Economic evaluation method for controllable phase shifter accessing power system

Abstract

The application discloses an economic evaluation method of controllable phase shifter access to a power system, the method constructs a power system application scene demand set, obtains a plurality of controllable phase shifter access schemes and investment costs of each controllable phase shifter access scheme, then obtains power system terminal power after the controllable phase shifter is accessed under each controllable phase shifter access scheme, obtains source and load network electrical stress change range after the controllable phase shifter is accessed and power system transient electrical quantity change characteristics after the controllable phase shifter is accessed based on the power system terminal power, further obtains total operation cost and risk cost of each controllable phase shifter access scheme, and performs economic evaluation of the controllable phase shifter access to the power system based on the investment cost, the total operation cost and the risk cost of each controllable phase shifter access scheme. The method can comprehensively evaluate safety and reliability after the phase shifter engineering is accessed, and provides a scientific basis for power system investment decision.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of controllable phase shifters, and particularly relates to an economic evaluation method for a controllable phase shifter accessing a power system. BACKGROUND

[0002] Engineering economic evaluation can help decision-makers choose appropriate engineering projects to maximize the use of resources, thereby avoiding mistakes in investment decisions and ensuring that resources are used reasonably and satisfactory economic results are achieved. Engineering economic evaluation methods are widely used in different engineering fields, and phase shifters, as important components in electronic engineering, are widely used in various fields. With the continuous progress of technology and changes in market demand, the economic evaluation of phase shifter engineering is particularly important.

[0003] In power system decision-making, economic efficiency is an important aspect of evaluating the rationality of decision-making. Common engineering economic evaluation theories mainly include traditional minimum cost evaluation method and benefit-cost evaluation method. The traditional minimum cost evaluation method is a single-attribute economic evaluation method, which aims to minimize the cost of the project throughout its life cycle, including maintenance costs, taxes, and investment costs. It is suitable for situations driven by standards and focusing on cost minimization. Since this method only aims to minimize costs and does not consider benefits or other value attributes, it limits the comprehensive evaluation of project economics. In addition, this method cannot meet the needs of multi-attribute decision-making and lacks flexibility. The benefit-cost evaluation method is a multi-attribute economic evaluation method that selects the optimal scheme by calculating the ratio of benefits to costs. This method allows projects to exceed the power supply obligations of power companies and only needs to meet the benefit limit, making it particularly suitable for evaluating special maintenance projects and demand-side projects. However, relying solely on the benefit-cost ratio may overlook other important factors such as risk, project feasibility, and practicality. SUMMARY

[0004] To solve the problems existing in the prior art, the application provides an economic evaluation method for a controllable phase shifter accessing a power system.

[0005] The technical scheme of the application is as follows:

[0006] An economic evaluation method for a controllable phase shifter accessing a power system, comprising:

[0007] Based on the power system application scenario requirements related to power flow control, harmonic control, reactive power compensation, and voltage frequency support, a power system application scenario requirement set with several demand elements is constructed;

[0008] Obtain the controllable phase shifter access scheme under each demand element in the power system application scenario requirement set and the investment cost of each controllable phase shifter access scheme;

[0009] Under each controllable phase shifter access scheme, the terminal power of the power system after the controllable phase shifter is accessed is obtained, and based on the terminal power of the power system, the range of variation of the source-load-network electrical stress after the controllable phase shifter is accessed and the variation characteristics of the transient electrical quantity of the power system after the controllable phase shifter is accessed are obtained;

[0010] Based on the range of variation of the source-load-network electrical stress after the controllable phase shifter is accessed and the variation characteristics of the transient electrical quantity of the system after the controllable phase shifter is accessed corresponding to each controllable phase shifter access scheme, the total operation cost and the risk cost of each controllable phase shifter access scheme are obtained;

[0011] Based on the investment cost, the total operation cost and the risk cost of each controllable phase shifter access scheme, the economic evaluation of the controllable phase shifter access power system is performed.

[0012] Further, the demand elements in the set of power system application scenario demands are any one application scenario demand or a combination of multiple application scenario demands.

[0013] Further, the harmonic control in the power system application scenario demand is used for total harmonic distortion control, and the calculation method of the total harmonic distortion is as follows:

[0014]

[0015] In the formula, THD is the total harmonic distortion; respectively represent the square of the total effective value, the first harmonic effective value and the n-th harmonic effective value of a periodic signal; DF is called distortion index, which represents the ratio of the first harmonic effective value to the total effective value.

[0016] Further, the reactive power compensation in the power system application scenario demand is used for realizing the reactive power compensation in the power system, and the calculation method of the reactive power compensation amount in the reactive power compensation is as follows:

[0017]

[0018] In the formula, Q c is the reactive power compensation amount; V is the voltage; X c is the capacitor reactance; ω is the system angular frequency.

[0019] Further, the specific method for obtaining the controllable phase shifter access scheme under each demand element in the set of power system application scenario demands and the investment cost of each controllable phase shifter access scheme includes:

[0020] For the demand elements of the power system application scenarios containing power flow control and / or reactive power compensation, a multi-point distributed access scheme is adopted in which controllable phase shifters are distributedly accessed at multiple key load nodes and transmission lines; for the multi-point distributed access scheme, the investment cost includes total equipment cost C device , installation cost C install and control communication system cost C control ;

[0021] For the demand elements of the power system application scenarios containing harmonic governance, a centralized access scheme is adopted in which controllable phase shifters are centrally accessed at main substations and load centers; for the centralized access scheme, the investment cost includes total equipment cost, filter cost C filter , installation cost and control communication system cost;

[0022] For the demand elements of the power system application scenarios containing voltage and frequency support, a dynamically adjustable access scheme is adopted in which controllable phase shifters are dynamically adjusted and accessed at fluctuating load areas of renewable energy access points; for the dynamically adjustable access scheme, the investment cost includes total equipment cost, dynamic adjustment module cost C dynamic , installation cost and control communication system cost;

[0023] For the demand elements containing multiple power system application scenarios, the controllable phase shifter access scheme corresponding to each power system application scenario is taken as a sub-scheme, and the sub-schemes are combined to form the controllable phase shifter access scheme, and the investment costs of each sub-scheme are added up.

[0024] Further, the calculation method of the power at the end of the power system after the controllable phase shifter is accessed is as follows:

[0025]

[0026] In the formula, U s and U r are the voltage at the head and the voltage at the end of the controllable phase shifter respectively; X L is the reactance value between the two nodes at the head and the end of the phase shifter; α pst is the phase shift angle; and δ is the angle between the apparent power and the active power.

[0027] Further, the source-load-grid electrical stress variation includes current stress variation and power factor variation; and the power system transient electrical quantity variation includes voltage sag depth and frequency deviation.

[0028] Further, the specific steps of obtaining the source-load-grid electrical stress variation range after the controllable phase shifter is accessed and the power system transient electrical quantity variation characteristics after the controllable phase shifter is accessed based on the power at the end of the power system include:

[0029] System current before the controllable phase shifter is connected: I1= P1 / (U1cosφ1)

[0030]

[0031] P1 is the terminal power before the controllable phase shifter is connected; φ1 is the power factor angle before the connection; and U1 is the voltage before the connection.

[0032] System current after the controllable phase shifter is connected: I2= P2 / (U2cosφ2)

[0033]

[0034] P2 is the terminal power after the controllable phase shifter is connected; φ2 is the power factor angle after the connection; and U2 is the voltage after the connection.

[0035] The current stress change amount ΔI=I2-I1 is determined by comparing the system current I1 before the phase shifter is connected with the system current I2 after the controllable phase shifter is connected.

[0036] The power factor angle before the connection φ1 is compared with the power factor angle after the connection φ2. The power factor change amount Δφ=φ2-φ1 is determined.

[0037] The voltage sag depth: ΔU=U2-U1

[0038]

[0039] V1 is the initial voltage; P is the power injected into the system during the fault; and P is the total power of the system. initial fault total

[0040] The frequency offset change amount: Δf= f2-f1

[0041]

[0042] ΔP is the change amount of the system load; and M is the frequency response constant of the system.

[0043] Further, the specific steps of obtaining the total operation cost and the risk cost of each controllable phase shifter connection scheme based on the source-load-network electrical stress change range after the controllable phase shifter is connected corresponding to each controllable phase shifter connection scheme and the transient electrical quantity change characteristics of the system after the phase shifter is connected include:

[0044] The total operation cost of the controllable phase shifter connection scheme is calculated according to the following formula:

[0045] ​​​​

[0046] C = P × C + P × C + P × C + P × C + P × C + P × C + P × C run is the total operation cost; k I is the current loss coefficient; is the power factor change coefficient; k V is the voltage sag coefficient; k f is the frequency deviation coefficient; t is the considered controllable phase shifter operation time;

[0047] The risk cost of the controllable phase shifter access scheme is calculated as follows:

[0048] C = P × C + P × C + P × C + P × C + P × C + P × C + P × C risk = P I × C I + P pf × C pf + P V × C V + P f × C f

[0049] P = P × C + P × C + P × C + P × C + P × C + P × C + P × C I is the ratio of current stress change amount to current safety margin; C I is the equipment damage cost; P pf is the ratio of power factor change amount to given change margin; C pf is the cost of additional energy consumption caused by power factor change; P V is the ratio of voltage sag depth to safety margin; C V is the production loss caused by voltage sag depth; P f is the ratio of frequency deviation to set margin; C f is the equipment damage cost caused by current impact.

[0050] Further, the specific steps of economic evaluation of controllable phase shifter access to power system based on the investment cost, total operation cost and risk cost of each controllable phase shifter access scheme include:

[0051] Taking the investment cost, total operation cost and risk cost of each controllable phase shifter access scheme as evaluation indexes, an economic evaluation model of controllable phase shifter access to power system is constructed:

[0052]

[0053] E = C + C + … + C in1 , C in2 … C inn are the investment costs of controllable phase shifter engineering schemes in different application scenarios, C run1 , C run2 … C runnW1, W2…W is the total operation cost of the controllable phase shifter engineering scheme in different application scenarios n C is the weight of different application scenarios risk Risk cost

[0054] Obtain the economic evaluation result of each controllable phase shifter access scheme corresponding to the economic evaluation model.

[0055] An electronic device includes a memory and a processor, the memory stores a computer program, and the processor is used to call and run the computer program stored in the memory to execute the method of any one of the above.

[0056] A computer readable storage medium stores a computer program, and the computer program is executed by a processor to implement the steps of the method of any one of the above.

[0057] Compared with the prior art, the present application has the following beneficial effects:

[0058] The present application proposes an economic evaluation method for controllable phase shifter access to a power system, which constructs a power system application scenario demand set with several demand elements, obtains controllable phase shifter access schemes under each demand element in the power system application scenario demand set and the investment cost of each controllable phase shifter access scheme, then obtains the power system terminal power after accessing the controllable phase shifter under each controllable phase shifter access scheme, and based on the power system terminal power, obtains the source and load network electrical stress change range after accessing the controllable phase shifter and the transient electrical quantity change characteristics of the power system after accessing the controllable phase shifter, and finally obtains the total operation cost and risk cost of each controllable phase shifter access scheme based on the source and load network electrical stress change range after accessing the controllable phase shifter corresponding to each controllable phase shifter access scheme and the system transient electrical quantity change characteristics after accessing the controllable phase shifter, and performs economic evaluation of the controllable phase shifter access to the power system based on the investment cost, total operation cost and risk cost of each controllable phase shifter access scheme. The method can comprehensively evaluate the safety and reliability of the phase shifter engineering access, provide multiple controllable phase shifter access schemes, and perform economic evaluation on these schemes, and provide a scientific basis for power system investment decision-making. BRIEF DESCRIPTION OF DRAWINGS

[0059] Figure 1 The flowchart of the economic evaluation method for controllable phase shifter access to a power system in the embodiment. DETAILED DESCRIPTION

[0060] The present application will be further illustrated below in conjunction with the accompanying drawings and specific embodiments. It should be understood that these embodiments are only used to illustrate the present application and are not used to limit the scope of the present application. After reading the present application, those skilled in the art can make various modifications to the equivalent forms of the present application, which fall within the scope defined by the appended claims.

[0061] Embodiment one:

[0062] An economic evaluation method of a controllable phase shifter accessing a power system, as shown in Figure 1 , includes:

[0063] S1, based on the power system application scenario demand related to power flow control, harmonic control, reactive power compensation, voltage frequency support, a power system application scenario demand set with a plurality of demand elements is constructed;

[0064] S2, obtaining the controllable phase shifter access scheme under each demand element in the power system application scenario demand set and the investment cost of each controllable phase shifter access scheme;

[0065] S3, under each controllable phase shifter access scheme, the power at the end of the power system after accessing the controllable phase shifter is obtained, and based on the power at the end of the power system, the source-load-network electrical stress variation range after the controllable phase shifter is accessed and the transient electrical quantity variation characteristic of the power system after the controllable phase shifter is accessed are obtained;

[0066] S4, based on the source-load-network electrical stress variation range after the controllable phase shifter is accessed and the transient electrical quantity variation characteristic of the system after the controllable phase shifter is accessed corresponding to each controllable phase shifter access scheme, the total operation cost and risk cost of each controllable phase shifter access scheme are obtained;

[0067] S5, based on the investment cost, total operation cost and risk cost of each controllable phase shifter access scheme, the economic evaluation of the controllable phase shifter accessing the power system is carried out.

[0068] Embodiment two:

[0069] The embodiment is further designed on the basis of embodiment one, and in this example, the demand elements in the power system application scenario demand set are any one application scenario demand or a combination of multiple application scenario demands.

[0070] The demand elements in the power system application scenario demand set are further illustrated below with an example. In this example, the power system application scenario demands set are power flow control, harmonic control, reactive power compensation, and voltage frequency support, respectively denoted as a, b, c, and d, and the constructed power system application scenario demand set is {a, ab, abc, abd, abcd, ac, acd, ad, b, bc, bcd, bd, c, cd, d}.

[0071] Embodiment three:

[0072] The embodiment is further designed on the basis of embodiment one, and in the embodiment, harmonic control in the power system application scenario requirement is used to control total harmonic distortion, and the calculation method of the total harmonic distortion is as follows:

[0073]

[0074] In the formula, THD is total harmonic distortion; respectively represent the square of the total effective value, the first harmonic effective value, and the n-th harmonic effective value of a periodic signal; DF is called distortion index, and represents the ratio of the first harmonic effective value to the total effective value.

[0075] Embodiment four:

[0076] The embodiment is further designed on the basis of embodiment one, and in the embodiment, the reactive power compensation in the power system application scenario requirement is used to realize reactive power compensation in the power system, and the calculation method of the reactive power compensation amount in the reactive power compensation is as follows:

[0077]

[0078] In the formula, Q c is the reactive power compensation amount; V is voltage; X c is the capacitor reactance; and ω is the system angular frequency.

[0079] Embodiment five:

[0080] The embodiment is further designed on the basis of embodiment one, and in the embodiment, the specific method for obtaining the controllable phase shifter access scheme under each requirement element in the power system application scenario requirement set and the investment cost of each controllable phase shifter access scheme includes:

[0081] For the requirement element of the power system application scenario requirement containing power flow control and / or reactive power compensation, a multi-point distributed access scheme of accessing controllable phase shifters in multiple key load nodes and power transmission lines is adopted; for the multi-point distributed access scheme, the investment cost includes the total equipment cost C device , the installation cost C install , and the control communication system cost C control ;

[0082] For the requirement element of the power system application scenario requirement containing harmonic control, a centralized access scheme of accessing controllable phase shifters in main substations and load centers is adopted; for the centralized access scheme, the investment cost includes the total equipment cost, the filter cost C filter , the installation cost, and the control communication system cost;

[0083] For the demand elements of the power system application scenario requirements containing voltage frequency support, a dynamically adjustable access scheme is adopted in the fluctuating load area of the renewable energy access point to dynamically adjust the access of the controllable phase shifter. For the dynamically adjustable access scheme, the investment cost includes the total cost of equipment, the cost of dynamic adjustment module C dynamic and installation cost, and the cost of control communication system;

[0084] For the demand elements containing multiple power system application scenario requirements, the controllable phase shifter access scheme corresponding to each power system application scenario requirement is taken as a sub-scheme, and the sub-schemes are combined to form a controllable phase shifter access scheme, and the investment costs of each sub-scheme are added up.

[0085] Embodiment six:

[0086] The embodiment is further designed on the basis of embodiment one, and in this embodiment, the calculation method of the power at the end of the power system after the controllable phase shifter is accessed is as follows:

[0087]

[0088] In the formula, U s and U r are the voltage at the head and the voltage at the end of the controllable phase shifter respectively; X L is the reactance value between the two nodes at the head and the end of the phase shifter; α pst is the phase shift angle; and δ is the angle between the apparent power and the active power.

[0089] Embodiment seven:

[0090] The embodiment is further designed on the basis of embodiment one, and in this embodiment, the source-load-network electrical stress variation includes the current stress variation and the power factor variation; and the power system transient electrical quantity variation includes the voltage sag depth and the frequency deviation.

[0091] Embodiment eight:

[0092] The embodiment is further designed on the basis of embodiment seven, and in this embodiment, the specific steps of obtaining the source-load-network electrical stress variation range after the controllable phase shifter is accessed and the power system transient electrical quantity variation characteristics after the controllable phase shifter is accessed based on the power at the end of the power system include:

[0093] The system current I1 before the controllable phase shifter is accessed is calculated:

[0094]

[0095] In the formula, P1 is the power at the end before the controllable phase shifter is accessed; is the power factor angle before the access; and U1 is the voltage before the access.

[0096] System current I2 after the controllable phase shifter is connected:

[0097]

[0098] In the formula, P2 is the terminal power after the controllable phase shifter is connected; is the power factor angle after the connection; and U2 is the voltage after the connection.

[0099] The system current I1 before the phase shifter is connected and the system current I2 after the controllable phase shifter is connected are compared to determine the current stress change amount ΔI = I2-I1;

[0100] The power factor angle before the connection and the power factor angle after the connection are compared to determine the power factor change amount

[0101] The voltage sag depth:

[0102]

[0103] In the formula, V initial is the initial voltage; P fault is the power injected into the system during the fault; and P total is the total power of the system.

[0104] The frequency offset change amount:

[0105]

[0106] In the formula, ΔP is the change of the system load; and M is the frequency response constant of the system.

[0107] Embodiment Nine:

[0108] The embodiment is further designed on the basis of Embodiment Eight, and in the embodiment, the specific steps of obtaining the total operation cost and the risk cost of each controllable phase shifter connection scheme based on the source-load network electrical stress change range after the corresponding controllable phase shifter is connected and the transient electrical quantity change characteristics of the system after the phase shifter is connected include:

[0109] The total operation cost of the controllable phase shifter connection scheme is calculated according to the following formula:

[0110]

[0111] In the formula, C run is the total operation cost; k I is the current loss coefficient; is the power factor change coefficient; k V is the voltage sag coefficient; and kf is the frequency offset coefficient; t is the time of the controllable phase shifter under consideration being put into operation;

[0112] The risk cost of the controllable phase shifter access scheme is calculated as follows:

[0113] C risk = P I × C I + P pf × C pf + P V × C V + P f × C f

[0114] In the formula, P I is the ratio of the current stress change amount to the current safety margin; C I is the equipment damage cost; P pf is the ratio of the power factor change amount to the given change margin; C pf is the cost of the additional energy consumption caused by the power factor change; P V is the ratio of the voltage sag depth to the safety margin; C V is the production loss caused by the voltage sag depth; P f is the ratio of the frequency offset to the set margin; C f is the equipment damage cost caused by the current impact.

[0115] Example Ten:

[0116] The embodiment is further designed on the basis of Example Nine, and in this example, the specific steps of the economic evaluation of the controllable phase shifter access power system based on the investment cost, the total operation cost and the risk cost of each controllable phase shifter access scheme include:

[0117] Taking the investment cost, the total operation cost and the risk cost of each controllable phase shifter access scheme as the evaluation indexes, an economic evaluation model of the controllable phase shifter access power system is constructed:

[0118]

[0119] In the formula, E is the economic evaluation result, and the closer the value of E is to 1, the better the economy of the phase shifter engineering scheme is; C in1 , C in2 … C inn are the investment costs of the controllable phase shifter engineering schemes in different application scenarios, C run1 , C run2 … C runn are the total operation costs of the controllable phase shifter engineering schemes in different application scenarios, W1, W2… W n are the weights of different application scenarios.risk Risk cost;

[0120] Obtain the economic evaluation result of each controllable phase shifter access scheme corresponding to the economic evaluation model.

[0121] Embodiment eleven:

[0122] An electronic device includes a memory and a processor, the memory stores a computer program, and the processor is configured to invoke and run the computer program stored in the memory to execute the method of any one of the above embodiments.

[0123] A computer readable storage medium stores a computer program, and the computer program is executed by a processor to implement the steps of the method of any one of the above embodiments.

[0124] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited to this. Any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. An economic evaluation method for connecting a controllable phase shifter to a power system, characterized in that, include: Based on the power system application scenario requirements related to power flow control, harmonic mitigation, reactive power compensation, and voltage and frequency support, a power system application scenario requirement set with several requirement elements is constructed. Obtain the controllable phase shifter access scheme and the investment cost of each controllable phase shifter access scheme under each requirement element in the power system application scenario requirement set; Under each controllable phase shifter access scheme, the power at the end of the power system after the controllable phase shifter is accessed is obtained, and based on the power at the end of the power system, the range of changes in electrical stress in the source-load grid after the controllable phase shifter is accessed and the characteristics of changes in transient electrical quantities in the power system after the controllable phase shifter is accessed are obtained. Based on the range of electrical stress change in the source-load grid after the controllable phase shifter is connected and the characteristics of transient electrical quantity change in the system after the phase shifter is connected, the total operating cost and risk cost of each controllable phase shifter connection scheme are obtained. An economic evaluation of the integration of controllable phase shifters into the power system is conducted based on the investment cost, total operating cost, and risk cost of each controllable phase shifter integration scheme. The changes in electrical stress in the power grid include changes in current stress and changes in power factor. Transient electrical quantities in a power system include voltage sag depth and frequency deviation; The specific steps for obtaining the range of changes in electrical stress in the source-load grid and the characteristics of transient electrical quantity changes in the power system after the controllable phase shifter is connected, based on the power at the end of the power system, include: Calculate the system current I1 before connecting the controllable phase shifter: In the formula, P r,1 To connect the power at the front end of the controllable phase shifter; U1 is the power factor angle before connection; U2 is the voltage before connection. Calculate the system current I2 after connecting the controllable phase shifter: In the formula, P r,2 For the end power after connecting to the controllable phase shifter; U1 is the power factor angle after connection; U2 is the voltage after connection. Compare the system current I1 before the phase shifter is connected and the system current I2 after the controllable phase shifter is connected to determine the current stress change Δi = i2 - I1; Compare the power factor angle before connection and the power factor angle after connection Determine the power factor change The voltage sag depth: In the formula, V initial P is the initial voltage; fault Power injected into the system during a fault; P total This represents the total power of the system. The frequency deviation: In the formula, ΔP is the change in system load; M is the system frequency response constant; The specific steps for obtaining the total operating cost and risk cost of each controllable phase shifter access scheme based on the range of electrical stress change in the source-load grid after the controllable phase shifter is connected and the transient electrical quantity change characteristics of the system after the phase shifter is connected include: The total operating cost of the controllable phase shifter access scheme is calculated using the following formula: In the formula, C run Total operating cost; k I This is the current loss coefficient; k is the power factor variation coefficient. V k is the voltage sag factor. f P is the frequency offset coefficient; t is the operating time of the controllable phase shifter under consideration; r The active power at the end of the power system after the controllable phase shifter is connected; The risk cost of the controllable phase shifter access scheme is calculated using the following formula: C risk＝ P I ×C I +P pf ×C pf +P V ×C V +P f ×C f In the formula, P I C is the ratio of the change in current stress to the current safety margin. I Cost of equipment damage; P pf C is the ratio of the change in power factor to a given margin of change. pf The cost of additional energy consumption due to power factor changes; P V C is the ratio of voltage sag depth to safety margin. V Production losses due to voltage sag depth; P f The ratio of frequency offset to set margin; C f Costs associated with equipment damage caused by electrical surges.

2. The economic evaluation method for connecting a controllable phase shifter to a power system according to claim 1, characterized in that, The requirement elements in the power system application scenario requirement set can be any one application scenario requirement or a combination of multiple application scenario requirements.

3. The economic evaluation method for connecting a controllable phase shifter to a power system according to claim 1, characterized in that, Harmonic mitigation in the power system application scenario is used to mitigate total harmonic distortion (THD). The calculation method for THD is as follows: In the formula, THD represents total harmonic distortion; These represent the total effective value, the first harmonic effective value, and the square of the nth harmonic effective value of a periodic signal, respectively; DF is called the distortion index, which represents the ratio of the first harmonic effective value to the total effective value.

4. The economic evaluation method for connecting a controllable phase shifter to a power system according to claim 1, characterized in that, The reactive power compensation required in the power system application scenario is used to achieve reactive power compensation in the power system. The calculation method for the reactive power compensation amount is as follows: In the formula, Q c V represents reactive power compensation; V represents voltage; X represents reactive power compensation. c ω is the capacitive reactance of the capacitor; ω is the angular frequency of the system.

5. The economic evaluation method for connecting a controllable phase shifter to a power system according to claim 1, characterized in that, The specific methods for obtaining the controllable phase shifter access scheme and the investment cost of each controllable phase shifter access scheme under each demand element in the power system application scenario demand set include: For power system application scenarios involving power flow control and / or reactive power compensation, a multi-point distributed access scheme is adopted, in which controllable phase shifters are distributed across multiple key load nodes and transmission lines. For this multi-point distributed access scheme, the investment cost includes the total equipment cost C. device Installation cost C install and control the cost of communication systems C controk ; For power system application scenarios involving harmonic mitigation, a centralized access scheme is adopted, using controllable phase shifters centrally connected at the main substation and load center. For this centralized access scheme, the investment cost includes the total equipment cost and the filter cost C. filter And installation costs and control of communication system costs; For power system application scenarios that include voltage and frequency support, a dynamically adjustable access scheme with controllable phase shifters is adopted in the fluctuating load area of ​​renewable energy access points. For this dynamically adjustable access scheme, the investment cost includes the total equipment cost and the cost of the dynamic adjustment module (C). dynamic And installation costs and control of communication system costs; For demand elements that include multiple power system application scenarios, the controllable phase shifter access scheme corresponding to each power system application scenario is taken as a sub-scheme, and the sub-schemes are combined to form a controllable phase shifter access scheme, and the investment cost of each sub-scheme is accumulated.

6. The economic evaluation method for connecting a controllable phase shifter to a power system according to claim 1, characterized in that, The calculation method for the power at the end of the power system after connecting the controllable phase shifter is as follows: In the formula, U s and U r These are the start and end voltages of the controllable phase shifter, respectively; X L α is the reactance between the two nodes at the beginning and end of the phase shifter. pst δ is the phase shift angle; δ is the angle between apparent power and active power.

7. The economic evaluation method for connecting a controllable phase shifter to a power system according to claim 1, characterized in that, The specific steps for evaluating the economic benefits of integrating controllable phase shifters into the power system based on the investment cost, total operating cost, and risk cost of each controllable phase shifter integration scheme include: Using the investment cost, total operating cost, and risk cost of each controllable phase shifter integration scheme as evaluation indicators, an economic evaluation model for the integration of controllable phase shifters into the power system is constructed: In the formula, E represents the economic evaluation result; C in1 C in2 ···C inn To determine the investment cost of controllable phase shifter engineering solutions for different application scenarios, C run1 C run ···C runn The total operating cost of controllable phase shifter engineering solutions in different application scenarios, W1, W2...W n C is weighted according to different application scenarios. risk For risk costs; Obtain the economic evaluation results of the economic evaluation model corresponding to each controllable phase shifter access scheme.

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