The medium voltage (MV) and low voltage (LV) distribution systems are usually built in a mixed three-phase three-wire and three-phase four-wire pattern, in which the conventional measurements are obtained through the two-wattmeter method (TWM) and three-wattmeter method (HWM). The existing three-phase state estimation (SE) models only involve the measurement characteristics of the HWM. Instead, a set of new and improved measurement equations are formulated in this paper for such buses measured by TWM, and the measurements include line-to-line complex power and virtual zero-sequence current. Along with the increasing underground cable, the neutral point of MV feeder head is normally grounded through a small resistance, and its voltage magnitude is not equal to zero. Accordingly, an accurate model for the slack bus together with its measurement equations is proposed herein, based on the conventional measurements and neutral point virtual measurement. Moreover, this work presents a three-phase SE model for MV and LV distribution systems that incorporates the constraints of zero-sequence current and zero injection, in combination with the exponentially weighted least squares method. The test results of the IEEE 34 bus system and IEEE 123 bus system verify that the proposed formulation takes full advantage of the measurements and structural characteristics of practical distribution networks, and simultaneously boosts the estimation accuracy.

The existing studies on probabilistic steady-state analysis of integrated energy systems (IES) are limited to integrated electricity and gas networks or integrated electricity and heating networks. This paper proposes a probabilistic steady-state analysis of integrated electricity, gas and heating networks (EGH-IES). Four typical operation modes of an EGH-IES are presented at first. The probabilistic energy flow problem of the EGS-IES considering its operation modes and correlated uncertainties in wind/solar power and electricity/gas/heat loads is then formulated and solved by the Monte Carlo method based on Latin hypercube sampling and Nataf transformation. Numerical simulations are conducted on a sample EGH-IES working in the “electricity/gas following heat” mode to verify the probabilistic analysis proposed in this paper and to study the effects of uncertainties and correlations on the operation of the EGH-IES, especially uncertainty transmissions among the subnetworks.

To promote the reformation of the electricity market in China, a market mechanism that can support collaboration between the contract market and the upcoming spot market was designed in this paper. The focus of this paper was to develop a mechanism to institutionally stabilize the market by way of disciplining market power abuse through limiting arbitrage opportunities generated from multi-markets. To quantitatively describe the arbitrage opportunity, the arbitrage opportunity function (AOF) was defined. Based on inferences of the no-arbitrage principle and the AOF, a cost-based decomposition algorithm for contracts that could improve contract coverage was proposed. The incentive compatible settlement rule for the uncovered generation on the spot market was designed to properly manipulate the arbitrage opportunity. The decomposition algorithm and the settlement rule constituted the designed market mechanism. To verify the applicability and effectiveness of the proposed mechanism, the principles of incentive compatibility, individual rationality, and payment cost minimization were employed to test the designed market mechanism based on the concept of dominant policy equilibrium. This test was conducted on a fictitious case based on the IEEE-14 system. The analysis and results may provide valuable insights on market design in China based on the functional correlation between the contract market and the spot market.

Fast and accurate self-healing after faults is an important way to improve the reliability of distribution networks. To improve the self-healing speed and accuracy of distribution networks, this paper proposes a fast and accurate self-healing scheme for distribution networks using mixed integer linear programming. Firstly, this method constructs a centralized 5G communication network architecture, which can effectively reduce the communication delay during the self-healing process. Secondly, the principle of logical algebraic transformation is utilized to linearize the switch function in the fault location model, thereby achieving equivalent transformation of the fault location model. Thirdly, using the polyhedral approximation method, the mixed integer second-order cone programming of the power supply recovery model is transformed into a mixed integer linear programming. The proposed method was validated by distribution network systems with different nodes in MATLAB/Simulink, and the results showed that the proposed method significantly improved self-healing speed and accuracy.

The reactive power compensation of large‐capacity synchronous condensers in a ultrahigh‐voltage direct current (UHVDC) converter station is not yet fully utilised, and there is no method for achieving effective coordination between synchronous condensers and DC systems. To realise their coordinated control of reactive power and voltage, a dynamic reactive power optimisation model that considers the coordination of synchronous condenser and filtering requirements of system is proposed in this study. The model considers the constraints of the variable steady reactive power capacity of synchronous condenser by taking into account its dynamic reserve demand, the minimum filter capacity of the system, and the switching sequence of AC filters and shunt capacitors. The model is solved by a two‐stage hybrid intelligent algorithm based on the interior point method and the differential evolution algorithm. Further, the effectiveness of the proposed method is verified by the example of a UHVDC sending converter station in Northeast China. The simulation results show that the proposed model can greatly reduce the number of times discrete devices enter operation in a converter station under satisfying the dynamic reactive power reserve of the synchronous condenser, providing a basis for the coordinated optimal control of synchronous condensers and DC systems.