TWI826011B - Strategy for reactive power compensation of distribution feeder - Google Patents

Abstract

A strategy for reactive power compensation of distribution feeder is disclosed. The strategy for reactive power compensation of distribution feeder includes the following steps: confirming the relationship between a parallel contact voltage ( ) on a feeder and a first set per unit value and a second set per unit value. When the parallel contact voltage ( ) is greater than the first set per unit value or less than the second set per unit value, perform an autonomous reactive power control procedure. Inputting a system parameter to perform an energy storage system reactive power regulation program at the same time. Setting a value of reactive power absorbed or provided by the energy storage system to zero. Setting an analysis times value (k) to 1, and performing a power flow analysis to calculate each bus voltage value ( ). Confirming the relationship between each of the bus voltage value ( ) and a third set per unit value and a fourth set per unit value. When each bus voltage value (

Description

Distribution feeder voltage virtual power compensation strategy

The present invention relates to a voltage compensation strategy, and in particular to a distribution feeder voltage virtual power compensation strategy.

As the concepts of ecological conservation and healthy living have become increasingly prominent in recent years, nuclear power units are being decommissioned one after another and the proportion of thermal power generation is also decreasing. In order to make up for the resulting power supply gap, renewable energy is currently being integrated into the grid for power generation on a large scale.

However, renewable energy has unstable and unpredictable characteristics, which will have an impact on the power supply quality and reliability of the grid connection and operation of the power system. When a large amount of renewable energy is connected to the end of the feeder, the voltage at the end of the line may be too high, affecting the safety of electrical equipment.

In addition, when renewable energy with unstable power generation is connected to the grid, the power flow of the distribution system changes rapidly, which can easily cause excessive changes in the voltage of distribution feeders. Traditional offline power flow analysis cannot provide system stability control strategies in real time, resulting in power quality such as voltage fluctuations and fluctuations in the power system. problem.

Therefore, how to provide a "distribution feeder voltage virtual power compensation strategy" has become a problem to be solved in the industry.

The embodiment of the present invention provides a distribution feeder voltage virtual power compensation strategy, which includes the following steps: Confirm the parallel contact voltage on a feeder ( ) and the relationship between the first set standard value and the second set standard value; when the parallel contact voltage ( ) is greater than the first set standard value or less than the second set standard value, the autonomous virtual power control process is carried out; a system parameter is input to simultaneously carry out the energy storage virtual work control process; the virtual power absorbed or provided by the energy storage system is set. The power value is zero; set the analysis times value (k) to 1, and perform power flow analysis to calculate the voltage value of each bus ( ); and confirm the voltage value of each bus ( ), the relationship between the third set standard value and the fourth set standard value, when each bus voltage value ( ) is greater than the third set standard value, or less than the fourth set standard value, the energy storage virtual work control program is performed.

In some embodiments, the first set value is between 1.01 and 1.04, and the second set value is between 0.97 and 0.99.

In some embodiments, the third setting value is between 1.05 and 1.07, and the fourth setting value is between 0.94 and 0.96.

In some embodiments, the energy storage virtual power control program includes the following steps: Confirm a maximum bus voltage ( ) value, or a minimum bus voltage ( ) value, and select a value closer to the energy storage system to perform the energy storage virtual work control program; confirm whether the virtual work compensation ratio of the energy storage virtual work control program does not reach a set upper limit; after confirming the virtual work When the compensation ratio does not reach the set upper limit, the closer energy storage system successively absorbs or provides the virtual work value with a compensation virtual work value; and sets the analysis times value (k) to increase 1, and conduct the next power flow analysis.

In some embodiments, when it is confirmed that the virtual work compensation ratio has not reached the set upper limit value, after the step of successively absorbing or providing the virtual work value with a compensation virtual work value, the closer energy storage system also includes There is no step to adjust the contactor (Tap) value of the on-load tap changer (OLTC).

In some embodiments, the set upper limit value is between 70% and 80%.

In some embodiments, when it is confirmed that the virtual power compensation ratio reaches the set upper limit value, the contact (Tap) value of the on-load tap changer (OLTC) is adjusted so that the The output voltage of the on-load tap changer (OLTC) decreases or increases.

In some embodiments, each bus voltage When it is greater than the third set standard value, the contact (Tap) value is adjusted to the next gear to reduce the output voltage of the on-load tap changer (OLTC).

In some embodiments, at each bus voltage When it is less than the fourth set standard value, the contact (Tap) value is adjusted to one gear to increase the output voltage of the on-load tap changer (OLTC).

In order to make the present invention more obvious and understandable, embodiments are given below and described in detail with reference to the accompanying drawings.

Specific implementations of the present invention will be further described below with reference to the accompanying drawings and examples. The following examples are only used to illustrate the technical solution of the present invention more clearly, but cannot limit the scope of protection of the present invention.

For the sake of clarity and convenience of illustration, the size and proportion of components in the drawings may be exaggerated or reduced. In the following description and/or patent claims, when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements may be present; and when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements may be present; When "directly connected" or "directly coupled" to another element, there are no intervening components present, and other words used to describe the relationship between components or layers should be interpreted in a like manner; "first", "second", Ordinal numbers such as "third" have no sequential relationship with each other. They are only used to mark and distinguish two different components with the same name. To facilitate understanding, the same components in the following embodiments are labeled with the same symbols for description.

Please refer to Figure 1, which is a block diagram of a distribution feeder voltage virtual power compensation system according to an embodiment of the present invention. As shown in Figure 1, the distribution feeder voltage virtual power compensation system 100 is electrically connected to the feeder 10. The feeder 10 includes: mains 70 , an on-load tap-changer (OLTC) 20 , an energy storage system 30 , a converter 40 , and a load 50 .

The primary side of the on-load tap changer 20 is electrically connected to the mains 70 , and the secondary side of the on-load tap changer 20 is electrically connected to the energy storage system 30 . The on-load tap changer 20 is also electrically connected to the monitoring platform 60 . The energy storage system 30 is electrically connected to the converter 40 . The energy storage system 30 is also electrically connected to the monitoring platform 60 . The monitoring platform 60 may be composed of a central operation platform with a computer system or an information processing device with computer functions.

The converter 40 is electrically connected to the load 50 . The converter 40 is also electrically connected to the renewable energy device 45 . Renewable energy equipment 45 may be, for example, solar power generation equipment and/or wind power generation equipment.

The feeder 10 is also provided with a Feeder Terminal Unit (FTU) (not shown in the figure). The feeder terminal unit is responsible for collecting the status of each automatic switch on the feeder 10 (for example, data on voltage, current and over-current fault signals).

In addition, the distribution feeder voltage virtual power compensation system of the embodiment of the present invention is only an example and is not used to limit the electrical connection of the on-load tap changer 20 , the energy storage system 30 , the converter 40 and the renewable energy equipment on the feeder 10 45. The number and connection method of load 50 can be adjusted and changed according to actual needs.

Next, please refer to Figures 2A to 2C, which are flow charts of the distribution feeder voltage virtual power compensation strategy according to the embodiment of the present invention. The distribution feeder voltage virtual power compensation strategy according to the embodiment of the present invention can be executed by a monitoring platform 60 with a computer system, or an information processing device with computer functions, together with the on-load tap changer 20 , the energy storage system 30 , and the converter 40 Follow the steps below.

Step S200, the converter 40 confirms the parallel contact voltage on the feeder 10 ( ) and the relationship between the first set standard value and the second set standard value, where the parallel contact voltage ( ) is the parallel contact voltage of the jth converter on feeder 10. In some embodiments, the first set value is between 1.01 and 1.04 (for example, 1.02), and the second set value is between 0.97 and 1.04. Between 0.99 and 0.99 (for example, 0.98 and 0.98).

Step S210, the converter 40 compares the parallel contact voltage ( ) is greater than the first set standard value, or compared with the parallel contact voltage ( ) is less than the second set value?

Step S220, when the parallel contact voltage ( ) is greater than the first set standard value or less than the second set standard value, the converter 40 performs an autonomous virtual power control procedure. For example, when the parallel contact voltage of the converter 40 ( ) is higher than 1.05 times the rated voltage of the mains 70 system, power factor control begins and the virtual power must be reduced by 10% within 1 second. When the parallel contact voltage ( ) is lower than 1.05 times the rated voltage of the mains 70 system, stop regulating, otherwise continue to reduce the power factor to 0.9.

When the parallel contact voltage ( ) is less than the first set standard value, or greater than the second set standard value, then returns to step S200, and the converter 40 continues to confirm the parallel contact voltage on the feeder 10 ( ), the relationship between the first set target value and the second set target value.

Step S230: Input a system parameter to the monitoring platform 60. The system parameters include topology, line length, line impedance, feeder terminal unit (FTU) current, feeder terminal unit (FTU) voltage, rated capacity of the energy storage system 30 and contacts of the on-load tap changer 20 Tap value to carry out the energy storage virtual work control program at the same time.

Step S240 mainly performs initialization settings, and sets the virtual work values absorbed or provided by all energy storage systems 30 on the feeder 10 to zero.

Step S250: Set the number of analysis times (k) of the power flow analysis of the monitoring platform 60 to 1.

In step S260, the monitoring platform 60 obtains the current and voltage returned by the feeder terminal unit (FTU), together with the existing topological structure, line length, line impedance and other data of the monitoring platform 60, to perform a power flow analysis process.

Step S270, the monitoring platform 60 calculates the voltage value of each busbar on the feeder 10 ( ).

Step S280, confirm the voltage value of each bus ( ), the relationship between the third setting value and the fourth setting value. When each bus voltage value ( ) is greater than the third set standard value, or less than the fourth set standard value, then the energy storage virtual work control procedure is performed. In some embodiments, the third set value is between 1.05 and 1.07 (for example, 1.05), and the fourth set value is between 0.94 and 1.07. Between 0.96 and 0.96 (for example, 0.95 and 0.95).

It is worth noting that since the third set value (for example, 1.05) is greater than the first set value (for example, 1.02), and the fourth set value (for example, 0.95) is less than The second setting is a standard value (for example, 0.98 standard value). Therefore, the operating frequency of the monitoring platform 60 and the converter 40 in the comparison process can be lower. In other words, the monitoring platform 60 does not need to confirm the node voltage value as frequently as the converter 40 does, and decide whether to perform the virtual power value control process currently. Therefore, the distribution feeder voltage virtual power compensation strategy according to the embodiment of the present invention can relatively save the monitoring platform. 60 system operating resources.

Step S290, confirm the maximum bus voltage according to the line length ( ) value, or minimum bus voltage ( ) value, and select a closer energy storage system 30 to perform the energy storage virtual work control program.

Step S300, confirm whether the virtual work compensation ratio of the energy storage virtual work control program does not reach a set upper limit value α? In some embodiments, the set upper limit value is between 70% and 80%.

Step S310, as shown in Figure 2B, when it is confirmed that the virtual power compensation ratio reaches the set upper limit value α, adjust the contactor (Tap) value of the on-load tap changer (OLTC) 20 to allow the on-load tap changer to switch. The output voltage of the converter (OLTC) 20 decreases or increases.

For example, at each bus voltage When it is greater than the third set standard value, adjust the contactor (Tap) value to the next gear to reduce the output voltage of the on-load tap changer (OLTC) 20. at each bus voltage When it is less than the fourth set standard value, adjust the contactor (Tap) value to one gear to increase the output voltage of the on-load tap changer (OLTC) 20. Until each bus voltage value ( ) are within the range, then the distribution feeder voltage virtual power compensation strategy process is stopped.

Step S320, set the number of analysis values (k) to be incremented by 1, and return to step S260 to perform the next power flow analysis.

Step S330, as shown in Figure 2C, when it is confirmed that the virtual work compensation ratio does not reach the set upper limit value α, the closer energy storage system 30 successively absorbs or provides the virtual work value with a compensation virtual work value β.

In step S340, the contactor (Tap) value of the on-load tap changer (OLTC) 20 is not adjusted. Then, step S320 is entered, the analysis number value (k) is set to be increased by 1, and the process returns to step S260 for the next power flow analysis.

To sum up, the distribution feeder voltage virtual power compensation strategy according to the embodiment of the present invention takes the feeder voltage as a consideration, calculates the voltage of each node of the feeder through power flow, and performs voltage regulation to effectively avoid the occurrence of over-high or under-voltage. Improve issues affecting the safety of electrical equipment.

In addition, the distribution feeder voltage virtual power compensation strategy according to the embodiment of the present invention integrates real-time power flow calculations to calculate the voltage of each node of the feeder. Through the independent virtual power control function of the converter, it is combined with the virtual power compensation control of the energy storage system to stabilize The local voltage is finally adjusted by the on-load tap changer (OLTC) to adjust the overall feeder voltage to stabilize the feeder voltage and improve the quality of power supply to users.

Although the present invention has been disclosed above through embodiments, they are not intended to limit the present invention. Anyone with ordinary knowledge in the technical field may make some modifications and modifications without departing from the spirit and scope of the present invention. Therefore, The protection scope of the present invention shall be determined by the appended patent application scope.

10:Feeder

20: On-load tap changer

30:Energy storage system

40:Converter

45: Renewable energy equipment

50:Load

60:Monitoring platform

70:Main electricity

100: Distribution feeder voltage virtual power compensation system

:parallel contact voltage

S200~S340: steps

Figure 1 is a block diagram of a distribution feeder voltage virtual power compensation system according to an embodiment of the present invention. Figures 2A to 2C are flow charts of the distribution feeder voltage virtual power compensation strategy according to the embodiment of the present invention.

S200~S340: steps

Claims (8)

A distribution feeder voltage virtual power compensation strategy includes the following steps: confirming the relationship between a parallel contact voltage ( V _PV,j ) on a feeder and a first set standard value and a second set standard value, where the The parallel contact voltage ( V _PV,j ) is the parallel contact voltage of the jth converter on the feeder; when the parallel contact voltage ( V _PV,j ) is greater than the first set standard value, or less than the When setting the standard value for the second time, an autonomous virtual power control process is performed; a system parameter is input, including a topology, a line length, a line impedance, a feeder terminal unit (FTU) current, a feeder terminal unit (FTU) The voltage, the rated capacity of an energy storage system and the contact (Tap) value of an on-load tap changer (OLTC) are used to simultaneously perform an energy storage virtual work control process; to set a virtual power absorbed or provided by the energy storage system. The power value is zero; set an analysis number value (k) to 1, and perform a power flow analysis to calculate the voltage value ( V _i ) of each bus; confirm that the voltage value ( V _i ) of each bus is consistent with There is a relationship between a third set value and a fourth set value. When each bus voltage value ( V _i ) is greater than the third set value or less than the fourth set value, proceed The energy storage virtual work control program: confirms a maximum bus voltage ( V _i,max ) value or a minimum bus voltage ( V _i,min ) value according to the line length, and selects a value closer to the energy storage system for the Energy storage virtual work control program; confirm whether the virtual work compensation ratio of the energy storage virtual work control program does not reach a set upper limit; when it is confirmed that the virtual work compensation ratio does not reach the set upper limit, it is closer to the energy storage system Absorb or provide the virtual power value successively with a compensation virtual power value; and set the analysis times value (k) to increase by 1, and perform the next power flow analysis. The distribution feeder voltage virtual power compensation strategy as described in request item 1, wherein the first setting value is between 1.01~1.04, and the second setting value is between 0.97~0.99 between. The distribution feeder voltage virtual power compensation strategy as described in request item 1, wherein the third setting value is between 1.05~1.07, and the fourth setting value is between 0.94~0.96 between. The distribution feeder voltage virtual power compensation strategy as described in claim 1, wherein when it is confirmed that the virtual power compensation ratio does not reach the set upper limit, the closer energy storage system absorbs or provides virtual power value successively with a compensation virtual power value. After the steps, there is also a step of not adjusting the contactor (Tap) value of the on-load tap changer (OLTC). The distribution feeder voltage virtual power compensation strategy as described in request item 1, wherein the setting upper limit is between 70% and 80%. The distribution feeder voltage reactive power compensation strategy as described in request item 1, wherein when it is confirmed that the reactive power compensation ratio reaches the set upper limit, the contact (Tap) value of the on-load tap changer (OLTC) is adjusted, In order to reduce or increase the output voltage of the on-load tap changer (OLTC). The distribution feeder voltage virtual power compensation strategy as described in claim 6, wherein each time the bus voltage ( V _i ) is greater than the third set standard value, the contact (Tap) value is adjusted to the next gear. , to reduce the output voltage of the on-load tap changer (OLTC). The distribution feeder voltage virtual power compensation strategy as described in claim 6, wherein every time the bus voltage ( V _i ) is less than the fourth set standard value, the contactor (Tap) value is adjusted to one gear. , to increase the output voltage of the on-load tap changer (OLTC).

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