Pump Station Flexibility Modeling for Urban Water-Power Load Shifting
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Solution Overview
Problem
The challenge lies in accurately quantifying the spatio-temporal flexible resources of electric-driven drainage pump stations in watershed networks to alleviate peak load pressure in urban distribution networks, particularly during rainy climates, due to the complex hydrodynamic characteristics and nonlinear constraints in the watershed network's optimization model.
Innovation Solution
A method involving a controller that constructs dynamic operation models, sensitivity matrices, and optimization models to quantify and optimize the flexible resources of drainage pump stations, converting nonlinear problems into mixed-integer linear programming for coordinated operation of urban and watershed networks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the pump station load is increased to handle rainwater drainage during rainy climates, then the drainage capability is improved, but the peak load pressure on the distribution network worsens
Solution Approach 1:
The patent applies preliminary action by using water storage facilities (rivers, lakes, reservoirs) to store rainwater in advance during rainfall events. This allows the pump stations to operate at reduced capacity during peak rainfall periods, as the stored water can be gradually discharged later, thereby preventing the sharp peak load increases that would otherwise occur when pumping all rainwater immediately.
2Adaptability or versatility
If the pump station power is increased to reduce peak load difference, then the load shifting capability is improved, but the complexity of coordinating water flow and power flow worsens
Solution Approach 1:
The patent introduces an intermediary optimization model that coordinates the watershed network and distribution network. This model uses sensitivity analysis to establish the relationship between pump station power adjustments and water level changes, and between power flow adjustments and node power balance. The intermediary model transforms the complex coupled optimization problem into a manageable form that can be solved efficiently while achieving load shifting goals.
Solution Approach 2:
The patent applies parameter changes by transforming the nonlinear hydrodynamic equations and power flow equations into linearized forms suitable for optimization. The sensitivity matrices derived from these equations allow the system to adjust operational parameters (pump power, water discharge rates) to achieve desired outcomes while managing complexity.
3Adaptability or versatility
If the natural water storage capacity is utilized to provide flexible resources, then the spatio-temporal flexibility is improved, but the difficulty of accurately quantifying the impact on river water level and flow rate worsens
Solution Approach 1:
The patent implements feedback through sensitivity analysis that continuously evaluates the impact of pump station power changes on water levels and flow rates. The optimization model uses this feedback information to adjust operational decisions, ensuring that the utilization of water storage capacity achieves the desired spatio-temporal flexibility while maintaining accurate knowledge of the impacts on river conditions.
4Measurement precision
If the complex hydrodynamic characteristics are modeled with nonlinear partial differential equations, then the model accuracy is improved, but the difficulty of solving the high-dimensional nonlinear optimization model worsens
Solution Approach 1:
The patent applies mechanics substitution by replacing the complex nonlinear hydrodynamic and power flow equations with linearized equivalent models. The sensitivity matrices serve as simplified representations that capture the essential relationships without requiring solution of the full nonlinear partial differential equations, thereby making the optimization problem computationally tractable while maintaining sufficient accuracy for operational decision-making.
Data Source
AI summary
A method for flexible coordinated operation of an urban distribution network and a watershed network, including: constructing a watershed network dynamic operation model; constructing a river water storage model a lake water storage model based on the watershed network dynamic operation model; constructing a distribution network linear alternating-current (AC) power flow model and an operating power-flow rate operation model of the pump stations to obtain a coordinated operation model of the urban distribution network and the watershed network; constructing a watershed-electricity composite sensitivity matrix; quantifying a time-varying adjustable power domain of each pump station through a pump station flexibility assessment method based on the watershed-electricity composite sensitivity matrix; constructing a power flow optimization model of the urban distribution network and a hydraulic energy flow optimization model of the watershed network; and performing electricity-water energy flow interactive optimization involving a flexible resource of the pump stations.