CN105633981A - Unified power flow controller additional damping control system capable of restraining subsynchronous oscillation - Google Patents

Abstract

The invention discloses a unified power flow controller additional damping control system capable of restraining subsynchronous oscillation. The unified power flow controller additional damping control system comprises a subsynchronous damping controller, wherein the additional control signals are superimposed in current inner loop control instructions of reactive control circuits of a shunt-wound side converter and a series-wound side converter of the unified power flow controller; the subsynchronous damping controller comprises multiple subsynchronous modal control circuits; each subsynchronous modal control circuit comprises a modal filter, a proportion amplifying module and a phase shifter for realizing phase compensation separately; the output signals of each subsynchronous modal control circuit are subjected to signal superposition and amplitude limiting to form the additional control signals output by the subsynchronous damping controller; and the subsynchronous damping controller takes generator shaft system rotating speed deviation as the input control signal. The unified power flow controller additional damping control system provided by the invention is capable of restraining subsynchronous oscillation of the power system successfully and the normal and steady operation of the system and the unified power flow controller is not affected.

Description

A kind of THE UPFC additional longitudinal forces system suppressing sub-synchronous oscillation

Technical field

The present invention relates to a kind of THE UPFC (UnifiedPowerFlowController suppressing sub-synchronous oscillation, UPFC) additional longitudinal forces system, belong to sub-synchronous oscillation (SubsynchronousOscillation, SSO) suppression technology field.

Background technology

Along with the propelling of China's " transferring electricity from the west to the east " electric power development strategy, sending demand outside for meeting the large-scale power supply base electric power away from load center, series capacitor compensation transmission of electricity, D.C. high voltage transmission (HVDC) are widely used in China; But, series capacitor compensation transmission of electricity and D.C. high voltage transmission, while improving power transmitting capability, bringing tremendous economic, also make power system be faced with the SSO problem of sternness.

As flexible AC transmission (FACTS) device that function now is the most powerful, THE UPFC (UPFC) not only can provide reactive-load compensation to system, regulate system voltage, also can realize the effective control to system effective power flow and reactive power flow, power system has popularizing application prospect widely. Existing Unified Power Flow controls system, and the sub-synchronous oscillation of power system is relatively larger.

UPFC device includes side transformer-inverter in parallel, series side transformator-inverter and DC capacitor, UPFC parallel connection side inverter (VSC1) and series side inverter (VSC2) and is respectively adopted the vector controlled that two ends node voltage is directed. Under the adjustment effect of its controller, UPFC series/parallel side inverter is respectively to the voltage U that system output amplitude and phase angle are controlled_seAnd U_sh. UPFC device wiring schematic diagram referring to Fig. 1 (a) and equivalent circuit diagram referring to Fig. 1 (b); Fig. 2 (a) is UPFC parallel connection side transformer-inverter VSC1 control block diagram; Fig. 2 (b) is UPFC series side transformator-inverter VSC2 control block diagram.

Summary of the invention

For the deficiency that prior art exists, it is an object of the present invention to provide a kind of THE UPFC additional longitudinal forces system suppressing sub-synchronous oscillation, designed THE UPFC supplementary subsynchronous damping control device, can successfully suppress the sub-synchronous oscillation of power system, and the normal table without influence on system and THE UPFC device runs.

To achieve these goals, the present invention realizes by the following technical solutions:

This system utilizes designed Subsynchronous Damping Controller to act on THE UPFC control loop, reaches the purpose that sub-synchronous oscillation suppresses.

A kind of THE UPFC additional longitudinal forces system suppressing sub-synchronous oscillation of the present invention, THE UPFC device includes side in parallel inverter, series side inverter and DC capacitor, including Subsynchronous Damping Controller, the additional control signals u of described Subsynchronous Damping Controller_{damp_sh}And u_{damp_se}It is superimposed upon the q shaft current internal ring control instruction place in side inverter in parallel and the idle control loop of series side inverter respectively; Described Subsynchronous Damping Controller includes multiple subsynchronous Model control loop, each described subsynchronous Model control loop includes modal filter, for the input scaling module that is amplified of signal with for realizing the phase shifter of phase compensation, the output signal in each subsynchronous Model control loop is superimposed and namely forms the additional control signals u of Subsynchronous Damping Controller output after clipping module_{damp_sh}And u_{damp_se}; Described Subsynchronous Damping Controller is with generator shaft system rotating speed deviation delta ��_GFor input control signal.

Wherein, described modal filter, for realizing the uneoupled control to different SSO mode, each modal filter controlling loop is composed in series by the band filter of corresponding model frequency and the band elimination filter of other model frequencies;

Wherein, described scaling module, for being amplified filtered mode signals regulating, provide sufficiently large signal for supplementary subsynchronous damping control device;

Wherein, the described phase shifter, for compensating modal filter, UPFC inverter-connection transformer, the power system lagging phase to SSO model frequency signal, Model control signal is generated;

Wherein, described clipping module, for the superposed signal of the Model control signal that each Model control loop generates is carried out amplitude limit, generate the subsynchronous additional control signals of final THE UPFC.

Above-mentioned Subsynchronous Damping Controller adopts the Multi Channel Controller structure of modal separation, for each synchronized oscillation mode is carried out uneoupled control.

Above-mentioned modal filter is composed in series by the band filter of corresponding model frequency and the band elimination filter of other model frequencies.

If the angular frequency of mode i component is �� in shaft system of unit rotating speed_i, amplitude be A_i, initial phase beSide in parallel inverter additional controller is to the phase shift of mode i frequency component and amplification respectively k_ishAnd ��_ish, then being superimposed in the Converter controller of UPFC parallel connection side the additional control signals of circular current control instruction is

Additional control signals can quickly be followed the tracks of by UPFC parallel connection side inverter, and the corresponding subsynchronous frequency current of its output is

In formula, T_shiFor the side in parallel inverter operating lag to mode i frequency signal, s is Laplace operator;

Flow into the subsynchronous electric current I of generator armature winding_{genq_shi}For

In formula, Z_{gen_i}��Z_{sys_shi}Respectively under mode i frequency, from UPFC node to the equivalent impedance of electromotor, the system equivalent impedance to UPFC; G_ishAnd ��_ishRespectively UPFC parallel connection side inverter and system are to the amplitude-frequency response of mode i frequency signal and phase-frequency response;

Thus, the subsynchronous electric current of the mode i frequency of UPFC parallel connection side inverter output can be obtained, through subsynchronous torque �� T additional produced by generator armature winding_{ei_sh}For

${\mathrm{\ΔT}}_{ei\_sh}=\frac{U_G{I}_{genq\_shi}{\mathrm{sin\δ}}_{sh}}{{\mathrm{\ω}}_G}$

In formula, U_GFor generator terminal voltage, ��_shPoint voltage U is entered for the advanced UPFC parallel connection side joint of generator terminal voltage₁Angle; ��_GFor generator speed, it is �� in the steady state_G�� 1.0p.u., thus above formula can abbreviation be

In like manner, the subsynchronous electric current of the mode i frequency of UPFC series side inverter output can be obtained, through subsynchronous torque �� T additional produced by generator armature winding_{ei_se}For

In formula, ��_iseAnd k_iseRespectively series side inverter additional controller is to the phase shift of mode i frequency component and amplification, G_iseAnd ��_iseRespectively UPFC series side inverter and system are to the amplitude-frequency response of mode i frequency signal and phase-frequency response, ��_seFor generator terminal voltage advanced UPFC series side access point voltage U₂Angle;

Additional subsynchronous electromagnetic torque �� T produced by UPFC supplementary subsynchronous damping control_{ei_sh}With �� T_{ei_se}Expression formula it can be seen that adjust additional controller mode i control loop phase shift theta_ishAnd ��_ise, and amplification k_ishAnd k_iseSo that it is in electromotor, produce sufficiently large positive additional electromagnetic torque �� T_{ei_sh}With �� T_{ei_se}, can reach to suppress the purpose of this mode sub-synchronous oscillation.

For the system that sub-synchronous oscillation is stable, i.e. A_i=0, thus there being the additional control signals u in each Model control loop_dampi=0, Jin Eryou

u_damp=�� u_dampi=0 (i=1,2 ..., n)

Namely Subsynchronous Damping Controller is output as 0 under steady state conditions, without influence on system and THE UPFC device in the steady state properly functioning.

The invention has the beneficial effects as follows:

By the secondary control loop supplementary subsynchronous damping control in THE UPFC, reach the purpose that sub-synchronous oscillation suppresses, it is not necessary to increasing a new electrical equipment, cost of investment is low; The suppression to the multi-modal sub-synchronous oscillation of power system can be realized simultaneously, ensure the safety of power equipment, improve the stability of power system.

Accompanying drawing explanation

Fig. 1 (a) is UPFC wiring schematic diagram;

Fig. 1 (b) is UPFC equivalent circuit diagram;

Fig. 2 (a) is UPFC parallel connection side transformer-inverter VSC1 control block diagram;

Fig. 2 (b) is UPFC series side transformator-inverter VSC2 control block diagram;

Fig. 3 is the compensated transmission system wiring diagram containing UPFC;

Fig. 4 is UPFC supplementary subsynchronous damping control device theory diagram;

Fig. 5 (a) is the subsynchronous electric current equivalent circuit of UPFC side inverter;

Fig. 5 (b) is UPFC side inverter phase place schematic diagram;

Fig. 6 (a) is steam-electric generating set shafting rotating speed deviation and moment of torsion;

Fig. 6 (b) puts into operation front and back system emulation result for series/parallel side inverter SSDC;

Fig. 7 (a) is steam-electric generating set shafting rotating speed deviation and moment of torsion;

Fig. 7 (b) puts into operation front and back system emulation result for series side inverter SSDC;

Fig. 8 (a) is steam-electric generating set shafting rotating speed deviation and moment of torsion;

Fig. 8 (b) puts into operation front and back system emulation result for side inverter SSDC in parallel;

Fig. 9 is the THE UPFC additional longitudinal forces system block diagram suppressing sub-synchronous oscillation.

Detailed description of the invention

For the technological means making the present invention realize, creation characteristic, reach purpose and effect and be easy to understand, below in conjunction with detailed description of the invention, the present invention is expanded on further.

Additional controller feedback control signal: for reaching the purpose of suppression system SSO, need to control UPFC device and inject the subsynchronous frequency current of complement frequency to system. Adopt generator shaft system rotating speed deviation as feedback control signal, and owing to UPFC Converter controller contains current inner loop controlling unit, UPFC export electric current can quick follow current inner loop control signal, therefore additional control signals is superimposed to current inner loop instruction place of UPFC converter Control. It is �� for frequency_iSSO mode, subsynchronous additional controller will in the dq shaft current internal ring instruction of UPFC converter Control superposition ��_iThe signal of frequency, after UPFC converter Control dq to adc Coordinate Conversion, namely controls UPFC and injects complement frequency (�� to system₀-��_i) subsynchronous electric current, ��₀For system power frequency angular frequency.

Additional control signals on-position: be maintain the properly functioning most important condition of UPFC owing to maintenance UPFC DC bus-bar voltage is constant, therefore be left out SSDC (subsynchronous additional damping controller) the signal u by suppressing SSO_{damp_sh}It is superimposed to the DC voltage control loop of UPFC parallel connection side inverter; Meanwhile, for reducing the disturbance to system power, the real power control loop superposition SSDC signal u at UPFC series side inverter also it is left out_{damp_se}. Therefore, for reducing the UPFC additional control impact on UPFC and system load flow as far as possible, UPFC series/parallel side is additional controls letter (u_{damp_sh}And u_{damp_se}) all it is superimposed upon q shaft current internal ring instruction place in idle control loop, shown in Fig. 2 (a) and Fig. 2 (b).

Additional controller integral link: for making additional controller reach the SSO effect suppressed, controller is made up of modal filter, phase shifter, scaling link and amplitude limit link. Performance requirement and the setting principle of each link are as follows:

For modal filter, for realizing the uneoupled control to different SSO mode, each modal filter controlling loop should be composed in series by the band elimination filter of the band filter of corresponding model frequency and other model frequencies;

The phase shift angle of corresponding mode frequency signal should be can compensate for the modal filter of correspondence, UPFC inverter-connection transformer, the power system lagging phase to this model frequency signal by the phase shifter, so that SSDC provides positive additional subsynchronous damping to this mode;

Scaling link gain should moderate, can not be too small or excessive, to ensure that SSDC provides the positive additional subsynchronous damping negative damping more than system itself to corresponding SSO mode, and do not endanger the stability of UPFC control system;

Amplitude limit link amplitude limit value should be not excessive, to ensure that the basic function such as system voltage, power flow regulating is not affected by UPFC device by SSDC.

Additional controller Multi-mode control structure: owing to single control loop is while suppressing a certain mode SSO, other subsynchronous mode may be had a negative impact by the effect of phase compensation that the phase shifter produces, therefore, in the present invention, UPFC series side inverter and side inverter SSDC in parallel all adopt the Multi Channel Controller structure of modal separation. The each subsynchronous Model control loop of SSDC by modal filter, scaling link, phase compensation link composition, each Model control loop output Signal averaging and namely formed after amplitude limit SSDC output additional control signals.

For the system shown in Fig. 3, research UPFC supplementary subsynchronous damping control device (SSDC) suppresses the application of power system SSO problem. In this system, 2 600MW Turbo-generator Set are through valve systems such as double back transmission line accesses, and wherein circuit 1 is equiped with the fixed series capacitor compensation of 45%; 2 600MW units all adopt the actual parameter of China's type unit, axle system forms by height-intermediate pressure cylinder mass (HIP), low pressure (LP) cylinder B mass (LBP), low pressure (LP) cylinder A mass (LAP) and electromotor mass (GEN) 4 mass, corresponding 3 the natural torsional oscillation mode frequency respectively 13.34Hz (mode 1) of axle system, 22.72Hz (mode 2) and 27.74Hz (mode 3).

Owing in system shown in Figure 3, steam-electric generating set shafting has 3 subsynchronous mode, therefore the UPFC device series/parallel side inverter SSDC designed by this system all contains 3 subsynchronous Model control loops, UPFC device series/parallel side inverter SSDC structure is as shown in Figure 4.

If the angular frequency of mode i component is �� in shaft system of unit rotating speed_i, amplitude be A_i, initial phase beAdditional controller is to the phase shift of mode i component and amplification respectively k_iAnd ��_i, then the additional control signals being superimposed to UPFC controller is

Below for the side additional control of inverter in parallel, derive its mechanism suppressing system SSO and parameter tuning principle.

Additional control signals can quickly be followed the tracks of by UPFC parallel connection side inverter, and the corresponding subsynchronous frequency current of its output is

In formula, T_shiFor the side in parallel inverter operating lag to mode i frequency signal.

Then flow into the subsynchronous electric current I of generator armature winding_{genq_shi}For

Z in formula_{gen_i}��Z_{sys_shi}Respectively under mode i frequency, from UPFC node to the equivalent impedance of electromotor, the system equivalent impedance to UPFC, shown in Figure 5; G_ishAnd ��_ishRespectively UPFC parallel connection side inverter and system are to the amplitude-frequency response of mode i frequency signal and phase-frequency response.

Thus, the subsynchronous electric current of the mode i frequency of UPFC parallel connection side inverter output can be obtained, produced additional subsynchronous torque �� T in electromotor_{ei_sh}For

${\mathrm{\ΔT}}_{ei\_sh}=\frac{U_G{I}_{genq\_shi}{\mathrm{sin\δ}}_{sh}}{{\mathrm{\ω}}_G}$

U in formula_GFor generator terminal voltage, ��_shPoint voltage U is entered for the advanced UPFC parallel connection side joint of generator terminal voltage₁Angle; ��_GFor generator speed, it is �� in the steady state_G�� 1.0p.u., thus above formula can abbreviation be

In like manner, the produced additional subsynchronous torque �� T of subsynchronous electric current of the mode i frequency of UPFC series side inverter output can be obtained_{ei_se}For

K in formula_ishAnd ��_ishRespectively side in parallel inverter additional controller is to the phase shift of mode i frequency component and amplification, G_iseAnd ��_iseRespectively UPFC series side inverter and system are to the amplitude-frequency response of mode i frequency signal and phase-frequency response, ��_seFor generator terminal voltage advanced UPFC series side access point voltage U₂Angle.

By additional subsynchronous torque �� T_{ei_sh}With �� T_{ei_se}Expression formula it can be seen that adjust additional controller mode i control loop phase shift theta_ishAnd ��_ise, and amplification k_ishAnd k_iseSo that it is in electromotor, produce sufficiently large positive electromagnetic torque �� T_{ei_sh}With �� T_{ei_se}, the SSO problem of this mode i can be suppressed.

Fig. 6 (a), Fig. 6 (b) give the present invention design UPFC series/parallel side inverter SSDC put into operation before and after (SSDC puts into operation when 4s), the simulation result of shaft system of unit and UPFC; Visible system SSO divergence instability before SSDC puts into operation, after SSDC puts into operation, system SSO is stable, and UPFC supplementary subsynchronous damping control device (SSDC) namely proposed by the invention can effectively suppress system SSO problem. Fig. 7 (a), Fig. 7 (b) and Fig. 8 (a), Fig. 8 (b) sets forth only UPFC series side inverter SSDC or only UPFC parallel connection side inverter SSDC put into operation before and after (SSDC puts into operation when 4s), the simulation result of shaft system of unit and UPFC, visible UPFC series/parallel side inverter SSDC proposed by the invention all can effectively suppress system SSO problem, namely both can each other standby, improve reliability of operation. Simultaneously, UPFC simulation result shows, UPFC DC bus-bar voltage, system alternating voltage and circuit be meritorious/and reactive power flow affects only small by SSDC in transient process and do not affect under steady state conditions, and UPFC supplementary subsynchronous damping control device (SSDC) namely proposed by the invention runs without influence on the normal table of system and UPFC device.

Referring to Fig. 9, the system of the present invention is using generator speed deviation as feedback control signal, for UPFC series side inverter and side in parallel converter Control, to reduce UPFC influence on system operation as starting point, selected UPFC supplementary subsynchronous damping control device (SSDC) on-position; Then, the method utilizing damping torque analysis is derived and gives principle and the parameter tuning principle that UPFC supplementary subsynchronous damping control device suppresses SSO; Finally, based on modal separation control principle, the SSDC controller of design UPFC series/parallel side inverter, the power system SSO purpose suppressed is reached. The present invention is not affecting on the UPFC device basis to functions such as electric system tide optimization controls, it is provided that a kind of UPFC additional longitudinal forces carries out the effective ways of power system SSO suppression.

The ultimate principle of the present invention and principal character and advantages of the present invention have more than been shown and described. Skilled person will appreciate that of the industry; the present invention is not restricted to the described embodiments; described in above-described embodiment and description is that principles of the invention is described; without departing from the spirit and scope of the present invention; the present invention also has various changes and modifications, and these changes and improvements both fall within the claimed scope of the invention. Claimed scope is defined by appending claims and equivalent thereof.

Claims (5)

1. the THE UPFC additional longitudinal forces system suppressing sub-synchronous oscillation, THE UPFC device includes side in parallel inverter, series side inverter and DC capacitor, it is characterized in that: system includes Subsynchronous Damping Controller, the additional control signals u of described Subsynchronous Damping Controller_{damp_sh}And u_{damp_se}It is superimposed upon the q shaft current internal ring control instruction place in side inverter in parallel and the idle control loop of series side inverter respectively;

Described Subsynchronous Damping Controller includes multiple subsynchronous Model control loop, each described subsynchronous Model control loop includes modal filter, for the input scaling module that is amplified of signal with for realizing the phase shifter of phase compensation, the output signal in each subsynchronous Model control loop is superimposed and namely forms the additional control signals u of Subsynchronous Damping Controller output after clipping module_{damp_sh}And u_{damp_se}; Described Subsynchronous Damping Controller is with generator shaft system rotating speed deviation delta ��_GFor input control signal.

2. the THE UPFC additional longitudinal forces system of suppression sub-synchronous oscillation according to claim 1, it is characterized in that, described Subsynchronous Damping Controller adopts the Multi Channel Controller structure of modal separation, for each synchronized oscillation mode is carried out uneoupled control.

3. the THE UPFC additional longitudinal forces system of suppression sub-synchronous oscillation according to claim 1, it is characterised in that described modal filter is composed in series by the band filter of corresponding model frequency and the band elimination filter of other model frequencies.

4. the THE UPFC additional longitudinal forces system of suppression sub-synchronous oscillation according to claim 1, it is characterised in that set in shaft system of unit rotating speed the angular frequency of mode i component as ��_i, amplitude be A_i, initial phase beSide in parallel inverter additional controller is to the phase shift of mode i frequency component and amplification respectively k_ishAnd ��_ish, then being superimposed in the Converter controller of UPFC parallel connection side the additional control signals of circular current control instruction is

Additional control signals can quickly be followed the tracks of by UPFC parallel connection side inverter, and the corresponding subsynchronous frequency current of its output is

In formula, T_shiFor the side in parallel inverter operating lag to mode i frequency signal, s is Laplace operator;

Flow into the subsynchronous electric current I of generator armature winding_{genq_shi}For

In formula, Z_{gen_i}��Z_{sys_shi}Respectively under mode i frequency, from UPFC node to the equivalent impedance of electromotor, the system equivalent impedance to UPFC; G_ishAnd ��_ishRespectively UPFC parallel connection side inverter and system are to the amplitude-frequency response of mode i frequency signal and phase-frequency response;

Thus, the subsynchronous electric current of the mode i frequency of UPFC parallel connection side inverter output can be obtained, through subsynchronous torque �� T additional produced by generator armature winding_{ei_sh}For

${\mathrm{\ΔT}}_{ei\_sh}=\frac{U_G{I}_{genq\_shi}{\mathrm{sin\δ}}_{sh}}{{\mathrm{\ω}}_G}$

In formula, U_GFor generator terminal voltage, ��_shPoint voltage U is entered for the advanced UPFC parallel connection side joint of generator terminal voltage₁Angle; ��_GFor generator speed, it is �� in the steady state_G�� 1.0p.u., thus above formula can abbreviation be

In like manner, the subsynchronous electric current of the mode i frequency of UPFC series side inverter output can be obtained, through subsynchronous torque �� T additional produced by generator armature winding_{ei_se}For

In formula, ��_iseAnd k_iseRespectively series side inverter additional controller is to the phase shift of mode i frequency component and amplification, G_iseAnd ��_iseRespectively UPFC series side inverter and system are to the amplitude-frequency response of mode i frequency signal and phase-frequency response, ��_seFor generator terminal voltage advanced UPFC series side access point voltage U₂Angle;

Additional subsynchronous electromagnetic torque �� T produced by UPFC supplementary subsynchronous damping control_{ei_sh}With �� T_{ei_se}Expression formula it can be seen that adjust additional controller mode i control loop phase shift theta_ishAnd ��_ise, and amplification k_ishAnd k_iseSo that it is in electromotor, produce sufficiently large positive additional electromagnetic torque �� T_{ei_sh}With �� T_{ei_se}, can reach to suppress the purpose of this mode sub-synchronous oscillation.

5. the THE UPFC additional longitudinal forces system of suppression sub-synchronous oscillation according to claim 4, it is characterised in that

For the system that sub-synchronous oscillation is stable, i.e. A_i=0, thus there being the additional control signals u in each Model control loop_dampi=0, Jin Eryou

u_damp=�� u_dampi=0 (i=1,2 ..., n)

Namely Subsynchronous Damping Controller is output as 0 under steady state conditions, without influence on system and THE UPFC device in the steady state properly functioning.