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This paper presents a coupled FEM and lumped circuit modelling approach that is primarily intended for high-frequency and overvoltage simulations of rotating electric machines with coaxially insulated windings, such as Powerformer and Motorformer. The magnetic fields and their interaction with the conductors of the winding are simulated with the aid of a FEM-program. The displacement current and its losses are modelled with an external lumped circuit. To consider eddy current losses, the stranded conductors and the laminated steel cores are replaced by homogeneous bodies with similar losses over a wide frequency range. The approach is illustrated and experimentally verified for a set-up with a cable wound around two slot cores. The model agrees well with measurements up to 1 MHz.

This paper analytically derives a Supply Function Equilibrium (SFE) of a real-time electricity market with multiple firms and asymmetric production capacities. There is a unique SFE, which is piece-wise symmetric when firms have identical constant marginal costs. It is believed that some of the properties of the derived SFE are valid for real-time markets in general. Firms’ capacity constraints bind at different prices (i). Still, firms with non-binding capacity constraints have smooth residual demand (ii). Approximating an asymmetric real-time market with a symmetric one, tends to overestimate mark-ups for small positive imbalances and underestimate mark-ups for large positive imbalances (iii).

Most balancing markets of electric power are organized as uniform-price auctions. In 2001, the balancing market of England and Wales switched to a pay-as-bid auction with the intention of reducing wholesale electricity prices. Numerical simulations of an electricity auction model have indicated that this should lead to decreased average prices. In this work we prove two inequalities which give an analytic proof of this claim in the same model.

In a real-time electric power auction, the bids of producers consist of committed supply as a function of price. The bids are submitted under uncertainty, before the demand by the Independent System Operator has been realized. In the Supply Function Equilibrium (SFE), every producer chooses the supply function maximizing his expected profit given his residual demand. I consider a uniform-price auction with a reservation price, where demand is inelastic and exceed the market capacity with a positive probability, and firms have identical constant marginal costs but asymmetric capacities. I show that under these conditions, there is a unique SFE, which is piece-wise symmetric.

This paper derives a Supply Function Equilibrium (SFE) of a pay-as-bid auction, also called discriminatory auction. Such an auction is used in the balancing market for electric power in Britain. For some probability distributions of demand a pure-strategy equilibrium does not exist. If demand follows an inverse polynomial probability distribution, SFE always exists. Assuming this probability distribution, the pay-as-bid procurement auction is compared to a SFE of a uniform-price procurement auction, the auction form of most electric power markets. The demand-weighted average price is found to be equal or lower in the pay-as-bid procurement auction.

Producers submit committed supply functions to a procurement auction, e.g. an electricity auction, before the uncertain demand has been realized. In the Supply Function Equilibrium (SFE), every firm chooses the bid maximizing his expected profit given the bids of the competitors. In case of asymmetric producers with general cost functions, previous work has shown that it is very difficult to find valid SFE. This paper presents a new numerical procedure that can solve the problem. It comprises numerical integration and an optimization algorithm that searches an end-condition. The procedure is illustrated by an example with three asymmetric firms.

Most balancing markets of electric power are organized as uniform-price auctions. In 2001, the balancing market of England and Wales switched to a pay-as-bid auction with the intention of reducing wholesale electricity prices. Numerical simulations of an electricity auction model have indicated that this should lead to decreased average prices. In this article we prove two inequalities which give an analytic proof of this claim in the same model.