CN115693713A - Three-phase smart load control-based power distribution network imbalance management method - Google Patents
Three-phase smart load control-based power distribution network imbalance management method Download PDFInfo
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Abstract
The invention relates to power distribution network imbalance management, in particular to a power distribution network imbalance management method based on three-phase intelligent load control. The invention solves the problem that the traditional unbalance treatment cannot solve the unbalance caused by large-scale uncertain disturbance by a method of manually adjusting the load average distribution among phases. And the problem that additional power loss is required to be generated in the traditional modes such as compensation and the like, and adverse effects are caused on the improvement of the energy efficiency of the whole system and the reduction of the carbon emission level is solved. The method firstly obtains the method for controlling the bidirectional power PWM of the bidirectional DC/AC converter through mathematical derivation. On the basis, three-phase unbalanced signals of the power distribution network are acquired, unbalanced power difference values among all phases are obtained, so that power consumed by loads of all phases is determined, signals of the switching tubes are controlled to be switched on and off through control of the switching tubes, power flowing of the bidirectional DC/AC converter is adjusted, unbalanced power consumption of the loads in abc three phases is achieved, and the unbalanced power consumption is balanced with three-phase unbalanced quantities of the power distribution network. Therefore, the unbalance treatment of the power distribution network is realized. The invention is suitable for the unbalanced management of the power distribution network and has good practicability.
Description
Technical Field
The invention relates to the field of power distribution network imbalance treatment, in particular to a power distribution network imbalance treatment method based on three-phase intelligent load control.
Background
With the exhaustion of fossil energy and the increasing prominence of environmental problems, the application of various distributed power sources is widely regarded. New energy mainly based on wind power and photovoltaic power generation is developed rapidly. With the continuous development of distributed energy technologies such as photovoltaic power generation and the like, the gradual popularization of household energy storage and electric vehicles, the power distribution network is subjected to the impact of large-scale distributed power sources and electric vehicle charging load grid connection, and due to the randomness and the volatility of the distributed power sources and the electric vehicles, the imbalance degree of the power distribution network can be further aggravated when a single-phase or three-phase grid connection mode is adopted. Therefore, the unbalance of the power distribution network needs to be treated.
At present, measures generally adopted for treating three-phase imbalance of distribution networks at home and abroad are commutation switching load and additional compensation devices, wherein the method for the commutation switching load is mainly manual commutation. The scheme of manual phase change adopts a phase balance control algorithm, and the adjustment strategy is to select a plurality of single-phase users of a certain distribution transformer and analyze real-time data acquired by an intelligent instrument and a power utilization information acquisition terminal system. The method has the advantages that the load on each phase of the low-voltage line is evenly distributed by workers according to data analysis results and adjustment experiences by adopting a trial-and-error method, although the cost of manual phase change adjustment is low, the method needs a large amount of preparation work, the phase change operation needs a large amount of workers, the workload is high, the labor cost is high, meanwhile, due to the randomness and uncertainty of the load, online load adjustment cannot be carried out in real time by the manual phase change method, the expected ideal effect is difficult to achieve, and potential safety hazards exist to a certain extent. According to research, capacitive three-phase unbalanced compensation is adopted, three-phase load unbalanced current is detected in real time, and a capacitor is controlled through a fling-cut switch to perform split-phase adjustment, so that a compensation function is realized. There is a document that an active unbalance compensation device is used to actively compensate the fundamental unbalance current of a load by using a power electronic converter technique, so as to reduce the unbalance degree and have a reactive compensation function. Both of these methods result in additional power loss.
The existing method for treating the imbalance of the power distribution network cannot solve the problem of imbalance caused by large-scale uncertain disturbance by manually adjusting the load average distribution among phases, additional power loss needs to be generated additionally in modes of compensation and the like, and the method has adverse effects on improving the energy efficiency of the whole system, reducing the carbon emission level and the like. Therefore, a three-phase imbalance management method for a system can be realized only by changing and optimizing an intelligent load control mechanism without using the traditional load switching or adding a compensation device.
Disclosure of Invention
The invention aims to solve the problem that the unbalance degree of a power distribution network is further aggravated when a single-phase or three-phase grid-connected mode is adopted due to the randomness and the volatility of a large-scale distributed power supply and the charging load of an electric automobile in grid connection. Aiming at the defects of the existing method, a three-phase intelligent load control-based power distribution network imbalance management method is designed.
The invention is realized by adopting the following technical scheme:
the invention relates to a control method based on a bidirectional DC/AC converter, which specifically comprises the following steps:
the invention provides a power distribution network imbalance management method based on intelligent load control on the basis of the existing bidirectional DC/AC converter topological structure. The unbalanced power difference value between each phase is obtained by acquiring signals of three-phase unbalance of the power distribution network, so that the power consumed by each phase load is determined, a bidirectional power PWM control strategy is provided, the load is unbalanced in abc three-phase power consumption by controlling the on-off of a switch tube, the power is further balanced with the three-phase unbalance of the power distribution network, and the unbalanced management of the power distribution network is realized.
Unbalance amount control: the unbalanced power difference value between each phase is calculated by collecting three-phase unbalanced power, so that the power consumed by each phase load is determined, the power flow of the bidirectional DC/AC converter is adjusted by adjusting the on-off of the switching tube according to the obtained unbalanced amount, the unbalanced three-phase power consumption of the load in abc is realized, and the unbalanced three-phase power consumption of the load is balanced with the three-phase unbalanced amount of the power distribution network.
Compared with the prior art, the power distribution network imbalance treatment method based on three-phase intelligent load control has the advantages and positive effects that: (1) The existing control method needs to manually adjust the load average distribution among all phases, or needs to additionally generate additional power loss through modes such as compensation and the like, and has adverse effects on improving the energy efficiency of the whole system, reducing the carbon emission level and the like. The method of the invention can realize the three-phase unbalance management of the system by only changing and optimizing a load control mechanism without the traditional load switching or adding a compensation device. (2) By using the intelligent load control-based power distribution network imbalance treatment method, the defect that the effect of the traditional imbalance treatment method is not ideal can be overcome. The reliability of the power distribution network is improved. (3) By using the intelligent load control-based power distribution network imbalance treatment method, the imbalance of the power distribution network can be dynamically adjusted in real time, and the three-phase imbalance treatment efficiency of the power distribution network is improved.
Drawings
Fig. 1 is a block diagram of a bidirectional DC/AC converter according to an embodiment of the present invention;
fig. 2 is a control block diagram of a power distribution network imbalance management method based on intelligent load control according to an embodiment of the present invention;
in FIG. 1: v 1 -V 6 6 IGBT switching tubes respectively; c is a filter capacitor; r is equivalent load; v dc Is a dc bus voltage; i all right angle dc Is a direct current bus current; l is a filter inductor; r s The equivalent internal resistance is formed by line impedance, power supply internal resistance and IGBT switching tube conducting resistance; u shape m And i m Respectively, the equivalent voltage and current of a three-phase power supply. Wherein: m =1,2,3.
In fig. 2: s a ,S b And S c Controlling signals for the IGBT switching tubes; v dc Is a direct current side voltage; v dcref Is a direct current side voltage reference value; i.e. i d And i q The amount of current in the d-axis and q-axis respectively; i.e. i dref And i qref Reference values of the amounts of current of the d-axis and q-axis, respectively; u shape d And U q The voltage quantities of the d-axis and q-axis of the three-phase power supply, respectively. U shape arcf ,U bref And U cref Respectively, the modulated signals of the system. The SPWM module can generate a driving waveform of the IGBT switching tube. In the output voltage loop, electricityVoltage reference value and voltage actual value V dc After the difference is made, a reference value i of the current amount of the d axis is output through the PI controller dref . And the unbalance amount control calculates the unbalance power difference value between each phase according to the collected three-phase unbalance power, so as to determine the power which is consumed by each phase load. In the input voltage-current loop, three-phase input voltage-current U m And i m Voltage and current components of a d axis and a q axis are obtained after dq conversion, and then a modulation signal U of the system is obtained through dq decoupling control and a PI controller aref ,U bref And U cref . Obtaining IGBT switch tube control signal S through SPWM module a ,S b And S c . Control signal S by switching tube a ,S b And S c To control the switch tube V 1 -V 6 The power flow of the bidirectional DC/AC converter is adjusted by switching on and switching off, so that the unbalanced power consumption of the load in the abc three phases is realized, and the unbalanced power consumption is further balanced with the unbalanced three phases of the power distribution network.
DETAILED DESCRIPTION OF EMBODIMENT (S) OF INVENTION
The present embodiment is directed to a bidirectional DC/AC converter control, the bidirectional DC/AC converter is composed of 6 IGBT switching tubes and an inductor capacitor, and the method specifically includes the following steps:
as shown in FIG. 2, where S is a ,S b And S c Controlling signals for the IGBT switching tubes; v dc Is a direct current side voltage; v dcref Is a direct current side voltage reference value; i all right angle d And i q The amount of current in d and q axes, respectively; i.e. i dref And i qref Reference values of the amounts of current of the d-axis and q-axis, respectively; u shape d And U q The voltage quantities of the d-axis and q-axis of the three-phase power supply, respectively. U shape aref ,U bref And U cref Respectively, the modulated signals of the system. The SPWM module can generate a driving waveform of the IGBT switching tube.
And (3) outputting a voltage ring: reference value of output voltage and actual value V of output voltage dc After the difference is made, a reference value i of the current amount of the d axis is output through the PI controller dref 。
Input voltage current loop: three-phase input voltage current U m And i m Is subjected to dq conversionThen, voltage and current components of a d axis and a q axis are obtained, and then a modulation signal U of the system is obtained through dq decoupling control and a PI controller aref ,U bref And U cref 。
Unbalance amount control: calculating the unbalanced power difference value between each phase by collecting three-phase unbalanced power so as to determine the power consumed by each phase load, and adjusting a switch tube V according to the obtained unbalanced amount 1 -V 6 The power flow of the bidirectional DC/AC converter is adjusted by switching on and switching off, so that the unbalanced power consumption of the load in the abc three phases is realized, and the unbalanced power consumption is further balanced with the unbalanced three phases of the power distribution network.
Claims (1)
1. The invention relates to power distribution network imbalance management, in particular to a power distribution network imbalance management method based on three-phase smart load control, which is characterized by comprising the following steps of:
acquiring three-phase unbalanced signals of the power distribution network on the basis of establishing a bidirectional DC/AC converter small signal model to obtain unbalanced power difference values among phases of the power distribution network; determining the power consumed by each phase of the three-phase load according to the difference value of each phase; the on-off of the switch tube is controlled by controlling the signal of the switch tube, so that the power flow of the bidirectional DC/AC converter is adjusted, the power consumed by the load among three phases abc is balanced with the three-phase unbalance of the power distribution network, and the three-phase unbalance of the power distribution network is treated.
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Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
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CN116742661A (en) * | 2023-08-14 | 2023-09-12 | 国网山西省电力公司临汾供电公司 | Three-phase unbalance treatment device based on three-sagging control |
CN116880159A (en) * | 2023-09-06 | 2023-10-13 | 国网山西省电力公司临汾供电公司 | Intelligent PID control method and device for grid-connected inverter of electric automobile |
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2021
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Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN116742661A (en) * | 2023-08-14 | 2023-09-12 | 国网山西省电力公司临汾供电公司 | Three-phase unbalance treatment device based on three-sagging control |
CN116742661B (en) * | 2023-08-14 | 2023-10-27 | 国网山西省电力公司临汾供电公司 | Three-phase unbalance treatment device based on three-phase sagging control |
CN116880159A (en) * | 2023-09-06 | 2023-10-13 | 国网山西省电力公司临汾供电公司 | Intelligent PID control method and device for grid-connected inverter of electric automobile |
CN116880159B (en) * | 2023-09-06 | 2023-11-28 | 国网山西省电力公司临汾供电公司 | Intelligent PID control method and device for grid-connected inverter of electric automobile |
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