CN109861311B - Micro-grid control method based on communication network - Google Patents
Micro-grid control method based on communication network Download PDFInfo
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- CN109861311B CN109861311B CN201910180439.XA CN201910180439A CN109861311B CN 109861311 B CN109861311 B CN 109861311B CN 201910180439 A CN201910180439 A CN 201910180439A CN 109861311 B CN109861311 B CN 109861311B
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Abstract
The invention provides a micro-grid control method based on a communication network, which comprises the following steps: s1, the n distributed generators send own voltage and power data to the voltage-power compensator through a communication network; s2, the voltage-power compensator calculates to obtain the reference voltage of the distribution static var compensator based on the received voltage, load impedance and power data of each generator; s3, the distribution static var compensator outputs reactive power based on the reference voltage; and if the output reactive power reaches the output limit value of the distribution static reactive compensator, adjusting the active power and voltage output of the distribution static reactive compensator through a power controller of the distributed generator based on the communication network. The microgrid control method can realize stable and rapid reactive power compensation within the voltage regulation limit value and ensure the stable operation of the microgrid and the reactive power compensator.
Description
Technical Field
The invention relates to the technical field of electric power, in particular to a micro-grid control method.
Background
In order to solve the energy and environmental problems, all countries in the world are always dedicated to promoting the development of the new energy field, and the application of new energy electric power is more and more extensive. However, the energy density of the new energy is low, a suitable site is needed for high-power generation, and the power is unstable, so that the situation that the voltage and the frequency are unstable frequently occurs in the new energy power generation, and serious impact is easily caused on a large power grid. The micro-grid technology provides an important technical direction for efficiently utilizing the new energy power. For a reliable micro-grid, the final aim is to ensure the power quality while generating power in both grid-connected and island modes, and the main power quality problem is voltage fluctuation, which leads to the fluctuation of the grid due to voltage instability. In a power distribution network, voltage regulation is usually performed at the feeder location, but the microgrid operates autonomously, and the voltage regulation on both sides of the feeder may exceed a limit value. Therefore, the micro-grid with the distributed generators and the static var compensator of the power distribution network running in parallel can realize the adjustment of voltage and the coordination of power.
In the operation of a microgrid, the feeder lines are located far apart from each other, and reactive power compensation cannot be realized by a three-phase device at a proper position. In order to realize the interlocking control of the distributed generator and the distribution static compensator, information exchange is required, and therefore a communication system is required. By means of the communication system, the working performance of the static var compensator and the distributed generator of the power distribution network can be improved.
Disclosure of Invention
The invention aims to provide a microgrid control method based on a communication network, which can realize stable and rapid reactive power compensation within a voltage regulation limit value and ensure the stable operation of a microgrid and a reactive power compensator.
In order to achieve the purpose, the invention adopts the following technical scheme:
a microgrid control method based on a communication network, wherein the microgrid comprises n distributed generators with voltage control, a voltage-power compensator connected with the n distributed generators through the communication network respectively, and a distribution static var compensator connected with the voltage-power compensator, and the method comprises the following steps:
s1, the n distributed generators send own voltage and power data to the voltage-power compensator through a communication network;
s2, the voltage-power compensator calculates the reference voltage of the distribution static var compensator based on the received voltage and power data of each generator and the load impedance;
s3, the distribution static var compensator outputs reactive power based on the reference voltage; and if the output reactive power reaches the output limit value of the distribution static reactive compensator, adjusting the active power and voltage output of the distribution static reactive compensator through a power controller of the distributed generator based on the communication network.
Further, in S2, the reference voltage is calculated based on the following formula:
wherein, VssIs a reference voltage, V0For nominal voltage, Q, of the mainssFor the reactive output of static var compensators for power distribution, Ri、Xi、Pi、QiAnd ViiRespectively corresponding bus impedance, inductive reactance, active power, reactive power and voltage, VsBus voltage, m, for static var compensator of power distributions、KiThe gain coefficients i are 1,2, … m, … n, respectively.
Further, in S3, when the power controller of the distributed generator adjusts its active power and voltage output, the output power of the power controller is:
Pi＝Pimax-ki(Viimax-Vii)
wherein the gain factor kiThe value taking conditions are as follows: the actual voltage is less than the nominal voltage of the line, i.e. the limit of the transmission voltage, and it is ensured that the fluctuations of the voltage are regulated within acceptable limits.
Further, in S3, the distribution static var compensator preferentially adjusts the active power and voltage output of the distributed power generator located farther away from the distribution static var compensator.
The microgrid control method can improve reactive power compensation through the interlocking control of the distributed generator and the distribution static reactive power compensator (DSTATCOM). The distributed generator with voltage control is applied to the microgrid, so that reactive power coordination of the distributed generator can be realized, the control of the static reactive compensator of the power distribution network is realized in the voltage control process, and the static reactive compensator controls the voltage and power output of the distributed generator through the power limit value of the static reactive compensator, so that a closed-loop system is formed, and the stable operation of the microgrid and the reactive compensator is ensured. The control method provided by the invention can realize stable and rapid reactive power compensation within the voltage regulation limit value.
Drawings
Fig. 1 is a schematic diagram of an embodiment of a microgrid composition and control method of the present invention.
Fig. 2 is a schematic diagram of the voltage regulation effect of the control method in the grid-connected mode.
Fig. 3 is a schematic diagram of the voltage regulation effect of the control method of the present invention in an island mode.
Fig. 4 is a schematic voltage simulation diagram when a communication node at a distribution static var compensator fails in a grid-connected mode.
Fig. 5 is a schematic diagram of voltage simulation when a communication node at a distribution static var compensator fails in an island mode.
Detailed Description
For a further understanding of the invention, reference will now be made to the preferred embodiments of the invention by way of example, and it is to be understood that the description is intended to further illustrate features and advantages of the invention, and not to limit the scope of the claims.
The embodiment of the invention provides a micro-grid control method based on a communication network. As shown in fig. 1, the microgrid comprises n distributed generators with voltage control, each coupled to a grid bus through a bus; the system also comprises a voltage-power compensator connected with the n distributed generators through a communication network respectively, and a distribution static var compensator (DSTATCOM) connected with the voltage-power compensator, wherein the distribution static var compensator is coupled with a power grid bus through a bus DSTATCOM.
The microgrid control method comprises the following steps:
firstly, the n distributed generators send own voltage and power data to the voltage-power compensator through a communication network;
then, the voltage-power compensator calculates the reference voltage of the distribution static var compensator based on the received voltage and power data of each generator and the load impedance; vss. Wherein, the resistance in the load impedance:
in engineering calculation, the resistance values of various types of wires can be directly searched from related manuals; inductive reactance:
in engineeringIn the calculation, the reactance values of the wires of various types can be directly found from related manuals.
Finally, the distribution static var compensator is based on the reference voltage VssOutputting reactive power; and if the output reactive power reaches the output limit value of the distribution static reactive compensator, adjusting the active power and voltage output of the distribution static reactive compensator through a power controller of the distributed generator based on the communication network.
In a preferred embodiment, the reference voltage V is set in the above stepssCalculated based on the following formula:
wherein, V0For nominal voltage, Q, of the mainssFor the reactive output of static var compensators for power distribution, Ri、Xi、Pi、QiAnd ViiRespectively corresponding bus impedance, inductive reactance, active power, reactive power and voltage, VsBus voltage, m, for static var compensator of power distributions、KiThe gain coefficients i are 1,2, … m, … n, respectively. In addition, in fig. 1, the active power and reactive power generation of the generator are respectively represented as PiiAnd QiiThe load power demand on each bus is denoted as PLiAnd QLi。
Further, when the power controller of the distributed generator adjusts the active power and the voltage output, the output power of the power controller is:
Pi＝Pimax-ki(Viimax-Vii)
wherein the gain factor kiThe value taking conditions are as follows: the actual voltage is less than the nominal voltage of the line, i.e. the limit of the transmission voltage, and it is ensured that the fluctuation of the voltage is regulated within acceptable limits, i.e. the following national standards are met:
the sum of the absolute values of the positive and negative deviations of the power supply voltage of 35kV and above does not exceed 10% of the nominal voltage; the deviation of three-phase power supply voltage of 20kV and below is 7% of the soil of the nominal voltage; the 220V single-phase supply voltage deviation is + 7% and-10% of the nominal voltage.
Taking distributed generator DG-1 as an example, the output power of the power controller therein is:
P＝P1max-k(V11max-V11)
in grid-tie mode, the voltage drop across the far end of the feeder is large, so the far-end Distributed Generators (DGs) are more likely to reach their reactive current limit first. In island mode, the voltage at any location may be below the acceptable voltage regulation limit. However, if a distribution static compensator (DSTATCOM) is provided, at either side, Distributed Generators (DGs) farther from the distribution static compensator (DSTATCOM) are more likely to reach their reactive power limits, while Distributed Generators (DGs) closer to the distribution static compensator (DSTATCOM) will operate at their respective reactive power ratios within the voltage regulation limits. Therefore, the distribution static var compensator preferentially adjusts the active power and voltage output of the distributed generators that are farther away from the distribution static var compensator.
The method of the invention is further described below with reference to specific examples of reactive power compensation using the control method of the invention.
For the grid tie mode, the voltages are as shown in FIG. 2. It can be seen that the voltage regulation effect of the side connected with the reactive compensator is obvious by applying the method provided by the invention, and the voltage change is kept within 2% at the middle end and the far end of the reactive compensator feeder line.
For island mode, the voltages are shown in fig. 3. It can be seen that the voltage regulation on the side of the static compensator for power distribution, the middle end or the far end of the feeder line is efficient and stable by applying the method provided by the invention.
On the other hand, if a communication node at the distribution static compensator (dstancom) fails, a great effect is produced, resulting in the stoppage of all communications with the distribution static compensator (dstancom). Cannot communicate with a distribution static compensator (dstancom),
in one test case, in grid-tie mode, it is assumed that a communication node at a distribution static compensator (dstancom) has failed. The system response is shown in fig. 4, which simulates the situation where voltage fluctuations occur at 1.25 seconds. From the simulation results, it can be seen that the static compensator side, the mid-feed and the far end all generate voltage drops.
Similarly, in the island mode, the voltage fluctuation at 1.25 seconds was simulated, and the system response is shown in fig. 5, and it can be seen from the simulation result that the voltage on the static compensator side decreases. However, the voltages at the middle and far ends of the feed line do not change significantly.
The microgrid control method based on the communication network in the embodiment of the invention has the main application environment that the distance is far, the feeder line is long, and the requirement of the load is met through the microgrid. The method provided by the invention can more effectively reduce the voltage drop through the voltage regulation of a plurality of Distributed Generators (DGs), and ensure the voltage stability of the power grid.
The above description of the embodiments is only intended to facilitate the understanding of the method of the invention and its core idea. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention.
Claims (3)
1. A microgrid control method based on a communication network is characterized in that the microgrid comprises n distributed generators with voltage control, a voltage-power compensator and a distribution static var compensator, wherein the voltage-power compensator is respectively connected with the n distributed generators through the communication network, and the distribution static var compensator is connected with the voltage-power compensator, and the method comprises the following steps:
s1, the n distributed generators send own voltage and power data to the voltage-power compensator through a communication network;
and S2, the voltage-power compensator calculates the reference voltage of the distribution static var compensator based on the received voltage and power data of each generator and the load impedance, and the reference voltage is calculated based on the following formula:
wherein, VssIs a reference voltage, V0For nominal voltage, Q, of the mainssFor the reactive output of static var compensators for power distribution, Ri、Xi、Pi、QiAnd ViiRespectively corresponding bus impedance, inductive reactance, active power, reactive power and voltage, VsBus voltage, m, for static var compensator of power distributions、KiGain coefficients, i ═ 1,2, … m, … n, respectively;
s3, the distribution static var compensator outputs reactive power based on the reference voltage; and if the output reactive power reaches the output limit value of the distribution static reactive compensator, adjusting the active power and voltage output of the distribution static reactive compensator through a power controller of the distributed generator based on the communication network.
2. The microgrid control method based on a communication network of claim 1, wherein in the step S3, when the power controller of the distributed generator adjusts its active power and voltage output, the output power of the power controller is:
Pi＝Pimax-ki(Viimax-Vii)
wherein the gain factor kiThe value taking conditions are as follows: the actual voltage is less than the nominal voltage of the line and ensures that the fluctuations in the voltage are regulated within acceptable limits.
3. The microgrid control method based on a communication network of claim 1 or 2, wherein in S3, the distribution static var compensator adjusts active power and voltage output of distributed generators far away from the distribution static var compensator preferentially.
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| CN102640378A (en) * | 2009-09-15 | 2012-08-15 | 西安大略大学 | Utilization of distributed generator inverters as statcom |
| CN102801182A (en) * | 2012-08-21 | 2012-11-28 | 广东明阳风电产业集团有限公司 | Topological structure using distributed wind farm grid-connected control |
| CN105449691A (en) * | 2015-12-25 | 2016-03-30 | 上海电力学院 | Reactive power compensation method for doubly-fed wind power system |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102640378A (en) * | 2009-09-15 | 2012-08-15 | 西安大略大学 | Utilization of distributed generator inverters as statcom |
| CN102801182A (en) * | 2012-08-21 | 2012-11-28 | 广东明阳风电产业集团有限公司 | Topological structure using distributed wind farm grid-connected control |
| CN105449691A (en) * | 2015-12-25 | 2016-03-30 | 上海电力学院 | Reactive power compensation method for doubly-fed wind power system |
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Effective date of registration: 20210706 Address after: Room 229, 2 / F, a11 building, 9 Jiusheng Road, Jianggan District, Hangzhou City, Zhejiang Province, 310019 Patentee after: Hangzhou HengYao Electric Power Engineering Design Co.,Ltd. Address before: No.18, Jiangyuan Road, West District, Quzhou City, Zhejiang Province Patentee before: QUZHOU College OF TECHNOLOGY |