CN103280833B - Based on the power distribution network control method that energy storage and the photovoltaic of active mechanisms are coordinated - Google Patents

Abstract

The invention discloses a distribution network control method based on an active mechanism for energy storage and photovoltaic coordination, which is applied to a photovoltaic energy storage power generation unit and an energy storage system connected to a distribution network, including the following process: establishing the photovoltaic energy storage power generation The optimal benefit function of the unit and the global optimal global benefit function of the distribution network; the constant items in the two functions are respectively collected; the optimal benefit target of the photovoltaic energy storage generation unit and the global distribution network are obtained through joint iteration Benefit target; wherein the photovoltaic energy storage power generation unit predicts its power generation according to historical data and guides the charging and discharging of energy storage. The invention realizes the autonomous optimization control of the photovoltaic energy storage power generation unit and the energy storage, obtains an optimized mode of distribution network operation, and improves the profit rate of the photovoltaic power generation unit connected to the grid.

Description

Distribution network control method based on energy storage and photovoltaic coordination based on active mechanism

technical field

The invention relates to the coordinated control of photovoltaics and energy storage in the active distribution network in the field of intelligent distribution networks. The invention proposes a distribution network control method based on the coordination of energy storage and photovoltaics based on an active mechanism.

Background technique

With its flexible, compatible and optimized characteristics, the active distribution network is an effective solution for the future distribution network to realize the active management of a large number of distributed photovoltaic energy storage generation units (DG).

Photovoltaic power is greatly affected by factors such as sunlight during grid-connected operation, and the combination of energy storage can better weaken the adverse effects of environmental factors. However, there is a lack of flexible and economical strategies for determining the operation mode, participating in power dispatching of the distribution network, and coordinating with energy storage in the system.

At present, the control technologies for photovoltaic and energy storage grid-connected operation mainly include:

(1) Study photovoltaic and energy storage combined power generation technology, so that the output power is stable, and the power quality indicators such as voltage meet the grid-connected regulations.

(2) The simple economic dispatch of new energy and energy storage is studied. In the present invention, through the active optimization output of the photovoltaic energy storage power generation unit and the coordinated cooperation with the system energy storage, the operational efficiency of the photovoltaic energy storage power generation unit and the system energy storage is considered uniformly, and the overall operation is optimal.

(3) Study the charging and discharging technology, charging and discharging strategy of energy storage batteries in the system, the ability to provide safety margins in emergency situations, and use energy storage as a load or constant power source to participate in power balance of the grid under normal working conditions.

(4) Study the indicators related to energy storage and photovoltaics, and evaluate their functions and technical levels.

Contents of the invention

In order to overcome the defects of the prior art, the present invention provides a distribution network control method based on the coordination of energy storage and photovoltaics based on an active mechanism. The distribution network globally includes photovoltaic energy storage generating units and system energy storage. The energy generating unit includes photovoltaics and energy storage matched therewith, and is characterized in that the method includes the following steps:

Establish energy storage supply and storage price benefit sub-function Photovoltaic-storage output ratio subfunction $\mathrm{Exrai}\left(P_{\mathrm{psi}}\right)=\frac{{\∫}_{t_{\mathrm{PV}0}\mathrm{Ppvi}\·\mathrm{dt}}^{t_{\mathrm{PV}1}}}{{\∫}_{t_{\mathrm{stow}0}\mathrm{Pstoi}\&Center\; Dot;\mathrm{dt}}^{t_{\mathrm{stow}1}}},$ Photovoltaic storage power generation depletion rate sub-function $\mathrm{Dep}=\frac{\underset{i=1}{\overset{\mathrm{no}}{\mathrm{\Σ}}}{L}_{\mathrm{PSi}}\left(P_{\mathrm{psi}}\right)}{\underset{i=1}{\overset{\mathrm{no}}{\mathrm{\Σ}}}{C}_{\mathrm{dei}}},$ Photovoltaic energy application rate sub-function Among them, Pro _i (t _stoi ) is the periodic profit function of the photovoltaic energy storage power generation unit with the energy storage discharge time t _stoi of the power generation unit as a variable, C _24i is the operating cost of the photovoltaic energy storage power generation unit in one cycle, and Ppvi is the photovoltaic energy storage power generation unit. The output function of the photovoltaic part of the energy unit with time as a variable, Pstoi is the power output function of the energy storage part of the unit with time as a variable, t is the start and end time of photovoltaic and energy storage power output, L _PSi (P _psi ) is The photovoltaic energy storage power generation unit of the i group takes the output power P _psi of the unit as the variable depletion, C _dei is the total equipment cost of the photovoltaic energy storage power generation unit of the i group, and P _load is the system load function in a photovoltaic power supply operating cycle;

Establish the optimal benefit function E _ffi (t _stoi , P _psi )=αC _i (t _stoi )+βDep _i (P _psi )+γExrai(P _psi ) of the photovoltaic energy storage power generation unit and the global optimal value of the distribution network optimal global benefit function $f\left(P_{\mathrm{ssi}}\right)=\frac{a\·P_{\mathrm{loss}}\left(P_{\mathrm{ssi}}\right)}{P_{\mathrm{load}}}+(-1)b\·\mathrm{Ura},$ Indicates the ratio of the loss of the distribution network system to the total load, with the system energy storage power P _ssi as the variable; where α, β, and γ are the weight coefficients of price benefit, depletion rate, and optical-storage output ratio in evaluating comprehensive benefits, respectively. a and b are the weight coefficients of the optimal global benefit function;

Respectively determine the weight coefficients α, β, γ and a, b in the optimal benefit function of the photovoltaic energy storage generating unit and the optimal global benefit function of the distribution network;

The optimal benefit target of the photovoltaic energy storage power generation unit and the global benefit target of the distribution network are solved through joint iteration;

Wherein the photovoltaic energy storage power generation unit predicts the power generation power of the photovoltaic according to historical data and guides the discharge of the energy storage according to historical data.

Preferably, the photovoltaic energy storage power generation unit accurately outputs power in a short period of time through real-time control of its energy storage.

Preferably, the constraint conditions of the optimal benefit function of the photovoltaic energy storage power generation unit include parameters and operating ranges of photovoltaic power storage and energy storage, and the full power generation or shutdown of the photovoltaic energy storage power generation unit is within the loadable range of the system.

Preferably, the constraints of the overall optimal global benefit function of the distribution network include equipment parameters and operating limits of the system energy storage, system power flow, voltage limits of each node, power limits of other distributed power sources, and line capacity.

Preferably, it uses alternate iterations to solve the optimal benefit function of the photovoltaic energy storage generating unit and the global optimal global benefit function of the distribution network to obtain the values of parameters P _ssi , t _stoi , and P _psi .

Compared with the prior art, the beneficial effects of the present invention are as follows:

1. The present invention realizes autonomous optimal control of photovoltaic energy storage power generation units connected to the distribution network, and formulates basic grid-connected and off-grid strategies based on historical data to ensure stable power output;

2. The present invention considers the optimal way of system energy storage in the active distribution network connected to photovoltaic energy storage units, fully utilizes the energy storage of the control system to regulate the operation of the system, and improves the utilization level of photovoltaics and the profitability of photovoltaic energy storage power generation units ;

3. The present invention considers the target coordination of photovoltaic energy storage power generation unit and system energy storage to realize operation coordination and achieve the global optimum of both.

Of course, any product implementing the present invention does not necessarily need to achieve all the above-mentioned advantages at the same time.

Description of drawings

Fig. 1 is a schematic diagram of a power distribution network based on an active mechanism for energy storage and photovoltaic coordination provided by the present invention;

Fig. 2 is a schematic diagram of coordinated control of photovoltaic energy storage power generation units provided by the present invention;

Fig. 3 is a schematic diagram of the global coordinated control of the distribution network provided by the present invention.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

Example

The present invention provides a distribution network control method based on an active mechanism for energy storage and photovoltaic coordination. The distribution network globally includes photovoltaic energy storage power generation units and system energy storage. The energy storage is characterized in that the method comprises the following steps:

Establish energy storage supply and storage price benefit sub-function Photovoltaic-storage output ratio subfunction $\mathrm{Exrai}\left(P_{\mathrm{psi}}\right)=\frac{{\∫}_{t_{\mathrm{PV}0}\mathrm{Ppvi}\&Center\; Dot;\mathrm{dt}}^{t_{\mathrm{PV}1}}}{{\∫}_{t_{\mathrm{stow}0}\mathrm{Pstoi}\&Center\; Dot;\mathrm{dt}}^{t_{\mathrm{stow}1}}},$ Photovoltaic storage power generation depletion rate sub-function $\mathrm{Dep}=\frac{\underset{i=1}{\overset{\mathrm{no}}{\mathrm{\Σ}}}{L}_{\mathrm{PSi}}\left(P_{\mathrm{psi}}\right)}{\underset{i=1}{\overset{\mathrm{no}}{\mathrm{\Σ}}}{C}_{\mathrm{dei}}},$ Photovoltaic energy application rate sub-function Among them, Pro _i (t _sto ) is the periodic profit function of the photovoltaic energy storage power generation unit with the energy storage discharge time t _stoi of the power generation unit as a variable, C ₂₄ is the operating cost of the photovoltaic energy storage power generation unit in one cycle, and Ppv is the photovoltaic energy storage power generation unit The output function of the photovoltaic part of the energy unit with time as a variable, Psto is the power output function of the energy storage part of the unit with time as a variable, t is the start and end time of photovoltaic and energy storage power output, L _PSi (P _psi ) is The photovoltaic energy storage power generation unit of the i group takes the output power P _psi of the unit as the variable depletion, C _dei is the total equipment cost of the photovoltaic energy storage power generation unit of the i group, and P _load is the system load function in a photovoltaic power supply operating cycle;

Establish the optimal benefit function E _ffi (t _stoi , P _psi )=αC _i (t _stoi )+βDep _i (P _psi )+γExrai(P _psi ) of the photovoltaic energy storage power generation unit and the global optimal value of the distribution network optimal global benefit function $f\left(P_{\mathrm{ssi}}\right)=\frac{a\&Center\; Dot;P_{\mathrm{loss}}\left(P_{\mathrm{ssi}}\right)}{P_{\mathrm{load}}}+(-1)b\·\mathrm{Ura},$ Indicates the ratio of the loss of the distribution network system to the total load, with the system energy storage power P _ssi as a variable; where, P _loss (P _ssi ) represents the loss of the distribution network system when the system energy storage power is P _ssi , α, β , γ are the weight coefficients of price benefit, depletion rate, and optical-storage output ratio in evaluating comprehensive benefits, respectively, and a and b are weight coefficients of the optimal global benefit function;

Respectively determine the weight coefficients α, β, γ and a, b in the optimal benefit function of the photovoltaic energy storage generating unit and the optimal global benefit function of the distribution network;

The optimal benefit target of the photovoltaic energy storage power generation unit and the global benefit target of the distribution network are solved through joint iteration;

Wherein the photovoltaic energy storage power generation unit predicts the power generation power of the photovoltaic according to historical data and guides the discharge of the energy storage according to historical data. ,

As shown in Figure 2, in _Effi (t _stoi ,P _psi )=αC _i (t _stoi )+βDep _i (P _psi )+γExrai(P _psi ), C _i (t _sto ) is the photovoltaic energy storage power generation unit The energy storage discharge time t _stoi is the benefit function of the variable, Dep _i (P _psi ) is the depletion rate function of the solar storage power generation with the output power P _psi of the photovoltaic energy storage unit as the variable, Exrai is the output ratio function of the solar storage, α, β and γ are the weight coefficients of price benefit, depletion rate, and PV-storage output ratio in evaluating comprehensive benefits, respectively, and α, β, and γ are obtained for the benefit requirements of photovoltaic energy storage power generation units during operation.

exist Among them, Pro _i (t _stoi ) is the periodic profit of the photovoltaic energy storage power generation unit, and C _24i is the operating cost of the photovoltaic energy storage power generation unit in one cycle.

exist Among them, Ppv is the output function of the photovoltaic part of the photovoltaic energy storage unit with time as a variable, Pstoi is the power output function of the energy storage part of the unit with time as a variable, t is the start and end time of photovoltaic and energy storage power output, Ppvi and Pstoi are obtained from historical data.

exist Among them, L _PSi (P _psi ) is the depletion of the i-th group of photovoltaic energy storage generation units with the output power P _psi of the unit as a variable; C _dei is the total equipment cost of the i-th group of photovoltaic energy storage generation units, which is a known parameter.

As shown in Figure 3, in $f\left(P_{\mathrm{ssi}}\right)=\frac{a\&Center\; Dot;P_{\mathrm{loss}}\left(P_{\mathrm{ssi}}\right)}{P_{\mathrm{load}}}+(-1)b\&Center\; Dot;\mathrm{Ura}$ middle, Indicates the ratio of the loss of the distribution network system to the total load, with the system energy storage power P _ssi as a variable, P _loss (P _ssi ) represents the loss of the distribution network system when the system energy storage power is P _ssi ; is a function of photovoltaic energy application rate, P _load is a system load function in a photovoltaic power supply cycle, Ppvi is the output function of the photovoltaic part of the photovoltaic energy storage unit with time as a variable; a and b are weight coefficients, which are based on real-time obtained from the operating conditions of the system.

Using alternate iterations to solve the optimal benefit function of the photovoltaic energy storage power generation unit and the global optimal global benefit function of the distribution network to obtain the optimal benefit of the photovoltaic energy storage power generation unit and the global optimal value of the distribution network respectively The global benefit target, obtain the parameters P _ssi , t _stoi , P _psi . Since Equation 1 contains the condition P _ssi about the system energy storage, and Equation 2 contains the condition t _stoi ,P _psi about the photovoltaic energy storage unit, so two sets of optimal objectives can be solved by alternating iterations to achieve the global optimum excellent. This process embodies the operation coordination characteristics between the photovoltaic energy storage power generation unit and the global side, and uses the crossover of variables as the expression method to balance the operating benefits of the two through the objective function to achieve the optimum of the two.

The photovoltaic energy storage power generation unit independently predicts the intermittent law of illumination based on historical data, formulates basic grid-connected and off-grid strategies, and relies on energy storage to stabilize short-term fluctuations; during the operation of the photovoltaic energy storage unit, it is expected to maximize the use of sunlight energy. According to statistics, the average light period in my country is from 9:00 to 15:00 every day. This period is in the peak price range of time-of-use electricity prices, and the system load is relatively high at this time. Therefore, the light energy should be fully utilized during this time period, so that the photovoltaic energy storage power generation unit side can obtain the maximum benefit. In actual operation, photovoltaics need to predict the power generation within an operation cycle based on historical data, and can make minute-level short-term predictions to predict power fluctuations, guide energy storage according to unit output targets, and stabilize small output caused by light fluctuations Variety.

During the normal operation of the photovoltaic energy storage power generation unit, the system energy storage reflects the load characteristics and absorbs energy. The part of photovoltaic energy storage unit supplying energy storage and power to the system will apply power flow tracking technology, which is reflected in Pro _i (t _stoi ) to reflect the interaction between photovoltaic energy storage and load, and evaluate the photovoltaic energy storage power generation unit in a cycle. income. During the period from the end of the light to the low load (electricity price) period, the energy storage of the photovoltaic energy storage unit is used as the unit output power to supply power to the system, and its energy comes from the power absorbed from the system during the low period as much as possible, which also includes Power supply to the system energy storage during sunshine hours.

In general, the distribution network control method based on the active mechanism of energy storage and photovoltaic coordination proposed by the present invention uses the power generation efficiency and utilization rate of photovoltaic energy storage units to solve the optimal benefit target of photovoltaic energy storage units and The overall benefit target of the system. The present invention fully considers the intermittent factors during the operation of the photovoltaic storage power generation unit, utilizes power generation prediction and short-term discharge of energy storage in the unit to achieve stable output in the working state; fully utilizes the influence of system energy storage and time-of-use electricity price, so that the photovoltaic energy storage power generation unit reaches Single-group runs benefit the most. While independently optimizing the control of the photovoltaic energy storage power generation unit, the influence of the energy storage operation mode of the system is considered, and through the coordination of the two, the network line loss is reduced, the utilization rate of photovoltaic power generation is improved, and the global optimum is achieved. Under the premise of ensuring the balance of the system, this method makes full use of two distributed energy sources, photovoltaic and energy storage, and can flexibly adjust the objective function of the photovoltaic energy storage power generation unit and the global side to realize the optimization of various operating scenarios. Optimal Coordinated Control.

The preferred embodiments of the invention disclosed above are only to help illustrate the invention. The preferred embodiments are not exhaustive in all detail, nor are the inventions limited to specific embodiments described. Obviously, many modifications and variations can be made based on the contents of this specification. This description selects and specifically describes these embodiments in order to better explain the principle and practical application of the present invention, so that those skilled in the art can well understand and utilize the present invention. The invention is to be limited only by the claims, along with their full scope and equivalents.

Claims (5)

1. A distribution network control method based on the coordination of energy storage and photovoltaics based on an active mechanism. The distribution network globally includes photovoltaic energy storage power generation units and system energy storage. Can, it is characterized in that, this method comprises the following steps: Establish energy storage supply and storage price benefit sub-function Photovoltaic-storage output ratio subfunction $\mathrm{Exrai}\left(P_{\mathrm{psi}}\right)=\frac{{\∫}_{t_{\mathrm{PV}0}}^{t_{\mathrm{PV}1}}\mathrm{Ppvi}\·\mathrm{dt}}{{\∫}_{t_{\mathrm{stow}0}}^{t_{\mathrm{stow}1}}\mathrm{Pstoi}\&Center\; Dot;\mathrm{dt}},$ Photovoltaic storage power generation depletion rate sub-function $\mathrm{Dep}=\frac{\underset{i=1}{\overset{\mathrm{no}}{\mathrm{\Σ}}}{L}_{\mathrm{PSi}}\left(P_{\mathrm{psi}}\right)}{\underset{i=1}{\overset{\mathrm{no}}{\mathrm{\Σ}}}{C}_{\mathrm{dei}}},$ Photovoltaic energy application rate sub-function Among them, Pro _i (t _stoi ) is the periodic profit function of the photovoltaic energy storage power generation unit with the energy storage discharge time t _stoi of the power generation unit as a variable, C _24i is the operating cost of the photovoltaic energy storage power generation unit in one cycle, and Ppvi is the photovoltaic energy storage power generation unit. The output function of the photovoltaic part of the energy unit with time as a variable, Pstoi is the power output function of the energy storage part of the unit with time as a variable, t is the start and end time of photovoltaic and energy storage power output, L _PSi (P _psi ) is The photovoltaic energy storage power generation unit of the i group takes the output power P _psi of the unit as the variable depletion, C _dei is the total equipment cost of the photovoltaic energy storage power generation unit of the i group, and P _load is the system load function in a photovoltaic power supply operating cycle; Establish the optimal benefit function of the photovoltaic energy storage power generation unit E _ffi (t _stoi ,P _psi )=αC _i (t _stoi )+βDep _i (P _psi )+γExrai(P _psi ) and the global optimal global benefit function of the distribution network Dep _i (P _psi ) is the depletion rate function of photovoltaic storage power generation with the output power P _psi of the photovoltaic energy storage generation unit as a variable, Indicates the ratio of the loss of the distribution network system to the total load, with the system energy storage power P _ssi as a variable; where, P _loss (P _ssi ) represents the loss of the distribution network system when the system energy storage power is P _ssi , α, β , γ are the weight coefficients of price benefit, depletion rate, and optical-storage output ratio in evaluating comprehensive benefits, respectively, and a and b are weight coefficients of the optimal global benefit function; Respectively determine the weight coefficients α, β, γ and a, b in the optimal benefit function of the photovoltaic energy storage generating unit and the optimal global benefit function of the distribution network; The optimal benefit target of the photovoltaic energy storage power generation unit and the global benefit target of the distribution network are solved through joint iteration; Wherein the photovoltaic energy storage power generation unit predicts the photovoltaic power generation power according to the historical data and guides the energy storage discharge according to the historical data. 2. The distribution network control method based on the active mechanism of energy storage and photovoltaic coordination according to claim 1, wherein the photovoltaic energy storage power generation unit accurately outputs power in a short period of time by controlling its energy storage in real time. 3. The distribution network control method based on the active mechanism of energy storage and photovoltaic coordination as claimed in claim 1, wherein the constraint conditions of the optimal benefit function of the photovoltaic energy storage generating unit include the parameters of photovoltaic and energy storage and operating range, the photovoltaic energy storage power generation unit is fully powered or out of service within the system's loadable range. 4. The distribution network control method based on the active mechanism of energy storage and photovoltaic coordination as claimed in claim 1, wherein the constraints of the overall optimal global benefit function of the distribution network include the system energy storage Equipment parameters and operating limits, system power flow, voltage limits of each node, power limits of other distributed power sources, and line capacity. 5. The distribution network control method based on the active mechanism of energy storage and photovoltaic coordination as claimed in claim 1, characterized in that it uses alternate iterations to solve the optimal benefit function of the photovoltaic energy storage generating unit and the power distribution network. The optimal global benefit function of the global network obtains the values of parameters P _ssi , t _stoi , and P _psi .