A power distribution network grid connection point voltage control method considering large-scale distributed power supply
By real-time monitoring of grid connection voltage and power in the distribution network, calculating reactive power output limits and control limits, and adjusting reactive power control commands for distributed power sources, the voltage problem caused by large-scale distributed power source grid connection is solved, and grid stability and the grid access capability of photovoltaic power generation systems are improved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- STATE GRID INNER MONGOLIA EASTERN ELECTRIC POWER CO LTD TONGLIAO POWER SUPPLY CO
- Filing Date
- 2023-01-30
- Publication Date
- 2026-07-21
AI Technical Summary
Large-scale distributed power generation grid connection may lead to voltage rise or overvoltage at the grid connection point, affecting power quality and increasing equipment losses, and limiting the access of photovoltaic power generation systems.
By deploying controllers in the distribution network, the voltage, active power, and reactive power at the grid connection point are monitored in real time. The reactive power output limit and total control amount of distributed power sources are calculated, and reactive power control commands are adjusted to stabilize the voltage.
Effectively regulate the voltage at the grid connection point to avoid damage to the lines caused by excessively high or low voltage, thereby improving grid stability and the penetration rate of photovoltaic power generation systems.
Smart Images
Figure CN115912492B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of power control technology, and more specifically to a voltage control method for the grid connection point of a distribution network that takes into account large-scale distributed power sources. Background Technology
[0002] A distribution network refers to a power grid that receives electrical energy from the transmission network or regional power plants and distributes it locally or in stages according to voltage to various users through distribution facilities. It consists of overhead lines, cables, poles, distribution transformers, disconnect switches, reactive power compensators, and some auxiliary facilities, and plays an important role in distributing electrical energy within the power grid.
[0003] In a distribution network, there are typically several grid connection points. For distributed generation systems with step-up substations, the grid connection point is the high-voltage side bus or node of the step-up substation; for distributed generation systems without step-up substations, the grid connection point is the output aggregation point of the distributed generation system. Traditional power system transmission and distribution networks are designed as unidirectional transmission and distribution systems from generation units to loads. The grid connection of large-scale photovoltaic (PV) or wind power systems can potentially cause power flow reversal issues, leading to voltage increases or overvoltages at the grid connection points of various generation systems. Voltage increases not only affect the power supply quality to local loads but also increase losses in transmission and distribution equipment such as lines and transformers, causing system overload. Furthermore, they limit the number of PV systems that can be connected to the grid, impacting the penetration rate of PV systems.
[0004] Therefore, there is an urgent need for a method to control the voltage at the grid connection point in a distribution network with large-scale distributed power sources. Summary of the Invention
[0005] This application provides a voltage control method for the grid connection point of a distribution network that considers large-scale distributed power sources, which avoids damage to the line caused by excessively high or low voltage at the common grid connection point as much as possible. The technical solution is as follows.
[0006] On the one hand, a voltage control method for the grid connection point of a distribution network considering large-scale distributed power sources is provided. The method is executed by a controller in the distribution network. The distribution network includes load branches and various power source branches. Each distributed power source is connected to the common grid connection point in the distribution network through its corresponding power source branch.
[0007] The method includes:
[0008] Obtain the voltage value of the common grid connection point, the active power of each distributed power source flowing into the common grid connection point, and the reactive power of each distributed power source flowing into the common grid connection point;
[0009] When the difference between the voltage value of the common grid connection point and the reference voltage is greater than the first threshold, the reactive power output limit connected to each distributed power source is calculated based on the active power of each distributed power source flowing into the common grid connection point and the reactive power of each distributed power source flowing into the common grid connection point.
[0010] The total reactive power control amount is obtained based on the difference between the voltage value of the common grid connection point and the reference voltage;
[0011] Based on the total reactive power control and the reactive power output limit of each distributed power source, the reactive power control command of each power source branch is adjusted to control each distributed power source to respond with reactive power output according to the adjusted reactive power control command.
[0012] On another front, a voltage control device for the grid connection point of a distribution network considering large-scale distributed power sources is provided, the device comprising:
[0013] The data acquisition module is used to acquire the voltage value of the common grid connection point, the active power of each distributed power source flowing into the common grid connection point, and the reactive power of each distributed power source flowing into the common grid connection point.
[0014] The reactive power output limit calculation module is used to calculate the reactive power output limit connected to each distributed power source when the difference between the voltage value of the common grid connection point and the reference voltage is greater than a first threshold, based on the active power of each distributed power source flowing into the common grid connection point and the reactive power of each distributed power source flowing into the common grid connection point.
[0015] The reactive power control total quantity acquisition module is used to acquire the total reactive power control quantity based on the difference between the voltage value of the common grid connection point and the reference voltage.
[0016] The output adjustment module is used to adjust the reactive power control command of each power branch according to the total reactive power control and the reactive power output limit of each distributed power source, so as to control each distributed power source to respond with reactive power output according to the adjusted reactive power control command.
[0017] In one possible implementation, when the reactive power output limit of the power supply branch is positive, the reactive power of the power supply branch flows into the common grid connection point.
[0018] When the reactive power output limit of the power supply branch is negative, the reactive power of the power supply branch flows out of the common grid connection point.
[0019] In one possible implementation, the reactive power control total acquisition module is further used for:
[0020] The difference between the voltage value of the common grid connection point and the reference voltage is input into the PD controller to obtain the total reactive power control amount.
[0021] In one possible implementation, the output adjustment module is further configured to generate reactive power adjustment command deviations corresponding to each power supply branch based on the total reactive power control and the reactive power output limits of each distributed power source.
[0022] The reactive power control command of each power supply branch is adjusted according to the reactive power adjustment command deviation corresponding to each power supply branch.
[0023] In one possible implementation, the output adjustment module is further configured to, when the total reactive power control is less than or equal to 0, distribute the total reactive power control to each power supply branch equally, and generate reactive power adjustment command deviations corresponding to each power supply branch.
[0024] In one possible implementation, the output adjustment module is further configured to, when the total reactive power control is greater than 0 and the reactive power of the load branch is greater than or equal to the sum of the reactive power output limits of each distributed power source, obtain the admittance modulus of the power branch corresponding to each distributed power source.
[0025] The distributed power sources are sorted in ascending order of admittance magnitude. The total reactive power control is then allocated to the reactive power adjustment command deviation of each power source branch according to the maximum value of the reactive power output limit of each distributed power source, until the total reactive power control is fully allocated or the reactive power command of each power source branch reaches its maximum value.
[0026] In one possible implementation, the output adjustment module is further configured to, when the total reactive power control is greater than 0 and the reactive power of the load branch is less than the sum of the reactive power output limits of each distributed power source, obtain the active power corresponding to each distributed power source.
[0027] The distributed power sources are sorted in ascending order of active power. The reactive power control quantity is then allocated to the reactive power adjustment command deviation of each power source branch according to the maximum value of the reactive power output limit of each distributed power source, until the reactive power control quantity is fully allocated or the reactive power command of each power source branch reaches its maximum value.
[0028] In another aspect, a computer device is provided, the computer device including a processor and a memory, the memory storing at least one instruction, the at least one instruction being loaded and executed by the processor to implement the above-described method for voltage control at the grid connection point of a distribution network considering large-scale distributed power sources.
[0029] In another aspect, a computer-readable storage medium is provided, wherein at least one instruction is stored therein, the at least one instruction being loaded and executed by a processor to implement the above-described method for voltage control at the grid connection point of a distribution network considering large-scale distributed power sources.
[0030] In another aspect, a computer program product or computer program is provided, the computer program product or computer program including computer instructions stored in a computer-readable storage medium. A processor of a computer device reads the computer instructions from the computer-readable storage medium, and the processor executes the computer instructions, causing the computer device to perform the aforementioned method for voltage control at the grid connection point of a distribution network considering large-scale distributed power sources.
[0031] The technical solution provided in this application may include the following beneficial effects:
[0032] In a distribution network with large-scale distributed power sources, when these distributed power sources are connected to a common grid connection point, the controller can detect the voltage value of the common grid connection point, the active power of each distributed power source flowing into the common grid connection point, and the reactive power of each distributed power source flowing into the common grid connection point. When the difference between the voltage value of the common grid connection point and the reference voltage exceeds a first threshold, it indicates that the voltage of the common grid connection point is too high or too low. At this point, it is necessary to determine the reactive power output limit of each distributed power source based on the reactive power and active power of each distributed power source flowing into the common grid connection point. Then, based on the difference between the voltage value of the common grid connection point and the reference voltage, the total reactive power control amount is determined. The controller then adjusts the reactive power control commands of each power source branch according to the total reactive power control amount and the reactive power output limits of each distributed power source, so that the distributed power sources can respond with reactive power output according to the adjusted reactive power control commands. At this point, the voltage value of the common grid connection point after adjustment is closer to the set reference voltage value, thus minimizing the damage to the line caused by excessively high or low voltage at the common grid connection point. Attached Figure Description
[0033] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.
[0034] Figure 1 This is a schematic diagram of the wiring for feeding large-scale distributed power sources into the low-voltage side of a 110kV substation in a power distribution network.
[0035] Figure 2This is a flowchart illustrating a method for voltage control at the grid connection point of a distribution network considering large-scale distributed power sources, according to an exemplary embodiment.
[0036] Figure 3 This is a flowchart illustrating a method for voltage control at the grid connection point of a distribution network considering large-scale distributed power sources, according to an exemplary embodiment.
[0037] Figure 4 A flowchart illustrating a common grid connection point voltage control method according to an embodiment of this application is shown.
[0038] Figure 5 A schematic diagram of the structure of a voltage control device at the grid connection point of a distribution network that considers large-scale distributed power sources, according to an embodiment of this application, is shown.
[0039] Figure 6 This is a schematic diagram of a computer device provided according to an exemplary embodiment of this application. Detailed Implementation
[0040] The technical solutions of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0041] It should be understood that the term "instruction" mentioned in the embodiments of this application can be a direct instruction, an indirect instruction, or an indication of a relationship. For example, A instructing B can mean that A directly instructs B, such as B being able to obtain information through A; it can also mean that A indirectly instructs B, such as A instructing C, so B can obtain information through C; or it can mean that there is a relationship between A and B.
[0042] In the description of the embodiments of this application, the term "correspondence" may indicate that there is a direct or indirect correspondence between two things, or that there is an association between two things, or that there is a relationship of instruction and being instructed, configuration and being configured, etc.
[0043] In the embodiments of this application, "predefined" can be achieved by pre-storing corresponding codes, tables or other means that can be used to indicate relevant information in the device (e.g., including terminal devices and network devices). This application does not limit the specific implementation method.
[0044] Figure 1 This is a wiring diagram showing the connection of a large-scale distributed generation source feeding into the low-voltage side of a 110kV substation in a distribution network. Figure 1 The distribution network shown includes load branches; the distribution network is connected to the distribution network loads through the load branches.
[0045] That is, the distribution network can supply power to the distribution network load through the load branch.
[0046] In such Figure 1 The distribution network shown also includes various power supply branches; each power supply branch contains distributed power sources (i.e., distributed power source 1, distributed power source 2... distributed power source i), and each distributed power source is connected to the common grid connection point in the distribution network through the power supply branch.
[0047] Optionally, each of these distributed power sources can be a photovoltaic (PV) generator (or a PV power station). In this case, the distributed power source can generate direct current (DC) through PV power generation, convert it into alternating current (AC), and transmit it to the common grid connection point in the distribution network to supply power to the distribution network.
[0048] Optionally, each distributed power source is connected to the common grid connection point in the distribution network via an inverter. That is, after the distributed power source obtains DC power through photovoltaic power generation, it can be converted into corresponding AC power through an inverter and transmitted to the common grid connection point in the distribution network.
[0049] Optionally, the inverter can control the output power transmitted to the common grid connection point in the distribution network, that is, it can issue reactive power control commands to the inverter to control the reactive power output of the distributed power source. The controllable reactive power output of the distributed power source should be within the reactive power output limit of the distributed power source.
[0050] Optional, such as Figure 1 As shown, the common grid connection point for each distributed power source is located on the low-voltage side of the substation (i.e., on the 35KV line). The low-voltage side can directly supply power to the distribution network load through the load branch; the low-voltage side can also convert the 35KV voltage to 110KV high voltage for transmission through a transformer.
[0051] Optionally, the controller in the distribution network can be implemented by computer equipment. That is, the computer equipment can collect parameters from various sensors in the substation, such as real-time voltage detection at the common grid connection point. The computer equipment can also adjust the parameters of various devices in the distribution network, thereby ensuring the stable operation of the distribution network.
[0052] Figure 2 This is a flowchart illustrating a method for voltage control at the grid connection point of a distribution network considering large-scale distributed power sources, according to an exemplary embodiment. The method is executed by a computer device, which may be, for example... Figure 1 The controller in the distribution network shown. Figure 2 As shown, the voltage control method at the grid connection point of this distribution network may include the following steps:
[0053] Step 201: Obtain the voltage value of the common grid connection point, the active power of each distributed power source flowing into the common grid connection point, and the reactive power of each distributed power source flowing into the common grid connection point.
[0054] In this embodiment, the common grid connection point is the output aggregation point of each distributed power source, meaning that the electrical energy of each distributed power source is transmitted to the distribution network through the output aggregation point. Since the distributed power sources are typically photovoltaic power generation systems, and the power generation of photovoltaic systems is not stable, this can easily lead to a drop in voltage or overvoltage at the common grid connection point.
[0055] Therefore, during the operation of the distribution network, the controller can monitor the voltage value at the common grid connection point in real time, and when the voltage at the common grid connection point differs too much from the stable value, it can adjust the distributed power source in a timely manner to avoid the distribution network accident caused by the voltage at the common grid connection point being too high or too low.
[0056] Therefore, when controlling the voltage of the common grid connection point in real time, in addition to obtaining the current voltage value of the common grid connection point, it is also necessary to obtain the active power and reactive power of the distributed power sources flowing into the common grid connection point, so as to determine the power output status of each distributed power source.
[0057] Step 202: When the difference between the voltage value of the common grid connection point and the reference voltage is greater than the first threshold, calculate the reactive power output limit connected to each distributed power source based on the active power of each distributed power source flowing into the common grid connection point and the reactive power of each distributed power source flowing into the common grid connection point.
[0058] When the voltage difference between the common grid connection point and the reference voltage exceeds the first threshold, it indicates that the voltage value of the common grid connection point exceeds expectations, possibly being too high or too low. In this case, the reactive power output limit for each distributed power source can be calculated based on the active power and reactive power of each distributed power source flowing into the common grid connection point. This reactive power output limit includes both an upper and lower limit for the reactive power output of the distributed power source. In other words, this reactive power output limit represents the adjustment range within which the distributed power source can regulate its own reactive power output.
[0059] Step 203: Obtain the total reactive power control amount based on the difference between the voltage value of the common grid connection point and the reference voltage.
[0060] When the difference between the voltage value at the common grid connection point and the reference voltage is greater than the first threshold, the total amount of reactive power control that the fair grid connection point needs to adjust under the current state can be determined based on the specific value of the difference between the voltage value at the common grid connection point and the reference voltage.
[0061] Step 204: Based on the total reactive power control and the reactive power output limit of each distributed power source, adjust the reactive power control command of each power source branch to control each distributed power source to respond with reactive power output according to the adjusted reactive power control command.
[0062] After determining the total reactive power control amount that needs to be adjusted at the common grid connection point, as well as the reactive power output limit of each distributed power source, the reactive power control commands of each power source branch can be adjusted. That is, without exceeding the reactive power output limit of each distributed power source, the reactive power control commands of the power source branch where each distributed power source is located are adjusted according to the magnitude of the total reactive power control amount, so that each distributed power source can respond and output power according to the adjusted reactive power control commands. At this time, the voltage value of the common grid connection point will tend to the reference voltage, thus realizing the voltage control of the common grid connection point.
[0063] In summary, in a distribution network with large-scale distributed power sources, when these distributed power sources are connected to a common grid connection point, the controller can detect the voltage value of the common grid connection point, the active power of each distributed power source flowing into the common grid connection point, and the reactive power of each distributed power source flowing into the common grid connection point. When the difference between the voltage value of the common grid connection point and the reference voltage exceeds a first threshold, it indicates that the voltage of the common grid connection point is too high or too low. At this point, it is necessary to determine the reactive power output limit of each distributed power source based on its reactive power and active power flowing into the common grid connection point. Then, based on the difference between the voltage value of the common grid connection point and the reference voltage, the total reactive power control amount is determined. The controller then adjusts the reactive power control commands of each power source branch according to the total reactive power control amount and the reactive power output limits of each distributed power source, so that the distributed power sources can respond with reactive power output according to the adjusted reactive power control commands. At this point, the adjusted voltage value of the common grid connection point is closer to the set reference voltage value, thus minimizing the damage to the lines caused by excessively high or low voltage at the common grid connection point.
[0064] Figure 3 This is a flowchart illustrating a method for voltage control at the grid connection point of a distribution network considering large-scale distributed power sources, according to an exemplary embodiment. The method is executed by a computer device, which may be, for example... Figure 1 The controller in the distribution network shown. Figure 3 As shown, the voltage control method at the grid connection point of this distribution network may include the following steps:
[0065] Step 301: Obtain the voltage value of the common grid connection point, the active power of each distributed power source flowing into the common grid connection point, and the reactive power of each distributed power source flowing into the common grid connection point.
[0066] That is, the controller can collect the real-time voltage U of the common grid connection point (PCC) of the distributed power source connected to the distribution network, the active power Pi of each distributed power source flowing into the PCC, and the reactive power Qi of each distributed power source flowing into the PCC.
[0067] Step 302: When the difference between the voltage value of the common grid connection point and the reference voltage is greater than the first threshold, calculate the reactive power output limit connected to each distributed power source based on the active power of each distributed power source flowing into the common grid connection point and the reactive power of each distributed power source flowing into the common grid connection point.
[0068] In this embodiment of the application, the following variables can be set: the reference voltage Uref of the common grid connection point PCC, the voltage dead zone ε, and the number of distributed power sources N.
[0069] In this embodiment, the voltage dead zone is the first threshold. When the difference between the voltage value of the common grid connection point and the reference voltage is greater than the first threshold, that is, when |U-Uref|>ε, the voltage fluctuation of the common grid connection point is large, and the voltage of the common grid connection point needs to be adjusted. If the difference between the voltage of the common grid connection point and the reference voltage is less than or equal to the first threshold, that is, when |U-Uref|≤ε, the voltage fluctuation of the common grid connection point is small, and the voltage of the common grid connection point does not need to be adjusted. The controller continues to monitor the voltage of the common grid connection point.
[0070] When it is confirmed that the voltage of the common grid connection point needs to be adjusted, the controller first sets the reactive power output limit [Qimin, Qimax] of the distributed power source i (i = 1 to N) connected to the PCC. That is, the reactive power output limit includes the upper limit and the lower limit of reactive power output, where Qimin is the lower limit of reactive power output, Qimin is less than or equal to 0; Qimax is the upper limit of reactive power output, Qimax is greater than or equal to 0.
[0071] Optionally, in the embodiments of this application, Qimax = -Qimin = tan(arccos0.98) * Pi = 0.2Pi - Qi.
[0072] Once the reactive power output limit of each distributed power source is calculated, the reactive power output limit of each distributed power source can be accumulated to calculate the sum of the reactive power output limits of all distributed sources flowing into the PCC [Qgmin, QGmax], where QGmax = -QGmin = ∑(0.2Pi - Qi).
[0073] At this point, the sum of the reactive power output limits of all distributed sources that are fed into the PCC represents the adjustable range of reactive power output of each distributed power source fed into the PCC.
[0074] Optionally, in this embodiment, when the reactive power output limit of the power supply branch is positive, the reactive power of the power supply branch flows into the common grid connection point.
[0075] When the reactive power output limit of the power supply branch is negative, the reactive power of the power supply branch flows out of the common grid connection point.
[0076] Step 303: Input the difference between the voltage value of the common grid connection point and the reference voltage into the PD controller to obtain the total reactive power control amount.
[0077] After calculating the difference between the voltage value at the common grid connection point and the reference voltage, the difference represents the voltage value that needs to be adjusted. As can be seen from the principle of the distribution network, the voltage at the common grid connection point is related to the reactive power flowing into the common grid connection point. Therefore, after obtaining the difference between the voltage value at the common grid connection point and the reference voltage, the difference can be calculated by the PD controller to determine the total reactive power control amount (that is, the reactive power that needs to be adjusted) to stabilize the voltage value.
[0078] Step 304: Based on the total reactive power control and the reactive power output limit of each distributed power source, generate reactive power adjustment command deviations corresponding to each power source branch.
[0079] In one possible implementation, when the total reactive power control is less than or equal to 0, the total reactive power control is evenly distributed to each power supply branch, generating reactive power adjustment command deviations corresponding to each power supply branch.
[0080] When the total reactive power control is less than or equal to 0, the total reactive power control can be directly divided into N equal parts to generate reactive power adjustment command deviation deltQiref corresponding to each power supply branch, so as to adjust the reactive power output of each power supply branch.
[0081] In one possible implementation, when the total reactive power control is greater than 0 and the reactive power of the load branch is greater than or equal to the sum of the reactive power output limits of each distributed power source, the admittance modulus of the power source branch corresponding to each distributed power source is obtained.
[0082] The distributed power sources are sorted in ascending order of admittance magnitude. The total reactive power control is then allocated to the reactive power adjustment command deviation of each power source branch according to the maximum value of the reactive power output limit of each distributed power source, until the total reactive power control is fully allocated or the reactive power command of each power source branch reaches its maximum value.
[0083] In one possible implementation, when the total reactive power control is greater than 0 and the reactive power of the load branch is less than the sum of the reactive power output limits of each distributed power source, the active power corresponding to each distributed power source is obtained.
[0084] The distributed power sources are sorted from smallest to largest based on their active power. Then, the total reactive power control is allocated to the reactive power adjustment command deviation of each power source branch according to the maximum value of the reactive power output limit of each distributed power source, until the total reactive power control is allocated or the reactive power command of each power source branch reaches its maximum value.
[0085] Step 305: Adjust the reactive power control command of each power supply branch according to the reactive power adjustment command deviation corresponding to each power supply branch.
[0086] After allocating the reactive power adjustment command deviations corresponding to each power supply branch, the controller can superimpose the reactive power control command of each power supply branch according to the reactive power adjustment command deviation, so as to realize the adjustment of the reactive power control command of each power supply branch.
[0087] Step 306: Control each distributed power source to respond with reactive power output according to the adjusted reactive power control command.
[0088] After the reactive power control commands of each power supply branch are adjusted, the inverters of each power supply branch can adjust their reactive power output response according to the adjusted reactive power control commands, so as to control each distributed power source to respond with reactive power output according to the adjusted reactive power control commands.
[0089] Please refer to Figure 4 The diagram illustrates a flowchart of a common grid connection point voltage control method according to an embodiment of this application. Figure 4 As shown, the common grid connection point voltage control method in this application embodiment can be executed through the following specific steps:
[0090] Step (1) Collect the following variables at a certain moment: real-time voltage U = 0.95pu at the common grid connection point (PCC) of the distributed power source connected to the distribution network; active power Pi (P1 = 505kW) of the distributed power source i flowing into the PCC.
[0091] P2 = 875kW, P3 = 340kW, P4 = 135kW), reactive power Qi (Q1 = 95kvar, Q2 = 50kW),
[0092] Q3 = 67kW, Q4 = 20kW); Admittance Yi of branch i (Y1 = 0.4640 - 1.5301i,
[0093] Y2 = 0.5800 - 1.9127i, Y3 = 0.6960 - 2.2952i, Y4 = 0.5354 - 1.7655i); Reactive power of load branch QL = 950 kvar;
[0094] Set the following variables: PCC point reference voltage Uref = 1.02 pu, voltage dead zone ε = 0.05; number of distributed power sources N = 4
[0095] Step (2) Determine if |U-Uref|=|0.95-1.02|=0.07>ε=0.05? Proceed to step (3);
[0096] Step (3) Calculate the reactive power output limit of the distributed power source i (i = 1~4) fed into PCC:
[0097] Q1max=-Q1min=0.2*P1=101kvar, Q2max=175kvar, Q3max=68kvar,
[0098] Q4max = 27kvar;
[0099] Step (4) Calculate the reactive power output limit of all distributed power sources fed into the PCC:
[0100] QGmax=-QGmin=∑(0.2Pi-Qi)=(6+125+1+7)=139kvar;
[0101] Step (5) The difference between Uref and U is 0.07, which enters the PD controller (kp = 5, kd = 0.08) to obtain the total reactive power control amount Q∑ = 0.89 * Qpu = 89 kvar;
[0102] Step (6) Determine if Q∑=89≤0? No, proceed to step (7);
[0103] Step (7) Q∑=89>0&QL=950≥QGmax=89? Proceed to step (9);
[0104] Step (8) The reactive power regulation command deviation of distributed power source i is deltQiref=Q∑ / N; proceed to step (11);
[0105] Step (9) The distributed power source allocates the reactive power regulation command deviation deltQiref according to the electrical distance Yi modulus from smallest to largest (|Y1|<|Y4|<|Y2|<|Y3|) in sequence according to the maximum value, that is, deltQ1ref=6, deltQ4ref=7, deltQ2ref=89-6-7=76, deltQ3ref=0; proceed to step (11);
[0106] Step (10): Distributed power sources allocate reactive power adjustment command deviation deltQiref in order of active power from smallest to largest according to the maximum value; proceed to step (11);
[0107] Step (11) N (N=4) distributed power sources obtain their respective reactive power control deviation commands:
[0108] deltQ1ref=6, deltQ4ref=7, deltQ2ref=89-6-7=76, deltQ3ref=0;
[0109] Large-scale distributed power sources respond to commands with reactive power output; return to step (1).
[0110] In summary, in a distribution network with large-scale distributed power sources, when these distributed power sources are connected to a common grid connection point, the controller can detect the voltage value of the common grid connection point, the active power of each distributed power source flowing into the common grid connection point, and the reactive power of each distributed power source flowing into the common grid connection point. When the difference between the voltage value of the common grid connection point and the reference voltage exceeds a first threshold, it indicates that the voltage of the common grid connection point is too high or too low. At this point, it is necessary to determine the reactive power output limit of each distributed power source based on its reactive power and active power flowing into the common grid connection point. Then, based on the difference between the voltage value of the common grid connection point and the reference voltage, the total reactive power control amount is determined. The controller then adjusts the reactive power control commands of each power source branch according to the total reactive power control amount and the reactive power output limits of each distributed power source, so that the distributed power sources can respond with reactive power output according to the adjusted reactive power control commands. At this point, the adjusted voltage value of the common grid connection point is closer to the set reference voltage value, thus minimizing the damage to the lines caused by excessively high or low voltage at the common grid connection point.
[0111] Please refer to Figure 5 The diagram illustrates a structural schematic of a voltage control device for a distribution network connection point considering large-scale distributed power sources, according to an embodiment of this application. The device includes:
[0112] The data acquisition module 501 is used to acquire the voltage value of the common grid connection point, the active power of each distributed power source flowing into the common grid connection point, and the reactive power of each distributed power source flowing into the common grid connection point.
[0113] The reactive power output limit calculation module 502 is used to calculate the reactive power output limit connected to each distributed power source when the difference between the voltage value of the common grid connection point and the reference voltage is greater than a first threshold, based on the active power of each distributed power source flowing into the common grid connection point and the reactive power of each distributed power source flowing into the common grid connection point.
[0114] The reactive power control total acquisition module 503 is used to acquire the total reactive power control based on the difference between the voltage value of the common grid connection point and the reference voltage.
[0115] The output adjustment module 504 is used to adjust the reactive power control command of each power branch according to the total reactive power control and the reactive power output limit of each distributed power source, so as to control each distributed power source to respond with reactive power output according to the adjusted reactive power control command.
[0116] In one possible implementation, when the reactive power output limit of the power supply branch is positive, the reactive power of the power supply branch flows into the common grid connection point.
[0117] When the reactive power output limit of the power supply branch is negative, the reactive power of the power supply branch flows out of the common grid connection point.
[0118] In one possible implementation, the reactive power control total acquisition module is further used for:
[0119] The difference between the voltage value of the common grid connection point and the reference voltage is input into the PD controller to obtain the total reactive power control amount.
[0120] In one possible implementation, the output adjustment module is further configured to generate reactive power adjustment command deviations corresponding to each power supply branch based on the total reactive power control and the reactive power output limits of each distributed power source.
[0121] The reactive power control command of each power supply branch is adjusted according to the reactive power adjustment command deviation corresponding to each power supply branch.
[0122] In one possible implementation, the output adjustment module is further configured to, when the total reactive power control is less than or equal to 0, distribute the total reactive power control to each power supply branch equally, and generate reactive power adjustment command deviations corresponding to each power supply branch.
[0123] In one possible implementation, the output adjustment module is further configured to, when the total reactive power control is greater than 0 and the reactive power of the load branch is greater than or equal to the sum of the reactive power output limits of each distributed power source, obtain the admittance modulus of the power branch corresponding to each distributed power source.
[0124] The distributed power sources are sorted in ascending order of admittance magnitude. The total reactive power control is then allocated to the reactive power adjustment command deviation of each power source branch according to the maximum value of the reactive power output limit of each distributed power source, until the total reactive power control is fully allocated or the reactive power command of each power source branch reaches its maximum value.
[0125] In one possible implementation, the output adjustment module is further configured to, when the total reactive power control is greater than 0 and the reactive power of the load branch is less than the sum of the reactive power output limits of each distributed power source, obtain the active power corresponding to each distributed power source.
[0126] The distributed power sources are sorted in ascending order of active power. The reactive power control quantity is then allocated to the reactive power adjustment command deviation of each power source branch according to the maximum value of the reactive power output limit of each distributed power source, until the reactive power control quantity is fully allocated or the reactive power command of each power source branch reaches its maximum value.
[0127] In summary, in a distribution network with large-scale distributed power sources, when these distributed power sources are connected to a common grid connection point, the controller can detect the voltage value of the common grid connection point, the active power of each distributed power source flowing into the common grid connection point, and the reactive power of each distributed power source flowing into the common grid connection point. When the difference between the voltage value of the common grid connection point and the reference voltage exceeds a first threshold, it indicates that the voltage of the common grid connection point is too high or too low. At this point, it is necessary to determine the reactive power output limit of each distributed power source based on its reactive power and active power flowing into the common grid connection point. Then, based on the difference between the voltage value of the common grid connection point and the reference voltage, the total reactive power control amount is determined. The controller then adjusts the reactive power control commands of each power source branch according to the total reactive power control amount and the reactive power output limits of each distributed power source, so that the distributed power sources can respond with reactive power output according to the adjusted reactive power control commands. At this point, the adjusted voltage value of the common grid connection point is closer to the set reference voltage value, thus minimizing the damage to the lines caused by excessively high or low voltage at the common grid connection point.
[0128] Please see Figure 6 This is a schematic diagram of a computer device provided according to an exemplary embodiment of the present application. The computer device includes a memory and a processor. The memory is used to store a computer program, which is executed by the processor to implement the above-described method.
[0129] The processor can be a central processing unit (CPU). It can also be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, or combinations thereof.
[0130] Memory, as a non-transitory computer-readable storage medium, can be used to store non-transitory software programs, non-transitory computer-executable programs, and modules, such as the program instructions / modules corresponding to the methods in the embodiments of this invention. The processor executes various functional applications and data processing by running the non-transitory software programs, instructions, and modules stored in the memory, thereby implementing the methods described in the above embodiments.
[0131] The memory may include a program storage area and a data storage area. The program storage area may store the operating system and applications required for at least one function; the data storage area may store data created by the processor, etc. Furthermore, the memory may include high-speed random access memory and non-transitory memory, such as at least one disk storage device, flash memory device, or other non-transitory solid-state storage device. In some embodiments, the memory may optionally include memory remotely located relative to the processor, which can be connected to the processor via a network. Examples of such networks include, but are not limited to, the Internet, corporate intranets, local area networks, mobile communication networks, and combinations thereof.
[0132] In one exemplary embodiment, a computer-readable storage medium is also provided for storing at least one computer program, which is loaded and executed by a processor to implement all or part of the steps in the above-described method. For example, the computer-readable storage medium may be a read-only memory (ROM), a random access memory (RAM), a compact disc read-only memory (CD-ROM), magnetic tape, floppy disk, or optical data storage device, etc.
[0133] In one exemplary embodiment, a computer program product or computer program is also provided, comprising computer instructions stored in a computer-readable storage medium. A processor of a computer device reads the computer instructions from the computer-readable storage medium and executes the computer instructions, causing the computer device to perform the aforementioned actions. Figure 2 or Figure 3 All or part of the steps of the method shown in any embodiment.
[0134] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this application are indicated by the following claims.
[0135] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this application is limited only by the appended claims.
Claims
1. A method for voltage control at the grid connection point of a distribution network considering large-scale distributed power sources, characterized in that, The method is executed by a controller in the distribution network, which includes load branches and various power supply branches; Each distributed power source is connected to the common grid connection point in the power distribution network through its corresponding power branch. The method includes: Obtain the voltage value of the common grid connection point, the active power of each distributed power source flowing into the common grid connection point, and the reactive power of each distributed power source flowing into the common grid connection point; When the difference between the voltage value of the common grid connection point and the reference voltage is greater than the first threshold, the reactive power output limit connected to each distributed power source is calculated based on the active power of each distributed power source flowing into the common grid connection point and the reactive power of each distributed power source flowing into the common grid connection point. The total reactive power control amount is obtained based on the difference between the voltage value of the common grid connection point and the reference voltage; Based on the total reactive power control and the reactive power output limit of each distributed power source, the reactive power control command of each power source branch is adjusted so as to control each distributed power source to respond with reactive power output according to the adjusted reactive power control command. The adjustment of reactive power control commands for each power supply branch based on the total reactive power control amount and the reactive power output limit of each distributed power source includes: Based on the total reactive power control and the reactive power output limit of each distributed power source, generate reactive power adjustment command deviations corresponding to each power source branch. The reactive power control command of each power supply branch is adjusted according to the reactive power adjustment command deviation corresponding to each power supply branch. The step of generating reactive power adjustment command deviations for each power supply branch based on the total reactive power control and the reactive power output limits of each distributed power source includes: When the total reactive power control is less than or equal to 0, the total reactive power control is evenly distributed to each power supply branch, generating reactive power adjustment command deviations corresponding to each power supply branch. The step of generating reactive power adjustment command deviations for each power supply branch based on the total reactive power control and the reactive power output limits of each distributed power source includes: When the total reactive power control is greater than 0, and the reactive power of the load branch is greater than or equal to the sum of the reactive power output limits of each distributed power source, the admittance modulus of the power branch corresponding to each distributed power source is obtained. The distributed power sources are sorted in ascending order of admittance magnitude. The reactive power control quantity is then allocated to the reactive power adjustment command deviation of each power source branch according to the maximum value of the reactive power output limit of each distributed power source, until the reactive power control quantity is fully allocated or the reactive power command of each power source branch reaches its maximum value. The step of generating reactive power adjustment command deviations for each power supply branch based on the total reactive power control and the reactive power output limits of each distributed power source includes: When the total reactive power control is greater than 0 and the reactive power of the load branch is less than the sum of the reactive power output limits of each distributed power source, the active power corresponding to each distributed power source is obtained. The distributed power sources are sorted in ascending order of active power. The reactive power control quantity is then allocated to the reactive power adjustment command deviation of each power source branch according to the maximum value of the reactive power output limit of each distributed power source, until the reactive power control quantity is fully allocated or the reactive power command of each power source branch reaches its maximum value.
2. The method according to claim 1, characterized in that, When the reactive power output limit of the power supply branch is positive, the reactive power of the power supply branch flows into the common grid connection point; When the reactive power output limit of the power supply branch is negative, the reactive power of the power supply branch flows out of the common grid connection point.
3. The method according to claim 2, characterized in that, The step of obtaining the total reactive power control amount based on the difference between the voltage value of the common grid connection point and the reference voltage includes: The difference between the voltage value of the common grid connection point and the reference voltage is input into the PD controller to obtain the total reactive power control amount.
4. A voltage control device for the grid connection point of a distribution network considering large-scale distributed power sources, characterized in that, The device is a controller located in the power distribution network; the power distribution network includes load branches and various power supply branches. Each distributed power source is connected to the common grid connection point in the power distribution network through its corresponding power branch. The device includes: The data acquisition module is used to acquire the voltage value of the common grid connection point, the active power of each distributed power source flowing into the common grid connection point, and the reactive power of each distributed power source flowing into the common grid connection point. The reactive power output limit calculation module is used to calculate the reactive power output limit connected to each distributed power source when the difference between the voltage value of the common grid connection point and the reference voltage is greater than a first threshold, based on the active power of each distributed power source flowing into the common grid connection point and the reactive power of each distributed power source flowing into the common grid connection point. The reactive power control total quantity acquisition module is used to acquire the total reactive power control quantity based on the difference between the voltage value of the common grid connection point and the reference voltage. The output adjustment module is used to adjust the reactive power control commands of each power supply branch according to the total reactive power control and the reactive power output limits of each distributed power source, so as to control each distributed power source to respond with reactive power output according to the adjusted reactive power control commands; the adjustment of the reactive power control commands of each power supply branch according to the total reactive power control and the reactive power output limits of each distributed power source includes: Based on the total reactive power control and the reactive power output limit of each distributed power source, generate reactive power adjustment command deviations corresponding to each power source branch. The reactive power control command of each power supply branch is adjusted according to the reactive power adjustment command deviation corresponding to each power supply branch. The step of generating reactive power adjustment command deviations for each power supply branch based on the total reactive power control and the reactive power output limits of each distributed power source includes: When the total reactive power control is less than or equal to 0, the total reactive power control is evenly distributed to each power supply branch, generating reactive power adjustment command deviations corresponding to each power supply branch. The step of generating reactive power adjustment command deviations for each power supply branch based on the total reactive power control and the reactive power output limits of each distributed power source includes: When the total reactive power control is greater than 0, and the reactive power of the load branch is greater than or equal to the sum of the reactive power output limits of each distributed power source, the admittance modulus of the power branch corresponding to each distributed power source is obtained. The distributed power sources are sorted in ascending order of admittance magnitude. The reactive power control quantity is then allocated to the reactive power adjustment command deviation of each power source branch according to the maximum value of the reactive power output limit of each distributed power source, until the reactive power control quantity is fully allocated or the reactive power command of each power source branch reaches its maximum value. The step of generating reactive power adjustment command deviations for each power supply branch based on the total reactive power control and the reactive power output limits of each distributed power source includes: When the total reactive power control is greater than 0 and the reactive power of the load branch is less than the sum of the reactive power output limits of each distributed power source, the active power corresponding to each distributed power source is obtained. The distributed power sources are sorted in ascending order of active power. The reactive power control quantity is then allocated to the reactive power adjustment command deviation of each power source branch according to the maximum value of the reactive power output limit of each distributed power source, until the reactive power control quantity is fully allocated or the reactive power command of each power source branch reaches its maximum value.
5. A computer device, characterized in that, The computer device includes a processor and a memory, the memory storing at least one instruction, which is loaded and executed by the processor to implement a voltage control method for a distribution network connection point considering large-scale distributed power sources as described in any one of claims 1 to 3.
6. A computer-readable storage medium, characterized in that, The storage medium stores at least one instruction, which is loaded and executed by a processor to implement a voltage control method for the grid connection point of a distribution network considering large-scale distributed power sources, as described in any one of claims 1 to 3.