based distributed control method for the photovoltaic grid-connected inverter for the users as claimed in claim 1, wherein the specific method for establishing the network structure model of the low-voltage distribution network in the step 1 is as follows:
step 1.1, the number of nodes of the power distribution network is N and Z i For the branch impedance, P, from node i-1 to node i i +jQ i Is the load of node i, P i For the loaded active power of node i, Q i Determining the upper limit allowable value of voltage as U for the load reactive power of the node i max Determining the lower limit allowable value of the voltage as U min ；i∈[1,N]；
And determining that the voltage of each node of the power distribution network should meet the following requirements by using the load of each node and the branch impedance:
Figure FDA0002158700630000011
in the formula of U i Is the voltage at node i, [ theta ] CN0,i Is a collection of lines and nodes on the path from node 0 to node i, P l And Q l Respectively representing active power and reactive power transmitted from a node l-1 to a node l;
step 1.2, obtaining a power distribution network active and reactive sensitivity matrix according to the load data of each node as follows:
Figure FDA0002158700630000021
Figure FDA0002158700630000022
in the formula
Figure FDA0002158700630000023
Representing the voltage-active sensitivity, U, of node i to node j i Is the voltage of node i, P j And Q j Respectively represents the active power and the reactive power of the node j, theta CN0,i ∩Θ CN0,j Is the intersection of the line and node on the path from node 0 to node i and node 0 to node j, U l Is the voltage data of node l, R l And X l Representing resistance and reactance data, respectively, of the load at node l.
3. The household photovoltaic grid-connected inverter distributed control method based on the voltage sensitivity matrix as claimed in claim 2, wherein the step 2 of calculating the influence weight W of the reactive power change value of each node on the voltage of the whole low-voltage distribution network is specifically performed by the following steps of:
step 2.1, calculating by the formula (3) to obtain the reactive sensitivity matrix S of the low-voltage distribution network with n nodes U-Q Comprises the following steps:
Figure FDA0002158700630000024
calculating the total voltage adjustment V according to the formula (4) adjust ：
Figure FDA0002158700630000025
Step 2.2, keeping the voltage within a reasonable range with the minimum output reactive power, and setting the voltage influence weight W i The method is used for reflecting the influence of the reactive power change of a single node on the global voltage, and specifically comprises the following steps:
Figure FDA0002158700630000031
in the formula
Figure FDA0002158700630000032
The voltage-reactive sensitivity of the node i +1 to the node j +1 is represented, and n represents the number of nodes of the power distribution network;
step 2.3, rearranging the nodes to form a set K according to the voltage influence weight from large to small, and controlling the voltage operation condition of each node in the power distribution network by controlling the nodes with higher voltage influence weight, wherein the number p of the voltage priority control nodes should meet the constraint condition:
Figure FDA0002158700630000033
in the formula, n represents the number of nodes of the power distribution network, K i Representing the magnitude of the ith voltage influencing weight in the new set K.
4. The household photovoltaic grid-connected inverter distributed control method based on the voltage sensitivity matrix as claimed in claim 1, characterized in that the active output starting value in step 3 is obtained by the following method: according to photovoltaic output and load conditions of each node, the power and voltage of each node are used as constraint conditions, and a preliminary power flow calculation model is constructed by using a forward-backward substitution algorithm:
Figure FDA0002158700630000034
in the formula P load,j And Q load,j Respectively represent the active and reactive load of the node j, theta CNi,n Representing a set of nodes, P, between node i and end node n line,i And Q line,i Representing the active and reactive power, P, transmitted between node i-1 to node i start,j The active output starting value of the photovoltaic system at the node j is represented, and delta is a deviation value between the node voltage and the voltage limiting value; delta is taken as 0.01p.u., and all voltage priority control points are determined by the formula (8) by utilizing a forward-backward substitution algorithmActive output starting value P of photovoltaic system start 。
5. The voltage sensitivity matrix-based decentralized control method for photovoltaic grid-connected inverters for users according to claim 3, wherein the step 4 of determining the power factor control value of the rooftop photovoltaic inverter at each voltage priority control node comprises the following steps:
step 4.1, calculating the number p of voltage-preferred control nodes according to the active and reactive sensitivity matrixes established by the formulas (2) and (3) and the formula (7), and calculating a control parameter threshold condition which should be met by voltage control in the voltage-preferred control node j by combining a power factor-active output control mode, wherein the power factor PF of the voltage-preferred control node j j The calculation formula of (2) is as follows:
Figure FDA0002158700630000041
(9) In the formula PF ct,j Maximum power angle, P, set for node j rated Rated output active power, P, for node photovoltaic start，j The active power when voltage regulation control is started for the node j;
step 4.2, after the power factor control value of the voltage optimal control node j is obtained, the voltage of each node is calculated by using the voltage sensitivity, and the method specifically comprises the following steps:
Figure FDA0002158700630000042
in the formula of U i ' is the voltage magnitude of node i after iteration, U i Is the initial voltage magnitude of the node i;
power factor PF of nodes ordered by j in a high permeability rooftop photovoltaic system j Determined by the voltage sensitivity and the amount of voltage adjustment required;
4.3, according to the reactive power change at the voltage priority control node, the influence weight of the voltage is subjected to descending order, and the power factor control value of the voltage priority control node is analyzed according to the following formula:
Figure FDA0002158700630000051
wherein r represents the number of the sequence numbers of the nodes j forming the set K in the formula (7), P pv Representing the output active power, PF, of a photovoltaic power generation system set For a power factor parameter, PF, preset at the maximum voltage influence weight node ct,j Represents the power factor threshold, U, of the photovoltaic inverter at node j lim,i A defined voltage value for node i; delta is a deviation value between the node voltage and the voltage limit value; delta is 0.01p.u., the node voltage is calculated by using a forward-backward substitution algorithm to obtain a power factor parameter PF preset at the node with the maximum voltage influence weight set And thereby determine the power factor parameter values at all preferred control nodes.
CN201910725267.XA 2019-08-07 2019-08-07 Household photovoltaic grid-connected inverter distributed control method based on voltage sensitivity matrix Active CN110460095B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN201910725267.XA CN110460095B (en) 2019-08-07 2019-08-07 Household photovoltaic grid-connected inverter distributed control method based on voltage sensitivity matrix

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN201910725267.XA CN110460095B (en) 2019-08-07 2019-08-07 Household photovoltaic grid-connected inverter distributed control method based on voltage sensitivity matrix

Publications (2)

Publication Number Publication Date
CN110460095A CN110460095A (en) 2019-11-15
CN110460095B true CN110460095B (en) 2022-12-02

Family

ID=68485239

Family Applications (1)

Application Number Title Priority Date Filing Date
CN201910725267.XA Active CN110460095B (en) 2019-08-07 2019-08-07 Household photovoltaic grid-connected inverter distributed control method based on voltage sensitivity matrix

Country Status (1)

Country Link
CN (1) CN110460095B (en)

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106356856B (en) * 2016-09-18 2018-10-09 国电南瑞科技股份有限公司 A kind of Security corrective computational methods based on partition load control
CN107276096B (en) * 2017-06-28 2019-08-23 国网江苏省电力公司电力科学研究院 A kind of distribution network voltage control method of photovoltaic and air conditioner load coordination optimization
CN108599259B (en) * 2018-06-20 2021-07-20 湘潭大学 Micro-grid active operation decision method based on sensitivity analysis

Also Published As

Publication number Publication date
CN110460095A (en) 2019-11-15

Similar Documents

Publication Publication Date Title
Parizad et al. Optimal placement of distributed generation with sensitivity factors considering voltage stability and losses indices
CN106208090B (en) A kind of voltage power-less optimized controlling method and system of photovoltaic generation access
CN106549392B (en) A kind of power distribution network control method for coordinating
CN106532710B (en) The micro-capacitance sensor tide optimization method of meter and Voltage Stability Constraints
CN109004653B (en) Method for treating rural power grid overvoltage caused by photovoltaic access through active and reactive coupling
CN110350597B (en) Distribution network voltage control method based on distributed photovoltaic active-reactive optimization
CN110707680A (en) Direct-current micro-grid power accurate distribution and bus voltage deviation optimization control method
CN104158198A (en) Optimization trend control apparatus and method for power distribution network
CN113224769B (en) Multi-time-scale power distribution network voltage optimization method considering photovoltaic multi-state adjustment
CN112526262B (en) Method for judging stability of direct current sending end power grid with high-proportion new energy access
CN114759620A (en) Reactive power cooperative optimization regulation and control method, device and system for wind and light storage station group
CN110380404B (en) Power transmission network excitation system adjustment coefficient optimization setting method considering high energy consumption point load
CN108376997B (en) Active power distribution network island division method considering distributed power supply uncertainty
CN111799812B (en) Reactive voltage sensitivity-based reactive coordination control method for offshore wind farm
CN107069757B (en) A kind of mixing multi-infeed HVDC system secondary voltage control method
CN110460095B (en) Household photovoltaic grid-connected inverter distributed control method based on voltage sensitivity matrix
CN107134783B (en) Bus voltage optimization adjustment method based on sensitivity rapid screening
CN115912372B (en) Voltage control method and system for high-proportion distributed photovoltaic access distribution network
CN110544960A (en) distributed control method for improving reactive power sharing capability of island microgrid
CN109904924B (en) Distributed optimal bus voltage control method for direct-current micro-grid
CN113809732B (en) Distributed direct-current intelligent load virtual inertia control method
CN108683194A (en) A kind of droop control parameter optimization setting method promoting isolated island microgrid voltage security
CN105186557A (en) Grid-connected inverter control system and control method thereof
CN116231672A (en) Reactive power optimization method and system for fan-containing power grid based on voltage weak point identification
CN108054758A (en) New energy power station balance of voltage optimization method and storage medium

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant